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ORGANIC SPECTROSCOPY

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DR ANTHONY MELVIN CRASTO Ph.D

DR ANTHONY MELVIN CRASTO Ph.D

DR ANTHONY MELVIN CRASTO, Born in Mumbai in 1964 and graduated from Mumbai University, Completed his Ph.D from ICT, 1991,Matunga, Mumbai, India, in Organic Chemistry, The thesis topic was Synthesis of Novel Pyrethroid Analogues, Currently he is working with GLENMARK PHARMACEUTICALS LTD, Research Centre as Principal Scientist, Process Research (bulk actives) at Mahape, Navi Mumbai, India. Total Industry exp 30 plus yrs, Prior to joining Glenmark, he has worked with major multinationals like Hoechst Marion Roussel, now Sanofi, Searle India Ltd, now RPG lifesciences, etc. He has worked with notable scientists like Dr K Nagarajan, Dr Ralph Stapel, Prof S Seshadri, Dr T.V. Radhakrishnan and Dr B. K. Kulkarni, etc, He did custom synthesis for major multinationals in his career like BASF, Novartis, Sanofi, etc., He has worked in Discovery, Natural products, Bulk drugs, Generics, Intermediates, Fine chemicals, Neutraceuticals, GMP, Scaleups, etc, he is now helping millions, has 9 million plus hits on Google on all Organic chemistry websites. His friends call him Open superstar worlddrugtracker. His New Drug Approvals, Green Chemistry International, All about drugs, Eurekamoments, Organic spectroscopy international, etc in organic chemistry are some most read blogs He has hands on experience in initiation and developing novel routes for drug molecules and implementation them on commercial scale over a 30 year tenure till date Dec 2017, Around 35 plus products in his career. He has good knowledge of IPM, GMP, Regulatory aspects, he has several International patents published worldwide . He has good proficiency in Technology transfer, Spectroscopy, Stereochemistry, Synthesis, Polymorphism etc., He suffered a paralytic stroke/ Acute Transverse mylitis in Dec 2007 and is 90 %Paralysed, He is bound to a wheelchair, this seems to have injected feul in him to help chemists all around the world, he is more active than before and is pushing boundaries, He has 9 million plus hits on Google, 2.5 lakh plus connections on all networking sites, 50 Lakh plus views on dozen plus blogs, He makes himself available to all, contact him on +91 9323115463, email amcrasto@gmail.com, Twitter, @amcrasto , He lives and will die for his family, 90% paralysis cannot kill his soul., Notably he has 19 lakh plus views on New Drug Approvals Blog in 216 countries......https://newdrugapprovals.wordpress.com/ , He appreciates the help he gets from one and all, Friends, Family, Glenmark, Readers, Wellwishers, Doctors, Drug authorities, His Contacts, Physiotherapist, etc

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GRAZOPREVIR, MK 5172


GRAZOPREVIR

  • Grazoprevir hydrate
  • UNII-4O2AB118LA
  • MK 5172
THERAPEUTIC CLAIM Antiviral
Note……..drug is k salt
MF C38H49N6O9SK
MW804.99
CHEMICAL NAMES
1. Cyclopropanecarboxamide, N-[[[(1R,2R)-2-[5-(3-hydroxy-6-methoxy-2-
quinoxalinyl)pentyl]cyclopropyl]oxy]carbonyl]-3-methyl-L-valyl-(4R)-4-hydroxy-L-prolyl-1-
amino-N-(cyclopropylsulfonyl)-2-ethenyl-, cyclic (1→2)-ether, hydrate (1 :1) (1R,2S)-
2. (1aR,5S,8S,10R,22aR)-N-{(1R,2S)-1-[(cyclopropylsulfonyl)carbamoyl]-2-
ethenylcyclopropyl}-5-(1,1-dimethylethyl)-14-methoxy-3,6-dioxo-
1,1a,3,4,5,6,9,10,18,19,20,21,22,22a-tetradecahydro-8H-7,10-
methanocyclopropa[18,19][1,10,3,6]dioxadiazacyclononadecino[11,12-b]quinoxaline-8-
carboxamide hydrate
MOLECULAR FORMULA C38H50N6O9S.H2O
MOLECULAR WEIGHT 784.92
SPONSOR Merck Sharp & Dohme Corp.
CAS REGISTRY NUMBER 1350462-55-3  HYDRATE, 1350514-68-9 (anhydrous)
WHO NUMBER
9857
GRAZOPREVIR
MERCK
MK-5172 is in phase II clinical development at Merck & Co. for the oral treatment of chronic hepatitis C in combination with peginterferon and ribavirin and in combination with MK-8742. Phase I clinical trials are ongoing for the treatment of hepatitis C in patients with genotype 1 and genotype 3. In 2013, breakthrough therapy designation was assigned to the compound.
 SYNTHESIS, THESIS PROCEDURES, NMR see………..http://www.allfordrugs.com/2015/07/31/mk-5172-grazoprevir/
Discovery of MK-5172, a macrocyclic hepatitis C virus NS3/4a protease inhibitor
ACS Med Chem Lett 2012, 3(4): 332DOI: 10.1021/ml300017p
Development of a practical, asymmetric synthesis of the hepatitis c virus protease inhibitor MK-5172
Org Lett 2013, 15(16): 4174
WO2013142159
WO 2013106631
WO 2013101550
WO 2013028470
WO 2013028471
WO2013028465
WO 2010011566
Description:
IC50 Value: 7.4nM and 7nM for genotype1b and 1a respectively, in replicon system [1]
MK-5172 is a novel P2-P4 quinoxaline macrocyclic HCV NS3/4a protease inhibitor currently in clinical development.
in vitro: In biochemical assays, MK-5172 was effective against a panel of major genotypes and variants engineered with common resistant mutations observed in clinical studies with other NS3/4a protease inhibitors. In the replicon assay, MK-5172 demonstrated subnanomolar to low-nanomolar EC50s against genotypes 1a, 1b, and 2a [2].
in vivo: In rats, MK-5172 showed a plasma clearance of 28 ml/min/kg and plasma half-life of 1.4 hr. When dosed p.o. at 5 mg/kg, the plasma exposure of MK-5172 was good with an AUC of 0.7 uM.hr. The liver exposure of the compound was quite good (23 uM at 4 hr), and MK-5172 remained in liver 24 hr after a single p.o. 5 mg/kg dose. At 24 hr, the liver concentration of MK-5172 was 0.2 uM, which was over 25-fold higher than the IC50 in the replicon assay with 50% NHS. When dosed to dogs, MK-5172 showed low clearance of 5 ml/min/kg and a 3 hr half-life after i.v. 2 mg/kg dosing and had good plasma exposure (AUC=0.4 uM.hr) after a p.o. 1 mg/kg dose [1].
Clinical trial: Evaluation of Hepatic Pharmacokinetics for MK-5172 in Participants With Chronic Hepatitis C . Phase1
Hepatitis C virus (HCV) infection is a major health problem that leads to chronic liver disease, such as cirrhosis and hepatocellular carcinoma, in a substantial number of infected individuals. Current treatments for HCV infection include immunotherapy with recombinant interferon-α alone or in combination with the nucleoside analog ribavirin.
Several virally-encoded enzymes are putative targets for therapeutic intervention, including a metalloprotease (NS2-3), a serine protease (NS3), a helicase (NS3), and an RNA-dependent RNA polymerase (NS5B). The NS3 protease is located in the N-terminal domain of the NS3 protein. NS4A provide a cofactor for NS3 activity.
Potential treatments for HCV infection have been discussed in the different references including Balsano, Mini Rev. Med. Chem. 8(4):307-318, 2008, Rönn et al., Current Topics in Medicinal Chemistry 8:533-562, 2008, Sheldon et al., Expert Opin. Investig. Drugs 16(8):1171-1181, 2007, and De Francesco et al., Antiviral Research 58:1-16, 2003
Different HCV inhibitors are described in different publications. Macrocyclic compounds useful as inhibitors the HCV protease inhibitors are described in WO 06/119061, WO 7/015785, WO 7/016441, WO 07/148,135, WO 08/051,475, WO 08/051,477, WO 08/051,514, WO 08/057,209. Additional HCV NS3 protease inhibitors are disclosed in International Patent Application Publications WO 98/22496, WO 98/46630, WO 99/07733, WO 99/07734, WO 99/38888, WO 99/50230, WO 99/64442, WO 00/09543, WO 00/59929, WO 02/48116, WO 02/48172, British Patent No. GB 2 337 262, and U.S. Pat. No. 6,323,180.
………………………
NMR
Figure US08080654-20111220-C00021
13C NMR (100 MHz, DMSO-d6) δ 172.32, 170.63, 169.04, 159.86, 156.95, 154.74, 148.10, 140.41, 133.55 (2 signals), 128.94, 118.21, 117.58, 105.89, 74.88, 59.75, 58.71, 55.68, 54.13, 54.01, 40.13, 34.49, 34.04, 33.76, 32.68, 30.71, 30.43, 28.55, 27.69, 27.28, 26.38, 21.98, 18.49, 10.67, 5.69, 5.46; MS (ES+) m/z 767 (M+H)+
(1aR,5S,8S,10R,22aR)-5-tert-butyl-N-((1R,2S)-1-{[(cyclopropylsulfonyl)amino]carbonyl}-2-vinylcyclopropyl)-14-methoxy-3,6-dioxo-1,1a,3,4,5,6,9,10,18,19,20,21,22,22a-tetradecahydro-8H-7,10-methanocyclopropa[18,19][1,10,3,6]dioxadiazacyclononadecino[11,12-b]quinoxaline-8-carboxamide
index1
………………….
NMR OF GRAZOPREVIR K SALT
Potassium {[(1R,2S)-1-({[(1aR,5S,8S,10R,22aR)-5-tert-butyl-14-methoxy-3,6-dioxo-
1,1a,3,4,5,6,9,10,18,19,20,21,22,22a-tetradecahydro-8H-7,10-
methanocyclopropa[18,19][1,10,3,6]dioxadiazacyclononadecino[11,12-b]quinoxalin-8-
yl]carbonyl}amino)-2-ethenylcyclopropyl]carbonyl}(cyclopropylsulfonyl)azanide (15 K-salt).
1H NMR (400 MHz, DMSO-d6) δ 7.91 (br s, 1 H), 7.75 (d, J =
8.3 Hz, 1 H), 7.15 (m, 1 H), 7.04 (m, 1 H), 5.97 (m, 1 H), 5.73 (br s, 1 H), 4.96 (m, 1 H), 4.79 (apparent q, J = 9.3 Hz, 1 H), 4.26 (dd, J = 9.7, 7.7 Hz, 1 H), 4.20 (d, J = 11.3 Hz, 1 H), 4.14 (d, J = 8.8 Hz, 1 H), 3.90 (dd, J = 11.1, 3.2 Hz, 1 H), 3.86 (s, 3 H), 3.62 (m, 1 H), 2.86-2.60 (m, 3 H), 2.38 (m, 1 H), 2.21 (m, 1 H), 1.80-1.48 (m, 6 H), 1.42 (m, 5 H), 1.14 (m, 1 H), 0.95 (m, 10 H), 0.81 (m, 2 H), 0.72-0.50 (m, 3 H), 0.41 (m, 1 H) ppm.http://pubs.acs.org/doi/suppl/10.1021/ml300017p/suppl_file/ml300017p_si_001.pdf
………………………………………………………
GRAZOPREVIR
(1aR,5S,8S,10R,22aR)-5-tert-Butyl-N-((1R,2S)-1-{[(cyclopropylsulfonyl)amino] carbonyl}-2-
vinylcyclopropyl)-14-methoxy-3,6-dioxo-1,1a,3,4,5,6,9,10,18,19,20,21,22,22a-tetradecahydro-8H-
7,10-methanocyclopropa[18,19][1,10,3,6]dioxadiazacyclononadecino[11,12-b]quinoxaline-8-
carboxamide (MK-5172, 15).
1H NMR (400 MHz, CD3
OD) δ 7.79 (dd, J = 9.6, 1.8 Hz, 1 H), 7.23 (s, 1 H), 7.22 (m, 1 H), 7.10 (d, J = 9.6 Hz, 1 H), 6.01 (apparent t, J = 3.6 Hz, 1 H), 5.74 (m, 1 H), 5.24 (dd, J = 17.0 Hz, 1.6 Hz, 1 H), 5.11 (dd, J = 10.4 Hz, 1.6 Hz, 1 H), 4.49 (d, J = 11.2 Hz, 1 H), 4.40 (m, 2 H), 4.13 (dd, J = 12.0 Hz, 4.0 Hz, 1 H), 3.92 (s, 3 H), 3.76 (m, 1 H), 2.92 (m, 2 H), 2.85 (m, 1 H), 2.55 (dd, J = 13.6 Hz, 6.4 Hz, 1 H), 2.28 (m, 1 H), 2.18 (apparent q, J =8.8 Hz, 1 H), 1.85 (dd, J = 8.0 Hz, 5.6 Hz, 1 H), 1.73 (m, 2 H), 1.5 (m, 2 H), 1.40 (dd, J = 9.6 Hz, 5.6 Hz, 1 H), 1.3 (m, 2 H), 1.23 (m, 4 H), 1.08 (s, 9 H), 0.99 (m, 2 H), 0.89 (m, 3 H), 0.73 (m, 1 H), 0.49 (m, 1 H) ppm; HRMS (ESI) m/z 767.3411 [(M+H)+; calcd for C38H51N6O9S: 767.3433].http://pubs.acs.org/doi/suppl/10.1021/ml300017p/suppl_file/ml300017p_si_001.pdf
…………………………..
HPLC
……………………
SYNTHESIS OF INTERMEDIATES Intermediates A
Intermediate # Structure Name Lit. Reference
A1 Figure US08080654-20111220-C00003 (1R,2S)-1-Amino-N- (cyclopropylsulfonyl)-2- vinylcyclopropanecarboxamide hydrochloride Wang et al., U.S. Pat. No. 6,995,174
Intermediate B1 3-methyl-N-({[(1R,2R)-2-pent-4-en-1-ylcyclopropyl]oxy}carbonyl)-L-valine
Figure US08080654-20111220-C00004
Step 1: [(1E)-hepta-1,6-dien-1-yloxy](trimethyl)silane
Figure US08080654-20111220-C00005
A solution (0.5 M) of butenyl magnesium bromide in THF (1.4 eq) was treated at −78° C. with Cu(I) Br.SMe(0.05 eq) and HMPA (2.4 eq). The mixture was stirred for 10 min, then a solution (1 M) of acrolein (1 eq) and TMSCl (2 eq) in THF was added over 1 h such that the internal temperature remained below −68° C. The resulting mixture was stirred at −78° C. for 2 h, then treated with excess Et3N and diluted with hexane. After reaching room temperature, the mixture was treated with a small portion of H2O and filtered through CELITE. The filtrate was washed 10 times with H2O and then with brine. The organic layer was dried, and the volatiles were removed to give a residue that was distilled under reduced pressure (20 mbar). The fraction collected at 80-86° C. contained the title compound (58%) as a colorless liquid. 1H NMR (400 MHz, CDCl3) δ 6.19 (d, J=11.6 Hz, 1H), 5.85-5.75 (m, 1H), 5.02-4.92 (m, 3H), 2.08-2.02 (m, 2H), 1.94-1.88 (m, 2H), 1.46-1.38 (m, 2H), 0.18 (s, 9H).
Step 2: trans-2-pent-4-en-1-ylcyclopropanol
Figure US08080654-20111220-C00006
A solution (0.45 M) of the preceding compound in hexane was treated with a solution (15%) of Et2Zn (1.2 eq) in toluene, and the resulting solution was cooled in an ice bath. Diiodomethane (1.2 eq) was added dropwise, then the solution was stirred for 1 h before being warmed to 20° C. Pyridine (6 eq) was added, and the slurry was stirred for 15 min then poured onto petroleum ether. The mixture was filtered repeatedly through CELITE until a transparent solution was obtained. This mixture was concentrated at 100 mbar, and the solution that remained (that contained trimethyl{[(trans)-2-pent-4-en-1-ylcyclopropyl]oxy}silane, toluene and pyridine) was further diluted with THF. The mixture was cooled to 0° C. then treated dropwise with a solution (1 M) of TBAF (1.2 eq) in THF. After 10 min, the mixture was allowed to warm to 20° C., and after a further 1 h was poured into H2O. The aqueous phase was extracted with EtOAc, and the combined organic extracts were washed with brine then dried. Removal of the volatiles afforded a residue that was purified by flash chromatography (eluent 0-66% Et2O/petroleum ether) to furnish the title compound (71%) as a colorless liquid. 1H NMR (400 MHz, CDCl3) δ 5.85-5.75 (m, 1H), 5.00 (dd, J=17.1, 1.6 Hz, 1H), 4.94 (br d, J=10.4 Hz, 1H), 3.20 (apparent dt, J=6.4, 2.5 Hz, 1H), 2.10-2.04 (m, 2H), 1.52-1.44 (m, 2H), 1.29-1.19 (m, 1H), 1.15-1.07 (m, 1H), 0.95-0.87 (m, 1H), 0.71-0.66 (m, 1H), 0.31 (apparent q, J=6.0 Hz, 1H).
Step 3: methyl 3-methyl-N-(oxomethylene)-L-valinate
Figure US08080654-20111220-C00007
A solution (0.39 M) of methyl 3-methyl-L-valinate in a 2:1 mixture of saturated aqueous NaHCOand CH2Clwas cooled in an ice bath and stirred rapidly. The mixture was treated with triphosgene (0.45 eq) in one portion, and the resulting mixture was stirred for 0.5 h. The reaction was diluted with CH2Cl2, and the layers were separated. The aqueous phase was extracted with CH2Cl2, then the combined organics were washed with brine and dried. Removal of the solvent gave the title compound as clear oil that was kept for 12 h under vacuum (0.1 mbar) then used directly in the subsequent step. 1H NMR (400 MHz, CDCl3) δ 3.79 (s, 3H), 3.75 (s, 1H), 1.00 (s, 9H).
Step 4: methyl 3-methyl-N-({[(1R,2R)-2-pent-4-en-1-ylcyclopropyl]oxy}carbonyl)-L-valinate and methyl 3-methyl-N-({[(1S,2S)-2-pent-4-en-1-ylcyclopropyl]oxy}carbonyl)-L-valinate
Figure US08080654-20111220-C00008
A solution (0.45 M) of trans-2-pent-4-en-1-ylcyclopropanol in toluene was treated with methyl 3-methyl-N-(oxomethylene)-L-valinate (1.1 eq) and then DMAP (1 eq). The resulting mixture was heated under reflux for 12 h then cooled to 20° C. H2O and EtOAc were added, and the organic layer was separated and washed with 1N HCl, brine and dried. Removal of the volatiles afforded a residue that was purified twice by flash chromatography (eluent 0-30% Et2O/petroleum ether). The first fractions contained methyl 3-methyl-N-({[(1R,2R)-2-pent-4-en-1-ylcyclopropyl]oxy}carbonyl)-L-valinate (38%) as an oil. MS (ES+) m/z 298 (M+H)+
The later fractions contained methyl 3-methyl-N-({[(1S,2S)-2-pent-4-en-1-ylcyclopropyl]oxy}carbonyl)-L-valinate (28%) as an oil. MS (ES+) m/z 298 (M+H)+
Step 5: 3-methyl-N-({[(1R,2R)-2-pent-4-en-1-ylcyclopropyl]oxy}carbonyl)-L-valine
Figure US08080654-20111220-C00009
A solution (0.1 M) of methyl 3-methyl-N-({[(1R,2R)-2-pent-4-en-1-ylcyclopropyl]oxy}carbonyl)-L-valinate in 2:1 mixture of MeOH/H2O was treated with LiOH.H2O (4 eq) and then heated at 60° C. for 4 h. The mixture was cooled and concentrated to half volume, then diluted with EtOAc and acidified with aqueous HCl (1 N). The organic layer was separated and washed with brine then dried. Removal of the volatiles afforded the title compound (98%) as an oil. MS (ES+) m/z 284 (M+H)+
Intermediates C Intermediate C1 methyl (4R)-4-[(3-chloro-7-methoxyquinoxalin-2-yl)oxy]-L-prolinate hydrochloride
Figure US08080654-20111220-C00010
Step 1: 6-methoxyquinoxaline-2,3-diol
Figure US08080654-20111220-C00011
A suspension of 4-methoxybenzene-1,2-diamine dihydrochloride in diethyl oxalate (8 eq) was treated with Et3N (2 eq) and then heated at 150° C. for 2 h. The mixture was cooled and filtered, and then the collected solid was washed with H2O and EtOH. The residue was dried to give the title compound (69%). MS (ES+) m/z 193 (M+H)+
Step 2: 3-chloro-6-methoxyquinoxalin-2-ol
Figure US08080654-20111220-C00012
A solution (1.53 M) of 6-methoxyquinoxaline-2,3-diol in DMF was treated with SOCl(1 eq) and heated at 110° C. After 1.5 h, the reaction mixture was cooled and poured into aqueous HCl (1 N). The resulting precipitate was filtered and washed with H2O and Et2O. The dried solid contained predominantly the title compound as a mixture with 6-methoxyquinoxaline-2,3-diol and 2,3-dichloro-6-methoxyquinoxaline. This material was used directly in the subsequent step. MS (ES+) m/z 211 (M+H)+
Step 3: 1-tert-butyl 2-methyl (2S,4R)-4-[(3-chloro-7-methoxyquinoxalin-2-yl)oxy]pyrrolidine-1,2-dicarboxylate
Figure US08080654-20111220-C00013
A solution (0.35 M) of 3-chloro-6-methoxyquinoxalin-2-ol in NMP was treated with Cs2CO(1.5 eq) and 1-tert-butyl 2-methyl (2S,4S)-4-{[(4-bromophenyl)sulfonyl]oxy}pyrrolidine-1,2-dicarboxylate (1.1 eq). The resulting mixture was stirred at 50° C. for 18 h, then a further portion (0.1 eq) of 1-tert-butyl 2-methyl (25,45)-4-{[(4-bromophenyl)sulfonyl]oxy}pyrrolidine-1,2-dicarboxylate was added. After stirring for 2 h, the mixture was cooled and diluted with H2O and EtOAc. The organic phases were washed with aqueous HCl (1 N), saturated aqueous NaHCOand brine. The dried organic phase was concentrated to a residue that was purified by flash-chromatography (0-60% EtOAc/petroleum ether) to give the title compound (35% for two steps) as a solid. MS (ES+) m/z 438 (M+H)+
Step 4: methyl (4R)-4-[(3-chloro-7-methoxyquinoxalin-2-yl)oxy]-L-prolinate hydrochloride
Figure US08080654-20111220-C00014
A solution (0.62 M) of 1-tert-butyl 2-methyl (2S,4R)-4-[(3-chloro-7-methoxyquinoxalin-2-yl)oxy]pyrrolidine-1,2-dicarboxylate in CH2Clwas treated with a solution (4 M) of HCl in dioxane (5 eq). The mixture was stirred at 20° C. for 2 h, then treated with a solution (4 M) of HCl in dioxane (2 eq). After 5 h, the reaction was judged complete and the mixture was concentrated under reduced pressure. The residue was triturated with Et2O to give the title compound (95%) as a solid. MS (ES+) m/z 338 (M+H)+
Example 1 Potassium {[(1R,2S)-1-({[(1aR,5S,8S,10R,22aR)-5-tert-butyl-14-methoxy-3,6-dioxo-1,1a,3,4,5,6,9,10,18,19,20,21,22,22a-tetradecahydro-8H-7,10-methanocyclopropa[18,19][1,10,3,6]dioxadiazacyclononadecino[11,12-b]quinoxalin-8-yl]carbonyl}amino)-2-vinylcyclopropyl]carbonyl}(cyclopropylsulfonyl)azanide
Figure US08080654-20111220-C00015
Step 1: methyl 3-methyl-N-({[(1R,2R)-2-pent-4-en-1-ylcyclopropyl]oxy}carbonyl)-L-valyl-(4R)-4-[(3-chloro-7-methoxyquinoxalin-2-yl)oxy]-L-prolinate
Figure US08080654-20111220-C00016
A solution (0.2 M) of methyl (4R)-4-[(3-chloro-7-methoxyquinoxalin-2-yl)oxy]-L-prolinate hydrochloride in DMF was treated with 3-methyl-N-({[(1R,2R)-2-pent-4-en-1-ylcyclopropyl]oxy}carbonyl)-L-valine (1.1 eq), DIEA (5 eq) and HATU (1.2 eq). The resulting mixture was stirred at 20° C. for 5 h, then diluted with EtOAc. The organic layer was separated and washed with aqueous HCl (1 N), saturated aqueous NaHCOand brine. The dried organic phase was concentrated under reduced pressure to give a residue that was purified by flash chromatography (eluent 10-30% EtOAc/petroleum ether) to furnish the title compound (96%) as an oil. MS (ES+) m/z 604 (M+H)+
Step 2: methyl 3-methyl-N-({[(1R,2R)-2-pent-4-en-1-ylcyclopropyl]oxy}carbonyl)-L-valyl-(4R)-4-[(7-methoxy-3-vinylquinoxalin-2-yl)oxy]-L-prolinate
Figure US08080654-20111220-C00017
A solution (0.1 M) of methyl 3-methyl-N-({[(1R,2R)-2-pent-4-en-1-ylcyclopropyl]oxy}carbonyl)-L-valyl-(4R)-4-[3-chloro-7-methoxyquinoxalin-2-yl)oxy]-L-prolinate in EtOH was treated with potassium trifluoro(vinyl)borate (1.5 eq) and triethylamine (1.5 eq). The resulting mixture was degassed, then PdCl2(dppf)-CH2Cladduct (0.1 eq) was added. The mixture was heated under reflux for 1 h, then cooled to room temperature and diluted with H2O and EtOAc. The organic phase was separated, washed with H2O and brine then dried. Removal of the volatiles afforded a residue that was purified by flash chromatography (20-30% EtOAc/petroleum ether) to give the title compound as a yellow foam that was used directly in the subsequent step. MS (ES+) m/z 595 (M+H)+
Step 3: methyl (1aR,5S,8S,10R,18E,22aR)-5-tert-butyl-14-methoxy-3,6-dioxo-1,1a,3,4,5,6,9,10,20,21,22,22a-dodecahydro-8H-7,10-methanocyclopropa[18,19][1,10,3,6]dioxadiazacyclononadecino[11,12-b]quinoxaline-8-carboxylate
Figure US08080654-20111220-C00018
A solution (0.02 M) of methyl 3-methyl-N-({[(1R,2R)-2-pent-4-en-1-ylcyclopropyl]oxy}carbonyl)-L-valyl-(4R)-4-[(7-methoxy-3-vinylquinoxalin-2-yl)oxy]-L-prolinate in DCE was heated to 80° C. then treated with Zhan 1 catalyst (0.15 eq). The resulting mixture was stirred at 80° C. for 1 h, then cooled to room temperature and concentrated under reduced pressure. The residue was purified by flash chromatography (20-50% EtOAc/petroleum ether) to give the title compound (25% for 2 steps) as a foam. MS (ES+) m/z 567 (M+H)+
Step 4: methyl (1aR,5S,8S,10R,22aR)-5-tert-butyl-14-methoxy-3,6-dioxo-1,1a,3,4,5,6,9,10,18,19,20,21,22,22a-tetradecahydro-8H-7,10-methanocyclopropa[18,19][1,10,3,6]dioxadiazacyclononadecino[11,12-b]quinoxaline-8-carboxylate
Figure US08080654-20111220-C00019
A solution (0.05 M) of methyl (1aR,5S,8S,10R,18E,22aR)-5-tert-butyl-14-methoxy-3,6-dioxo-1,1a,3,4,5,6,9,10,20,21,22,22a-dodecahydro-8H-7,10-methanocyclopropa[18,19][1,10,3,6]dioxadiazacyclononadecino[11,12-b]quinoxaline-8-carboxylate in MeOH/dioxane (1:1 ratio) was treated with Pd/C (8% in weight). The resulting mixture was stirred under atmosphere of hydrogen for 4 h. The catalyst was filtered off, and the filtrate was concentrated under reduced pressure to give the title compound (98%) as a solid. MS (ES+) m/z 569 (M+H)+
Step 5: (1aR,5S,8S,10R,22aR)-5-tert-butyl-14-methoxy-3,6-dioxo-1,1a,3,4,5,6,9,10,18,19,20,21,22,22a-tetradecahydro-8H-7,10-methanocyclopropa[18,19][1,10,3,6]dioxadiazacyclononadecino[11,12-b]quinoxaline-8-carboxylic acid
Figure US08080654-20111220-C00020
A solution (0.1 M) of methyl (1aR,5S,8S,10R,22aR)-5-tert-butyl-14-methoxy-3,6-dioxo-1,1a,3,4,5,6,9,10,18,19,20,21,22,22a-tetradecahydro-8H-7,10-methanocyclopropa[18,19][1,10,3,6]dioxadiazacyclononadecino[11,12-b]quinoxaline-8-carboxylate in a 1:1 mixture of H2O/THF was treated with LiOH.H2O (3 eq). The resulting mixture was stirred at 20° C. for 18 h, acidified with aqueous HCl (0.2 M) and diluted with EtOAc. The organic phase was separated, washed with aqueous HCl (0.2 M) and brine then dried. Removal of the volatiles afforded the title compound (98%) as a solid. MS (ES+) m/z 555 (M+H)+
Step 6: (1aR,5S,8S,10R,22aR)-5-tert-butyl-N-((1R,2S)-1-{[(cyclopropylsulfonyl)amino]carbonyl}-2-vinylcyclopropyl)-14-methoxy-3,6-dioxo-1,1a,3,4,5,6,9,10,18,19,20,21,22,22a-tetradecahydro-8H-7,10-methanocyclopropa[18,19][1,10,3,6]dioxadiazacyclononadecino[11,12-b]quinoxaline-8-carboxamide
Figure US08080654-20111220-C00021
A solution (0.1 M) of (1aR,5S,8S,10R,22aR)-5-tert-butyl-14-methoxy-3,6-dioxo-1,1a,3,4,5,6,9,10,18,19,20,21,22,22a-tetradecahydro-8H-7,10-methanocyclopropa[18,19][1,10,3,6]dioxadiazacyclononadecino[11,12-b]quinoxaline-8-carboxylic acid in CH2Clwas treated with (1R,2S)-1-{[(cyclopropylsulfonyl)amino]carbonyl}-2-vinylcyclopropanaminium chloride (1.3 eq), DIEA (3 eq), DMAP (1.5 eq) and TBTU (1.45 eq). The resulting mixture was stirred at 20° C. for 18 h and then diluted with EtOAc. The solution was washed with aqueous HCl (0.2 M), saturated aqueous NaHCOand brine. The organic phases were dried and concentrated to give a residue that was purified by flash-chromatography (eluent 2.5% MeOH/CH2Cl2) to give the title compound (89%) as a solid. 13C NMR (100 MHz, DMSO-d6) δ 172.32, 170.63, 169.04, 159.86, 156.95, 154.74, 148.10, 140.41, 133.55 (2 signals), 128.94, 118.21, 117.58, 105.89, 74.88, 59.75, 58.71, 55.68, 54.13, 54.01, 40.13, 34.49, 34.04, 33.76, 32.68, 30.71, 30.43, 28.55, 27.69, 27.28, 26.38, 21.98, 18.49, 10.67, 5.69, 5.46; MS (ES+) m/z 767 (M+H)+
GRAZOPREVIR POTASSIUM
Step 7: potassium {[(1R,2S)-1-({[(1aR,5S,8S,10R,22aR)-5-tert-butyl-14-methoxy-3,6-dioxo-1,1a,3,4,5,6,9,10,18,19,20,21,22,22a-tetradecahydro-8H-7,10-methanocyclopropa[18,19][1,10,3,6]dioxadiazacyclononadecino[11,12-b]quinoxalin-8-yl]carbonyl}amino)-2-vinylcyclopropyl]carbonyl}(cyclopropylsulfonyl)azanide
Figure US08080654-20111220-C00022
The preceding material was taken up in EtOH and the resulting solution (0.025 M) was cooled to 0° C. A solution (0.02 M) of tert-BuOK (1.5 eq) in EtOH was added leading to the formation of a precipitate. The mixture was stirred at 20° C. for 18 h, then the solid was collected by filtration. This material was washed with EtOH and dried to give the title compound (93%) as a white crystalline solid. MS (ES+) m/z 767 (M+H)+http://www.google.nl/patents/US8080654
………………………..
PATENT
WO 2015095437

Step 1: Quinoxaline Hydroxyproline Methyl Ester HCl Salt

A 250-ml RB, equipped with magnetic stirrer and N2 bubbler, was charged with chloroquinoxaline BOC hydroxyproline adduct in MeOH (100 ml), and the mixture was cooled in an ice bath. Acetyl chloride (17.9 g) was then added, and the mixture was stirred at RT for 2 h. The batch was diluted with IP Ac (80 ml). Solids were filtered off and washed with IPAc (20 ml). The washed solids were dried under vacuum for 3 d, to provide 48.9 g (100% yield ). Part of this material was used in the next step.

…………………..
WO2015057611

Example 17: Preparation of Compound A, Method A

Macrocyclic acid hemihydrate, the product of Example 15 (10.16 g, 18.03 mmol) was dissolved in THF (50 mL to 90 mL). The solution was azetropically dried at a final volume of 100 mL. Sulfonamide pTSA salt (7.98 g, 1.983 mmol) followed by DMAc (15 mL) was added at RT. The batch was cooled to 0°C to 10°C, and pyridine (10 mL) was added dropwise. Then, EDC HCl (4.49 g, 23.44 mmol) was added in portions or one portion at 0°C to 10°C. The reaction mixture was aged at 0°C to 10°C for 1 h, and then warmed to 15°C to 20°C for 2 h to 4 h. MeOAc (100 mL) followed by 15 wt% citric acid in 5% NaCl in water (50 mL) was added, while the internal temperature was maintained to < 25°C with external cooling. The separated organic phase was washed with 15 wt% citric acid in 5% NaCl in water (50 mL) followed by 5% NaCl (50 mL). The organic phase was solvent-switched to acetone at a final volume of ~80 mL. Water (10 mL) was added dropwise at 35°C to 40°C. The batch was seeded with Compound A monohydrate form III (~10 mg) and aged for 0.5 h tol h at 35°C to 40°C. Additional water (22 mL) was added dropwise over 2 h to 4 h at 35°C to 40°C. The slurry was aged at 20°C for 2 h to 4 h before filtration. The wet cake was displacement washed with 60% acetone in water (2x 40 mL). Suction drying at RT gave Compound A monohydrate form III as a white solid.

XH NMR (400 MHz, CDC13) δ 9.95 (s, br, 1 H), 7.81 (d, J = 9.1 Hz, 1 H), 7.18 (dd, J = 9.1, 2.7 Hz, 1 H), 7.16 (s, br, 1 H), 7.13 (d, J = 2.7 Hz, 1 H), 5.96 (t, J = 3.8 Hz, 1 H), 5.72 (m, 1 H), 5.68 (d, J = 10.1 Hz, 1 H), 5.19 (d, J = 17.1 Hz, 1 H), 5.07 (d, J = 10.1 Hz, 1 H), 4.52 (d, J = 11.4 Hz, 1 H), 4.45 (d, J = 9.8 Hz, 1 H), 4.36 (d, J = 10.5, 6.9 Hz, 1 H), 4.05 (dd, J = 11.5, 3.9 Hz, 1 H), 3.93 (s, 3 H), 3.78 (m, 1 H), 2.90 (m, 1 H), 2.82 (tt, J = 8.0, 4.8 Hz, 1 H), 2.74 (dt, J = 13.2, 4.8 Hz, 1 H), 2.59 (dd, J = 14.0, 6.7 Hz, 1 H), 2.40 (ddd, J = 14.0, 10.6, 4.0 Hz, 1 H), 2.10 (dd, J = 17.7, 8.7 Hz, 1 H), 1.98 (2 H, mono hydrate H20), 1.88 (dd, J 8.2, 5.9 Hz, 1 HO, 1.74 (m, 3 H), 1.61 (m, 1 H), 1.50 (m, 3 H), 1.42 (dd, J = 9.6, 5.8 Hz, 1 H), 1.22 (m, 2 H), 1.07 (s, 9 H), 0.95 (m, 4 H), 0.69 (m, 1 H), 0.47 (m, 1 H).

1 C NMR (100 MHz, CDC13) δ 173.5, 172.1, 169.1, 160.4, 157.7, 154.9, 148.4, 141.0, 134.3, 132.7, 129.1, 118.8, 118.7, 106.5, 74.4, 59.6, 59.4, 55.8, 55.5, 54.9, 41.8, 35.4, 35.3, 35.2, 34.3,. 31.2, 30.7, 29.5, 28.6, 28.2, 26.6, 22.6, 18.7, 11.2, 6.31, 6.17.

HPLC conditions: Ascentis Express Column, 10 cm x 4.6 mm, 2.7 μηι; Column temperature of 40°C; Flow rate of 1.8 mL/min; and Wavelength of 215 nm.

Gradiant: mm 0.1% ¾PO4

0 20 80

5 55 45

15 55 45

25 95 5

27 95 5

27.1 20 80

32 20 80

Retention time: mm.

Compound A 14.50

Example 18: Preparation of Compound A, Method B

To a 50-L flask equipped with overhead stirring was added macrocyclic acid (1.06 kg crude, 1.00 eq), amine-pTSA (862 g crude, 1.12 eq) and MeCN (7.42 L) at 19°C. The slurry was cooled in a water bath, pyridine (2.12 L, 13.8 eq) was added, aged 15 min, and then added EDC (586 g, 1.60 eq) in one portion, aged 1.5 h, while it turned into a clear homogeneous solution.

The solution cooled in a water bath, then quenched with 2 N HC1 (1.7 L), and seeded (9.2 g), aged 15 min, and the rest of the aqueous HC1 was added over 2.5 h. A yellow slurry was formed. The slurry was aged overnight at RT, filtered, washed with MeCN/water (1 : 1 v/v, 8 L), to obtain Compound A (Hydrate II).

Compound A was dissolved in acetone (4 L) at RT, filtered and transferred to a

12-L round-bottom flask with overhead stirring, rinsed with extra acetone (1 L), heated to 50°C, water (0.9 L) was added, seeded with Compound A monohydrate form III (-10 mg), and aged 15 min, and then added water (0.8 L) over 2.5 h, extra water 3.3 v over 2.5 h was added, stopped heating, cooled to RT, aged at RT overnight, filtered, washed with water/acetone (1 : 1 v/v, 4 L), and dried in air under vacuum. Compound A Hydrate III, 670 g, was obtained as an off-white solid.

Example 19: Preparation of Compound A, Method C

Macrocyclic acid hemihydrate from Example 15 (10.16 g, 18.03 mmol) was dissolved in THF (50 ml to 90 mL). The solution was azetropically dried at a final volume of 100 mL. Sulfonamide pTSA salt (7.98 g, 19.83 mmol) was added, followed by DMAc (15 mL), at RT. The batch was cooled to 0° to 10°C, and pyridine (10 mL) was added dropwise. Then, EDC HC1 (4.49 g, 23.44 mmol) was added (in portions or one portion) at 0°C to 10°C. The reaction mixture was aged at 0°C to 10°C for 1 h, and then warmed to 15°C to 20°C for 2 h to 4 h. THF (50 mL) was added, followed by 15 wt% citric acid in 15 wt% aq. NaCl (50 mL), while the internal temperature was maintained at < 25°C with external cooling. The separated organic phase was washed with 15 wt% citric acid in 1 % aq. NaCl (40 mL), followed by 15% NaCl (40 mL). The organic phase was solvent-switched to acetone at a final volume of ~75 mL Water (1 1 mL to 12 mL) was added dropwise at 35°C to 40°C. The batch was seeded with Compound A monohydrate form III (~20 mg) and aged for 0.5 h to 1 h at 35°C to 40°C.

Additional water (22 mL) was added dropwise over 2 h to 4 h at 35°C to 40°C. The slurry was aged at 20°C for 2 h to 4 h before filtration. The wet cake was displacement washed with 60% acetone in water (40 mL x 2). Suction drying at RT or vacuum-oven drying at 45°C gave Compound A monohydrate form III as a white solid.

Example 20: Preparation of Compound A, Method D

Macrocyclic acid hemihydrate from Example 12 (10 g, 98.4wt%, 17.74 mmol) was dissolved in THF (70 mL). The solution was azetropically dried at a final volume of ~60 mL. Sulfonamide pTSA salt (7.53 g, 18.7 mmol) was added at RT. The batch was cooled to 0°C to 5°C, and pyridine (1 1.4 mL) was added dropwise. Then, EDC HC1 (4.26 g, 22.2 mmol) was added in portions at 0°C to 15°C. The reaction mixture was aged at 10°C to 15°C for 2 h to 4 h. 35 wt% Citric acid in 10 wt% aq. NaCl (80 mL) was added, while the internal temperature was maintained at < 25°C with external cooling. The separated organic phase was solvent-switched to acetone at a final volume of ~75 mL. Water (12 mL) was added dropwise at 50°C. The batch was seeded with Compound A monohydrate form III (-300 mg) and aged for 0.5 h to 1 h at 50°C. Additional water (25 mL) was added dropwise over 6 h at 35°C to 40°C. The slurry was aged at 20°C for 2 h to 4 h before filtration. The wet cake was displacement washed with 65%) acetone in water (40 mL). Suction drying at RT or vacuum-oven drying at 45°C gave Compound A monohydrate form III as a white solid.

………………….
WO2015095430

Example 24: Ring Closing Metathesis

To a 50 mL 2-neck RB flask with reflux condenser and needle for N2 bubbling was charged the product of Example 20 (1.034 g, 0.869 mmol, 1.0 eq), toluene (20.68 ml, 20X), and the resulting solution was degassed with N2. Hoveyda-Grubbs 2nd generation catalyst (10.90 mg, 0.017 mmol) was charged to the pot, and the system was heated to 80°C with constant sparge of N2, with color change from green to reddish. The reaction was sampled (5 h) and assay by HPLC to be approximately 80% converted. The system was removed from the heat and allowed to stir at RT overnight under N2. The reaction was again assayed and deemed complete by HPLC. Toluene was removed by concentration and the resulting red oil was purified by gradient silica gel chromatography (50 g BlOTAGE SNAP Si gel column; loaded with DCM; eluted with 0 to 10% EtOAc in DCM over 10 column volumes; then 10 to 20% EtOAc in DCM over 3 column volumes; then hold; detect by TLC-UV) to yield a yellow solid, which was further slurried in EtOAc (3 mL) and hexanes (6 mL). The resulting slurry was filtered and washed with 25% EtOAc in hexanes (6 mL) to yield the product (445 mg, 0.754 mmol, 87% yield) as a white solid.

…………

http://anewmerckreviewed.wordpress.com/2013/04/23/okay-trivial-pursuit-will-the-real-mk-5172-please-stand-up/

Synthesis of MK-5172_NS3 protease inhibitor_Hepatitis C_Merck 默沙东丙型肝炎药物MK-5172的的化学合成

Merck reported interim data from the Phase 2 C-WORTHY study in April 2014 at the International Liver Congress (ILC) in London that evaluated the efficacy and safety of its two-drug regimen based on NS3/4A protease inhibitor MK-5172 and NS5A replication complex inhibitor MK-8742, given with or without ribavirin, in GT1 HCV patients with cirrhosis. The once-daily single pill (without ribavirin) showed a 98% SVR12 (12-week sustained virologic response) in genotype-1, treatment-naive patients. Merck will start the phase III clinical trials (NCT02105688NCT02105662NCT02105467 andNCT02105701) for the combination in June 2014.

 

MK-5172 is a novel, competitive inhibitor of the HCV NS3/4a protease with selective, potent in vitro activity against a broad range of HCV genotypes (GTs) and known viral variants that are resistant to other protease inhibitors in development.
MK-5172 is a Next Generation HCV NS3/4a Protease Inhibitor with a Broad HCV Genotypic Activity Spectrum and Potent Activity Against Known Resistance Mutants, in Genotype 1 and 3 HCV-Infected Patients. MK-5172 exhibits excellent selectivity over other serine proteases such as elastase and trypsin (no measurable inhibition), and shows only modest inhibitory potency with chymotrypsin (IC50 = 1.5 µM; 75,000-fold selective). In the genotype 1b replicon assay, MK-5172 potently inhibits viral replication (IC50 = 2 nM) and demonstrates a modest shift in the presence of 50% NHS (EC50 = 9.5 nM). In vitro, MK-5172 inhibits the NS3/4A enzyme from genotypes 1b, 2a, 2b, and 3a with Ki values of <0.02, 0.15, 0.02, and 0.7 nM, respectively. The genotype 2a replicon is also potently inhibited by MK 5172 (EC50 = 5 nM).
Kuethe J, * Zhong Y.-L, * Yasuda N, * Beutner G, Linn K, Kim M, Marcune B, Dreher SD, Humphrey G, Pei T. Merck Research Laboratories, Rahway, USA
Development of a Practical, Asymmetric Synthesis of the Hepatitis C Virus Protease Inhibitor MK-5172.Org. Lett. 2013;
15: 4174-4177
SignificanceNotify Users About this Post

MK-5172 is a hepatitis C virus protease inhibitor. Key steps in the synthesis depicted are (1) the regioselective SNAr reaction of dichloroquinoxaline A with prolinol derivative B and (2) construction of the 18-membered macrocycle ­using a macrolactamization (F → G).

Comment

The medicinal chemistry route to MK-5172 is based on a ring-closing metathesis strategy (S. Harper et al.ACS Med. Chem. Lett. 2012, 3, 332). The best regioselectivity (20:1) and minimization of double substitution in the SNAr reaction of A with B was achieved using 1,8-diaza­bicyclo[5.4.0]undec-7-ene (DBU) as the base in polar solvents such as DMSO, NMP, or DMAc.

 

SYNTHESIS, THESIS PROCEDURES, NMR see………..http://www.allfordrugs.com/2015/07/31/mk-5172-grazoprevir/

/////////////http://www.allfordrugs.com/2015/07/31/mk-5172-grazoprevir/

 

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Biota Reports That Laninamivir Octanoate is Approved for the Prevention of Influenza in Japan


Laninamivir

(4S,5R,6R)-5-acetamido-4-carbamimidamido-6-[(1R,2R)-3-hydroxy-2-methoxypropyl]-5,6-dihydro-4H-pyran-2-carboxylic acid

Formula C13H22N4O7 
Mol. mass 346.33638 g/mol

cas 203120-17-6,

Laninamivir (L174000) prodrug; a novel long-acting neuraminidase inhibitor.

laninamivir octanoate

472.53254, C21H36N4O8,   cas no 203120-46-1, R-125489, CS-8958 

Daiichi Sankyo (Originator)

R-118958 is a potent, long-acting neuraminidase inhibitor (LANI) approved and launched in 2010 in Japan as an inhalable formulation for the treatment of influenza A and influenza B in adults and pediatric patients. In 2013 the product was approved in Japan for the prevention of influenza A and influenza B.

5-(Acetylamino)-4-[(aminoiminomethyl)amino]-2,6-anhydro-3,4,5-trideoxy-7-O-methyl-D-glycero-D-galacto-non-2-enonic Acid 9-Octanoate
(2R,3R,4S)-3-Acetamido-4-guanidino-2-[(1R,2R)-2-hydroxy-1-methoxy-3-(octanoyloxy)propyl]-3,4-dihydro-2H-pyran-6-carboxylic Acid
(4S,5R,6R)-5-Acetamido-4-guanidino-6-[(1R,2R)-2-hydroxy-1-methoxy-3-(octanoyloxy)propyl]-5,6-dihydro-4H-pyran-2-carboxylic Acid
CS 8958

ATLANTA, Dec. 20, 2013 (GLOBE NEWSWIRE) — Biota Pharmaceuticals, Inc.
(Nasdaq:BOTA) (“Biota” or the “Company”) today reported that Daiichi Sankyo Company, Limited (“Daiichi Sankyo”) has been granted regulatory approval in Japan to manufacture and market Inavir(R) Dry Powder Inhaler 20mg (generic name laninamivir octanoate) for the prevention of influenza A and B. Inavir(R) was successfully developed and launched by Daiichi Sankyo in Japan for treatment of influenza A and B viruses in October, 2010. Biota is developing laninamivir octanoate outside of Japan for the treatment of influenza, and is currently conducting a large, multi-national Phase 2 trial of laninamivir octanoate in adults infected with influenza. In 2003, the Company and Daiichi Sankyo entered into a collaboration and license agreement to develop long-acting neuraminidase inhibitors, including laninamivir octanoate, and in March 2009, the parties entered into a commercialization agreement, pursuant to which Daiichi Sankyo obtained exclusive marketing rights to laninamivir octanoate in Japan.http://www.pharmalive.com/biota-flu-drug-okd-in-japan

Laninamivir (CS-8958) is a neuraminidase inhibitor which is being researched for the treatment and prophylaxis of Influenzavirus A and Influenzavirus B.[1] It is currently in Phase III clinical trials. [2]

Laninamivir was approved for influenza treatment in Japan in 2010 and is currently marketed under the name “Inavir” by Daiichi Sankyo. Biota Pharmaceuticals [3] and Daiichi Sankyo co-own Laninamivir. On 1st April 2011, BARDA awarded up to an estimated U$231m to Biota Pharmaceuticals (Formerly Biota Holdings Ltd) wholly owned subsidiary, Biota Scientific Management Pty Ltd, for the advanced development of Laninamivir in the US. [4]

patent

8-13-2010
DRUG FOR TREATMENT OF INFLUENZA
WO 2013089168
WO 2008126943

The recent flu scares – first H5N1 bird flu and then H1N1 swine flu – transformed Roche’s neuraminidase inhibitor Tamiflu (oseltamivir) into a household name, along with GSK’s Relenza (zanamivir). Both of these require twice-daily dosing, and the orally available oseltamivir is the first choice, but resistance is starting to appear.

A new neuraminidase inhibitor, laninamivir, is being developed by Daiichi Sankyo.5 When administered as the octanoate prodrug form, it appears that a single dose might be sufficient to treat influenza, weekly doses could be preventative, and it is active against extremely pathogenic H5N1 strains.

Laninamivir octanoate

In a double blind, randomised, placebo-controlled Phase I study in 76 healthy male volunteers, subjects were given inhaled single doses of 5, 10, 20, 40, 80 or 120mg of the prodrug, or twice-daily doses of 20 or 40mg for three days.6 No adverse events were observed, and while the prodrug disappeared from the plasma with a half-life of about two hours, the laninamivir itself was much more slowly eliminated, with a half-life of the order of three days, suggesting the potential for giving long-lasting activity against influenza.

In another Phase I trial, a total of 20 healthy subjects with renal function ranging from normal to severely impaired were given single inhaled 20mg doses of the prodrug.7 The degree of renal impairment did not affect the maximum concentration or the time to achieve it, but the half-life increased as renal function reduced. This indicates that the rate-limiting step for elimination is drug release rate to plasma from tissues rather than renal excretion. It was well tolerated, but systemic exposure increased with increasing renal impairment.

It has also been compared with oseltamivir in patients with influenza. A total of 186 children under 10 who had had febrile influenza symptoms for no longer than 36 hours were randomised to receive 20 or 40mg of laninamivir octanoate as a single inhalation or 2mg/kg oseltamivir orally twice a day for five days.8

The new drug gave a significant reduction, of 61 hours for the 40mg group and 66 for the 20mg group, in median time to illness alleviation compared with oseltamivir in those with oseltamivir-resistant H1N1 influenza A. However, there was no significant difference in the time to alleviation of illness with H3N2 influenza A, or influenza B.

The most common side-effects were gastrointestinal problems.

In a Phase III trial, a total of 1,003 adult patients with febrile influenza symptoms for no more than 36 hours were given similar doses to those in the trial in children.9 Median time to alleviation of illness was 73h for 40mg, 86h for 20mg, and 74h for oseltamivir, and the proportion of patients shedding virus at day 3 was significantly lower in the 40mg group than for those given oseltamivir.

  1.  Yamashita M, Tomozawa T, Kakuta M, Tokumitsu A, Nasu H, Kubo S (January 2009).“CS-8958, a prodrug of the new neuraminidase inhibitor R-125489, shows long-acting anti-influenza virus activity”Antimicrobial Agents and Chemotherapy53 (1): 186–92.doi:10.1128/AAC.00333-08PMC2612152PMID18955520.
  2.  Hayden F (January 2009). “Developing new antiviral agents for influenza treatment: what does the future hold?”. Clinical Infectious Diseases. 48. Suppl 1 (S1): S3–13.doi:10.1086/591851PMID19067613.
  3. http://www.biotapharma.com
  4. http://www.biotapharma.com/?page=1021001&subpage=1021019

5. T. Honda et al. Synthesis and in vivo influenza virus-inhibitory effect of ester prodrug of 4-guanidino-7-O-methyl-Neu5Ac2en, Bioorg Med Chem Lett 2009, 19(11): 2938

6. H. Ishizuka et al. J. Clin. Pharmacol. 2010, 50, 1319

7. H. Ishizuka et al. J. Clin. Pharmacol. 2010, epub ahead of print, doi 10.1177/0091270010361914

8. N. Sugaya and Y. Ohashi, Antimicrob. Ag. Chemother. 2010, 54, 2575

9 A. Watanabe et al. Clin. Inf. Dis. 2010, 51, 1167

A new route toward 2-acetamido-4-O-methyl-2-deoxy-D-mannopyranose from a Ferrier derivative of tri-O-acetyl-D-glucal, which contributes to aldolase-catalyzed synthesis of laninamivir (CS-8958)
Tetrahedron 2013, 39(37): 7931

Infection of poultry with H5N1 avian influenza virus has been expanding since 2003 in wide areas including Asia, Europe and Africa. Humans infected with this virus have been found not only in Asia but also in Middle East and Africa. If a new type of H5N1 influenza virus has appeared and its infection has started, it is believed that the infection will rapidly expand to cause a worldwide spread (i.e., influenza pandemic) because most people do not possess immunity against that virus and influenza viruses spread via droplet infection and airborne infection. More than half of human patients infected with H5N1 influenza virus have died so far. Thus, the virus is highly pathogenic. It is known that three influenza pandemics, the Spanish Flu, the Asian Flu and the Hong Kong Flu, occurred in the 20th century. In the Spanish Flu which caused the largest number of patients, it is estimated that about 20-40 million people died in the world and about 0.5 million people in Japan.

According to a report from Japanese Ministry of Health, Labour and Welfare made in November, 2005, if a new type influenza virus has spread, the number of patients who will consult medical doctors in Japan as a result of infection with that virus is estimated about 18-25 million. Further, when the pathogenicity of that new type influenza virus is severe, the number of inpatients is estimated about 0.2 million while the number of dead is estimated about 0.64 million. Therefore, not only health hazard but also significant influences upon social activities are feared.

Thus, a new type influenza can cause a highly severe disease. Early development of effective therapeutics is demanded.

Although it is reported that zanamivir (in particular, zanamivir hydrate) and oseltamivir (in particular, oseltamivir phosphate or oseltamivir carboxylate) which are influenza therapeutics with neuraminidase inhibitory activity show an inhibitory activity against H5N1 influenza virus, compounds with more excellent activity are desired (Non-Patent Document 1 or 2). Further, H5N1 influenza virus strains against which oseltamivir does not show any inhibitory activity (i.e., oseltamivir resistant virus strains) have been reported. Compounds which possess an inhibitory activity against these oseltamivir resistant H5N1 influenza virus strains are desired (Non-Patent Document 1 or 2).

Compounds represented by formula (I) are known to be useful as influenza therapeutics with neuraminidase inhibitory activity (Patent Documents 1 to 3). However, it has not been reported that these compounds have an inhibitory activity against H5N1 influenza virus. Further, the structures of the compounds represented by formula (I) resemble the structure of zanamivir but are completely different from the structure of oseltamivir.

Non-Patent Document 1: Nature, 2005, vol. 437, p. 1108

Non-Patent Document 2: N. Engl. J. Med., 2005, vol. 353, (25):2667-72
Patent Document 1: U.S. Pat. No. 6,340,702 (Japanese Patent No. 3209946)
Patent Document 2: U.S. Pat. No. 6,451,766 (Japanese Patent Publication No. Hei 10-109981)
Patent Document 3: U.S. Pat. No. 6,844,363 (Japanese Patent Publication No. 2002-012590)

Figure US20100204314A1-20100812-C00004

………………………

US20100204314

Preparation Example 1 5-Acetamido-4-guanidino-9-O-octanoyl-2,3,4,5-tetradeoxy-7-O-methyl-D-glycero-D-galacto-non-2-enopyranosoic acid

Figure US20100204314A1-20100812-C00005

(1) Diphenylmethyl 5-acetamido-4-(N,N-bis-t-butyloxycarbonyl)guanidino-9-O-octanoyl-2,3,4,5-tetradeoxy-7-O-methyl-D-glycero-D-galacto-non-2-enopyranosoate (3.46 g, 4.1 mmol) disclosed in Example 35 (i) of U.S. Pat. No. 6,340,702 (Japanese Patent No. 3209946) was dissolved in methylene chloride (27 ml) and trifluoroacetic acid (14 ml). The resultant solution was stirred at room temperature overnight. The reaction solution was concentrated to dryness under reduced pressure, followed by three cycles of azeotropic distillation to dryness with toluene (5 ml). The resultant oily material was dissolved in ethyl acetate (10 ml). The solution was poured into a saturated aqueous solution of sodium hydrogencarbonate (50 ml). The pH of the resultant solution was adjusted to 8.5 by addition of 20% aqueous solution of sodium carbonate. Then, the solution was stirred at room temperature for 3 hr and its pH was adjusted to 5.0 with hydrochloric acid (3 ml), followed by stirring at room temperature for another 1 hr. The solution was further stirred for 1 hr while ice-cooling. Subsequently, precipitating crystals were suction filtered and vacuum dried for 10 hr at an external temperature of 50° C. The resultant crystals were left in the air for one day to thereby yield the subject compound as a hydrate crystal (0.97 g; yield 51%).

Infrared Absorption Spectrum (KBr) ν max cm−1: 3412, 2929, 2856, 1676, 1401, 1320, 1285, 1205, 1137, 722.

1H Nuclear Magnetic Resonance Spectrum (400 MHz, CD3OD) δ ppm: 5.88 (1H, d, J=2.5 Hz), 4.45 (3H, m), 4.27 (1H, dd, J=10.0 Hz, 10.0 Hz), 4.15 (1H, m), 3.47 (21-1, m), 3.42 (3H, s), 2.37 (2H, t, J=7.4 Hz), 2.10 (3H, s), 1.31 (2H, m), 1.20-1.40 (8H, m), 0.85-0.95 (3H, m).

13C Nuclear Magnetic Resonance Spectrum (100 MHz, CD3OD) δ ppm: 176.5, 173.7, 164.7, 158.9, 146.7, 108.7, 80.1, 78.0, 69.3, 66.8, 61.4, 52.4, 35.1, 32.8, 30.2, 30.1, 26.0, 23.7, 22.8, 14.4.

(2) The subject compound was also obtained by the method described below.

5-Acetamido-4-guanidino-9-O-octanoyl-2,3,4,5-tetradeoxy-7-O-methyl-D-glycero-D-galacto-non-2-enopyranosoic acid trifluoroacetic acid salt (3.0 g, 5.1 mmol) disclosed in Example 35 (ii) of U.S. Pat. No. 6,340,702 (Japanese Patent No. 3209946) was subjected to reversed phase column chromatography [Cosmosil 75C 18PREP (nacalai tesque), 100 g] and eluted with methanol/water (0/1-1/1-2/1). Fractions containing the compound of interest were vacuum concentrated. The precipitating crystals were suction filtered and vacuum dried. The resultant crystals were left in the air for one day to thereby yield the subject compound as a hydrate crystal (1.2 g; yield 49%). The property data of the resultant compound were consistent with those of the compound obtained in (1) above.

Preparation Example 2 5-Acetamido-4-guanidino-2,3,4,5-tetradeoxy-7-O-methyl-D-glycero-D-galacto-non-2-enopyranosoic acid

Figure US20100204314A1-20100812-C00006

5-Acetamido-4-guanidino-2,3,4,5-tetradeoxy-7-O-methyl-D-glycero-D-galacto-non-2-enopyranosoic acid trifluoroacetic acid salt (3.0 g, 5.1 mmol) disclosed in Example 28 (viii) of U.S. Pat. No. 6,340,702 (Japanese Patent No. 3209946) was purified in an ion-exchange resin column [Dowex-50X; (i) water and (ii) 5% aqueous ammonium solution] and further purified by reversed phase column chromatography [Cosmosil 75C 18PREP (nacalai tesque); water]. Fractions containing the compound of interest were vacuum concentrated. The resultant solid was washed with methanol, filtered and dried to thereby yield the subject compound (1.43 g) as a colorless solid.

1H Nuclear Magnetic Resonance Spectrum (400 MHz, CD3OD) δ ppm: 5.64 (1H, d, J=2.0 Hz), 4.43 (2H, m), 4.22 (1H, dd, J=10.0 Hz, 10.0 Hz), 4.00 (1H, m), 3.85 (1H, dd, J=10.0 Hz, 2.4 Hz), 3.68 (1H, dd, J=10.0 Hz, 5.5 Hz), 3.58 (1H, m), 3.43 (3H, s).

………………………….

WO 2013089168

Figure JPOXMLDOC01-appb-C000008

Figure JPOXMLDOC01-appb-C000009

…………………………..

US8455659

Process W is known as a method for manufacturing a compound represented by the formula (Ia), which is embraced in a compound represented by the formula (I) or a pharmacologically acceptable salt thereof, (hereinafter also referred to as “compound (Ia)”; the same shall be applied with respect to other (Patent Document 1). In Process W, n-Hep represents a 1-heptyl group.

Figure US08455659-20130604-C00004
Figure US08455659-20130604-C00005

Process X is known as a method for manufacturing compound (Ib), which is embraced in compound (I) or a pharmacologically acceptable salt thereof (Patent Document 2). Compound (IVk) is a synthetic intermediate in Process W. In Process X, n-Hep represents a 1-heptyl group.

Figure US08455659-20130604-C00006

Process Y is known as a method for manufacturing compound (IIIa), which is a trifluoroacetic acid salt of compound (III) (Non-patent Document 1). The procedures from compound (IVc) to compound (IVe) and from compound (IVf) to compound (IVh) in Process Y are the same as in Process W.

Figure US08455659-20130604-C00007
Figure US08455659-20130604-C00008

Process Z is known as a method for manufacturing compound (IIIa), which is a trifluoroacetic acid salt of compound (III) (Non-patent Document 2). In Process Z, the procedure from compound (IVf) to compound (IVh) is the same as in Process W, and the procedure from compound (IVh) to compound (IIIa) is the same as in Process Y.

Figure US08455659-20130604-C00009
Figure US08455659-20130604-C00010

From the viewpoint of industrial production, the aforementioned Process W, Process Y, or Process Z could be improved in points such as the following:

Want to know everything on vir series

click

http://drugsynthesisint.blogspot.in/p/vir-series-hep-c-virus-22.html

AND

http://medcheminternational.blogspot.in/p/vir-series-hep-c-virus.html

update…………


:ACIE 10.1002/anie.201408138

Scheme zanamivir and Lanimiwei is based on N- acetylneuraminic acid as a starting material, the price is more expensive (ca.13000RMB / kg). Ma recently from Shanghai Institute of Organic Chemistry greatly researcher on ACIE published zanamivir, Lanimiwei and CS-8958 is more simple synthetic route. References: ACIE 10.1002 / anie.201408138

DARUNAVIR


DARUNAVIR

206361-99-1  CAS NO

[(1S,2R)-3-[[(4-Aminophenyl)sulfonyl] (2-methylpropyl)amino]-2-hydroxy-1-(phenylmethyl)propyl]carbamic acid (3R,3aS,6aR)-hexahydrofuro[2,3-b]furan-3-yl ester

M. P.:- 72-74 °C (dec)

MW: 547.66

Darunavir and processes for its preparation are disclosed in EP0715618, W09967417, EP1725566 and Bioorganic & Medicinal Chemistry Letters (2004), 14(4), 959-963.

J Med Chem. 2013 May 23;56(10):4017-27. doi: 10.1021/jm400231v

US20050250845 discloses various pseudopolymorphs of darunavir and processes for their preparation. According to this application, “pseudopolymorph” is defined as a crystalline form of a compound in which solvent molecules are incorporated in the lattice structure. The Form B disclosed in the patent application is a pseudopolymorph wherein water is used as solvent. The thermogravimetric experiments of the Form B shows weight loss of 3.4% in the temperature range 25-78°C (water), 5.1% in the temperature range 25-1 10°C (ethanol and water) and further 1.1% weight loss (ethanol) in temperature range 110-200° C. Further at the drying step the Form B showed about 5.6% weight loss. The obtained dried product was hygroscopic and it adsorbed up to 6.8% water at high relative humidity. Amorphous form of darunavir is disclosed in US20050250845 and the publication in J.Org. Chem. 2004, 69, 7822 – 7829.

US 7700645 patent disclosed amorphous Darunavir, various solvates of Darunavir including ethanolate and method for their preparation as well as their use as a medicament. Journal of Organic Chemistry 2004, 69, 7822-7829 disclosed amorphous Darunavir is obtained by purification with column chromatography in 2% methanol in chloroform as eluent. PCT publication WO2010086844A1 disclosed crystalline dimethylsulfoxide solvate and crystalline tetrahydrofuran solvate of darunavir. The publication also disclosed the amorphous darunavir having the IR spectrum with characteristic peaks at about 1454 and 1365 cm“1

PCT publication WO201 1083287A2 disclosed crystalline darunavir hydrate substantially free of any non aqueous solvent.

Drug information:- Darunavir is an Anti-microbial drug further classified as anti-viral agent of the class protease inhibitor. It is used either single or in combination with other drugs for the treatment of human immunodeficiency virus.

Darunavir (brand name Prezista, formerly known as TMC114) is a drug used to treat HIV infection. It is in the protease inhibitor class. Prezista is an OARAC recommended treatment option for treatment-naïve and treatment-experienced adults and adolescents.Developed by pharmaceutical company Tibotec, darunavir is named after Arun K. Ghosh, the chemist who discovered the molecule at the University of Illinois at Chicago. It was approved by the Food and Drug Administration (FDA) on June 23, 2006.[2]

Darunavir is a second-generation protease inhibitor (PIs), designed specifically to overcome problems with the older agents in this class, such as indinavir. Early PIs often have severe side effects and drug toxicities, require a high therapeutic dose, are costly to manufacture, and show a disturbing susceptibility to drug resistant mutations. Such mutations can develop in as little as a year of use, and effectively render the drugs useless.

Darunavir was designed to form robust interactions with the protease enzyme from many strains of HIV, including strains from treatment-experienced patients with multiple resistance mutations to PIs.

Darunavir received much attention at the time of its release, as it represents an important treatment option for patients with drug-resistant HIV. Patient advocacy groups pressured developer Tibotec not to follow the previous trend of releasing new drugs at prices higher than existing drugs in the same class. Darunavir was priced to match other common PIs already in use, such as the fixed-dose combination drug lopinavir/ritonavir.

PREZISTA (darunavir) is an inhibitor of the human immunodeficiency virus (HIV-1) protease.

PREZISTA (darunavir), in the form of darunavir ethanolate, has the following chemical name: [(1S,2R)-3-[[(4-aminophenyl)sulfonyl](2-methylpropyl)amino]-2-hydroxy-1-(phenylmethyl)propyl]-carbamic acid (3R,3aS,6aR)-hexahydrofuro[2,3-b]furan-3-yl ester monoethanolate. Its molecular formula is C27H37N3O7S • C2H5OH and its molecular weight is 593.73. Darunavir ethanolate has the following structural formula:

PREZISTA (darunavir) Structural Formula Illustration

Darunavir ethanolate is a white to off-white powder with a solubility of approximately 0.15 mg/mL in water at 20°C.

Patent
Country
Patent Number
Approved
Expires (estimated)
United States 7700645 2006-12-26 2026-12-26
United States 6335460 1992-08-25 2012-08-25
Canada 2469343 2008-05-13 2022-12-12
Canada 2224738 2002-08-27 2016-06-28
4-11-2012
METHODS FOR THE PREPARATION OF HEXAHYDROFURO[2,3-b]FURAN-3-OL
12-28-2011
Substituted Aminophenylsulfonamide Compounds as Hiv Protease Inhibitor
12-23-2011
POLYMORPHS OF DARUNAVIR
12-14-2011
METHODS FOR THE PREPARATION OF N-ISOBUTYL-N-(2-HYDROXY-3-AMINO-4-PHENYLBUTYL)-P-NITROBENZENESULFONYLAMIDE DERIVATIVES
11-30-2011
Protease inhibitor precursor synthesis
6-31-2011
PROCESS FOR THE PREPARATION OF (3R,3AS,6AR)-HEXAHYDROFURO [2,3-B] FURAN-3-YL (1S,2R)-3-[[(4-AMINOPHENYL) SULFONYL] (ISOBUTYL) AMINO]-1-BENZYL-2-HYDROXYPROPYLCARBAMATE
9-29-2010
Aminophenylsulfonamide Derivatives as Hiv Protease Inhibitor
8-11-2010
Process for the preparation of (3R,3aS,6aR)-hexahydrofuro [2,3-b] furan-3-yl (1S,2R)-3[[(4-aminophenyl) sulfonyl] (isobutyl) amino]-1-benzyl-2-hydroxypropylcarbamate
7-30-2010
RELATING TO ANTI-HIV TABLET FORMULATIONS
7-30-2010
COMBINATION FORMULATIONS
7-2-2010
METHODS AND INTERMEDIATES USEFUL IN THE SYNTHESIS OF HEXAHYDROFURO [2,3-B]FURAN-3-OL
5-7-2010
METHODS AND COMPOSITIONS FOR TREATING HIV INFECTIONS
4-21-2010
Pseudopolymorphic forms of a hiv protease inhibitor
9-21-2007
Immunoassays, Haptens, Immunogens and Antibodies for Anti-HIV Therapeutics
6-23-2006
Method for treating HIV infection through co-administration of tipranavir and darunavir
6-3-2005
Combination of cytochome p450 dependent protease inhibitors
Cited Patent Filing date Publication date Applicant Title
WO2010086844A1 Dec 8, 2009 Aug 5, 2010 Mapi Pharma Hk Limited Polymorphs of darunavir
WO2011048604A2 * Sep 16, 2010 Apr 28, 2011 Matrix Laboratories Limited An improved process for the preparation of darunavir
WO2011083287A2 Oct 6, 2010 Jul 14, 2011 Cipla Limited Darunavir polymorph and process for preparation thereof
CN102584844A * Jan 11, 2011 Jul 18, 2012 浙江九洲药业股份有限公司 Darunavir crystal form and method for preparing same
US6248775 Apr 8, 1999 Jun 19, 2001 G. D. Searle & Co. α- and β-amino acid hydroxyethylamino sulfonamides useful as retroviral protease inhibitors
US7700645 May 16, 2003 Apr 20, 2010 Tibotec Pharmaceuticals Ltd. Pseudopolymorphic forms of a HIV protease inhibitor
Reference
1 JOURNAL OF ORGANIC CHEMISTRY vol. 69, 2004, pages 7822 – 7829
2 * VAN GYSEGHEM E ET AL: “Solid state characterization of the anti-HIV drug TMC114: Interconversion of amorphous TMC114, TMC114 ethanolate and hydrate“, EUROPEAN JOURNAL OF PHARMACEUTICAL SCIENCES, ELSEVIER, AMSTERDAM, NL, vol. 38, no. 5, 8 December 2009 (2009-12-08), pages 489-497, XP026764329, ISSN: 0928-0987, DOI: 10.1016/J.EJPS.2009.09.013 [retrieved on 2009-09-24]

Virus-encoded proteases, which are essential for viral replication, are required for the processing of viral protein precursors. Interference with the processing of protein precursors inhibits the formation of infectious virions. Accordingly, inhibitors of viral proteases may be used to prevent or treat chronic and acute viral infections. Darunavir has HIV protease inhibitory activity and is particularly well suited for inhibiting HIV-I and HIV -2 viruses. Darunavir, chemically (1 S^R.S’R.S’aS.e’aRJ-fS’he ahydrofuro^.S-b ]furanyl-[3-( 4-aminobenzenesulfonyl)isobutylamino [- 1-benzyl-zhydroxypropyl]carbamate. Darunavir is represented by the following structure:

Darunavir and its pharmaceutically acceptable salts were disclosed in US 6248775 patent, wherein Darunavir is prepared by condensing 2R-hydroxy-3-[[(4-aminophenyl)sulfonyl](2- methylpropyl)amino]-1S(phenylmethyl)propylamine with hexahydro-furo[2,3-b]furan-3-ol in anhydrous acetonitrile in the presence of anhydrous pyridine and Ν,Ν’-disuccinimidyl carbonate at ambient temperature.

US 7700645 patent disclosed amorphous Darunavir, various solvates of Darunavir including ethanolate and method for their preparation as well as their use as a medicament. Journal of Organic Chemistry 2004, 69, 7822-7829 disclosed amorphous Darunavir is obtained by purification with column chromatography in 2% methanol in chloroform as eluent. PCT publication WO2010086844A1 disclosed crystalline dimethylsulfoxide solvate and crystalline tetrahydrofuran solvate of darunavir. The publication also disclosed the amorphous darunavir having the IR spectrum with characteristic peaks at about 1454 and 1365 cm“1

PCT publication WO201 1083287A2 disclosed crystalline darunavir hydrate substantially free of any non aqueous solvent.

Darunavir Ethanolate, has the chemical name: [(1 S, 2R)-3-[[(4-aminophenyl) sulfonyl](2- methylpropyl)amino]-2-hydroxy-1-(phenylmethyl)propyl]carbamic acid (3/?, 3aS, 6a/?)- hexahydrofuro[2,3-i>]furan-3-yl ester monoethanolate and has the following structural formula:

Darunavir and its process are first disclosed in US 6248775, wherein 2 ?-hydroxy-3-[[(4- aminophenyl)sulfonyl](2-methylpropyl)amino]-1 S(phenylmethyl) propylamine (4) is reacted with (3R, 3aS, 6aR)-hexahydrofuro[2,3- >]furan-3-ol in anhydrous acetonitrile in the presence of N, W-disuccinimidyl carbonate, anhydrous pyridine at ambient temperature followed by workup to get Darunavir (Scheme A).

Scheme A

Darunavir

US 20050250845 disclosed the various solvates of Darunavir including ethanolate and method for their preparation as well as their use as a medicament. The same application disclosed the amorphous Darunavir by Raman spectra without process details.

WO 2005063770 discloses process for the preparation of Darunavir ethanolate, wherein 2R-hydroxy-3-[[(4-aminophenyl)sulfonyl](2-methylpropyl)amino]-1 S-(phenylmethyl)propyl amine (4) is reacted with (3R, 3aS, 6a ?)-hexahydrofuro[2,3-b]furan-3-ol in the presence of N, /V-disuccinimidyl carbonate, triethylamine, 41% methylamine in ethanol in a mixture of ethyl acetate and acetonitrile followed by workup and crystallization from ethanol to get Darunavir ethanolate (Scheme B).

Scheme B

In the prior art process, compound of formula 4 condensed with (3/?, 3aS, 6aR)- hexahydrofuro[2,3-6]furan-3-ol in large excess of solvent or solvent mixture containing large excess of base or mixture of bases to get Darunavir. Further, the obtained products by the processes described in the prior art are not satisfactory, from purity point of view. We have repeated the Darunavir synthetic procedures as described in the prior art and found that relatively large amounts of impurities were obtained along with Darunavir (Table-1) which need repeated crystallizations in different solvents to get desired quality of the final product resulting in poor yields. Among other impurities, the carbonic acid [(1/?,2S)-1-{((4-amino-benzenesulfonyl)-isobutyl-amino)-methyl}-2-((3R,3aSI6aR)- hexahydro-furot2,3-/3]furan-3-yloxycarbonylamino)-3-phenyl-propylester (3R,3aS,6aR)- hexahydro-furo[2,3-ft]furan-3-yl ester (difuranyl impurity of formula 1) is identified.

Conditions:-

i. Phenyl magnesium bromide, Cuprous cyanide, tetrahydrofuran, 23 °C, 1 h,

ii. t-Butyl hydroperoxide, titanium tetraisopropoxide, diethyl D-tartrate, dichloromethane, -22 °C, 24 h,

iii. Azidotrimethylsilane, titanium tetraisopropoxide, Benzene, reflux, 25 min,

iv. 2-Acetoxyisobutyryl chloride, Chloroform, 23 °C, 8 h,

v. Isobutyl amine, isopropanol, 80 °C, 12 h,

vi 4-aminobenzenesulfonyl chloride, aq. Sodium bicarbonate, dichloromethane, 23 °C, 12 h,

vii. 10% palladium on carbon, hydrogen gas (50 psi), methanol, acetic acid, tetrahydrofuran, room temperature, 2 h,

viii. [3R, 3aS,6aS]-3-hydroxyhexahydrofuro[2,3-b]-furan, disuccanamidyl carbonate, triethylamine, acetonitrile, 23 °C, 12 h

Schematic Representation for Synthesis of Darunavir

Preparation of Darunavir is described in US patent 05,158,713, and also in WO9967417 and WO9967254. Accordingly, 2-vinyloxirane 1 on reacting with phenyl magnesium bromide in presence of tetrahydrofuran solvent and cuprous cyanide catalyst give 4-phenylbut-2-ene-1-ol 2. Oxidizing 2 with t-Butyl hydroperoxide in presence of titanium tetraisopropoxide and diethyl D-tartrate using dichloromethane as solvent give [(3S)-3-benzyloxiran-2-yl]methanol 3.

Heating 3 with azidotrimethylsilane in presence of titanium tetraisopropoxide using benzene as solvent give (2S,3S)-3-azido-4-phenyl-butane-1,2-diol 4. The 1,2-dipl compound 4 underwent cyclization when treated with 2-acetoxyisobutyryl chloride in chloroform give (2S)-2-[(1S)-1-azido-2-phenyl-ethyl]oxirane 5, which was further heating with isobutylamine and isopropanol at higher temperature give (2R,3S)-3-azido-1-(isobutylamino)-4-phenyl-butan-2-ol 6. Compound 6 was reacted with 4-aminobenzenesulfonyl chloride in presence of aq. Sodium bicarbonate as base and dichloromethane as solvent resulting in to 4-amino-N-[(2R,3S)-3-azido-2-hydroxy-4-phenyl-butyl]-N-isobutyl-benzenesulfonamide 7.

Hydrogenating 7 with 10% palladium on carbon catalyst using hydrogen gas (50 psi) in methanol and tetrahydrofuran solvent in presence of small amount of acetic acid at ambient temperature resulted in to 4-amino-N-[(2R,3S)-3-amino-2-hydroxy-4-phenyl-butyl]-N-isobutyl-benzenesulfonamide 8. The final step involves reacting 8 with [3R,3aS,6aS]-3-hydroxyhexahydrofuro[2,3-b]-furan and disuccanamidyl carbonate in presence of triethylamine base and acetonitrile as solvent afford [(1S,2R)-3-[[(4-Aminophenyl)sulfonyl] (2-methylpropyl)amino]-2-hydroxy-1-(phenylmethyl)propyl]carbamic acid (3R,3aS,6aR)-hexahydrofuro[2,3-b]furan-3-yl ester also called Darunavir 9.

…………………………

http://www.google.com/patents/WO2013114382A1?cl=en

process for the preparation of amorphous Darunavir is as

Process for the preparation of intermediate 2 is as shown in below scheme.

Examples

Example -1 : Preparation of [(1S, 2S)-3-chloro-2-hydroxy-1-(phenyl methyl) propyl] carbamic acid tert-butyl ester (5).

The solution of (3S)-3-(tert-butoxycarbonyl) amino-1-chloro-4-phenyl-2-butanone (Chloromethyl ketone 6,100 g) and aluminium isopropoxide (35 g) in isoprpylalcohol was heated to mild reflux and maintained for 3 hours. After completion of reaction distilled off isopropyl alcohol up to 50 % under vacuum and the resultant mass was cooled to 25-35°C. Water was added to the distillate, pH was adjusted to 3.0-4.0 with acetic acid and maintained the stirring for 2 hours at 25-35°C. The obtained solid was filtered and washed with water. The wet cake was taken into isopropyl alcohol (400mL) and heated to reflux for 60minutes, the mass was cooled to 25-35°C again maintain the stirring for 60minutes, the obtained solid was filtered and washed with isopropyl alcohol. The wet product was dried under normal drying to get title compound 5 (yield 80 g). Example -2: Preparation of [(1 S, 2R)-3-[(2-methylpropyl) amino]-2-hydroxy-1- (phenylmethyl) propyl] carbamic acid tert-butyl ester (4).

The mixture of [(1S, 2S)-3-chloro-2-hydroxy-1-(phenylmethyl) propyl] carbamic acid tert-butyl ester (5,100 g), isobutyl amine (294 g), sodium carbonate (31.3 g) and water was heated to 60 – 65°C and maintained for 3hours. After completion of reaction water (200 mL) was added and distilled out excess isobutyl amine under vacuum at below 75°C. Water (800 mL) was added to the distillate, cooled to 25-35°C and stirred for 2 hours. The obtained solid was filtered and washed with water to get title compound 4 (yield 105 g).

Example -3: Preparation of [(1S, 2R)-3-[[(4-nitrophenyl) sulfonyl] (2-methylpropyl) amino]- 2-hydroxy-1-(phenylmethyl) propyl] carbmic acid tert-butylester (3).

[(1 S, 2R)-3-[(2-methylpropyl) amino]-2-hydroxy-1 -(phenyl methyl) propyl] carbamic acid tert-butyl ester (4, 100 gm) and triethylamine (39.04 g) was added to methylenedichloride (1200 mL) and the temperature was raised to 40°C. p-nitro benzene sulfonyl chloride solution (72.3g of p-NBSC dissolve in 300mL methylenedichloride) was added slowly at 40-45°C for 2-3 hrs. The reaction was maintained for 3hours at 40 – 45°C. After completion of the reaction, water (500 mL) was added, separated the organic layer and distilled out methylene dichloride at atmospheric pressure. Finally, strip out the methylene dichloride by using isopropyl alcohol (200 mL). Isopropyl alcohol (1000 mL) was added to the distillate and maintained the stirring for 60 minutes at 70- 80°C. Cooled the mass to 30 – 35°C, filtered and washed with Isopropyl alcohol to get title compound 3 (yield 145 g). Example – 4: Preparation of 4-Amino-N-(2R, 3S) (3-amino-2-hydroxy-4-phenylbutyl)-N- isobutyl-benzene sulfonamide (1).

(1S, 2R)-{1-benzyl-2-hydroxy-3-[isobutyl-(4-nitro-benzenesulfonyl)-amino]-propyl}-carbamic acid tert-butyl ester (3, 100g), 10% palladium carbon (10gm) and triethanolamine (2gm) were suspended in isopropyl alcohol. The reaction was heated to 40 – 45°C and maintained under 4 – 6kg/cm2 of hydrogen pressure for 3 hours. After completion of reaction, the mass was filtered and hydrochloric acid (70mL) was added to the filtered mass. The solution was heated to reflux and maintained for 2-3hours. After completion of reaction the mass was cooled to 25-35°C, the reaction mass pH was adjusted to 6.0 – 7.0 with 20% sodium hydroxide solution and distilled out isopropyl alcohol under vacuum at below 55°C. Ethanol (200mL) and water (400mL) was added to the distillate, the mass pH was adjusted to 9.0 – 10.0 with 20% sodium hydroxide solution at 25-35°C and maintained the stirring for 2 hours at 25-35°C. The mass was cooled to 0 – 5°C, filtered and wash with water. The wet product was taken into ethanol (350mL), maintained the stirring for 30minutes at reflux temperature. The mass was cooled to 2 – 4°C, stirred for 2 hours, filtered and washed with ethanol (50 mL). The wet product was dried under normal drying to get title compound 1 (Yield 60 g).

Example-5: Preparation of ethyl-2-(4,5-dihydrofuran-3-yl)-2-oxoacetate (VI).

2, 3-Dihydrofuran (250 g) was taken in toluene (2000 mL) and triethyl amine (505 g) was added to above solution. Ethyl oxalyl chloride (536.5 g) was slowly added to the above mixture by maintaining temperature at 25-30°C and maintained the stirring for 5 hours. After completion of reaction separated the organic layer, washed the organic layer with 8% sodium bicarbonate solution (2x500mL). Organic layer was distilled completely under vacuum to get title compound VI (Yield 560g).

1 H NMR : 1.38 (t, 3H), 2.93 (t, 2H), 4.34 (q, 2H), 4.63 (t, 2H), 8.02 (s, 1 H).

Example-6: Preparation of ethyl-2-(3-bromo-2-ethoxytetrahydrofuran-3-yl)-2-oxoacetate (V).

Ethyl-2-(4,5-dihydrofuran-3-yl)-2-oxoacetate (Vl, 100g) was dissolved in dichloromethane (500ml) and Ethanol (150mL) was added. The reaction mass was cooled to 5 to 10°C. N- bromosuccinimide (1 15 g) was added lot wise by maintaining temp below 10°C. Reaction mass was then stirred at 20-30°C till completion of reaction. Reaction mass was washed with sodium bicarbonate solution (2%, 3x400mL) and the organic layer was used for the next step.

Example-7: Preparation of hexahydrofuro [2, 3-b] furan-3-ol (IV).

To the solution of Ethyl-2-(3-bromo-2-ethoxy tetra hydrofuran-3-yl)-2-oxoacetate in dichloromethane (V, 500mL) as prepared in above example, sodium sulphite solution (225g was dissolved in 1700mL of water) was added at 25-35°C. Reaction mass was stirred for 5-8hours at the same temperature and separated the organic and aqueous layers. Organic layer was washed with water (340mL). Distilled out the solvent completely get ethyl-2-(2-ethoxy tetra hydrofuran-3- yl)-2-oxoacetate. Sodium borohydride (35.5g)was dissolved in ethanol (400mL) under nitrogen atmosphere, ethyl-2-(2-ethoxytetra hydrofuran-3-yl)-2-oxoacetate was dissolved in ethanol (100mL) and slowly added to above solution at 15-30°C. Reaction mass was heated to 30-45X, maintained for 5-8 hours, the reaction mass temperature was raised to 55°C and stirred for 8 hours. The reaction mass was cooled to 20-30°C, ammonium chloride solution (1 5g in 200mL water) was slowly added and stirred for 1-2hours. The reaction mass was filtered and filtrate was distilled out under vacuum to get residue. Dichloromethane (600mL) was added to residue and cooled to -10°C. Hydrochloric acid (85mL) was added slowly drop wise in 2 hours by maintaining temp -5 to 0°C, reaction mass was stirred for 60minutes at -5 to 0°C and distilled the solvent completely. The obtained residue was stripped out with isopropyl alcohol (2x200mL, 1x100mL), ethyl acetate (500mL) was added to the resultant residue, stirred for 30-60minutes and cooled to 10-15°C. The solution was filtered and filtrate was concentrated to get title compound IV (yield 56 g).

Example-8: Preparation of Hexahydrofuro [2, 3-b] furan-3-yl acetate (III).

Hexahydrofuro [2, 3-b] furan-3-ol (IV, 60g) was dissolved in dichloromethane (300mL) and cooled to 0-5°C. To the cooled solution triethylamine (58.2 g), N, N-dimethylaminopyridine (1.12g) was added, acetic anhydride (56.5g) was added for 30-60 minutes at the same temperature, the mass temperature was raised to 25-35°C and stirred for 2-4hours. After completion of reaction the mass was cooled to 10-20°C, water (120mL) was added, stirred for 30minutes, separated the organic layer, washed with 10% sodium chloride solution (120mL) and distilled out dichloromethane to get title compound (yield 72g). Further, the product was purified by fractional distillation to get pure Hexahydrofuro [2, 3-b] furan-3-yl acetate III (yield 54g).

1 H NMR : 1.9-2.09(m, 2H), 2.10(s, 3H), 3.0-3.1 (m, 1 H), 3.86-4.03(m, 2H), 3.73(dd, 1 H), 4.10(dd, 1 H), 5.19(m, 1 H), 5.72 (d, 1 H)

Example-9: Preparation of (3R, 3aS, 6aR)-Hexahydrofuro [2, 3-b] furan-3-yl acetate (II). To the buffer solution (104.3g of sodium dihydrogen orthophosphate dissolved in 530mL of water & pH adjusted to 6.0-6.5 with saturated sodium bicarbonate solution(68g in 680 mL water) solution) hexahydrofuro [2, 3-b] furan-3-yl acetate (111,115g) and CAL-B (17.25g) was added at 25-35°C, heated to 38-45°C and stirred for 24 hours. CAL-B (17.25g) was added stirred for 16 hours, again CAL- B (11.5g) was added at 38-45°C and stirred for 16 hours (pH should maintain 6.0-6.5). The reaction mass was cooled to 20-30°C, methylenedichloride (1 150mL) was added to the mass and stirred for 30 minutes. The reaction mass was filtered through hyflowbed then separated the organic layer and washed with 10%sodiumchloride solution (575mL). Organic layer was distilled completely under vacuum to get title compound II (yield 40. Og). Example-10: Preparation of (3R, 3aS, 6aR)-Hexahydrofuro [2, 3-b] furan-3-ol (I).

(3R, 3aS, 6aR)-Hexahydrofuro [2, 3-b] furan-3-yl acetate (II, 14.0g) was dissolved in methanol (42mL). Potassium carbonate (0.34g) was added and stirred at 25-35°C for 6-8hours. Methanol was distilled out completely under vacuum, to the distillate methylenedichloride (28mL) was added, stirred the mass for 30 minutes and again distilled the solvent to get residue. Dissolved the residue in dichloromethane (56mL), the resultant solution was treated with carbon and the solvent was completely distilled out get title compound I (yield 10.5g). Example-11 : Preparation of (3R, 3aS, 6aR)-Hexahydrofuro [2, 3-b]-furan-3-yl-4-nitrophenyl carbonate (2).

To the solution of (3R, 3aS, 6aR)-Hexahydrofuro [2, 3-b] furan-3-ol (l,100g) and Bis-nitrophenyl carbonate (257.2g) in methylene dichloride (1200mL), triethylamine solution (132 g in 300 mL of methylene dichloride) was added slowly at 20-30°C for 2-3hours. Maintained the reaction at the same temperature for 8-10hours, after completion of reaction water (500mL) was added for 30- 60minut.es and settled the reaction mass then separated the organic layer. Organic layer was washed with 10% acetic acid (100mL) and 10% sodium chloride solution (500mL), distilled the organic layer and co distilled with ethyl acetate (100mL). Ethyl acetate (300mL) was added to the distillate and heated to 50-55°C for 30-45minut.es to get clear solution, the solution was cooled to 5-10°C and maintained at the same temperature for 60 minutes. The obtained solid was filtered, washed with ethanol (100mL) and dried the wet material at 40-45°C for 10-14 hours to get title compound 2 (yield 160g). Example-12: Preparation of dimethylformamide solvate of Darunavir.

To a mixture of 4-amino-N-(2r,3S)(3-amino-2-hydroxy-4-phenylbutyl)-N-lsobutyl- benzenesulfonamide (1 ,25g) and N-methyl-2-pyrrolidinone (NMPO, 50mL), a solution of (3R,3aS,6aR)-Hexahydrofuro[2,3-b]-furan-3-yl-4-nitrophenyl carbonate (2, 8.85g) and N-methyl- 2-pyrrolidinone (75mL) was added at -5 to 0°C for 2 to 3 hours under nitrogen atmosphere. The mass temperature was slowly raised to 25 to 30°C and stirred for 6 to 8 hours. The reaction mass was quenched in to the solution of methylene chloride (125mL) and water (250mL) at 25-35°C for 30 to 45 minutes. Separated the organic layer followed by washed with 10% sodium carbonate solution (150mL), 10% sodium chloride solution (150mL) and with water (6x150mL). Organic layer was dried over sodium sulphate and distill off the solvent under vacuum at below 50°C to obtain darunavir as a residue. To the residue Ν,Ν-dimethyl formamide (50mL) was added and cooled to 0 to -5°C, water (25mL) was added to the solution and maintained for 12hours at 0 to -5 °C, the obtained solid was filtered and washed with pre-cooled mixture of N,N-dimethyl formamide & water (25mL+25mL) to get dimethylformamide solvate of darunavir.

Example-13: Preparation of non-solvated crystalline Darunavir.

To a mixture of 4-amino-N-(2r,3S)(3-amino-2-hydroxy-4-phenylbutyl)-N-lsobutyl- benzenesulfonamide (1, 25g) and N-methyl-2-pyrrolidinone (NMPO, 50mL), a solution of (3R,3aS,6aR)-Hexahydrofuro[2,3-b]-furan-3-yl-4-nitrophenyl carbonate (2, 18.85g) and N- methyl-2-pyrrolidinone (75mL) was added at -5 – 0°C for 2 to 3 hours under nitrogen atmosphere. The mass temperature was slowly raised to 25 – 30°C and stirred for 6 to 8 hours. The reaction mass was quenched in to the solution of methylene chloride (250mL) and water (250mL) at 25- 35°C for 30 – 45 minutes. Separated the organic layer followed by washed with 10% potassium carbonate solution (5x125mL), water (5x125mL), 20% sodium chloride solution (25mL), finally washed with 20% citric acid solution (125mL). The organic layer was treated with carbon and distilled off the solvent under vacuum at below 50°C to obtain darunavir as a residue. To the residue ethylacetate (250mL) was added and cooled to 0 to -5°C, to the cooled solution hexane (225mL) was added and maintained for 12hours at 0 to -5 °C, the obtained solid was filtered, washed with pre-cooled mixture of ethylacetate and hexane (25mL+25mL) and dried the compound to get non-solvated crystalline darunavir(yield 25g).

Example -14: Preparation of Amorphous Darunavir.

Darunavir (200g) as obtained in above example was dissolved in methylene dichloride (10L) and washed with water (3×1000 mL). Organic layer was taken into agitated thin film dryer (ATFD) feed tank. Applied initial temperature about 36 – 40°C and high vacuum (580mm/Hg) to the vessel. Slowly feed the solution to the Vessel (feed rate 5L r) over 1hour finally given the methylene chloride (3L) flushing. The material is collected in the material collecter. Dried at 58 -62°C for 40 hours to get amorphous darunavir (yield 160g).

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http://www.google.com/patents/WO2011048604A2?cl=en

Figure imgf000010_0001

Preparation of Durumvir ethanolate

A solution of (3R,3aS,6a ?)-hexahydrofuro[2,3-D]furan-3-yl 4-nitrophenyl carbonate (5b, 75.4 g) in A -methyl-2-pyrrolidinone (300 mL) was added to a pre-cooled (-2 ± 2°C) solution of the compound of formula 4 (100 g) in W-methyl-2-pyrrolidinone (200 mL) at -4 to 0°C over a period of 2 h. The temperature of the reaction mass was slowly raised to 25 – 30°C and maintained for 8 h. After completion of the reaction (TLC monitoring), ethyl acetate (1000 mL) and purified water (500 mL) were added to the reaction mass. The layers were separated; organic layer was washed with sodium carbonate solution (2 X 500 mL) followed by sodium chloride solution. The organic layer was concentrated; ethanol (300 mL) was added, heated to 45 – 50°C, maintained for 1 h, filtered and washed with ethanol. The wet compound was taken into a mixture of ethyl acetate- ethanol (7:93, 600 mL), heated to reflux, charcoal was added and filtered. The resultant filtrate was cooled to 0 – 5°C, filtered the separated solid and washed with ethanol. The wet compound was dried at 45°C to obtain the in 124.3 g (yield-82.5%). The obtained Darunavir ethanolate had purity of 99.79% on area by HPLC and contained 0.08% on area by HPLC of the difuranyl impurity. Preparation of Amorphous Darunavir

Example – 4

A solution of Darunavir ethanolate (200 g) in dichloromethane (10 L) was taken into ATFD Feed tank. The solvent was evaporated by fed the solution slowly to the ATFD Vessel (feed rate 5 L /h) at 36 – 40°C and high vacuum (580 mm/Hg) over 2 h and then flushed with dichloromethane (3 L). The material is collected in the material collector in 160g with the HPLC Purity of 99.60% and particle size D50 of approximately 50 micrometers and Dgo of approximately 100 to 180 micrometers. Example-5

Darunavir Ethanolate (200 gm) was dissolved in Methylene chloride (1000 ml) and solvent was evaporated by applying vacuum followed by isolation of amorphous Darunavir as a solid as such or by charging n-Heptane or Isopropyl ether. Example – 6

Darunavir Ethanolate (10 g) was dissolved in ethyl acetate (50 mL). The solution was heated to 40 – 45°C and maintained for 30 min. Ethyl acetate was distilled off under vacuum completely to get residue in the form of semisolid. n-Heptane (50 mL) was added to the residue and stirred for 30 min. at ambient temperature. The separated solid was filtered, washed the wet cake with n-heptane (5 mL) and dried at 40 – 45°C under vacuum to get 8.0 g of amorphous Darunavir.

Example – 7

Darunavir Ethanolate (10 g) was placed into a dry round bottom flask and heated to 110 – 120°C to melt and maintained under vacuum for 4 h. The reaction mass was slowly cooled to 25 – 35°C. The obtained glass type crystal was broken into powder to afford 8.5 g of amorphous Darunavir.

Example – 8

Darunavir Ethanolate (5.0 g) was suspended into glycerol (25 g), heated to 110 – 120°C under vacuum and maintained for 30min. Water (50 mL) was added to the cooled reaction mass at 25 – 35°C under stirring and the obtained suspension was stirred for 30 min at 25 – 35°C. The separated solid was filtered and dried at 40 – 45°C under vacuum to yield 3.5 g of amorphous Darunavir. Example – 9

Carbonic acid [(1 R,2S)-1-{((4-amino-benzenesulfonyl)-isobutyl-amino)-methyl}-2- ((3/?,3aS,6aR)-hexahydro-furo[2,3-ft]furan-3-yloxycarbonylamino)-3-phenyl-propylester (3R,3aS,6a ?)-hexahydro-furo[2,3- )]furan-3-yl ester (difuranyl impurity, 1).

The difuranyl impurity (1) isolated from the mother liquor by preparative HPLC using a mixture of formic acid-water (1 :99) as eluent. The 1H-NMR, 13C-NMR and mass spectral data complies with proposed structure.

1H-NMR (DMSO-cfe, 300 MHz, ppm) – δ 0.79 (d, J=6.6 Hz, 6H, 15 & 15′), 1.14-1.20 (m, 1 H, 20Ha), 1.34-1.42 (m, 1 H, 20Hb), 1.75-1.85 (m, 2H, 20’Ha & 14), 1.94-2.01(m, 1 H, 20’Hb), 2.54-2.64 (m, 2H, 8Ha & 13Ha), 2.74-2.89 (m, 3H, 8Hb, 13Hb & 19), 3.00-3.11 (m, 2H, 5Ha & 19′), 3.34-3.39 (m, 1H, 5Hb), 3.54-2.63 (m, 3H, 21 Ha & 17Ha), 3.65-3.74 (m, 3H, 21’Ha, 21 Hb &17Hb), 3.81-3.89 (m, 2H, 21’Hb & 17’Ha), 3.94-4.04 (m, 2H, 7 & 17’Hb), 4.81-4.88 (m, 1 H, 6), 4.92-4.96 (m, 1 H, 18′), 5.03-5.10 (m, 1 H, 18), 5.11 (d, J=5.4 Hz, 1 H, 22′), 5.61 (d, J=5.1 Hz, 1 H, 22), 6.03 (brs, 2H, NH2, D20 exchangeable), 6.63 (d, J=8.7 Hz, 2H, 2 & 2″), 7.15-7.28 (m, 5H, 10H, 10Ή, 11 H, 11′ & 12), 7.40 (d, J=8.7 Hz, 2H, 3 & 3′), 7.55 (d, J=9.3 Hz, 1 H, NH, D20 exchangeable).

“H-NMR (DMSO-d6, 75 MHz, ppm)- δ 19.56 & 19.81 (15C & 15’C), 25.42 (20 ), 25.47 (20C), 26.28 (14C), 35.14 (8C), 44.45(19’C), 45.01 (19C), 49.21 (5C), 53.39 (7C), 57.55 (13C), 68.70 (21 ‘C), 68.74 (21C), 69.95 (17’C), 70.20(17C), 72.65 (6C), 76.27 (18C), 79.59 (18’C), 108.70 (22’C), 108.75 (22C), 112.69 (2C), 122.56 (4C), 126.12 (12C), 128.04 (11 C & 11’C), 129.03 (10C & 10’C), 129.08 (3C), 138.03 (9C), 152.99 (1C), 153.55 (16’C), 155.32 (16C).

DIP MS: m/z (%) 1108 [M+Hf, 1131 [M+Naf

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http://www.google.com/patents/US20130244297

Figure US20130244297A1-20130919-C00025

According to the present invention Darunavir having the below impurity not more than 0.1, preferably 0.05%.

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DARUNAVIR

Zosuquidar


LY335979(Zosuquidar)

LY335979, RS-33295-198  (Zosuquidar)

Roche Palo Alto (Originator)

LY335979 (Zosuquidar) is a selective Pgp (P-glycoprotein) inhibitor with a Ki of 59 nM. LY335979 significantly enhanced the survival of mice implanted with Pgp-expressing murine leukemia (P388/ADR) when administered in combination with either daunorubicin, doxorubicin or etoposide.


LY335979 (Zosuquidar)

M.Wt: 636.99

Formula: C32H31F2N3O2.3HCl

Name: Zosuquidar trihydrochloride

 Elemental Analysis: C, 60.34; H, 5.38; Cl, 16.70; F, 5.97; N, 6.60; O, 5.02

CAS : 167465-36-3

167354-41-8 (free base)

Roche Bioscience (Originator), Eli Lilly and Company (Licensee).

US5654304WO1994024107A1WO2000075121US6570016

Drug Des Discov 1992, 9(1): 69, Bioorg Med Chem Lett 1995, 5(21): 2473, Drugs Fut 2003, 28(2): 125

Zosuquidar is currently under development. It is now in “Phase 3” of clinical tests in the United States. Its action mechanism consists of the inhibition of P-glycoproteins; other drugs with this mechanism include tariquidar and laniquidar. P-glycoproteins are proteins which convert the energy derived from the hydrolysis of ATP to structural changes in protein molecules, in order to perform coupling, thus discharging medicine from cells. If P-glycoprotein coded with the MDR1 gene manifests itself in cancer cells, it discharges much of the antineoplastic drugs from the cells, making cancer cells medicine tolerant, and rendering antineoplastic drugs ineffective. This protein also manifests itself in normal organs not affected by the cancer (such as the liver, small intestine, and skin cells in blood vessels of the brain), and participates in the transportation of medicine. The compound Zosuquidar inhibits this P-glycoprotein, causing the cancer cells to lose their medicine tolerance, and making antineoplastic drugs effective

Clinicial trials: Clinical report published in 2010 showed that  zosuquidar did not improve outcome in older acute myeloid leukemia, in part, because of the presence P-gp independent mechanisms of resistance. (Blood. 2010 Nov 18;116(20):4077-85.)

Zosuquidar  is a potent P-glycoprotein inhibitor, which binds with high affinity to P-glycoprotein and inhibits P-glycoprotein-mediated multidrug resistance (MDR). P-glycoprotein, encoded by the MDR-1 gene, is a member of the ATP-binding cassette superfamily of transmembrane transporters and prevents the intracellular accumulation of many natural product-derived cytotoxic agents

Zosuquidar

U.S. Patent No. 5,112,817 to Fukazawa et al. discloses certain quinoline derivatives useful as anticancer drug potentiators for the treatment of multidrug resistance. One of the initially promising active agents there-disclosed is MS-073, which has the following structure:

Figure imgf000004_0001

MS-073

U.S. Pat. Nos. 5,643,909 and 5,654,304 disclose a series of 10,11- methanobenzosuberane derivatives useful in enhancing the efficacy of existing cancer chemotherapeutics and for treating multidrug resistance. One such derivative having good activity, oral bioavailability, and stability, is zosuquidar, a compound of formula (2R)-anti-5-

3 – [4-( 10, 11 -difluoromethanodibenzosuber-5-yl)piperazin- 1 -yl]-2-hydroxypropoxy) quinoline.

Figure imgf000010_0001

Zosuquidar

Given the limitations of previous generations of MDR modulators, three preclinical critical success factors were identified and met for zosuquidar: 1) it is a potent inhibitor of P-glycoprotein; 2) it is selective for P-glycoprotein; and 3) no pharmacokinetic interaction with co-administered chemotherapy is observed.

Zosuquidar is extremely potent in vitro (Kj = 59 nM) and is among the most active modulators of P-gp-associated resistance described to date. Zosuquidar has also demonstrated good in vivo activity in preclinical animal studies. In addition, the compound does not appear to be a substrate for P-gp efflux, resulting in a relatively long duration of reversal activity in resistant cells even after the modulator has been withdrawn.

Another significant attribute of zosuquidar as an MDR modulator is the minimal pharmacokinetic (PK) interactions with several oncolytics tested in preclinical models. Such minimal PK interaction permits normal doses of oncolytics to be administered and also a more straightforward interpretation of the clinical results.

Zosuquidar is generally administered in the form of the trihydrochloride salt. Conventional zosuquidar trihydrochloride formulations include those containing zosuquidar (50 mg as free base), glycine (15 mg), and mannitol (200 mg) dissolved in enough water for injection, to yield a free base concentration of 5 mg/mL. The formulation is filled into vials and lyophilized to give a vial containing 50 mg of free base. For such formulations, a 30 mL vial size is necessary to contain 50 mg of thezosuquidar formulation. For a typical >200 mg dose of zosuquidar, multiple 50 mg vials are needed to contain the formulation, greatly increasing manufacturing costs and reducing convenience for the end user {e.g., a pharmacist). Modified Cyclodextrins

Cyclodextrins are cyclic oligomers of glucose; these compounds form inclusion complexes with any drug whose molecule can fit into the lipophile-seeking cavities of the cyclodextrin molecule. See U.S. Pat. No. 4,727,064 for a description of various cyclodextrin derivatives. Cyclodextrins of preferred embodiments can include α-, β-, and χ-cyclodextrins. The α-cyclodextrins include six glucopyranose units, the β- cyclodextrins include seven glucopyranose units, and the χ-cyclodextrins include eight glucopyranose units. The β -cyclodextrins are generally preferred as having a suitable cavity size for zosuquidar. Cyclodextrin can be in any suitable form, including amorphous and crystalline forms, with the amorphous form generally preferred. Cyclodextrins suitable for use in the formulations of preferred embodiments include the hydroxypropyl, hydroxyethyl, glucosyl, maltosyl, and maltotrosyl derivatives of β- cyclodextrin, carboxyamidomethyl-β-cyclodextrin, carboxymethyl-β-cyclodextrin, and diethylamino-β-cyclodextrin.

Pharmaceutical complexes including various cyclodextrins and cyclodextrin derivatives are disclosed in the following United States patents: U.S. Pat. No. 4,024,223; U.S. Pat. No. 4,228,160; U.S. Pat. No. 4,232,009; U.S. Pat. No. 4,351,846; U.S. Pat. No. 4,352,793; U.S. Pat. No. 4,383,992; U.S. Pat. No. 4,407,795; U.S. Pat. No. 4,424,209; U.S. Pat. No. 4,425,336; U.S. Pat. No. 4,438,106; U.S. Pat. No. 4,474,881; U.S. Pat. No. 4,478,995; U.S. Pat. No. 4,479,944; U.S. Pat. No. 4,479,966; U.S. Pat. No. 4,497,803; U.S. Pat. No. 4,499,085; U.S. Pat. No. 4,524,068; U.S. Pat. No. 4,555,504; U.S. Pat. No. 4,565,807; U.S. Pat. No. 4,575,548; U.S. Pat. No. 4,598,070; U.S. Pat. No. 4,603,123; U.S. Pat. No. 4,608,366; U.S. Pat. No. 4,659,696; U.S. Pat. No. 4,623,641; U.S. Pat No. 4,663,316; U.S. Pat. No. 4,675,395; U.S. Pat. No. 4,728,509; U.S. Pat. No. 4,728,510; and U.S. Pat. No. 4,751,095.

Chemically modified and substituted α-, β-, and χ-cyclodextrins are generally preferred over unmodified α-, β-, and χ-cyclodextrins due to improved toxicity and solubility properties. The degree of substitution of the hydroxy 1 groups of the glucopyranose units of the cyclodextrin ring can affect solubility. In general, a higher average degree of substitution of substituent groups in the cyclodextrin molecule yields a cyclodextrin of higher solubility.

Examples for Pgp inhibitors are cyclosporine A, valpodar, elacridar, tariquidar, zosuquidar, laniquidar, biricodar, S-9788, MS-209, BIBW-22 (BIBW-22-BS) , toremifene, verapamil, dexverapamil , quinine, quinidine, trans- flupentixol, chinchonine and others (J. Roberts, C. Jarry (2003) : J. Med. Chem. 46, 4805 – 4817) . The list of inhibitors of P-glycoprotein is increasing (e.g. Wang et al . (2002) : Bioorg. Med. Chem. Lett. 12, 571 – 574) .

Figure imgf000005_0001

Figure 2: Structures of BIBW-22, MS-209 and S-9788

7-12-2000
10,11-methanodibenzosuberane derivatives
10-17-2007
Salt and crystalline forms of (2R)-anti-5-{3-[4-(10,11-difluoromethanodibenzosuber-5-yl)piperazin-1-yl]-2-hydroxypropoxy}quinoline
9-2-2009
Salt and crystalline forms of (2R)-anti-5-{3-[4-(10,11-difluoromethanodibenzosuber-5-YL)piperazin-1-YL]-2-hydroxypropoxy}quinoline

……………………

 

U.S. Pat. Nos. 5,643,909 and 5,654,304, incorporated herein by reference, disclose a series of 10,11-methanobenzosuberane derivatives useful in enhancing the efficacy of existing cancer chemotherapeutics and for treating multidrug resistance. (2R)-anti-5-{3-[4-(10,11-difluoromethanodibenzosuber-5-yl)piperazin-1-yl]-2-hydroxypropoxy}quinoline trihydrochloride disclosed therein, is currently under development as a pharmaceutical agent.

U.S. pat. No. 5,654,304 (‘304), incorporated by reference herein, discloses a series of 10,11-(optionally substituted)methanodibenzosuberane derivatives useful in enhancing, the efficacy of existing cancer chemotherapeutics and for treating multidrug resistance. (2R)-anti-5-{3-[4-(10,11-Difluoromethanodibenzosuber-5-yl)piperazin-1-yl]-2-hydroxypropoxy}quinolone trihydrochloride is disclosed in ‘304 and is currently under development as a pharmaceutical agent. WO00/75121 discloses Form I, a crystalline form of (2R)-anti-5-{3-[4-(10,11-difluoromethanodibenzosuber-5-yl)piperazin-1-yl]-2-hydroxypropoxy}quinolone trihydrochloride.

The art disclosed in U.S. Pat. No. 5,776,939, and U.S. Pat. No. 5,643,909 both incorporated herein by reference, and PCT Patent Applications (Publication numbers WO 94/24107 and 98/22112) teach the use of 1-formylpiperazine to introduce the piperazine group of the compound of formula II

Figure US06570016-20030527-C00002

Compound II is a mixture of syn isomer (III)

Figure US06570016-20030527-C00003

and anti isomer (IV)

Figure US06570016-20030527-C00004

The process as disclosed in U.S. Pat. Nos. 5,643,909 and 5,654,304 (represented by scheme A, below) involves (a) chromatographic separation(s) of the formyl piperazine compound; and (b) deformylation of the formyl piperazine compound to provide compound IV.https://www.google.co.in/patents/US6570016?cl=en

Figure US06570016-20030527-C00005

The process of the present invention uses piperazine to react with the (1aα,6α,10bα)-6-halo-1,1-difluoro-1,1a,6,10b-tetrahydrodibenzo[a,e]cyclopropa[c]-cycloheptene compound or derivative, instead of formylpiperazine.

The process of the present invention is advantageous because piperazine is readily available in commercial quantities whereas 1-formylpiperazine, which was utilized in the process disclosed in U.S. Pat. No. 5,643,909 is often not readily available in commercial quantities. Additionally piperazine enjoys a significant cost advantage over 1-formylpiperazine.

The use of piperazine instead of 1-formylpiperazine is a significant advancement over the prior art because it obviates the need to deformylate or hydrolyze off the formyl group (step 6, scheme A), thereby providing fewer operational steps. U.S. Pat. No. 5,643,909 teaches the separation of the 1-formylpiperazine compounds by chromatography or repeated crystallization. The present invention obviates the need for chromatographic separations of the formylpiperazine diastereomeric addition compounds (see step 4, scheme A)

Figure US06570016-20030527-C00018

Figure US06570016-20030527-C00019

EXAMPLES

The following examples and preparations are illustrative only and are not intended to limit the scope of the invention in any way.

Preparation 1 R-1-(5-Quinolinyloxy)-2,3-epoxypropane

Figure US06570016-20030527-C00022

A mixture of 5-hydroxyquinoline (5.60 g, 38.6 mmol), R-glycidyl nosylate (10.0 g, 38.6 mmol), powdered potassium carbonate (11.7 g, 84.9 mmol), and N,N-dimethylformamide (100 mL) was stirred at ambient temperature until HPLC analysis (40% acetonitrile/60% of a 0.5% aqueous ammonium acetate solution, 1 mL/min, wavelength=230 nm, Zorbax RX-C8 25 cm×4.6 mm column) indicated complete disappearance of glycidyl nosylate (approximately 6 hours). The reaction mixture was filtered through paper and the filter cake was washed with 200 mL of a 3:1 mixture of MTBE and methylene chloride. The filtrate was washed with 200 mL of water and the aqueous layer was extracted four times with 100 mL of 3:1 MTBE/methylene chloride. The combined organic layers were dried over 30 grams of magnesium sulfate and the dried solution was then stirred with 50 grams of basic alumina for 30 minutes. The alumina was removed by filtration and the filter cake was washed with 200 mL of 3:1 MTBE/methylene chloride. The filtrate was concentrated to a volume of 100 mL, 300 mL of MTBE were added, and the solution was again concentrated to 80 mL. After heating to 50° C., the solution was treated with 160 mL of heptane dropwise over 15 minutes, allowed to cool to 40° C., and seeded, causing the formation of a crystalline precipitate. The mixture was stirred for two hours at ambient temperature and then at 0-5° C. for an additional 2 hours. The crystals were filtered, washed with cold heptane, and dried to provide 5.68 g (73.2%) of (2R)-1-(5-quinolinyloxy)-2,3-epoxypropane as white needles.

mp 79-81° C.;

[α]25 D−36.4° (c 2.1, EtOH);

1H NMR (500 MHz, CDCl3)δ 2.83 (dd, J=4.8, 2.7 Hz, 1H), 2.97 (m, 1H), 3.48 (m, 1H), 4.10 (dd, J=11.0, 6.0 Hz, 1H), 4.43 (dd, J=11.0, 2.7 Hz, 1H), 6.85 (d, J=7.8 Hz, 1H), 7.38 (dd, J=8.5 Hz, 4.1 Hz, 1H), 7.59 (m, 1H), 7.71 (d, J=8.5 Hz, 1H), 8.61 (m, 1H), 8.90 (m, 1H).

Example 1 (2R)-Anti-1-[4-(10,11-difluoromethano-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5-yl)-piperazin-1-yl]-3-qunolin-5-yloxy)-propan-2-ol Trihydrochloride

Figure US06570016-20030527-C00023

Preparation of the above compound is exemplified in the following preparative steps.

Step 1 1,1-Difluoro-1a,10b-dihydrodibenzo[a,e]cyclopropa[c]-cyclohepten-6 (1H)-one

Figure US06570016-20030527-C00024

A solution of sodium chlorodifluoroacetate (350 g) in diglyme (1400 mL) was added dropwise over 4 to 8 hours, preferably over 6 hours, to a solution of 5H-dibenzo[a,d]cyclo-hepten-5-one (25 g) in diglyme (500 mL), with stirring, and under nitrogen, maintaining the reaction temperature at 160°-165° C. The cooled reaction mixture was poured into water (1.8 L) and extracted with ether (1.8 L). The organic phase was washed with water, dried over sodium sulfate (Na2SO4), and evaporated. The residue was recrystallized from ethanol, then from acetone/hexane to give 14 g of 1,1-difluoro-1a,10b-dihydrodibenzo[a,e]cyclopropa[c]-cyclohepten-6(1H)-one.

mp 149.6° C.

Flash chromatography of the combined mother liquors on silica gel, eluting with 20% acetone/hexane, gave an additional 6.5 g of the target compound.

Step 2 (1aα,6β,10bα)-1,1-Difluoro-1,1a,6,10b-tetrahydrodibenzo[a,e]cyclopropa[c]cyclohepten-6-ol

Figure US06570016-20030527-C00025

A solution of 1,1-difluoro-1a,10b-dihydro-dibenzo[a,e]cyclopropa[c]cyclohepten-6(1H)-one (20.4 g) in tetrahydrofuran/methanol (1:2, 900 mL) was cooled in an ice bath. Sodium borohydride (12 g) was added in portions. The cooling bath was removed and the reaction mixture was stirred at ambient temperature for 2 hours, then poured into water. The product was filtered off, washed with water, and dried to give 20 g of (1aα,6β,10bα)-1,1-difluoro-1,1a,6,10b-tetrahydrodibenzo[a,e]cyclopropa[c]cyclohepten-6-ol (ii).

mp 230.1°-230.6° C.

Step 2A Combined Steps 1 and 2 Procedure (1aα,6β,10bα)-1,1-Difluoro-1,1a,6,10b-tetrahydrodibenzo[a,e]cyclopropa[c]cyclohepten-6-ol

Figure US06570016-20030527-C00026

To a solution of 103.1 g (0.500 mol) of 5H-dibenzo[a,d]cyclohepten-5-one (2) in 515 mL of triethylene glycol dimethyl ether heated to between 180° C. and 210° C. was added over 7 hours, 293.3 g (2.15 mol) of chlorodifluoroacetic acid lithium salt (as a 53% by weight solution in ethylene glycol dimethyl ether). The ethylene glycol dimethyl ether was allowed to distill from the reaction as the salt addition proceeded. The GC analysis of an aliquot indicated that all of the 5H-dibenzo[a,d]cyclohepten-5-one had been consumed. The reaction was cooled to ambient temperature and then combined with 400 mL of ethyl acetate and 75 g of diatomaceous earth. The solids were removed by filtration and washed with 300 mL of ethyl acetate. The washes and filtrate were combined and the ethyl acetate was removed by concentration under vacuum leaving 635 g of dark liquid. The dark liquid was cooled to 18° C. and to this was added, over 15 minutes, 6.62 g (0.175 mol) of sodium borohydride (as a 12% by wt solution in 14 M NaOH). After stirring for 2 h the reaction was quenched by careful addition of 900 mL of a 1:3.5:4.5 solution of conc. HCl-methanol-water. The suspension was stirred for 30 min and the crude product was collected by filtration, washed with 600 mL of 1:1 methanol-water and dried to 126.4 g of dark brown solid. The crude product was slurried in 600 mL of methylene chloride, filtered, washed twice with 150 mL portions of methylene chloride, and dried to 91.6 g (71%) of (1aα,6β,10bα)-1,1-difluoro-1,1a,6,10b-tetrahydrodibenzo[a,e]cyclopropa[c]-cyclohepten-6-ol. Gas Chromatography (GC) Conditions; Column: JW Scientific DB-1, Initial Temperature 150° C. for 5 min, 10° C./min ramp, Final temp 250° C. for 5 min. tR: intermediate, 11.5 min; reaction product (alcohol), 11.9 min; starting material, 12.3 minutes.

Step 3 Preparation of (1aα,6α,10b)-6-bromo-1,1-difluoro-1,1a,6,10b-tetrahydrodibenzo[a,e]cyclopropa-[c]cycloheptene

Figure US06570016-20030527-C00027

A slurry of (1aα,6β,10bα)-1,1-difluoro-1,1a,6,10b-tetrahydrodibenzo[a,e]cyclopropa[c]-cyclohepten-6-ol (3.0 g, 11.6 mmol, 1.0 equiv) in heptane (24 mL) was treated with 48% HBr (1.58 mL, 14.0 mmol, 1.2 equiv) and the reaction was heated at reflux with vigorous stirring for 2.5 hr. Solvent was then removed by atmospheric distillation (bp 95-98° C.) until approximately 9 mL of distillate was collected. The reaction was cooled and treated with EtOAc (15 mL), Na2SOand activated charcoal. The mixture was stirred at RT for 15 min and filtered through hyflo. The filter cake was washed with 50:50 EtOAc:heptane and the filtrate was concentrated in vacuo to provide the title product as a crystalline solid.

mp 119° C. (3.46 g corr., 93%);

1H NMR (500 MHz CDCl3) δ 7.20-7.41 (8H, m), 5.81 (1H, s), 3.41 (2H, d, J 12.5 Hz);

13CNMR (126 MHz CDCl3) δ 141.3, 141.2, 133.5, 130.1, 129.8, 128.3, 128.2, 112.9, 110.6, 110.5, 108.3, 53.6, 30.2, 30.1, 30.0.

Anal. Calcd. For C16H11BrF2: C, 59.84; H, 3.45. Found: C, 60.13; H, 3.50.

Step 3A Preparation of (1aα,6α,10bα)-6-Bromo-1-difluoro-1,1a,6,10b-tetrahydrodibenzo[a,e]cyclopropa[c]cycloheptene

Figure US06570016-20030527-C00028

To a stirred suspension of (1aα,6β,10bα)-1,1-difluoro-1,1a,6,10b-tetrahydrodibenzo[a,e]cyclopropa[c]-cyclohepten-6-ol, (18.4 g, 71.2 mmol) in 151 mL of methylene chloride which had been cooled to 10-17° C. was added phosphorous tribromide (9.6 g, 35.6 mmol) dropwise over 15 minutes. The cooling bath was removed and the reaction was stirred for 2 hours at ambient temperature. Analysis by gas chromatography indicated complete consumption of starting material. Cold water (92 mL) and activated carbon (1.84 g) were added and the resulting mixture was stirred for 30 minutes. The activated carbon was removed by filtration through Hyflo brand filter aid and the two phases were separated. The organic phase was washed with water (184 mL×2), brine (184 ml), dried over magnesium sulfate and concentrated to dryness under vacuum, affording 21.7 g (94.8%) of (1aα,6α,10bα)-6-bromo-1,1-difluoro-1,1a,6,10b-tetrahydrodibenzo[a,e]cyclopropa[c]cycloheptene.

1H NMR (CDCl3, 300 MHz) δ 3.36 (s, 1H), 3.40 (s, 1H), 5.77 (s, 1H), 7.16-7.38 (m, 8H).

Steps 4 and 5 (1aα,6α,10bα)-1-(1,1-Difluoro-1,1a,6,10b-tetrahydrodibenzo[a,e]cyclopropa[c]cyclohepten-6-yl)-piperazine, Hydrobromide Salt

Figure US06570016-20030527-C00029

To a solution of 237.5 g (0.739 mol) of (1aα,6α,10bα)-6-bromo-1,1-difluoro-1,1a,6,10b-tetrahydrodibenzo[a,e]-cyclopropa[c]cycloheptene in 3.56 L of acetonitrile was added 207.7 g (2.41 mol) of piperazine and the mixture was heated to reflux for 2 hours, at which time analysis by gas chromatography showed complete consumption of (1aα,6α,10bα)-6-bromo-1,1-difluoro-1,1a,6,10b-tetrahydrodibenzo[a,e]cyclopropa[c]cycloheptene (iii) and formation of a mixture of syn and anti piperazine compounds (III and IV) in an anti-syn ratio of 55:45. The reaction was cooled to about 7° C. and stirred for 30 minutes at that temperature. The reaction mixture was filtered to remove the precipitated syn-isomer (III) and the filter cake was washed with 250 mL of acetonitrile. The combined filtrate and wash were concentrated under vacuum to 262.4 grams of a foam which was dissolved in 450 mL of acetonitrile with heating. The solution was cooled to about 12° C. in an ice bath and stirred for 1 hour at that temperature. The precipitated syn-piperazine compound of formula (III) was filtered and washed with 125 ml of acetonitrile. The combined filtrate and wash were concentrated under vacuum to 194.1 g and dissolved in 1.19 L of ethyl acetate. The organic solution was washed sequentially with 500 mL portions of 1N sodium hydroxide, water, and saturated sodium chloride. The ethyl acetate solution was dried over sodium sulfate and concentrated to give 137.0 grams of residue which was dissolved in 1.37 L of methylene chloride and seeded with (1aα,6α,10bα)-1-(1,1-difluoro-1,1a,6,10b-tetrahydrodibenzo[a,e]cyclopropa[c]-cyclohepten-6-yl)-piperazine, hydrobromide salt, followed by the addition of 70.8 grams of 48% aqueous hydrobromic acid. The mixture was stirred for about 45 minutes, causing the anti-isomer to crystallize as its hydrobromide salt. The crystals were filtered, washed with methylene chloride, and dried to provide purified hydrobromide salt of compound (IVa), shown by HPLC to have an anti-syn ratio of 99.3:0.7. Treatment of the isolated hydrobromide salt of compound (IVa) with aqueous sodium hydroxide, extraction into methylene chloride, separation of the aqueous layer and concentration to dryness gave 80.1 grams (33.2% yield based on starting material) of (1aα,6α,10bα)-1-(1,1-difluoro-1,1a,6,10b-tetrahydrodibenzo[a,e]cyclopropa[c]-cyclohepten-6-yl)-piperazine as the free base. Acidification of a solution of the free base in 800 mL of methylene chloride by addition of 41.2 g of 48% hydrobromic acid as described above afforded 96.4 g of pure hydrobromide salt (title compound) with an anti-syn ratio of 99.8:0.2 (HPLC), mp 282-284° C. 1H NMR (DMSO-d6) δ 2.41 (m, 4H), 3.11 (m, 4H), 3.48 (d, J=12.4 Hz, 2H), 4.13 (s, 1H), 7.2 (m, 8H), 8.65 (bs, 2H). 13C NMR (DMSO-d6) δ 28.0, 42.9, 48.0, 75.1, 108.5, 112.9, 117.3, 127.5, 128.0, 128.6, 129.6, 132.4, 141.3. IR: (KBr) 3019, 2481, 1587, 1497, 1298 cm−1. Anal. Calcd for C20H21BrF2N2: C, 58.98; H, 5.20; N, 6.88. Found: C, 58.75; H, 5.29; N, 7.05.

Step 6 Preparation of (2R)-Anti-1-[4-(10,11-difluoromethano-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5-yl)-piperazin-1-yl]-3-quinolin-5-yloxy)propan-2-ol Trihydrochloride

A suspension of (1aα,6α,10bα)-1-(1,1-difluoro-1,1a,6,10b-tetrahydrodibenzo[a,e]cyclopropa[c]-cyclohepten-6-yl)-piperazine, hydrochloride compound of formula IVa (5.41 g, 14.9 mmol) and powdered sodium carbonate (3.16 g, 29.8 mmol) in 54 mL of 3A ethanol was stirred at ambient temperature for 1 hour. R-1-(5-quinolinyloxy)-2,3-epoxypropane (3.00 g, 14.9 mmol) was added in one portion and the reaction mixture was heated to 65° C. for 19 hours. HPLC analysis (Gradient system with solvent A (acetonitrile) and solvent B (0.02M sodium monophosphate buffer containing 0.1% triethylamine adjusted to pH 3.5 with phosphoric acid) as follows: 0-12 min, 30% solvent A/70% solvent B; 12-30 min, linear gradient from 30% to 55% solvent A/70% to 45% solvent B; 30-35 min, 55% solvent A/45% solvent B, 1 mL/min, 1=240 nm, Synchropak SCD-100 25 cm×4.6 mm column) indicated the total consumption of the piperazinyl compound of formula (IV). The mixture was allowed to cool to room temperature, filtered through a plug of silica gel, and eluted with an additional 90 mL of ethanol. The eluent was concentrated to a volume of approximately 60 mL and heated to 65° C. with stirring. A solution of HCl in ethanol (16.1 g at 0.135 g/g of solution, 59.6 mmol) was added dropwise over 10 minutes and the resultant product solution was seeded, causing the trihydrochloride salt to precipitate. The mixture was allowed to cool to ambient temperature and stirred slowly (less than 100 RPM) for 2 hours. The precipitate was filtered, washed with ethanol, and dried in vacuo at 50° C. to give the crude trihydrochloride salt which was further purified by recrystallization from methanol/ethyl acetate to provide 7.45 g (78.4%) of (2R)-anti-1-[4-(10,11-difluoromethano-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5-yl)-piperazin-1-yl]-3-quinolin-5-yloxy)-propan-2-ol trihydrochloride.

Step 6a

The syn isomer compound of formula (III) isolated as described supra (combined steps 4 and 5), can be utilized to produce the corresponding syn-5-{3-[4-(10,11-difluoromethano-dibenzosuber-5-yl)piperazin-1-yl]-2-hydroxypropoxy}quinoline trihydrochloride (XII) essentially as shown below for the free base of the anti isomer (IVa)in step 6.

https://www.google.co.in/patents/US6570016?cl=en

………………………………………

http://www.google.it/patents/WO1994024107A1?cl=en

REACTION SCHEME 1

Figure imgf000012_0001

FormuIa 1

Formula 1

Figure imgf000012_0002

Formula 2 Formula 2

Figure imgf000013_0001

Formula 3

Formula 3

Figure imgf000013_0002

Formula 4

Figure imgf000013_0003

Formula I

……………………………………….

http://www.google.com/patents/WO2000075121A3

Figure US06521755-20030218-C00028

1HNMR (500 MHz DMSO-d6) δ9.41 (2H, br. s), 7.17-7.31 (8H, m), 4.17 (1H, s), 3.52 (2H, d, J=12.4 Hz), 3.11 (4H, br. s), 2.48-2.51 (4H, m)

13CNMR (126 MHz DMSO-d6) δ142.3, 133.4, 130.5, 129.6, 129.0, 128.4, 115.9, 113.6, 111.3, 76.2, 49.0, 43.6, 29.2, 29.1, 29.0; FD MS: m/e 326 (M+).

Anal. Calcd. For C20H21ClF2N2: C, 66.20; H, 5.83; N, 7.72.

Found: C, 66.08; H, 5.90; N, 7.72.

…………………………………………..

http://www.google.com/patents/US6570016?cl=fr

Figure US06570016-20030527-C00019

Figure US06570016-20030527-C00023

(2R)-Anti-1-[4-(10,11-difluoromethano-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5-yl)-piperazin-1-yl]-3-qunolin-5-yloxy)-propan-2-ol Trihydrochloride

……………….

Chemical Shift Data and Peak Assignments for the Crystal Forms.

https://www.google.co.in/patents/US7282585?pg=PA1&dq=US+7282585&hl=en&sa=X&ei=zN64UsC2FIaSrgfS8YGIBQ&ved=0CDcQ6AEwAA

Figure US07282585-20071016-C00001

Form II has a solid-state 13C NMR spectrum comprised of isotropic peaks at the following chemical shifts: 29.9, 50.1, 55.3, 62.0, 66.5, 72.0, 75.8, 104.8, 107.5, 108.2, 109.1, 110.2, 112.0, 118.4, 119.5, 120.1, 123.1, 128.7, 131.1, 133.0, 134.8, 136.4, 136.9, 139.9, 140.0, 142.3, 144.5, 146.6, 149.0, 144.2, 153.0 and 153.6 ppm.

Form III has a solid-state 13C NMR spectrum comprised of isotropic peaks at the following chemical shifts: 30.3, 50.4, 59.1, 63.2, 72.8, 77.2, 109.1, 110.2, 112.2, 112.8, 118.7, 119.5, 119.9, 121.0, 122.2, 123.0, 128.9, 130.6, 132.7, 134.0, 136.4, 140.0, 141.0, 141.8, 142.5, 143.3, 146.1, 153.1, 153.8 and 154.7 ppm.

Sprout Pharmaceuticals Appeals FDA Decision on NDA for Flibanserin to Treat Hypoactive Sexual Desire Disorder in Premenopausal Women


Flibanserin, girosa
167933-07-5
 cas no

147359-76-0 (monoHCl)

Flibanserin, BIMT-17-BS, BIMT-17
1 – [2 – [4 – [3 – (Trifluoromethyl) phenyl] piperazin-1-yl] ethyl] -2,3-dihydro-1H-benzimidazol-2-one
1-[2-(4-(3-trifluoromethyl-phenyl)piperazin-1-yl)ethyl]-2,3-dihydro-1H-benzimidazol-2-one
C20-H21-F3-N4-O, 390.412, Boehringer Ingelheim (Originator)
  • Bimt 17
  • BIMT 17 BS
  • Bimt-17
  • Flibanserin
  • Girosa
  • UNII-37JK4STR6Z
Boehringer Ingelheim (Originator)
Antidepressants, Disorders of Sexual Function and Reproduction, Treatment of, ENDOCRINE DRUGS, Mood Disorders, Treatment of, PSYCHOPHARMACOLOGIC DRUGS, Treatment of Female Sexual Dysfunction, 5-HT1A Receptor Agonists, 5-HT2A Antagonists
Patents
EP 526434, JP 94509575, US 5576318, WO 9303016.
 WO2010/128516 , US2007/265276
Papers
Pharmaceutical Research, 2002 ,  vol. 19,  3,   pg. 345 – 349
Naunyn-Schmiedeberg’s Archives of Pharmacology, 1995 ,  vol. 352, 3  pg. 283 – 290
Journal of Pharmaceutical and Biomedical Analysis, v.57, 2012 Jan 5, p.104(5)
FLIBANSERIN
…………………….

December 11, 2013 – Sprout Pharmaceuticals today announced that it has received and appealed the Food and Drug Administration’s (FDA) Complete Response Letter (CRL) for flibanserin through the Formal Dispute Resolution process.

Flibanserin is an investigational, once-daily treatment for Hypoactive Sexual Desire Disorder, or HSDD, in premenopausal women. HSDD is the most commonly reported form of female sexual dysfunction

read all here picture    animation

A new drug being developed by Boehringer Ingelheim could give a boost to the sex drive of women with low libido. The drug, known as flibanserin, has been shown in clinical trials to increase their sexual desire when taken once a day at bedtime.

The results from four pivotal Phase III clinical trials on women with hypoactive sexual desire disorder (HSDD) were presented this week at the European Society for Sexual Medicine’s congress in Lyon, France. The trials showed that participants taking flibanserin had a significant improvement in their sexual desire compared to those given a placebo. They also experienced less of the distress associated with sexual dysfunction.

The drug was initially being investigated as a treatment for depression, and acts on the serotonin receptors in the brain – it is both a 5-HT1A receptor agonist and a 5-HT2A receptor antagonist. It is also a partial agonist at the dopamine D4 receptor.

Neurotransmitters such as serotonin are believed to be involved in sexual function, and antidepressants are commonly associated with a loss of libido, so this was an obvious side-effect to look out for during clinical trials in depression. But far from suppressing the libido in women, it appeared to have the opposite effect, so trials in women with HSDD were initiated.

Hormone replacement can improve the libido of women who have had their ovaries removed, but there is no available drug to treat those who have not. There have been accusations that pharma companies invent new diseases like HSDD in order to sell more medicines, but according to Kathleen Segraves, an assistant professor at Case Western Reserve University in the US who has worked in the field of sexual functioning for many years, this is not the case here. HSDD is a very real disorder, she says, and the potential for a treatment for these women is very exciting.

Mona Lisa Painting animation

Flibanserin (code name BIMT-17; proposed trade name Girosa) is a drug that was investigated by Boehringer Ingelheim as a novel, non-hormonal treatment for pre-menopausal women with Hypoactive Sexual Desire Disorder (HSDD).[1][2] Development was terminated in October 2010 following a negative report by the U.S. Food and Drug Administration.[3]

HSDD is the most commonly reported female sexual complaint and characterized by a decrease in sexual desire that causes marked personal distress and/or personal difficulties. According to prevalence studies about 1 in 10 women reported low sexual desire with associated distress, which may be HSDD.[4] The neurobiological pathway of female sexual desire involves interactions among multiple neurotransmitters, sex hormones and various psychosocial factors. Sexual desire is modulated in distinct brain areas by a balance between inhibitory and excitatory neurotransmitters, serotonin acting as an inhibitor while dopamine and norepinephrine act as a stimulator of sexual desire.[5][6]Flibanserin is a 5-HT1A receptor agonist and 5-HT2A receptor antagonist that had initially been investigated as an antidepressant. Preclinical evidence suggested that flibanserin targets these receptors preferentially in selective brain areas and helps to restore a balance between these inhibitory and excitatory effects.[6] HSDD has been recognized as a distinct sexual function disorder for more than 30 years.

The proposed mechanism of action refers back to the Kinsey dual control model. Several sex steroids, neurotransmitters, and hormones have important excitatory or inhibitory effects on the sexual response. Among the neurotransmitters, the excitatory activity is driven by dopamine and norepinephrine, while the inhibitory activity is driven by serotonin. The balance between these systems is relevant for a healthy sexual response. By modulating these neurotransmitters in selective brain areas, flibanserin, a 5-HT1A receptoragonist and 5-HT2A receptor antagonist, is likely to restore the balance between these neurotransmitter systems.[6]

Several large pivotal Phase III studies with Flibanserin were conducted in the USA, Canada and Europe. They involved more than 5,000 pre-menopausal women with generalized acquired Hypoactive Sexual Desire Disorder (HSDD). The results of the Phase III North American Trials demonstrated that

Although the two North American trials that used the flibanserin 100 mg qhs dose showed a statistically significant difference between flibanserin and placebo for the endpoint of [satisfying sexual events], they both failed to demonstrate a statistically significant improvement on the co-primary endpoint of sexual desire. Therefore, neither study met the agreed-upon criteria for success in establishing the efficacy of flibanserin for the treatment of [Hypoactive Sexual Desire Disorder].

These data were first presented on November 16, 2009 at the congress of the European Society for Sexual Medicine in Lyon, France. The women receiving Flibanserin reported that the average number of times they had “satisfying sexual events” rose from 2.8 to 4.5 times a month. However, women receiving placebo reported also an increase of “satisfying sexual events” from 2.7 to 3.7 times a month.

Evaluation of the overall improvement of their condition and whether the benefit was meaningful to the women, showed a significantly higher rate of a meaningful benefit in the flibanserin-treated patient group versus the placebo group.The onset of the Flibanserin effect was seen from the first timepoint measured after 4 weeks of treatment and maintained throughout the treatment period.

The overall incidence of adverse events among women taking flibanserin was low, the majority of adverse events being mild to moderate and resolved during the treatment. The most commonly reported adverse events included dizziness, nausea, fatigue, somnolence and insomnia.

On June 18, 2010, a federal advisory panel to the U.S. Food and Drug Administration (FDA) unanimously voted against recommending approval of Flibanserin.

Earlier in the week, a FDA staff report also recommended non-approval of the drug. While the FDA still might approve Flibanserin, in the past, negative panel votes tended to cause the FDA not to approve.

On October 8, 2010, Boehringer Ingelheim announced that it would discontinue its development of flibanserin in light of the FDA advisory panel’s recommendation.

On June 27, 2013, Sprout Pharmaceuticals confirmed they had resubmitted flibanserin for FDA approval.

Flibanserin, chemically 1 -[2-(4-(3-trifluoromethylphenyl)piperazin-1 – yl)ethyl]-2,3-dihydro-1 H-benzimidazole-2-one was disclosed in form of its hydrochloride in European Patent No. 526,434 (‘434) and has the following chemical structure:

Figure imgf000002_0001

Process for preparation of flibanserin were disclosed in European Patent No. ‘434, U.S. Application Publication No. 2007/0032655 and Drugs of the future 1998, 23(1): 9-16.

According to European Patent No. ‘434 flibanserin is prepared by condensing 1-(2-chloroethyl)-2,3-dihydro-1 H-benzimidazol-one with m- trifluoromethyl phenyl piperazine. According to U.S. Application Publication No. 2007/0032655 flibanserin is prepared by condensing 1-[(3-trifluoromethyl)phenyl]-4-(2- chloroethyl)piperazine with 1 -(2-propenyl)-1 ,3-dihydro-benzimidazol-2H-one.

According to Drugs of the future 1998, 23(1): 9-16 flibanserin is prepared by reacting 1-(2-chloroethyl)-2,3-dihydro-1 H-benzimidazol-one with m- trifluoromethylphenylpiperazine.

…………………

EP0526434A1

1-[2-(4-(3-trifluoromethyl-phenyl)piperazin-1-yl)ethyl]-2,3-dihydro-1H-benzimidazol-2-one

Compound 3

  • Hydrochloride salt (isopropanol) M.p. 230-231°C

Analysis

  • Figure imgb0022

    ¹H NMR (DMSO-d₆/CDCL₃ 5:2) 11.09 (b, 1H), 11.04 (s, 1H), 7.5-6.9 (8H), 4.36 (t, 2H), 4.1-3.1 (10H)

…………………………………

 drawing   animation

The compound 1-[2-(4-(3-trifluoromethyl-phenyl)piperazin-1-yl)ethyl]-2,3-dihydro-1 H- benzimidazol-2-one (flibanserin) is disclosed in form of its hydrochlorid in European Patent Application EP-A-526434 and has the following chemical structure:

Figure imgf000003_0001

Flibanserin shows affinity for the 5-HTιA and 5-HT2-receptor. It is therefore a promising therapeutic agent for the treatment of a variety of diseases, for instance depression, schizophrenia, Parkinson, anxiety, sleep disturbances, sexual and mental disorders and age associated memory impairment.

EXAMPLE……… EP1518858A1

375 kg of 1-[(3-trifluoromethyl)phenyl]-4-(2-cloroethyl)piperazin are charged in a reactor with 2500 kg of water and 200 kg of aqueous Sodium Hydroxide 45%. Under stirring 169.2 kg of 1-(2-propenyl)-1,3-dihydro-benzimidazol-2H-one, 780 kg of isopropanol, 2000 kg of water and 220 kg of aqueous Sodium Hydroxide 45% are added. The reaction mixture is heated to 75-85° C. and 160 kg of concentrated hydrochloric acid and 200 kg of water are added.

The reaction mixture is stirred at constant temperature for about 45 minutes. After distillation of a mixture of water and Isopropanol (about 3000 kg) the remaining residue is cooled to about 65-75° C. and the pH is adjusted to 6.5-7.5 by addition of 125 kg of aqueous Sodium Hydroxide 45%. After cooling to a temperature of 45-50° C., the pH value is adjusted to 8-9 by addition of about 4 kg of aqueous Sodium Hydroxide 45%. Subsequently the mixture is cooled to 30-35° C. and centrifuged. The residue thus obtained is washed with 340 l of water and 126 l of isopropanol and then with water until chlorides elimination.

The wet product is dried under vacuum at a temperature of about 45-55° C. which leads to 358 kg of crude flibanserin polymorph A. The crude product thus obtained is loaded in a reactor with 1750 kg of Acetone and the resulting mixture is heated under stirring until reflux. The obtained solution is filtered and the filtrate is concentrated by distillation. The temperature is maintained for about 1 hour 0-5° C., then the precipitate solid is isolated by filtration and dried at 55° C. for at least 12 hours.

The final yield is 280 kg of pure flibanserin polymorph A.

………………………….

Flibanserin may be prepared by reacting 1-(phenylvinyl)-2,3-dihydro-1H-benzimidazol-2-one (I) with 1,2-dichloroethane (II) in the presence of NaH in warm dimethylformamide. The resulting 1-(2-chloroethyl)-2,3-dihydro-1H-benzimidazol-one (III) is in turn coupled with commercially available m-trifluoromethylphenylpiperazine hydrochloride (IV) in the presence of sodium carbonate and catalytic potassium iodide in refluxing ethanol. The crude flibanserin hydrochloride (V) is then dissolved in aqueous ethanol and the pure base is precipitated upon addition of sodium hydroxide.

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1-(1-phenylvinyl)-1,3-dihydro-2H-benzimidazol-2-one (I)
1,2-dichloroethane (II)
1-(2-chloroethyl)-1,3-dihydro-2H-benzimidazol-2-one (III)
1-[3-(trifluoromethyl)phenyl]piperazine; N-[3-(trifluoromethyl)phenyl]piperazine (IV)
1-(2-[4-[3-(trifluoromethyl)phenyl]piperazino]ethyl)-1,3-dihydro-2H-benzimidazol-2-one (V)

………………………..

WO2010128516A2

A process for the preparation of a compound of formula X or a salt thereof:
Figure imgf000026_0001
wherein R2 is hydrogen or an amino protecting group which comprises reacting the compound of formula VII
Figure imgf000026_0002

wherein R2 is as defined in formula X; with a compound of formula Xl:

Figure imgf000026_0003

According to another aspect of the present invention there is provided a novel compound or a salt thereof selected from the compounds of formula I, IV and VII:

Figure imgf000014_0001
Figure imgf000014_0002

Wherein R is hydrogen or an amino protecting group.

Preferable the amino protecting groups are selected from butyl, 1 ,1- diphenylmethyl, methoxymethyl, benzyloxymethyl, trichloroethoxymethyl, pyrrolidinomethyl, cyanomethyl, pivaloyloxymethyl, allyl, 2-propenyl, t- butyldimethylsilyl, methoxy, thiomethyl, phenylvinyl, 4-methoxyphenyl, benzyl, A- methoxybenzyl, 2,4-dimethoxybenzyl, 2-nitrobenzyl, t-butoxycarbonyl, benzyloxycarbonyl, phenoxycarbonyl, 4-chlorophenoxycarbonyl, A- nitrophenoxycarbonyl, methoxycarbonyl and ethoxycarbonyl. Still more preferable protecting groups are selected from t- butoxycarbonyl, ethoxycarbonyl, methoxycarbonyl, benzyloxycarbonyl, phenoxycarbonyl, phenylvinyl and 2-propenyl.

R1 is independently selected from chlorine, bromine, iodine, methanesulphonate, trifluoromethanesulphonate, paratoluenesulphonate or benzenesulphonate. Preferable R1 is independently selected from chlorine, bromine or iodine and more preferable R1 is chlorine.

Wherein R2 is hydrogen or an amino protecting group.

The amino protecting group may be any of the groups commonly used to protect the amino function such as alkyl, substituted alkyl, hetero substituted alkyl, substituted or unsubstituted unsaturated alkyl, alkyl substituted hetero atoms, substituted or unsubstituted phenyl, substituted or unsubstituted benzyl, alkyoxy carbonyl groups and aryloxy carbonyl groups.

Preferable the amino protecting groups are selected from butyl, 1 ,1 – diphenylmethyl, methoxymethyl, benzyloxymethyl, trichloroethoxymethyl, pyrrolidinomethyl, cyanomethyl, pivaloyloxymethyl, allyl, 2-propenyl, t- butyldimethylsilyl, methoxy, thiomethyl, phenylvinyl, 4-methoxyphenyl, benzyl, A- methoxybenzyl, 2,4-dimethoxybenzyl, 2-nitrobenzyl, t-butoxycarbonyl, benzyloxycarbonyl, phenoxycarbonyl, 4-chlorophenoxycarbonyl, A- nitrophenoxycarbonyl, methoxycarbonyl and ethoxycarbonyl. Still more preferable protecting groups are selected from t- butoxycarbonyl, ethoxycarbonyl, methoxycarbonyl, benzyloxycarbonyl, phenoxycarbonyl, phenylvinyl and 2-propenyl. The following examples are given for the purpose of illustrating the present invention and should not be considered as limitations on the scope and spirit of the invention.

EXAMPLES Example 1

A mixture of sodium hydroxide (47 gm) and i-(α-methylvinyl) benzimidazol-2-one (100 gm) in dimethylformamide (400 ml) was .stirred for 1 hour at room temperature. Dibromoethane (217 gm) was slowly added to the mixture and stirred at 1 hour 30 minutes. The resulting solution after addition water (500 ml) was extracted with ethyl acetate. The combined ethyl acetate extract washed with water. After drying the solvent was removed under vacuum to yield 132 gm of 1 ,3-dihydro-1-(2-bromoethyl)-3-isopropenyl-2H-benzimidazol- 2-one as a yellow oily liquid.

Example 2 A mixture of 1 ,3-dihydro-1-(2-bromoethyl)-3-isopropenyl-2H- benzimidazol-2-one (100 gm), diethanolamine (175 ml), sodium carbonate (40 gm) and potassium iodide (10 gm) was heated to 90 to 95 deg C and stirred for 2 hours. The reaction mass was cooled to room temperature and added water (500 ml). The resulting mixture extracted into ethyl acetate and the organic layer washed with water. After drying the solvent was removed under vacuum to yield 105 gm of 1 ,3-dihydro-1-[2-[N-bis-(2-hydroxyethyl)amino]ethyl]-3-isopropenyl- 2H-benzimidazol-2-one as a thick yellow oily liquid.

Example 3

To the mixture of 1 ,3-dihydro-1-[2-[N-bis-(2-hydroxyethyl)amino]ethyl]-3- isopropenyl-2H-benzimidazol-2-one (100 gm) obtained as in example 2 and chloroform (300 ml), thionyl chloride (95 ml) was slowly added. The mixture was heated to reflux and stirred for 2 hours. The excess thionyl chloride and chloroform was distilled off to yield 98 gm of 1 ,3-dihydro-1-[2-[N-[bis-(2- chloroethyl)amino]ethyl]-3-isopropenyl-2H-benzimidazol-2-one as a brown coloured sticky residue.

Example 4

1 ,3-dihydro-1-[2-[N-[bis-(2-chloroethyl)amino]ethyl]-3-isopropenyl-2H- benzimidazol-2-one (98 gm) obtained as in example 3 was added to water (500 ml) and concentrated hydrochloric acid (200 ml) mixture. The mixture was heated to 60 to 65 deg C and stirred for 1 hour. The contents of the flask cooled to room temperature and pH of the solution adjusted to 9 – 10 with 10% sodium hydroxide solution. The resulting solution extracted with ethyl acetate and washed the organic layer with water. Evaporate the solvent under reduced pressure to yield 82 gm of 1 ,3-dihydro-1-[2-[N-bis-(2-chloroethyl)amino]ethyl]- 2H-benzimidazol-2-one as a dark brown coloured oily liquid

Example 5

A mixture of 1 ,3-dihydro-1-[2-[N-bis-(2-chloroethyl)amino]ethyl]-1,2-H- benzimidazol-2-one (82 gm) obtained as in example 4, xylene (300 ml) and m- trifluoromethyl aniline (58 gm) was refluxed for 64 hours. The reaction mass was cooled to room temperature and filtered to obtain 1-[2-(4-(3- thfluoromethylphenyl)piperazin-1-yl)ethyl]-2,3-dihydro-1 H-benzimidazole-2-one hydrochloride (Flibanserin hydrochloride) as a light brown coloured solid.

The crude flibanserin hydrochloride was purified in isopropyl alcohol to give 85 gm of pure flibanserin hydrochloride as off white solid.

Example 6

Piperazine (12 gm), toluene(60 ml) and tetra butyl ammonium bromide (1 gm) mixture was heated to 60 deg C, added 1 ,3-dihydro-1-(2-bromoethyl)-3- isopropenyl-2H-benzimidazol-2-one (10 gm) and stirred for 4 hours at 90 to 95 deg C. The mixture was cooled to 60 deg C and added water (50 ml). The separated toluene layer distilled under vacuum to give 8.5 gm of 1 ,3-dihydro-1- (2-piperazinyl)ethyl-3-isopropenyl-2H-benzimidazol-2-one as a white solid.

Example 7

To the mixture of concentrated hydrochloric acid (20 ml) and water (100 ml) was added 1 ,3-dihydro-1-(2-piperazinylethyl)-3-isopropenyl-2H- benzimidazol-2-one (10 gm) obtained as in example 6 and heated to 60 to 65 deg C 1 hour. The mixture was cooled to room temperature and pH of the solution was adjusted to 9 – 10 with 10% sodium hydroxide solution, extracted with ethyl acetate and the organic layer was washed with water. After drying the solvent was removed under vacuum to yield 8.5 gm of 1 ,3-dihydro-1-(2- piperazinyl ethyl)-2H-benzimidazol-2-one as a white solid.

Example 8

3-trifluoromethylaniline (40 gm) and hydrobromic acid (85 ml; 48- 50%w/w) mixture was cooled to 0 to 5 deg C. To this mixture added sodium nitrite solution (18.5 gm in 25 ml of water) at 5 to 10 deg C and copper powder (1 gm). The temperature was slowly raised to 50 to 55 deg C and stirred for 30 minutes. Added water (200 ml) to reaction mass and applied steam distillation, collected m-trifluoromethylbromobenzene as oily liquid. The oily liquid washed with sulfuric acid for two times (2 X 10 ml) followed by washed with water (2 X 20 ml) and dried the liquid with sodium sulphate to give 22 gm of m- trifluoromethylbromobenzene.

Example 9

To a mixture of 1 ,3-dihydro-1-(2-piperazinyl ethyl)-2H-benzimidazol-2- one (10 gm) obtained as in example 7, m-trifluoromethylbromobenzene (9 gm) obtained as in example 8, sodium tert-butoxide (5.5 gm), palladium acetate (4.5 mg) and xylene (80 ml) was added tri-tert.-butylphosphine (0.2 ml). The mixture was heated to 120 deg C and stirred for 3 hours. The reaction mass was cooled, added water (100 ml) and extracted with ethyl acetate and the organic layer was washed with water. After drying the solvent was removed under vacuum to yield

10 gm of 1-[2-(4-(3-trifluoromethylphenyl)piperazin-1-yl)ethyl]-2,3-dihydro-1 H- benzimidazole-2-one (Flibanserin).

Example 10

To a mixture of 1 ,3-dihydro-1-[2-[N-bis-(2-hydroxyethyl)amino]ethyl]-3- isopropenyl-2H-benzimidazol-2-one (100 gm) obtained as in example 3, cyclohexane (400 ml) and sodium carbonate (35 gm) was added benzene sulfonyl chloride (116 gm) at room temperature. The mixture was heated to 80 to

85 deg C and stirred for 8 hours . The contents were cooled to room temperature and added water (500 ml). Distilled the organic layer to give 182 gm of 1 ,3-dihydro-1-[2-[N-[bis-(2-benzenesulfonyloxy)- ethyl]amino]ethyl]-3- isopropenyl- 2H-benzimidazol-2-one.

Example 11

1 ,3-dihydro-1 -[2-[N-[bis-(2-benzenesulfonyloxy)- ethyl]amino]ethyl]-3- isopropenyl- 2H-benzitηidazol-2-one (100 gm) obtained as in example 10, dimethylformamide (500 ml) and sodium corbonate (18 gm) was mixed and heated to 70 deg C. To the mixture was added m-trifluoromethyl aniline (27 gm) and heated to 80 to 85 deg C, stirred for 5 hours. The reaction mass was cooled and added water (2000 ml), filtered the solid to yield 1 ,3-dihydro-1-[2-[4-(3- trifluoromethylphenyl)piperazinyl]ethyl]-3-isopropenyl-2H benzimidazol-2-one. Example 12

1 ,3-dihydro-1-[2-[N-[bis-(2-benzenesulfonyloxy)- ethyl]amino]ethyl]-3- isopropenyl- 2H-benzimidazol-2-one (100 gm) obtained as in example 11 added to the mixture of water (500 ml) and concentrated hydrochloric acid (200 ml), heated to 65 deg C and stirred for 1 hour. The reaction mass was cooled to room temperature and pH adjusted to 10 to 10-5 with 10% sodium hydroxide solution. The resulting mixture was extracted with ethyl acetate and the organic

 layer was washed with water. After drying the solvent was removed under vacuum to yield 87 gm of 1-[2-(4-(3-trifluoromethylphenyl)piperazin-1-yl)ethyl]- 2,3-dihydro-1 H-benzimidazole -2-one (Flibanserin).

…………………..

Paper

Journal of Pharmaceutical and Biomedical Analysis, v.57, 2012 Jan 5, p.104(5)

Isolation and structural elucidation of flibanserin as an adulterant in a health supplement used for female sexual performance enhancement

Low, Min-Yong et al

http://www.sciencedirect.com/science/article/pii/S0731708511004833

Full-size image (5 K)

This proposed formula and structure was further confirmed by 1H and 13C NMR data which indicated the presence of 20 carbon atoms and 21 protons.

1H NMR

Inline image 6

13C NMR

Inline image 5

1D and 2DNMR data were used to assign the protons and carbon atoms.

Inline image 2

In the1H NMR spectrum , a sharp singlet at 10.00 ppm integrating for one
proton is a typical proton attached to nitrogen. HMBC correlated this proton to C-2, C-4, and C-9 suggesting that it was H-3.

Complex signals were observedbetween 7.00 to 7.31 ppm, integrating for eight protons. A triplet at 7.31 ppm,integrating for a proton has a coupling constant of 8.0 Hz. HMBC correlated thisproton with C-16, C-19, and C-21 suggesting that it was H-20.

A double-doubletsplitting pattern at chemical shift 7.11 ppm, integrating for a proton, has couplingconstants of 6.3 Hz and 1.6 Hz.

HMBC correlated this proton to C-6, C-7, and C-9 showing that it was H-8. Overlapped signals were observed from 7.04 ppm to7.10 ppm, integrating for five protons. A double-doublet splitting pattern at 7.01ppm with coupling constant 8.0 Hz and 2.0 Hz, integrating for a proton was
observed.

HMBC correlated this proton to C-17 suggesting that it was either H-19or H-21. Four triplet signals were also observed from 2.73 ppm to 4.08 ppm,integrating for a total of twelve protons.

Two of these triplet signals at 2.74 ppmand 3.22 ppm integrated for four protons each, suggesting overlapping signals ofmethylene protons. This was further confirmed by 13C and DEPT NMR.

13C and DEPT NMR data showed the signals of four methylene, eight methineand six quaternary carbon atoms. The DEPT signals at 53.1 ppm and 48.6 ppmhave intensities which were double of those from the rest of the methylene carbonsignals, suggesting two methylene carbon atoms each contributing to the signal at 53.1 ppm and 48.6 ppm.

DEPT

Inline image 4

HMQC results further indicated that these two methylene carbon signals at 53.1 ppm and 48.6 ppm were correlated to the protons signal at 2.73 ppm and 4.08 ppm respectively, which corresponded to four protons each. The finding confirmed overlapping methylene carbon signals (at 53.1 ppm and 48.6 ppm) and methylene proton signals (at 2.73 ppm and 4.08 ppm). Hence, the unknown compound has six methylene carbon atoms with a total of twelve methylene protons.

The chemical shifts of the twelve methylene protons suggested that they were attached to relatively electronegative atoms. It was speculated that the six methylene groups were attached to the nitrogen atoms and the electron withdrawing effect of these electronegative nitrogen atoms resulted in the deshielding of the protons. HMBC and COSY correlations were used to assign the rest of the protons

The 13C NMR data  showed that there were two quaternary carbon at
155.6 ppm and 151.3 ppm. The carbon with chemical shift 155.6 ppm was C-2. Inthe structure of imidazolone, carbonyl carbon C-2 was attached to two nitrogenatoms which helped to withdraw electrons from oxygen to C-2. Hence, C-2 wasless deshielded as compared to a normal carbonyl carbon which has chemical shiftabove 170 ppm.

Eight methine carbons and two quaternary carbons with chemicalshifts above 108 ppm suggested the presence of two aromatic rings. Thequaternary carbon with chemical shift 125.4 ppm was C-22 which was attached tothree fluorine atoms. Due to the strong electron withdrawing effect of the fluorineatoms, C-22 was highly deshielded and had a high chemical shift.

The IR spectrum of the isolated compound showed absorption bands of amide (νC=O 1685 cm-1, νN-H (stretch) 3180 cm-1, νN-H (bending) 1610 cm-1), alkyl fluoride (νC-F1077 cm-1, 1112 cm-1, 1158 cm-1), aromatic ring (ν Ar-H 3028 cm-1, 3078 cm-1 andνC=C 1401 cm-1, 1446 cm-1, 1453 cm-1, 1468 cm-1, 1487 cm-1) and alkane (νC-H2891 cm-1, 2930 cm-1 2948 cm-).

Inline image 1

COSY

Inline image 3

……………………………….

US5576318, 1996

1 H NMR (DMSO-d6 /CDCL3 5:2) 11.09 (b, 1H), 11.04 (s, 1H), 7.5-6.9 (SH), 4.36 (t, 2H), 4.1-3.1 (10 H)

,,,,,,,,,,,,,,,,,,

  1.  Borsini F, Evans K, Jason K, Rohde F, Alexander B, Pollentier S (summer 2002). “Pharmacology of flibanserin”. CNS Drug Rev. 8 (2): 117–142. doi:10.1111/j.1527-3458.2002.tb00219.xPMID 12177684.
  2.  Jolly E, Clayton A, Thorp J, Lewis-D’Agostino D, Wunderlich G, Lesko L (April 2008). “Design of Phase III pivotal trials of flibanserin in female Hypoactive Sexual Desire Disorder (HSDD)”. Sexologies 17 (Suppl 1): S133–4. doi:10.1016/S1158-1360(08)72886-X.
  3.  Spiegel online: Pharmakonzern stoppt Lustpille für die Frau, 8 October 2010 (in German)
  4.  Nygaard I (November 2008). “Sexual dysfunction prevalence rates: marketing or real?”. Obstet Gynecol 112 (5): 968–9.doi:10.1097/01.AOG.0000335775.68187.b2PMID 18978094.
  5.  Clayton AH (July 2010). “The pathophysiology of hypoactive sexual desire disorder in women”Int J Gynaecol Obstet 110 (1): 7–11.doi:10.1016/j.ijgo.2010.02.014PMID 20434725.
  6.  Pfaus JG (June 2009). “Pathways of sexual desire”. J Sex Med 6 (6): 1506–33. doi:10.1111/j.1743-6109.2009.01309.x.PMID 19453889.
EP0200322A1 * Mar 18, 1986 Nov 5, 1986 H. Lundbeck A/S Heterocyclic compounds
BE904945A1 * Title not available
GB2023594A * Title not available
US3472854 * May 29, 1967 Oct 14, 1969 Sterling Drug Inc 1-((benzimidazolyl)-lower-alkyl)-4-substituted-piperazines
US4954503 * Sep 11, 1989 Sep 4, 1990 Hoechst-Roussel Pharmaceuticals, Inc. 3-(1-substituted-4-piperazinyl)-1H-indazoles

Rilpivirine


Rilpivirine

500287-72-9  cas no

4-{[4-({4-[(E)-2-cyanovinyl]-2,6-dimethylphenyl}amino)pyrimidin-2-yl]amino}benzonitrile

Rilpivirine (TMC278, trade name Edurant) is a pharmaceutical drug, developed byTibotec, for the treatment of HIV infection.[1][2] It is a second-generation non-nucleoside reverse transcriptase inhibitor (NNRTI) with higher potency, longer half-life and reducedside-effect profile compared with older NNRTIs, such as efavirenz.[3][4]

Rilpivirine entered phase III clinical trials in April 2008,[5][6] and was approved for use in the United States in May 2011.[7] A fixed-dose drug combining rilpivirine with emtricitabine andtenofovir, was approved by the U.S. Food and Drug Administration in August 2011 under the brand name Complera.[8]

Like etravirine, a second-generation NNRTI approved in 2008, rilpivirine is a diarylpyrimidine(DAPY). Rilpivirine in combination with emtricitabine and tenofovir has been shown to have higher rates of virologic failure than Atripla in patients with baseline HIV viral loads greater than 100,000 copies.

  1.  “TMC278 – A new NNRTI”. Tibotec. Retrieved 2010-03-07.
  2.  Stellbrink HJ (2007). “Antiviral drugs in the treatment of AIDS: what is in the pipeline ?”.Eur. J. Med. Res. 12 (9): 483–95. PMID 17933730.
  3.  Goebel F, Yakovlev A, Pozniak AL, Vinogradova E, Boogaerts G, Hoetelmans R, de Béthune MP, Peeters M, Woodfall B (2006). “Short-term antiviral activity of TMC278–a novel NNRTI–in treatment-naive HIV-1-infected subjects”AIDS 20 (13): 1721–6.doi:10.1097/01.aids.0000242818.65215.bdPMID 16931936.
  4.  Pozniak A, Morales-Ramirez J, Mohap L et al. 48-Week Primary Analysis of Trial TMC278-C204: TMC278 Demonstrates Potent and Sustained Efficacy in ART-naïve Patients. Oral abstract 144LB.
  5.  ClinicalTrials.gov A Clinical Trial in Treatment naïve HIV-1 Patients Comparing TMC278 to Efavirenz in Combination With Tenofovir + Emtricitabine
  6.  ClinicalTrials.gov A Clinical Trial in Treatment naïve HIV-Subjects Patients Comparing TMC278 to Efavirenz in Combination With 2 Nucleoside/Nucleotide Reverse Transcriptase Inhibitors
  7.  “FDA approves new HIV treatment”. FDA. Retrieved 2011-05-20.
  8.  “Approval of Complera: emtricitabine/rilpivirine/tenofovir DF fixed dose combination”. FDA. August 10, 2011.

FORMULATION

EDURANT (rilpivirine, Janssen Therapeutics) is a non-nucleoside reverse transcriptase inhibitor (NNRTI) of human immunodeficiency virus type 1 (HIV-1). EDURANT is available as a white to off-white, film-coated, round, biconvex, 6.4 mm tablet for oral administration. Each tablet contains 27.5 mg of rilpivirine hydrochloride, which is equivalent to 25 mg of rilpivirine.

The chemical name for rilpivirine hydrochloride is 4-[[4-[[4-[(E)-2-cyanoethenyl]-2,6-dimethylphenyl]amino]2-pyrimidinyl]amino]benzonitrile monohydrochloride. Its molecular formula is C22H18N6 • HCl and its molecular weight is 402.88. Rilpivirine hydrochloride has the following structural formula:

EDURANT (rilpivirine) Structural Formula Illustration

Rilpivirine hydrochloride is a white to almost white powder. Rilpivirine hydrochloride is practically insoluble in water over a wide pH range.

Each EDURANT tablet also contains the inactive ingredients croscarmellose sodium, lactose monohydrate, magnesium stearate, polysorbate 20, povidone K30 and silicified microcrystalline cellulose. The tablet coating contains hypromellose 2910 6 mPa.s, lactose monohydrate, PEG 3000, titanium dioxide and triacetin.

…………………………….

papers

Sun, et al.: J. Med. Chem., 41, 4648 (1998),

Kashiwada, et al.: Bioorg. Med. Chem. Lett., 11, 183 (2001)

Journal of Medicinal Chemistry, 2005 ,  vol. 48,  6  , pg. 2072 – 2079

………………………………………………

patents

WO201356003, WO200635067,

WO2013038425 

The following PCT Publications describe the synthesis of Rilpivirine:

WO03016306, WO2005021001, WO2006024667, WO2006024668, W02994916581, WO2009007441, WO2006125809, and WO2005123662. [0006] Crystalline Rilpivirine base Forms I and II are described in the US Patent

Publication: US2010189796. Crystalline Rilpivirine HC1, Forms A, B, C, and D, are described in the US Patent Publications: US2009/012108, and US2011/0008434. Rilpivirine fumarate and a synthesis thereof are disclosed in WO2006024667.

country……………….patent……………approved……………expiry

United States 6838464 2011-05-20 2021-02-26
United States 7067522 2011-05-20 2019-12-20
United States 7125879 2011-05-20 2014-04-14
United States 7638522 2011-05-20 2014-04-14
United States 8080551 2011-05-20 2023-04-11
United States 8101629 2011-05-20 2022-08-09
Rilpivirine and its hydrochloride salt were disclosed in U.S. patent no. 7,125,879.Process for the preparation of rilpivirine was disclosed in U.S. patent no. 7,399,856 (‘856 patent). According to the ‘856 patent, rilpivirine can be prepared by reacting the (E)-3-(4-amino-3,5-dimethylphenyI)acrylonitrile hydrochloride of formula II with 4-(4-chloropyrimidin-2-ylamino)benzonitrile of formula III-a in the presence of potassium carbonate and acetonitrile under reflux for 69 hours. The synthetic procedure is illustrated in scheme I, below:

Figure imgf000003_0001

Scheme 1 Process for the preparation of rilpivirine was disclosed in U.S. patent no.

7,705,148 (Ί48 patent). According to the Ί48 patent, rilpivirine can be prepared by reacting the 4-[[4-[[4-bromo-2,6-dimethylphenyl]amino]-2- pyrimidinyl]amino]benzonitrile with acrylonitrile in the presence of palladium acetate, Ν,Ν-diethylethanamine and tris(2-methylphenyl)phosphine in acetonitrile. According to the Ί48 patent, rilpivirine can be prepared by reacting the compound of formula IV with 4-(4-chloropyrimidin-2-ylamino)benzonitrile formula Ill-a in the presence of hydrochloric acid and n-propanol to obtain a compound of formula Vll, and then the compound was treated with acetonitrile and potassium carbonate under reflux for 69 hours. The synthetic procedure is illustrated in scheme II, below:

Figure imgf000004_0001

Rilpivirine

Scheme II

U.S. patent no. 7,563,922 disclosed a process for the preparation of (E)-3-(4- amino-3,5-dimethylphenyl)acrylonitrile hydrochloride. According to the patent, (E)-3-(4- amino-3,5-dimethylphenyl)acrylonitrile hydrochloride can be prepared by reacting the 4- iodo-2,6-dimethyl-benzenamine in Ν,Ν-dimethylacetamide with acrylonitrile in the presence of sodium acetate and toluene, and then the solid thus obtained was reacted with hydrochloric acid in 2-propanol in the presence of ethanol and diisopropyl ether.

U.S. patent no. 7,956,063 described a polymorphic Form A, Form B, Form C and Form D of rilpivirine hydrochloride.

An unpublished application, IN 1415/CHE/201 1 assigned to Hetero Research

Foundation discloses a process for the preparation of rilpivirine. According to the application, rilpivirine can be prepared by reacting the 4-(4-chloropyrimidin-2- ylamino)benzonitrile with (E)-3-(4-amino-3,5-dimethylphenyl)acrylonitrile hydrochloride in the presence of p-toluene sulfonic acid monohydrate and 1 ,4-dioxane. It has been found that the rilpivirine produced according to the prior art procedures results in low yields.

 

The synthesis is as follows:

………………

more info………………………..

Rilpivirine, which is chemically known as 4-{[4-({4-[(lE)-2-cyanoethenyl]-2,6- dimethylphenyl} amino) pyrimidin-2-yl]amino}benzonitrile, is a non-nucleoside reverse transcriptase inhibitor (NNRTI) and exhibits human immunodeficiency virus (HIV) replication inhibiting properties. Rilpivirine is used as its hydrochloride salt in the anti-HIV formulations.

Figure imgf000002_0001

Conventionally, various processes followed for the synthesis of Rilpivirine hydrochloride (I), generally involve preparation of the key intermediate, (E)-4-(2- cyanoemenyl)-2,6-dimethylphenylamine hydrochloride of formula (II).

Figure imgf000003_0001

(E)-4-(2-cyanoethenyl)-2,6-dimethylphenylamine hydrochloride (II)

WO 03/016306 first disclosed the synthesis of Rilpivirine involving different routes for synthesis of 4-(2-cyanoethenyl)-2,6-dimethylphenylamine. The first route involved protection of the amino group of 4-bromo-2,6-dimemylphenylarnine by converting to Ν,Ν-dimethylmethanimidamide, followed by formylation involving n- butyl lithium and dimethylformamide. The resulting formyl derivative was treated with diethyl(cyanomethyl) phosphonate to give the cyanoethenyl compound which was deprotected using zinc chloride to yield the cyanoethenylphenylamine intermediate having an undisclosed E/Z ratio. This route involved an elaborate sequence of synthesis comprising protection of amine by its conversion into imide, use of a highly moisture sensitive and pyrophoric base such as butyl lithium and a low yielding formylation reaction. All these factors made the process highly unviable on industrial scale.

The second route disclosed in WO 03/016306 employed 4-iodo-2,6- dimethylphenylamine as a starting material for synthesis of cyanoemenylphenylamine intermediate, which involved reaction of the dimethylphenylamine derivative with acrylonitrile for atleast 12 hours at 130 C in presence of sodium acetate and a heterogeneous catalyst such as palladium on carbon. Isolation of the desired compound involved solvent treatment with multiple solvents followed by evaporation. This route also does not give any details of the E/Z ratio of the unsaturated intermediate product. Although this route avoids use of phosphine ligands but lengthy reaction time and problem of availability of pure halo-phenylamine derivatives coupled with moderate yields hampers the commercial usefulness of this route.

The third route disclosed in WO 03/016306 involved reaction of 4-bromo-2,6- dimethylphenylamine with acrylamide in presence of palladium acetate, tris(2- methylphenyl)phosphine and N,N-diethylethanamine. The resulting amide was dehydrated using phosphoryl chloride to give 4-(2-cyanoethenyi)-2,6- dimethylphenylamine in a moderate yield of 67% without mentioning the E/Z ratio. Although the E/Z isomer ratio for the cyanoethenyl derivative obtained from these routes is not specifically disclosed in the patent, however, reproducibility of the abovementioned reactions were found to provide an E/Z ratio between 70/30 and 80/20. Various other methods have also been reported in the literature for introduction of the ‘ cyanoethenyl group in Rilpivirine. The Journal of Medicinal Chemistry (2005), 48, 2072-79 discloses Wittig or Wadsworth-Emmons reaction of the corresponding aldehyde with cyanomethyl triphenylphosphonium chloride to provide a product having an E/Z isomer ratio of 80/20. An alternate method of Heck reaction comprising reaction of aryl bromide with acrylonitrile in presence of tri-o- tolylphosphine and palladium acetate gave the same compound with a higher E/Z isomer ratio of 90/10. The method required further purification in view of the presence of a significant proportion of the Z isomer in the unsaturated intermediate. A similar method was disclosed in Organic Process Research and Development (2008), 12, 530-536. However, the E/Z ratio of 4-(2-cyanoethenyl)-2,6- dimethylphenylamine was found to be 80/20, which was found to improve to 98/2 (E/Z) after the compound was converted to its hydrochloride salt utilizing ethanol and isopropanol mixture.

It would be evident from the foregoing that prior art methods are associated with the following drawbacks:

a) High proportion of Z isomer, which requires elaborate purification by utilizing column chromatographic techniques, crystallization, or successive treatment with multiple solvents, which decreases the overall yield,

b) Introduction of cyanoethenyl group to the formylated benzenamine derivatives involves a moisture sensitive reagent like n-butyl lithium, which is not preferred on industrial scale. Further, the method utilizes cyanomethyl phosphonate esters and is silent about the proportion of the Z isomer and the higher percentage of impurities which requires elaborate purification and ultimately lowers the yield,

c) Prior art routes involve use of phosphine ligands which are expensive, environmentally toxic for large scale operations,

d) Prior art methods utilize phase transfer catalysts such as tetrabutyl ammonium bromide in stoichiometric amounts and the reactions are carried out at very high temperatures of upto 140-150°C.

Thus, there is a need to develop an improved, convenient and cost effective process for preparation of (E)-4-(2-cyanoethenyl)-2,6-dimethylphenylamine hydrochloride of formula (II) having Z-isomer less than 0.5%, without involving any purification and does not involve use of phosphine reagent and which subsequently provides Rilpivirine hydrochloride (I) conforming to regulatory specifications.

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http://www.google.com/patents/EP2643294A2?cl=en

The present inventors have developed a process for stereoselective synthesis of the key Rilpivirine intermediate, (E)-4-(2-cyanoethenyl)-2,6-dimemylphenylarnine hydrochloride (II), comprising diazotization of 2,6-dimethyl-4-amino-l- carboxybenzyl phenylamine followed by treatment with alkali tetrafluoroborate to provide the tetrafluoroborate salt of the diazonium ion which is followed by reaction with acrylonitrile in presence of palladium (II) acetate and subsequent deprotection of the amino group with an acid followed by treatment with hydrochloric acid to give the desired E isomer of compound (II) having Z isomer content less than 0.5% and with a yield of 75-80%. The compound (II) was subsequently converted to Rilpivirine hydrochloride of formula (I) with Z isomer content less than 0.1%.

Figure imgf000008_0001

Figure imgf000008_0002

Figure imgf000011_0001

……………………………………

Figure

Chemical structures of selected NNRTIs

 

 

…………………………….

http://pubs.acs.org/doi/full/10.1021/jm040840e

J. Med. Chem., 2005, 48 (6), pp 1901–1909
DOI: 10.1021/jm040840e
R278474, rilpivirine is the E-isomer of 4-[[4-[[4-(2-cyanoethenyl)-2,6-dimethylphenyl]amino]-2-pyrimidinyl]amino]benzonitrile, which can be synthesized in six high-yield reaction steps.60 The end product contains minimal amounts (less than 0.5%) of the Z-isomer.
R278474 is a slightly yellow crystalline powder with molecular mass of 366.4 Da and a melting point of 242 °C. It is practically insoluble in water (20 ng/mL at pH 7.0), moderately soluble in poly(ethylene glycol) (PEG 400, 40 mg/mL), and readily soluble in dimethyl sulfoxide (>50 mg/mL). The compound is ionizable in aqueous solution (pKa = 5.6) and is very lipophilic (log P = 4.8 at pH 8.0). For comparison, the pKa value for TMC120 is 5.8 and the corresponding log P value amounts to 5.3.
Under daylight and in weak acid solution a conversion of 8% of the E-isomer of R278474 into the Z-isomer has been observed.

Iloperidone (Fanapt)


Iloperidone(Fanapt)

Iloperidone (Fanapt), ILO-522, HP-873, Zomaril, 133454-47-4, antipsychotic

1-[4-[3-[4-(6-Fluoro-1,2-benzisoxazol-3-yl)-1-piperidinyl]propoxy]-3-methoxyphenyl]ethanone; 1-[3-(4-Acetyl-2-methoxyphenoxy)propyl]-4-(6-fluoro-1,2-benzisoxazol-3-yl)piperidine; 4′-[3-[4-(6-Fluoro-1,2-benzisoxazol-3-yl)-1-piperidinyl]propoxy]-3′-methoxyacetophenone

Aventis Pharma (Originator), Novartis (Licensee), Titan (Licensee)Vanda Pharmaceuticals (Licensee)

Iloperidone(Fanapt) is a monoamine directed towards acting upon and antagonizing specific neurotransmitters, particularly multiple dopamine and serotonin receptor subtypes.

Schizophrenia is a chronic, severe, and debilitating mental disorder that affects approximately 2.4 million Americans, around 1.1% of the population. The net cost of this disorder is staggering as estimates from 2002 reveal this disorder to cost $62.7 billion. A major issue with the treatment of schizophrenia is that patients show varying levels of response and tolerance to available therapies. Although the symptoms of the disease are very severe, estimates show that approximately 3 out of 4 patients discontinue medication prior to completing 18 months of treatment, many times due to the severe side effects of the approved medications.

Synthesis

J.T. Strupczewski, K.J. Bordeau, Y. Chiang, E.J. Glamkowski, P.G.
Conway, R. Corbett, H.B. Hartman, M.R. Szewczak, C.A. Wilmot andG.C. Helsley, J. Med. Chem., 38, 1119 (1995).

US 4355037
V. Miklos, WO Patent 031497 (2010).
J.T. Strupczewski, EP Patent 0402644 (1990)

The product is protected by the U.S. Pat. No. 5,364,866, U.S. Pat. No. RE 39198 E and EP 402644 B1.U.S. Pat. No. 5,364,866 and U.S. Pat. No. 5,663,449.EP 542136, EP 612318, EP 730452, JP 95501055, JP 97511215, US 5364866, US 5776963, WO 9309102, WO 9511680.US 4355037,EP 0542136; EP 0612318; EP 0730452; EP 0957102; EP 0959075; EP 0959076; EP 0963984; JP 1995501055; JP 1997511215; US 5364866; US 5776963; WO 9309102; WO 9511680

The first reported synthetic method for Iloperidone is described in patent EP 402644 A1.

In U.S. Patent US5776963 and patent family EP4 (^ 644, there is disclosed a method for preparing iloperidone,

The synthetic method reported(4, 5) for 1 involves two chemical steps: O-alkylation of acetovanillone (2) with 1-bromo-3-chloropropane (3) to obtain chloro derivative 4 followed byN-alkylation of piperidine intermediate 5 with 4. The reported process for 4 comprises O-alkylation of 2 with 3 in acetone in the presence of potassium carbonate for 20 h to provide 4as an oil after usual work up, which was then vacuum (0.1 mmHg) distilled to collect desired product 4 at 141–143 °C with around 85% yield (Scheme 1, Path A). Some of the drawbacks of this process are as follows: longer reaction time (around 20 h), formation of 6–7% of dimer impurity (10, Scheme 2), high-vacuum distillation to achieve the quality, which is always a cumbersome process at industrial scale, requiring special apparatus and skill set, and degradation and charring of some portion of product during high-vacuum distillation. Further, the next step comprises N-alkylation of 4 with 5 in N,N-dimethylformamide (DMF) in the presence of potassium carbonate to provide iloperidone (1) as a crude solid, which was purified by crystallization using ethanol to yield pure 1 with 58% yield (Scheme 1, Path A). Some of the lacunae observed with the above process includes the following: (a) low yields, (b) formation of carbamate impurity 13 (Scheme 2) in the range 15–20% due to the use of potassium carbonate, (c) ineffective purification by crystallization using ethanol to eliminate carbamate impurity below 0.15%, and (d) iloperidone obtained by the above synthetic process was beige in color.

Figure
Scheme 1. Reported (Path A) and Improved (Path B) Process for Preparation of 1
Figure
Scheme 2. Flow Chart Representing the Formation of Impurities
A few other improved processes reported…(Improved and Efficient Process for the Production of Highly Pure Iloperidone: A Psychotropic Agent)subsequently for 1 follow the same reaction sequence (Scheme 1, Path A) using compounds 4 and 5 as key starting materials with different bases and solvents.(6-13) However, the reported processes do not address a control mechanism for impurities 8911, and 13 (Scheme 2) formed during the synthesis of 1. In order to eliminate these impurities, the reported processes involve employment of multiple purifications using a single solvent or mixture of solvents or purification by means of formation of the acid addition salt of 1 followed by converting back to pure 1.(6-13)

The synthetic route is as follows:

The reaction of piperidine-4-carboxylic acid (I) with formic acid and acetic anhydride gives 1-formylpiperidine-4-carboxylic acid (II), which is treated with SOCl2 and acetic anhydride to yield the corresponding acyl chloride (III). The Friedel-Crafts condensation of (III) with refluxing 1,3-difluorobenzene (IV) by means of AlCl3 affords 4-(2,4-difluorobenzoyl)-1-formylpiperidine (V), which is treated with hydroxylamine in refluxing ethanol to give the corresponding oxime (VI). The cyclization of (VI) by means of NaH in hot THF/DMF yields 6-fluoro-3-(1-formylpiperidin-4-yl)-1,2-benzisoxazole (VII), which is treated with HCl in refluxing ethanol to afford 6-fluoro-3-(4-piperidyl)-1,2-benzisoxazole (VIII). Finally, this compound is condensed with 4-(3-chloropropoxy)-3-methoxyacetophenone (IX) by means of K2CO3 in hot DMF. The intermediate 4-(3-chloropropoxy)-3-methoxyacetophenone (IX) can be obtained by condensation of 4-hydroxy-3-methoxyacetophenone (IX) with 3-chcloropropyl bromide (X) by means of NaH or K2CO3 in DMF.

Figure CN102443000AD00032

Iloperidone, also known as FanaptFanapta, and previously known as Zomaril, is an atypical antipsychotic for the treatment ofschizophrenia.

 

Accordingly, 6-fluoro-3-(4-piperidyl)-1,2-benzoxazole 1 and 1-[4-(3-chloropropoxy)-3-methoxy-phenyl]ethanone 2 were heated in presence of potassium carbonate using dimethylformamide solvent to afford 1-[4-[3-[4-(6-fluoro-1,2-benzoxazol-3-yl)-1-piperidyl]propoxy]-3-methoxy-phenyl]ethanone also called Iloperidone

It was approved by the U.S. Food and Drug Administration (FDA) for use in the United States on May 6, 2009.

It’s not yet approved in India.

Hoechst Marion Roussel Inc. made initial inquiries into the drug; however, in May 1996, they discontinued research, and in June 1997 gave research rights to Titan Pharmaceuticals. Titan then handed over worldwide development, manufacturing and marketing rights to Novartis in August 1998. On June 9, 2004, Titan Pharmaceuticals announced that the Phase III development rights have been acquired by Vanda Pharmaceuticals. The original launch date was scheduled for 2002. On November 27, 2007, Vanda Pharmaceuticals announced that the U.S. Food and Drug Administration (FDA) had accepted their New Drug Application for iloperidone, confirming the application is ready for FDA review and approval. On July 28, 2008, the FDA issued a “Not Approvable” letter to Vanda Pharmaceuticals concerning the drug, stating that further trials are required before a decision can be made concerning marketed usage of iloperidone.

Chemically designated as 1-[4-[3-[4-(6-fluoro-1,2-benzisoxazol-3-yl)-1-piperidinyl]propoxy]-3-methoxyphenyl]ethanone, is a second generation atypical antipsychotic agent. Iloperidone, also known as Fanapt, Fanapta, and Zomaril, was approved by the U.S. Food and Drug Administration (FDA) for use in the United States on May 6, 2009 and is indicated for the acute treatment of schizophrenia in adults. Iloperidone has been shown to act as an antagonist at all tested receptors. It was found to block the sites of noradrenalin (α2C), dopamine (D2A and D3), and serotonin (5-HT1A and 5-HT6) receptors.(2) In addition, pharmacogenomic studies identified single nucleotide polymorphisms associated with an enhanced response to iloperidone during acute treatment of schizophrenia. It is considered an “atypical” antipsychotic because it displays serotonin receptor antagonism, similar to other atypical antipsychotics. The older typical antipsychotics are primarily dopamine antagonists.(3)

Iloperidone won FDA approval for use treating schizophrenia in the United States on May 6, 2009

Iloperidone (1-[4-[3-[4-(6-fluoro-1,2-benzisoxazole-3-yl)-1-piperidinyl]propoxy]-3-methoxyphenyl]ethanone) is an atypical new-generation antipsychotic medicament belonging to the class of piperidinyl-benzisoxazole derivatives, which is used to treat schizophrenia, bipolar disorder and other psychiatric conditions. Iloperidone acts as a serotonin/dopamine receptor antagonist (5-HT2A/D2).

Iloperidone, also known as Fanapt, Fanapta, and previously known as Zomaril, is an atypical antipsychotic drug used for the treatment of schizophrenia. The chemical name of iloperidone is l-[4-[3-[4-(6-fluoro-l,2-benzisoxazol-3-yl)-l- piperidinyl]propoxy] -3-methoxyphenyl]ethanone.

EP 0402644 patent discloses first synthetic route of synthesis of iloperidone as shown in Scheme I, which consists of alkylation reaction between l-(4-(3-chloropropoxy-3- methoxyphenyl)ethanone of the formula (II) and 6-fluoro-3-piperidin-4-yl-l ,2 benzisoxazole hydrochloride of the formula (III) in presence of potassium carbonate in N,N dimethyl formamide. The reaction has been subsequently worked up and the compound of formula (I) is extracted from water using ethyl acetate. The compound of formula (I) is purified by crystallization using ethanol. The overall yield of compound of formula (I) is 58%.

Figure imgf000003_0001

Formula (I)

SCHEME 1 Further, we have analyzed the reported synthetic route for synthesis of iloperidone; following limitations have been observed and identified in the reported synthetic route:

a) The yield obtained using said synthetic route as reported in US RE39198 is 58%. Hence, this route of synthesis is not cost efficient at commercial scale due to low yield;

b) Use of potassium carbonate as a base in reaction leads to formation of carbon dioxide as one of the side products during the reaction, which further hinders in the manufacturing process by actively participating in manufacturing process and thereby leads to the formation o

Figure imgf000004_0001

Formula (IV)

which is in the range of 15-20%, and thereby resulting in low yield of iloperidone;

c) Purification by crystallization using ethanol as a solvent is not effective in eliminating or controlling carbamate impurity below 0.15% as per the ICH guide lines for the known impurities; and

d) Iloperidone obtained by the above synthetic process is beige in colour.

CN101768154 discloses the synthesis of iloperidone by N-alkylation reaction between l-(4-(3- chloropropoxy-3-methoxyphenyl)ethanone of the formula (II) and 6-fluoro-3-piperidin-4-yl-l,2 benzisoxazole hydrochloride of the formula (III) in inorganic alkaline solution, particularly; alkali metal carbonate solution. We have analyzed the reported synthetic route for synthesis of iloperidone and have observed and identified that the use of alkaline carbonate solution leads to the formation of carbamate impurity in the range of 1 to 1.5%.

Several patents were published after, describing essentially the same synthetic way such as US5364866 and US5663449.

The synthesis of iloperidone is described in USRE39198 (corresponding to EP 0 402 644 example 3) according to the following synthesis scheme:

Figure US20130261308A1-20131003-C00002

In agreement with said patent, the intermediate isolated, 1-[4-(3-chloropropoxy)-3-methoxyphenyl]ethanone, is reacted with 6-fluoro-3-(4-piperidinyl)-1,2-benzisoxazole hydrochloride in N,N-dimethyl formamide at 90° C. for 16 hours. When the reaction is complete, the mixture is poured into water and extracted with ethyl acetate. The crude product thus obtained is crystallised twice from ethanol to give crystallised iloperidone with a total yield of 58%.

The yield of this process is very low; moreover, the process begins with two isolated intermediates, and requires an aqueous extractive work-up step with an increase in volumes and consequent reduction in the productivity and efficiency of the process. Said process also requires a double crystallisation step to obtain a beige product. The quality levels obtained are not described in the text of the example, but a beige color does not suggest a high-quality product, as iloperidone is a white substance.

The synthesis of intermediate 1-[4-(3-chloropropoxy)-3-methoxyphenyl]ethanone is disclosed in U.S. Pat. No. 4,366,162. Example 1 describes the preparation of said intermediate by reacting acetovanillone with 1-bromo-3-chloropropane in acetone with potassium carbonate. At the end of the reaction the resulting product is purified by distillation and obtained as an oily intermediate which is left to stand in order to obtain the solid intermediate.

The synthesis of intermediate 1-[4-(3-chloropropoxy)-3-methoxyphenyl]ethanone is also disclosed in U.S. Pat. No. 4,810,713. Preparation 12 describes the synthesis of said intermediate from acetovanillone and 1-bromo-3-chloropropane in sodium hydroxide alkalinized water. At the end of the reaction the product obtained is extracted in toluene, the organic phases are washed with basic aqueous solutions and finally, the intermediate 1-[4-(3-chloropropoxy)-3-methoxyphenyl]ethanone is crystallised with the aid of diisopropyl ether. The intermediate isolated is then recrystallised twice from cyclohexane and twice from petroleum ether.

An alternative process for the synthesis of iloperidone is reported in CN 102070626.

Scheme 2 shows the synthesis procedure:

Figure US20130261308A1-20131003-C00003

The decision to alkylate acetovanillone with 1-chloro-3-propanol requires an extra synthesis step (to convert the OH group to an OR leaving group) compared with the procedure reported by the combination of patents USRE39198 (EP402644) and U.S. Pat. No. 4,366,162/U.S. Pat. No. 4,810,713, making said process less efficient from the economic standpoint.

WO2011061750 discloses an alternative iloperidone synthesis process as reported in Scheme 3:

Figure US20130261308A1-20131003-C00004

Said process uses reagents such as methyl magnesium chloride to effect the Grignard reaction to convert the aldehyde group to a secondary alcohol group, which are much more complicated to manage on an industrial scale than the synthesis methods previously described. Moreover, the oxidation reaction of the next step uses reagents such as chromic acid or potassium permanganate, which have a very high environmental impact and very low industrial applicability.

WO2011055188 discloses a process for the synthesis of iloperidone comparable to the one reported in USRE39198 from two isolated intermediates 1-[4-(3-chloropropoxy)-3-methoxyphenyl]ethanone and 6-fluoro-3-(4-piperidinyl)-1,2-benzisoxazole hydrochloride. The same patent application also gives preparation examples of the intermediate 1-[4-(3-chloropropoxy)-3-methoxyphenyl]ethanone isolated as crystalline solid by procedures similar to those known in the literature.

CN 101824030 reports an iloperidone synthesis method similar to that of CN 102070626 which involves the same problems of inefficiency due to the additional step of inserting the leaving group required for alkylation with 6-fluoro-3-(4-piperidinyl)-1,2-benzisoxazole hydrochloride.

CN 101781243 discloses an alternative iloperidone synthesis process as reported in Scheme 4.

Figure US20130261308A1-20131003-C00005

Said process is not advantageous compared with the preceding processes as the intermediate with the oxime group, due to the nature of this functional group, is particularly liable to degradation due to the action of numerous factors such as the presence of metals, acid pHs and basic pHs.

CN101768154 discloses a process for the synthesis of iloperidone comparable to the one reported in USRE39198 from two isolated intermediates, 1-[4-(3-chloropropoxy)-3-methoxyphenyl]ethanone and 6-fluoro-3-(4-piperidinyl)-1,2-benzisoxazole hydrochloride.

CN 101735208 describes a process for the synthesis of iloperidone comparable to the one reported in CN 101781243, namely through the intermediate with the functional oxime group.

IN 2007MU01980 discloses a process for the synthesis of iloperidone comparable to the one reported in USRE39198 from two isolated intermediates, 1-[4-(3-chloropropoxy)-3-methoxyphenyl]ethanone and 6-fluoro-3-(4-piperidinyl)-1,2-benzisoxazole hydrochloride.

WO 2010031497 describes an alternative iloperidone synthesis process as reported in Scheme 5.

Figure US20130261308A1-20131003-C00006

The considerable economic disadvantage of the process reported in WO2010031497 is based on the fact that by reversing the order of alkylation and performing that of intermediate 6-fluoro-3-(4-piperidinyl)-1,2-benzisoxazole hydrochloride first, a greater loss of yield is generated on this intermediate which, according to the literature, is more difficult to synthesise and consequently more expensive than the intermediate 1-[4-(3-chloropropoxy)-3-methoxyphenyl]ethanone, with a globally greater economic inefficiency of the iloperidone preparation process.

CN 102212063 discloses a process for the synthesis of iloperidone with the same arrangement of the synthesis steps as patent application WO 2010031497.

WO2011154860 describes a process for the synthesis of iloperidone wherein a phase transfer catalyst is used to prepare the intermediate 1-[4-(3-chloropropoxy)-3-methoxyphenyl]ethanone which, as in all the other preparation examples previously described, is crystallised, isolated and dried before use in the next step with 6-fluoro-3-(4-piperidinyl)-1,2-benzisoxazole hydrochloride. Scheme 6 shows the synthesis scheme of the process of WO2011154860.

Figure US20130261308A1-20131003-C00007

………………………………

US20100076196

Figure US20100076196A1-20100325-C00003

……………………………………

WO2012123963A2

EXAMPLE 1:

Tetrabutyl ammonium bromide (2.40 gm) was added to a stirred solution of Potassium hydroxide (0.724 kg) in mixture of Heptane (2.0L). and water (10.0L), followed by addition of 1- [4-(3-chloropropoxy)-3-methoxyphenyl]ethanone (2, 1.0kg) and 6-fluoro-3-piperidin-4-yl-l,2- benzisoxazole hydrochloride^, 1.1 1kg) at 30°C. This reaction mass was stirred for 15 to 20 min. The temperature of the reaction mass was raised to 70°C and was maintained for 8 to 10 hours. After completion of reaction (by TLC, Mobile Phase: Toluene/ Acetone/Ethyl acetate = 6:2:2 mL), the mixture was cooled to 30°C, diluted with dichloromethane (2.5 L) and stirred for 30 minutes. The dichloromethane layer was separated. The aqueous layer was re-extracted with dichloromethane (1.0L). The combined dichloromethane layer was washed with water (1.5L) and decolorized with activated charcoal (0.05 kg). The solvent was distilled off completely to obtain the residue. The residue obtained was dissolved in isopropyl alcohol (5.0L) at reflux temperature to obtain the clear solution. The clear solution obtained was cooled to 30°C followed by 0°C and stirred for 60 min to precipitate out crystals. The colorless crystals of compound (I) obtained were filtered. The crystalline solid was dried under vacuum (650-700 mm/Hg) to obtain pure compound (I) as a crystalline solid. HPLC analysis was performed for the crystalline solid obtained. The purity of Iloperidone, impurity profile and yield are shown in table 1 below.

Table 1 : Analysis data of iloperidone i.e. purity, yield and impurity profile.

Figure imgf000023_0001

EXAMPLE 2:

Tetrabutyl ammonium bromide (2.40 gm) was added to a stirred solution of Potassium hydroxide (0.724 kg) in mixture of Heptane (2.0L) and water (10.0L), followed by addition of 1- [4-(3-chloropropoxy)-3-methoxyphenyl]ethanone (2, 1.0kg) and 6-fluoro-3-piperidin-4-yl-l,2- benzisoxazole hydrochloride^, 1.1 1kg) at 30°C. This reaction mass was stirred for 15 to 20 min. The temperature of the reaction mass was raised to 70°C and maintained for 8 to 10 hours. After completion of reaction (by TLC, Mobile Phase: Toluene/ Acetone/Ethyl acetate = 6:2:2 mL), the mixture was cooled to 30°C, the reaction mixture was filtered to obtain wet crude iloperidone. Further, the obtained wet crude was dried at 60-65 °C under vacuum to furnish crude iloperidone (1.72 kg). The dried crude iloperidone was dissolved in isopropyl alcohol (5.0 L) at reflux temperature and decolorized with activated charcoal (0.05 kg). Obtained filtrate was cooled to 30°C followed by 0°C and stirred for 60 min to precipitate out crystals. The colorless crystals of compound (I) obtained were filtered. The crystalline solid was dried under vacuum (650-700 mm/Hg) to obtain pure compound (I) as a crystalline solid. HPLC analysis was performed for the crystalline solid obtained. The purity of Iloperidone, impurity profile and yield are shown in table 2 below.

Table 2: Analysis data of iloperidone i.e. purity, yield and impurity profile.

Figure imgf000024_0001

EXAMPLE-3:

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US20130261308

UPLC-MS [M+H+]=427

1H-NMR (in DMSO) (chemical shifts expressed in ppm with respect to the TMS signal): 2.06-1.78 (6H, m); 2.13 (2H, m); 2.49 (2H, t); 2.52 (2H, m); 2.97 (2H, m); 3.11 (1H, tt); 3.83 (3H, s); 4.12 (2H, t); 7.06 (1H, d); 7.22 (1H, m); 7.46 (1H, d); 7.61-7.58 (2H, m); 7.94 (1H, dd).

………………………………

.Improved and Efficient Process for the Production of Highly Pure Iloperidone: A Psychotropic Agent

Org. Process Res. Dev., Article ASAP
DOI: 10.1021/op400335p

http://pubs.acs.org/doi/full/10.1021/op400335p?prevSearch=iloperidone&searchHistoryKey=

Abstract Image

The present work describes an improved and highly efficient process for the synthesis ofiloperidone (1), an antipsychotic agent, which is free from potential impurities. The synthesis comprises N-alkylation of 1-(4-(3-chloropropoxy)-3-methoxyphenyl)ethanone (4) with 6-fluoro-3-piperidin-4-yl-1,2-benzisoxazole hydrochloride (5) in a mixture of water and heptane as solvent and sodium hydroxide as a base in the presence of tetrabutylammonium bromide as a phase transfer catalyst to yield iloperidone (1) with a yield of around 95% and a purity of 99.80% by HPLC. The present work also describes the optimization details performed to achieve the process attributes responsible for high yield and purity.

FT-IR (KBr, λmax, cm–1): 3031, 2949, 2779, 2746, 2822, 1669, 1614, 1585, 1510, 1462, 1448, 1415, 1380, 1313, 1262, 1221, 1177, 1150, 1123, 1077, 1034, 997, 985, 955, 884, 876, 853, 812, 781, 643, 610, 569, 475.

1H NMR (CDCl3): δ 2.03–2.10 (m, 6H), 2.12–2.18 (m, 2H), 2.55–2.56 (s, 3H), 2.58–2.60 (t, 2H), 3.02–3.09 (m, 3H), 3.91 (s, 3H), 4.10–4.19 (t, 2H), 6.91–6.93 (d, 1H), 7.01–7.06 (dd, 1H), 7.21–7.24 (dd, 1H), 7.51–7.52 (d, 1H), 7.53–7.56 (dd, 1H), 7.69–7.65 (dd, 1H).

13C NMR (CDCl3): 26.02, 26.40, 30.36, 34.34, 53.36, 54.90, 55.80, 67.16, 97.04, 97.31, 110.20, 111.02, 111.98, 112.23, 117.12, 122.36, 122.46, 123.06, 130.11, 149.00, 152.66, 160.91, 162.60, 163.53, 163.66, 165.09, 198.59.

MS (ESI, m/z): 427.2 [M + H].+

Anal. Calcd (%) for C24H27FN2O4(426.48): C, 67.54; H, 6.33; found (%): C, 67.24; H, 6.18.

HPLC

HPLC analysis developed at Megafine  India using a Hypersil BDS C18 column (250 mm × 4.6 mm, particle size 5 μm); mobile phase A comprising a mixture of 5.0 mM ammonium dihydrogen orthophosphate buffer and 0.1% triethylamine; mobile phase B comprising a mixture of acetonitrile/methanol in the ratio 80:20 v/v; gradient elution: time (min)/A (v/v): B (v/v); T0.01/65:35, T8.0/65:35, T25.0/35:65, T35.0/35:65, T37.0/65:35, T45.0/65:35; flow rate 1.0 mL/min; column temperature 30 °C; wavelength 225 nm. The observed retention time of iloperidone under these chromatographic conditions is about 17.0 min.

…….

http://www.asianjournalofchemistry.co.in/User/ViewFreeArticle.aspx?ArticleID=25_10_2

N oxide impurity

m.p. 155-157 ºC;

FT-IR (KBr, νmax, cm-1):
3083, 2958, 2878, 1655, 1606, 1584, 1509, 1467, 1419, 1348,1273, 1223, 1182, 1143, 1121, 1032, 971, 957, 881, 857, 813,
802;

1H NMR (300 MHz, CDCl3)

δ 1.89-1.93 (m, 2H), 2.31-2.40 (m, 2H), 2.55 (s, 3H), 2.60-2.72 (m, 2H), 3.29-3.52 (m,
2H), 3.29-3.52 (m, 2H), 3.29-3.52 (m, 2H), 3.29-3.52 (m, 1H),3.85 (s, 3H), 4.23(t, 2H, J = 6.0 Hz), 7.11 (d, 1H, J = 8.4 Hz),7.30-7.36 (m, 1H), 7.62-7.65 (m, 1H), 7.71-7.74 (dd, J = 9.3and 2.0 Hz, 1H), 8.02-8.07 (dd, J = 8.7 and 5.4 Hz, 1H);

13CNMR (75 MHz, CDCl3)

δ 22.13, 24.70, 26.35, 31.49, 55.54,63.21, 67.07, 67.82, 97.51, 110.35, 111.86, 112.67, 123.11,
123.67, 129.95, 148.63, 152.22, 160.79, 163.10, 163.69,196.40;

MS (ESI, m/z): 443 [M + H]+.

Anal. calcd. (%) forC24H27N2O5F (442.19): C, 65.15; H, 6.15; N, 6.33; found (%):C, 65.11; H, 6.09; N, 6.29.

………………………

INTERMEDIATES

Figure

Acetovanillon (4-hydroxy-3-methoxyacetophenone) 6 is also a first-generation fine chemical obtained as a reaction product from the oxidation−hydrolysis of lignosulfonate LS. The compound serves as substrate in synthetic processes leading to several second-generation fine chemicals, such as acetoveratron, veratric acid, and veratric acid chloride. Moreover, recently, a new compound iloperidone REF 20,21   34 [1-(3-(4-acetyl-2-methoxyphenoxy)propyl)-4-(6-fluorobenzisoxazol-3-yl)piperidine] that includes an acetovanillon 6 moiety was reported to be under development for use as an antipsychotic dopamine D2 antagonist and a 5-HT2Aantagonist.
The synthesis of iloperidone 34 is performed by means of an eight-step synthetic process. The acetovanillon 6, which constitutes an integral part of this substance, is condensed with 3-chloropropylbromide 43 in DMF in the presence of potassium carbonate or sodium hydride as base to obtain the key intermediate 44. In the last step of the process 44 is reacted with 42 to afford iloperidone 34. The intermediate 42 is synthesised by reacting piperidine-4-carboxylic acid 35 with formic acid and acetic acid anhydride to obtain 1-formylpiperidine-4-carboxylic acid 36 that upon treatment with thionyl chloride in acetic acid anhydide gives the corresponding acyl chloride 37 (1-formylpiperidine-4-carbonyl chloride). Under Friedel−Craft conditions, the acyl chloride 37 is condensed with 1,3-difluorobenzene 38 to afford 4-(2,4-difluorobenzoyl)piperidine-1-carbaldehyde 39. Treatment of this intermediate with hydroxylamine in refluxing ethanol yields the oxime 40 (4-[(2,4-difluorophenyl)hydroxyiminomethyl]piperidine-1-carbaldehyde). When the oxime 40 is exposed to basic conditions by means of sodium hydride in hot DMF and THF in the following step, a cyclisation proceeds to afford benzo[d]isoxazol 41 (4-(6-fluorobenzo[d]isoxazol-3-yl)piperidine-1-carbaldehyde), which upon treatment with HCl in refluxing ethanol affords the key intermediate 42.

 

FANAPT is a psychotropic agent belonging to the chemical class of piperidinyl-benzisoxazole derivatives. Its chemical name is 4′-[3-[4-(6-Fluoro-1,2-benzisoxazol-3-yl)piperidino]propoxy]-3′-methoxyacetophenone. Its molecular formula is C24H27FN2O4 and its molecular weight is 426.48. The structural formula is:

FANAPT® (iloperidone) Structural Formula Illustration

Iloperidone is a white to off-white finely crystalline powder. It is practically insoluble in water, very slightly soluble in 0.1 N HCl and freely soluble in chloroform, ethanol, methanol, and acetonitrile.

Title: Iloperidone
CAS Registry Number: 133454-47-4
CAS Name: 1-[4-[3-[4-(6-Fluoro-1,2-benzisoxazol-3-yl)-1-piperidinyl]propoxy]-3-methoxyphenyl]ethanone
Manufacturers’ Codes: HP-873; ILO-522
Trademarks: Zomaril (Novartis)
Molecular Formula: C24H27FN2O4
Molecular Weight: 426.48
Percent Composition: C 67.59%, H 6.38%, F 4.45%, N 6.57%, O 15.01%
Literature References: Combined dopamine (D2) and serotonin (5HT2) receptor antagonist. Prepn: J. T. Strupczewski et al., EP402644eidem, US 5364866 (1990, 1994 both to Hoechst-Roussel); eidem, J. Med. Chem. 38, 1119 (1995).
Pharmacology: M. R. Szewczak et al., J. Pharmacol. Exp. Ther. 274, 1404 (1995).
Clinical pharmacokinetics: S. M. Sainati et al., J. Clin. Pharmacol.35, 713 (1995).
HPLC determn in plasma: A. E. Mutlib, J. T. Strupczewski, J. Chromatogr. B 669, 237 (1995). Receptor binding study: S. Kongsamut et al., Eur. J. Pharmacol. 317, 417 (1996).
Review of pharmacology and therapeutic potential in schizophrenia: J. M. K. Hesselink, Curr. Opin. Cent. Peripher. Nerv. Syst. Invest. Drugs 2, 71-78 (2000); K. K. Jain, Expert Opin. Invest. Drugs 9, 2935-2943 (2000).
Properties: Crystals from ethanol, mp 118-120°.
Melting point: mp 118-120°
Therap-Cat: Antipsychotic.
Keywords: Antipsychotic; Benzisoxazoles; Serotonin-Dopamine Antagonist.

..

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IRBESARTAN


IRBESARTAN, SR 47436, BMS-186295

Avapro® (Bristol-Myers Squibb) and Karvea®
(Sanofi-Winthrop)

2-butyl-3-({4-[2-(2H-1,2,3,4-tetrazol-5-yl)phenyl]phenyl}methyl)-1,3-diazaspiro[4.4]non-1-en-4-one

138402-11-6  CAS NO

U.S. Patents 5,270,317 and 5,352,788, 6,162,922

The compound prepared according to US 5270317 is polymorph A

  • Irbesartan is known by following chemical names:

    1. (a) 2-Butyl-3-[[2′-(1H-tetrazol-5-yl)[1,1′-biphenyl]-4-yl]methyl]-1,3-diazaspiro[4,4]non-1-en-4-one
    2. (b) 2-Butyl-3-[p-(o-1H-tetrazol-5-ylphenyl)benzyl]-1,3-diazaspiro[4,4]non-1-en-4-one
    3. (c) 2-n-butyl-4-spirocyclopentane-1-[(2′-(tetrazol-5-yl)biphenyl-4-yl) methyl]-2-imidazolin-5-one.
  •  
    The structural formula of Irbesartan is represented below.

    Figure imgb0001

    Irbesartan

  •  
    The synthesis of irbesartan is first disclosed in US5270317 (equivalentEP0454511 ) and subsequently, several other patents disclose the synthesis of irbesartan by different methods. Basically the synthesis of this molecule involves two common intermediates namely spiroimidazole and substituted 4′-bromomethylbiphenyl.
  •  
    US 5270317 describes preparation of irbesartan wherein 1-[(2′-cyanobiphenyl-4-yl)methyl]-2-n-butyl-4-spirocyclopentane-2-imidazolin -5-one which is reacted with tributyltin azide in xylene at reflux temperature for 66 hours to give a product which is isolated from the reaction mass as trityl irbesartan and then deprotected in methanol/THF mixture using 4N hydrochloric acid to get irbesartan.
  •  
    US5629331 describes a process for the preparation of irbesartan from 1-[(2′-cyanobiphenyl)4-yl)methyl]-2-n-butyl-4-spirocyclopentane-2-imidazolin-5-one using sodium azide, TEA.HCl in N-methylpyrrolidone. The product is isolated from the alkaline reaction mass after acidification to pH 4.7 to 5.8 and the crude product is recrystallised from IPA/water to get Form A and ethanol/water to get Form B.

Irbesartan (INN/ɜrbəˈsɑrtən/ is an angiotensin II receptor antagonist used mainly for the treatment of hypertension. Irbesartan was developed by Sanofi Research (now part ofsanofi-aventis). It is jointly marketed by sanofi-aventis and Bristol-Myers Squibb under thetrade names AprovelKarvea, and Avapro.

It is marketed in Brazil by Sanofi-Aventis under the trade name Aprovel .

As with all angiotensin II receptor antagonists, irbesartan is indicated for the treatment ofhypertension. Irbesartan may also delay progression of diabetic nephropathy and is also indicated for the reduction of renal disease progression in patients with type 2 diabetes,[1]hypertension and microalbuminuria (>30 mg/24 hours) or proteinuria (>900 mg/24 hours).[2]

Irbesartan is also available in a combination formulation with a low dose thiazide diuretic, invariably hydrochlorothiazide, to achieve an additive antihypertensive effect. Irbesartan/hydrochlorothiazide combination preparations are marketed under similar trade names to irbesartan preparations, including IrdaCoIrdaCoAprovelKarvezide,Avalide and Avapro HCT.

A large randomized trial following 4100+ men and women with heart failure and normal ejection fraction (>=45%) over 4+ years found no improvement in study outcomes or survival with irbesartan as compared to placebo.[3]

BMS annual sales approx $1.3bn. Sanofi-aventis annual sales approx $2.1bn. In the United States, a generic version is available. Patent expired March 2012.

  1. Lewis EJ, Hunsicker LG, Clarke WR, Berl T, Pohl MA, Lewis JB, Ritz E, Atkins RC, Rohde R, Raz I; Collaborative Study Group. (2001). “Renoprotective effect of the angiotensin-receptor antagonist irbesartan in patients with nephropathy due to type 2 diabetes”. N Engl J Med 345 (12): 851–60. doi:10.1056/NEJMoa011303.PMID 11565517.
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Irbesartan of formula (I).

Figure imgf000002_0001

The chemical name of Irbesartan is 2-Butyl-3-[[2′-(lH-tetrazol-5-yl)[l,l’-biphenyl]-4- yl]methyl]-l,3-diazaspiro[4,4]non-l-en-4-one and formula is C2SH2SN6O and molecular weight is 428.53. The current pharmaceutical product containing this drug is being sold by Sanofi Synthelabo using the tradename AVAPRO, in the form of tablets. Irbesartan is useful in the treatment of diabetic neuropathy, heart failure therapy and hypertension. Irbesartan is angiotension II type I (AΙIi)-receptor antagonist. Angiotension II is the principal pressor agent of the rennin-angiotension system and also stimulates aldosterone synthesis and secretion by adrenal cortex, cardiac contraction, renal resorption of sodium, activity of the sympathetic nervous system and smooth muscle cell growth. Irbesartan blocks the vasoconstrictor and aldosterone- secreting effects of angiotension II by selectively binding to the ATi angiotension II receptor. U.S. Pat. Nos. 5,270,317 and 5,559,233 describes a process for the preparation of N- substituted heterocyclic derivatives which involves reacting a heterocyclic compound of the formula

Figure imgf000002_0002

with a (biphenyl-4-yl)methyl derivative of the formula

Figure imgf000003_0001

wherein R1, R2, R3, R4, R5, and t, z and Hal have the meanings given in said U.S. Pat. No.

5,270,317, in the presence of an inert solvent such as DMF, DMSO or THF, with a basic reagent, for example KOH, a metal alcoholate, a metal hydride, calcium carbonate or triethylamine. The products of the reaction were purified by chromatography.

U.S. Pat. Nos. 5,352,788, and 5,559,233, and WO 91/14679 also describe identical alkylation of the nitrogen atom of the heterocyclic compound with the halo-biphenyl compound using the same inert solvent and the same basic reagents.

  • US5629331 describes a process for the preparation of irbesartan from 1-[(2′-cyanobiphenyl)4-yl)methyl]-2-n-butyl-4-spirocyclopentane-2-imidazolin-5-one using sodium azide, TEA.HCl in N-methylpyrrolidone. The product is isolated from the alkaline reaction mass after acidification to pH 4.7 to 5.8 and the crude product is recrystallised from IPA/water to get Form A and ethanol/water to get Form B.
  •  
    WO 2005/051943 A1 describes a process for the preparing irbesartan wherein 1-[(2′-cyanobiphenyl-4-yl)methyl]-2-n-butyl-4-spirocyclopentane-2-imidazolin-5-one is reacted with tributyltin chloride, sodium azide and TBAB in toluene at reflux temperature for 20 hours. Product is isolated from the reaction mass as trityl irbesartan and then deprotected in methanol and formic acid to get irbesartan.
  •  
    WO 2006/023889 describes a method for preparing irbesartan, wherein 1-(2′-cyanobiphenyl-4-yl)methyl)-2-n-butyl-4-spirocyclopentane-2-imidazolin-5-one is reacted with sodium azide and triethylamine hydrochloride in N-methyl-2-pyrrolidone to give irbesartan.
  •  
    WO 2005/113518 describes a process for preparing irbesartan wherein cyano irbesartan in xylene, is reacted with tributyltin chloride and sodium azide at reflux temperature till reaction is completed followed by aqueous work-up and recrystallization to give irbesartaN
  • The process involving use of zinc salt for the transformation of nitrile to tetrazole is a safe and efficient process as reported in JOC (2001) 66, 7945-50. The use of zinc salt for transforming nitrile to tetrazole has also been published in WO9637481 and US5502191 

Also Canadian Patent No. 2050769 describes the alkylation of the nitrogen atom of the heterocycle of the formula

Figure imgf000003_0002

with a compound of the formula

Figure imgf000003_0003

wherein X, R1, Z1 and Z6 have the meanings given therein, in the presence of N,N- dimethylformamide and a basic reagent, such as alkali metal hydrides for example sodium or potassium hydride.

All of the above identified patents describe alkylation in solvents, such as N5N- dimethylformamide or DMSO, etc. in the presence of a basic reagent, for example, a metal hydride or a metal alcoholate etc. The strong bases, such as metal hydride or a metal alcoholate require anhydrous reaction conditions. Since N,N-dimethylformamide is used as a solvent, its removal requires high temperature concentration by distillation, which can result in degradation of the final product. The product intermediate is also purified by chromatography which is commercially not feasible and cumbersome on large scale. Another process given in Canadian Patent No. 2050769 provides synthetic scheme as herein given below.

Figure imgf000004_0001

This process comprises the steps of protecting carboxylic group present on cyclopentane ring which is deprotected in consecutive step by vigourous hydrogenation condition in autoclave which is operationally difficult at a large scale.

US Patent No. 2004242894 also discloses the process of preparation of lrbesartan from 4- bromomethyl biphenyl 2′-(lH-tetrazol (2-triphenylmethyl) 5-yl) and Ethyl ester of 1- Valeramido cyclopentanecarboxylic acid in toluene in presence of base and PTC, and then hydrolyzing the protecting group. However this requires chromatographic purification.

This patent also discloses the process of preparation of tetrazolyl protected lrbesartan using 2,6 lutidine and oxalylchloride in toluene. However in this process the yield is as low as 30%.

US Patent No. 2004192713 discloses the process of preparation of lrbesartan by condensing the two intermediates via Suzuki coupling reaction. The reaction scheme is as given herein below.

Figure imgf000005_0001

However, this process has several disadvantages such as use of the reagents like butyl lithium and triisobutyl borate at low temp such as -20 to -30°C under Argon atmosphere condition which is difficult to maintain at commercial scale.

WO2005113518 discloses the process of preparation of Irbesartan by condensing n- pentanoyl cycloleucine (V) with 2-(4-aminomethyl phenyl) benzonitrile (VI) using dicyclocarbodiimide (DCC) and 1 -hydroxy benzotriazole as catalyst to give an open chain intermediate of formula (VIII) which is then cyclized in the presence of an acid, preferably trifluoro acetic acid to give cyano derivative of formula (VII) and which in turn is converted to Irbesartan by treating it with tributyl tin chloride and sodium azide.

Figure imgf000006_0001

In this application further describes another process comprising the steps of reacting 2- butyl-l,3-diazasρiro[4,4]non-l-en-4-one monohydrochloride (A) with 4-bromobenzyl bromide (B) in presence of base and solvent to give 3-[4-bromobenzyl]-2-butyl-l,3- diazaspiro[4,4]non-l-en-4-one (C) which is condensed with 2-[2′-(triphenylmethyl-2’H- tetrazol-5′-yl)phenyl boronic acid in the presence of tetrakis triphenyl phosphine palladium and base to give lrbesartan (I). However these processes suffer with several disadvantages such as it uses trifluoroacetic acid for the cyclization step which is highly corrosive material. The process requires an additional step of activation by DCC. This step not only increases number of steps but also create problem in handling DCC at an industrial scale as it is highly prone to hazard which makes the process least preferred on a large scale production of lrbesartan. Further it uses phenyl boronic acid derivative and triphenyl phosphine complex which are harmful for the skin and eye tissue and also harmful for respiratory system. Tetrakis triphenyl phosphine palladium is also a costly material which increases overall cost for the production of lrbesartan. Moreover the yield is as low as 22%. All the above patents/applications are incorporated herein as reference. In summary, prior art relating to the process for the preparation of lrbesartan suffers with several drawbacks such as i) It requires chromatographic purification of intermediates at various stages. ii) It requires specific autoclave conditions for a deprotection of protecting group. iii) It requires maintaining low temperature conditions such as -300C and requires special handling care and air and moisture tight condition with the reagents such as butyl lithium and triisobutyl borate. iv) It uses hazardous and highly corrosive reagents, v) It suffers low yield problem. vi) All the process is having more number of reaction steps.

  • Irbesartan is described in Bernhart et al., U.S. Patent No. 5,270,317 
  • Irbesartan, is a potent, long-acting angiotensin II receptor antagonist which is particularly useful in the treatment of cardiovascular ailments such as hypertension and heart failure. Its chemical name is2-n-butyl-4-spirocyclopentane-1-[(2′-(tetrazol-5-yl)biphenyl-4-yl)methyl]-2-imidazolin-5-one.

Irbesartan is an antihypertensive agent known from EP 454511. From EP 708103, which discloses their X-ray spectra, two polymorphs are known where form A can be produced form a solvent system containing less than 10% of water, while Form B from a system with more than 10% of water. The specific morphological variant of form A can be prepared having properties as disclosed in EP 1089994. Additional form has been disclosed in WO 04089938. Amorphous irbesartan is known from WO 03050110. It is said that Irbesartan produced as taught in EP 454511 is a fluffy material with relatively low bulk and tap densities and undesirable flow characteristics, which consequently has unadvantageous electrostatic properties, among them a high chargeability as measured by tribugeneration between -30 and -40 nanocoulomb/g (10‘9As/g). Alternativelyirbesartan could be prepared by complex process using sonifications and/or temperature oscillations according to EP 1089994 to exhibit a chargeability as measured by tribugeneration between -0 and -10 nanocoulomb/g.

According to EP 454511 a solid composition in form of tablets is prepared by mixing the active ingredient with a vehicle such as gelatine, starch, lactose, magnesium stearate, talc, gum Arabic or the like and can be optionally coated. The compositions containing from 20% to 70% by weight of irbesartan are known from EP 747050.

WO 04/007482 teaches the acidification to pH 2 – 3,5 of trityl irbesartan, which is sufficient to remove the protecting group, but not to convert into an acid addition salt; WO 04/065383 is likewise silent on hydrohalide acid addition salts. WO
06/011859 relates to the preparation of a hydrochloride salt of irbesartan in order to incorporate it into a pharmaceutical formulation. W099/38847 mentions optional conversion of irbesartan into hydrochloride, hydrobromide or hydrogen sulfate salts

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Figure imgb0006

WO2006023889A2

Example 1Preparation of Compounds of formula IVa and IVb:

    •  
      Figure imgb0007
    •  
      A jacketed 1,000 mL 3-neck flask was charged with 4′-methylbiphenyl-2-carbonitrile (Compound 1, 100.0 g) and CH2CI2 (500 mL) under nitrogen. To a 500 mL Erlenmeyer flask with magnetic stirrer, sodium bromate (NaBrO3; 31.2 g) was dissolved in water (170 mL). The NaBrO3 solution was transferred to the 1,000 mL flask and the reaction mixture was cooled to about 5 °C or less. Aqueous HBr solution (48 %, 105.0 g) was added to the 1,000 mL flask and the resulting reaction mixture was recycled though a UV lamp reactor. The reaction mixture was kept at 0-20 °C and the recycling was continued until the reaction was deemed complete by HPLC. Optionally, additional sodium bromate and hydrogen bromide may be added. The relative amounts of Compound 2 and Compound 3 were about 80-90% and about 10-20% respectively. Aqueous sodium metabisulfite solution (2.0 g of in 10 mL water) was added to the reaction mixture. Allow the phases to settle and the methylene chloride phase was washed with water and used in the next step without further purification.

Example 2Preparation of Compound II:

    •  
      Figure imgb0008
    •  
      A 1L 3-neck flask was charged with Compound V (134.0 g), MTBAC (5.0 g) and CH2Cl2 (170 mL) and cool to -5 to 5 °C. An aqueous solution of KOH (182.6 g in 212 mL water) was added slowly to the 1L flask and the reaction temperature was kept at ≤ 5 °C. The methylene chloride solution of Compound IVa and Compound IVb from Example 1 was added to the reaction mixture slowly, while maintaining the temperature at 0-10 °C. Diethyl phosphite (39.66g) was added drop wise at 0-10 °C. Check the reaction mixture for completion of the reduction reaction, and additional diethyl phosphite may be added.
    •  
      The reaction mixture was allowed to warm to ambient (20-30 °C) and agitated until the reaction was deemed complete by HPLC. Water (150 mL) was added and the phases were separated. The organic layer was extracted with water (230 mL) and polish filtered.
    •  
      The methylene chloride (which contained the crude Compound II) was distilled off and exchanged with about 400 mL of methyl tert-butyl ether (MTBE) (optionally, the MTBE recycled from washing below can be used here). Upon cooling, crystallization occurred (optionally seeds were added) and after further cooling to below 25°C, crystals of Compound II were isolated, washed with MTBE and dried in vacuum at a temperature of less than 60°C. HPLC retention time: 18.126 min. Typically, the yield was about 85 to about 88%. Alternatively, IPA could be used as the crystallization and washing solvent
    •  
      Optionally, the solvent (i.e., MTBE or IPA) used to wash the crystals of Compound II above can be recycled and used to crystallize the crude Compound II in the next batch. Since the washed solvent contains Compound II as well as impurities, it was surprisingly found that the washed solvent can be recovered and used again in crystallizing the crude compound of formula II in the next batch without sacrificing its purity while increasing its yield.

Example 3Preparation of Compound I:

  •  
    Figure imgb0009
  •  
    A reactor was charged with Compound II (1 kg), triethylamine chlorhydrate (0.713 kg), sodium azide (0.337 kg) and N-methyl pyrrolidinone (2.07 kg), and the reaction mixture was heated to about 122°C under stirring. After completion of the reaction as determined by HPLC, the reaction mixture was cooled to about 45°C, and an aqueous solution of sodium hydroxide (35%, 5.99 kg) and water (3.0 kg) were added, the resulting mixture was stirred at a temperature between about 20 and about 40°C for about 0.5 hours. The aqueous phase was discarded and the organic phase was treated with toluene (1.73 kg) and water (5.0 kg), and stirred for about 0.5 hours at about 20 – about 30°C. The toluene phase was discarded and the aqueous phase was washed with ethyl acetate (1.8 kg) and treated with aqueous HCl until pH was adjusted to about 4.8 – about 5.2. Precipitation occurred and the resulting suspension was stirred for about 1 hour at about 20 – about 25°C. The precipitation was collected and washed with water three times (1.0 kg x 3). The crude wet product was recrystallized using a mixture of iso-propanol (0.393 kg) and water (4.5 kg). HPLC retention time: 11.725 min. The yield for Compound I was about 87%.

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SPECTRAL DATA

The ESI mass spectrum of irbesartan showed a protonated molecular ion peak at m/z 429.3 confirming the molecular weight 428. The fragmentation pattern of parent ion 429.3 showed the fragment ions at m/z 385.9, 235.1, 207, 195.4, 192.1, 180.2 and 84

Inline image 1

The FT-IR spectrum exhibited a characteristic stretching absorption band at 1732 cm-1 for the carbonyl group of amide functionality. The presence of this band at higher frequency was due to the ring stretching due to five member ring system. Another band at 1614cm-1 was due to C=N stretching vibrations

Inline image 2

1H and 13C- NMR were recorded using DMSO-d6 as a solvent. In 1H-NMR the signal due to tetrazole NH proton was not detected may probably due to the tautomerism.

SEE

http://orgspectroscopyint.blogspot.in/2013/12/irbesartan-spectral-data.html

Inline image 2

Inline image 1

Inline image 3

Inline image 4

DP 1 IS IMPURITY

Inline image 5

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NMR

WO2007049293A1

1H-NMR (DMSO d6): δppm 0.78 (t, 3H); 1.17-1.30 (sex, 2H); 1.40-1.50 (quent, 2H); 1.64-1.66 (m, 2H); 1.80-1.82 (m, 6H); 2.22-2.29 (t, 2H); 4.67 (s, 2H); 7.07 (s, 4H); 7.50- 7.68 (m, 4H) M+: 429.6

,…………………..

m.p:181-182oC,

IR (KBr, cm-1) 1732 (C=O), 1616 (C=N); 1H NMR (DMSO-d6): δ 7.95–7.32 (m, 8 H), 4.80 –4.60 (s, 2 H), 3.60– 3.00 (br s, 1 H), 2.40– 2.20 (t, 2 H , J = 6.04 Hz), 2.00– 1.60 (m, 8 H),1.60–1.45 (quint, 2 H), 1.40– 1.20 (sext, 2 H), 0.91–0.70 (t, 3H, J = 7.41 Hz);

13C-NMR (DMSOd6): δ 186.5, 162.0,155.9, 141.9, 139.2, 137.2. 131.9, 131.4, 130.1, 128.7, 127.1, 124.3, 76.7, 43.1,
37.7, 28.3, 27.4, 26.3, 22.4, 14.5;

MS: m/z= 429 [M+1];

Anal. Calcd for C25H28N6O : C, 70.07; H,
6.59; N, 19.61. Found: C, 70.04; H, 6.57; N, 19.58.

http://www.acgpubs.org/OC/2011/Volume%204/Issue%201/13-OC-1106-199.pdf

 

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1H NMR in DMSO-D6 : 7.68 (d. 2H, Ar-H), 7.52 (d, 2 H, Ar-H), 7.08 (s, 4 H, Ar-H), 4.68(s, 2H, -CH2), 2.69(t,2H,-CH2),2.18(m,2H,-CH2),1.83(m,2H,-CH2),1.81 (t, 2H, -CH2), 1.65 (t, 2H, -CH2), 1.45 (m, 2 H, -CH2), 1.24(m , 2H, -CH2), 0.77 (t, 3H, -CH3),

 

IR (KBR): 3061 (Aromatic C-H stretching), 2960 (Aliphatic C-H stretching), 3443 (N-H stretching), 1733 (C=0 stretching), 1617(CN stretching), 1337.99(CN stretching), 1407(N=N stretching) cm“1.

 

 

WO2013171643

 

 

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HPLC condition:

Column: Alltima C18 (Alltech 88050) 15.0cm in length x 4.6mm in internal diameter and 5 micron particle size;
Column temperature: 40 C;
Solvent A: Buffer solution A 1.1 g of heptanesulfonic acid in 1 liter of water and adjust the pH to 2.5;
Solvent B: Methanol Flow rate: 1.2mL/min;
Gradient Elution Condition:
Time% A % %B
0 min 50 50
35 min 15 85
Detector: 240 nm;
Injection volume: 10 uL.

The chromatographic purity of
the compounds was analyzed using Agilent 1200 series HPLC instrument under the following conditions:
Column : Symmetry C18, 4.6 × 75 mm, 3.5 µm
Mobile phase : Eluent A: Deionized water, Eluent B: HPLC grade Methanol
Chromatographic Conditions
a. Column temperature : Ambient
b. Sample compartment : Ambient
c. Detector : 225 nm
d. Injection volume : 10 µL
e. Run time : 45 minutes
f. Flow rate :1.0 mL/min
g. Injector :Auto sampler with variable volume injector
h. Diluent : HPLC grade Acetonitrile

Argatroban


Argatroban

Argatroban
Molecular Formula: C23H36N6O5S
Formula Weight: 508.63
CAS No.: 74863-84-6 

(2R,4R)-1-[(2S)-5-(diaminomethylideneamino)-2-
[[(3R)-3-methyl-1,2,3,4-tetrahydroquinolin-8-yl]
sulfonylamino]pentanoyl]-4-methyl-piperidine-2-
carboxylic acid

PATENT

US 7,589,106, 7,687,516, EP 0008746; US 4258192, US 4201863

Argatroban is an anticoagulant that is a small molecule direct thrombin inhibitor.[1] In 2000, argatroban was licensed by the Food and Drug Administration (FDA) for prophylaxis or treatment of thrombosis in patients with heparin-induced thrombocytopenia (HIT). In 2002, it was approved for use during percutaneous coronary interventions in patients who have HIT or are at risk for developing it. In 2012, it was approved by the MHRA in the UK for anticoagulation in patients with Heparin-Induced Thrombocytopenia Type II (HIT) who require parenteral antithrombotic therapy.[2]

Argatroban is given intravenously and drug plasma concentrations reach steady state in 1-3 hours.[3] Argatroban is metabolized in the liver and has a half-life of about 50 minutes. It is monitored by PTT. Because of its hepatic metabolism, it may be used in patients with renal dysfunction. (This is in contrast to lepirudin, a direct thrombin inhibitor that is primarily renally cleared).

Argatroban is used as an anticoagulant in individuals with thrombosis and heparin induced thrombocytopenia. Often these individuals require long term anticoagulation. If warfarin is chosen as the long term anticoagulant, this poses particular challenges due to the falsely elevated prothrombin time and INR caused by argatroban. The combination of argatroban and warfarin may raise the INR to greater than 5.0 without a significant increased risk of bleeding complications.[4] One solution to this problem is to measure the chromogenic factor X level. A level < 40-45% typically indicates that the INR will be therapeutic (2-3) when the argatroban is discontinued.

 ……………………………………………………….

Argatroban monohydrate

Argatroban is a synthetic direct thrombin inhibitor and the chemical name is 1-[5-[(aminoiminomethyl) amino]-1-oxo2[[(1,2,3,4-tetrahydro-3-methyl-8-quinolinyl)sulfonyl]amino]pentyl]-4-methyl-2- piperidinecarboxylic acid, monohydrate. Argatroban has 4 asymmetric carbons. One of the asymmetric carbons has an R configuration (stereoisomer Type I) and an S configuration (stereoisomer Type II). Argatroban consists of a mixture of R and S stereoisomers at a ratio of approximately 65:35.

The molecular formula of argatroban is C23H36N6O5S•H2O. Its molecular weight is 526.66 g/mol. cas 141396-28-3

Argipidine, Argatroban monohydrate, GN1600, DK-7419, MDI-805 Acova, Slonnon, Novastan

Mitsubishi Chemical (Originator), Encysive Pharmaceuticals (Licensee), Mitsubishi Pharma (Distributor), Daiichi Pharmaceutical (Codevelopment), GlaxoSmithKline (Codevelopment), Mitsubishi Pharma (Codevelopment), Sanofi-SynthLabo (Codevelopment)

Antithrombocytopenic, CARDIOVASCULAR DRUGS, Cerebrovascular Diseases, Treatment of, HEMATOLOGIC DRUGS, Hematopoiesis Disorders Therapy, Ischemic Stroke, Treatment of, NEUROLOGIC DRUGS, Peripheral Vascular Disease, Treatment of, Stroke, Treatment of, Treatment of Peripheral Obstructive Vascular Disease, Thrombin Inhibitors

Synthesis of argatroban on the method reported in the literature there are two synthetic routes, patent EP8746, US4258192, US4201863, JP8115267 relates to a route is: with 4 – methyl-piperidine as a starting material was prepared first intermediate body (2R, 4R) -4 – methyl-2 – ethyl-piperidine, and the first and a t-BOC protected amino nitro-L-arginine condensation, and then the 3 – methyl – 8 – quinoline sulfonyl chloride condensation after hydrolysis, hydrogenation, hydration be argatroban. This entry route synthesis process complicated procedure to be carried out under the protection of nitrogen, the raw material is highly toxic gas phosgene, the operation more difficult.

US4117127, JP02-212473, EP823430, EP8746, JC S Perk Transl 1981 (5), JP02-212473 relates to an alternative route is: nitro L-arginine prior to the 3 – methyl-8 – subsequent condensation quinoline sulfonyl chloride Intermediate (2R, 4R) -4 – methyl-2 – piperidinecarboxylate condensation, and then after hydrolysis, hydrogenation, hydration be argatroban. This synthetic route despite the relatively simple process method, to obtain raw materials, but this method using reagents such as phosphorus oxychloride, phosphorus trichloride has a pungent odor, easy to absorb moisture in humid air, intense smoke, environmental pollution, greater stimulation of the body’s respiratory tract, can cause eye and skin irritation and burning, and the use of this method, complex operation, low yield, high cost.

Patent CN100586946C Argatroban discloses a method for separating optically active isomeric compounds, the feedstock argatroban mixed solvent of alcohol and water was heated to reflux 5-10 hours, cooled and allowed to stand, and filtered to give White crystalline product, dried, repeated 2-6 times. [0008] Patent CN101033223A discloses a Argatroban is the main by-product (2R, 4R)-l_ [N2-(3_ methyl-8 – quinolinesulfonyl)-L-arginyl] -4 – methyl-2 – carboxylic acid, argatroban, and the byproducts are difficult to isolate, argatroban two diastereomeric isomer 21 (S) and 21 (R) separation of work attracted a lot of research persons. Because both physical and chemical properties are very similar, so separation is very difficult. 1993 Rawson, Thomas E.; VanGorp, Kimmie A.; Yang, Janet so first by high pressure liquid chromatography and column chromatography separation to obtain a single 21 (S) and 21 (R) argatroban [ Journal of Pharmaceutical Sciences vol. 82, No. 6,672]; Thibaudeau Karen et al. reported Protein A chromatographic separation [US6440417]. However, due to the separation of these methods a small amount of low efficiency, so there is no practical value industrialization. 2006 China Tianjin Weijie Technology Co., Ltd. Song Honghai et al. Reported using recrystallization Separation 21 (S) and 21 (R) argatroban way [0 With 951,936 it], so that the mass 21 (5) Aga music classes as possible, but the law of low yield, complicated operation, high cost, and a large amount of a small amount of 21 (S) of 21 (R)-product argatroban, from the viewpoint of industrial production, is still a ideal method. [0009] These methods can be effectively prepared argatroban, but the purity of the desired product is not high, poor color, content is low, affecting the quality of the results of its preparation.

U.S. Pat. No. 4,201,863 (6 May 1980) and EP 8746 (filed on 22 Aug. 1979 with priority based on the application for the cited US patent) describe a class of N2-arylsulphonyl-L-argininamide drugs, with anti-thrombotic activity, and the processes for obtaining them. Of these, the compound 4-methyl-1-[N2-(3-methyl-1,2,3,4-tetrahydro-8-quinolinesulphonyl)-L-arginyl]-2-piperidine carboxylic acid (argatroban, isomers mixture) is described. The described process comprises the synthesis of an intermediate NG-substituted-N2-quinolinesulphonyl-L-argininamide from which the desired compound is obtained by catalyzed hydrogenolysis or acidolysis and catalyzed hydrogenation. The general conditions provided for the hydrogenolysis and hydrogenation reaction are: i) inert solvents (methanol, ethanol, tetrahydrofuran or dioxane); ii) presence of a catalyst (Raney nickel, palladium, platinum, ruthenium, rhodium); iii) hydrogen atmosphere at a pressure between 1 and 100 kg/cm2 and preferably between 5 and 50 kg/cm2; iv) temperature between 0° C. and 200° C. and preferably between 50° C. and 150° C.; v) reaction temperature from 2 hours to 120 hours. The crude product obtained is then purified by trituration or by re-crystallization from diethyl ether-tetrahydrofuran, diethyl ether-methanol or from water-methanol or by chromatography. No example is given of this purification step. In particular, both U.S. Pat. No. 4,210,863 and EP 8746 in example 1(E) describe the preparation of argatroban, isomers mixture. This compound is obtained in amorphous form by hydrogenation of [NG-nitro-N2-(3-methyl-8-quinolinesulphonyl)-L-arginyl]-4-methyl-2-piperidine carboxylic acid in ethanol in the presence of Pd/C with hydrogen pressure of 10 kg/cm2 at 100° C. for 8 hours. The catalyst is removed by filtration of the ethanol solution which is then evaporated without further purification and/or re-crystallization steps. In the US patent at issue as indeed in patent application EP 8746, no mention is made of polymorphic forms of the compounds and, for the obtained compound, the following characteristics are reported: Amorphous solid, I.R. (KBr) (cm−1) 3400; 1620; 1460; 1380; Molecular composition (%): theoretical C 54.31; H 7.13; N 16.52; found (%) C 54.01; H 6.98; N 16.61.

U.S. Pat. No. 4,258,192 (24 Mar. 1981) (continuation-in-part of the aforesaid patent application U.S. Pat. No. 4,201,863) and the same patent application EP 8746 describe the stereoisomers and the preparation thereof, including argatroban used as an active principle in medicaments, i.e. the stereoisomer (2R,4R)-4methyl-[4N2-(3-methyl-1,2,3,4-tetrahydro-8-quinolinesulphonyl)-L-arginyl]-2-piperidine carboxylic acid, with the following characteristics: melting point (m.p.). 188-191° C.; I.R. (KBr) (cm−1) 3400, 1620, 1460, 1380; Molecular composition (%): theoretical C 54.31; H 7.13; N 16.52; found (%) C 54.05; H 6.94; N 16.65. The compound is prepared according to the description given in examples 1(E) in U.S. Pat. No. 4,258,192 and 2(E) and 3 in EP 8746 respectively by hydrogenation of (2R,4R) 1-[NG-nitro-N2-(3-methyl-1,2,3,4-tetrahydro-8-quinolinesulphonyl)-L-arginyl]-2-piperidine carboxylic acid in ethanol in presence of acetic acid catalyzed by Pd/C. After filtering the mass to remove the catalyst, the solvent is evaporated and the residue suspended in chloroform, the solution treated with a saturated sodium bicarbonate solution or 1N sodium hydroxide solution and after washing, the solvent is evaporated. The compound is then re-crystallized from ethanol. Again in this case, no reference is made to the obtainment of monohydrate polymorphic forms.

Said polymorphic forms are described instead in the publication Biochem. Biophys. Res. Comm. 1981, 101, 440-446 in the context of stereoisomer preparation. The monohydrate polymorph of the (2R,4R) stereoisomer is prepared by re-crystallization from ethanol/water and the reported characteristics are: m.p. 176-180° C.; [α]D 27 +76.1° (c 1, 0.2N HCl).

U.S. Pat. No. 5,925,760 (20 Jul. 1999) and EP 0823430 (filed 4 Aug. 1997) subsequently describe a new method for preparing argatroban by means of a new intermediate N2-(3-methyl-8-quinolinesulphonyl)-NG-nitro-L-arginine. In particular the patent makes reference to the preparation of a crystalline monohydrate form of argatroban, referring back to examples (D) and (E) of Japanese patent publication No. (Hei)-2-31055/1990 and generically to an I.R. spectrum identical to that of the commercially available argatroban compound. The relevant example in the cited patent publication is example (E), while example (D) concerns the preparation of (2R,4R)-1-[NG-nitro-N2-(3-methyl-8-quinolinesulphonyl)-L-arginyl]-4-methyl-2-piperidine carboxylic acid. This compound represents the starting compound for argatroban preparation by catalytic reduction in the presence of Pd/C. The crude argatroban obtained is then purified by extraction with chloroform, treatment with a saturated sodium bicarbonate solution and, after solvent evaporation, re-crystallization from ethanol or from 15% alcohol in water. It should be noted however that the Japanese patent makes no mention of the monohydrate form of argatroban being obtained and that for the compound the following characteristics are reported: m.p. 188-191° C.; molecular composition (theoretical/found) (%): C 54.31/54.01; H 7.13/6.98; N 16.52/16.61; I.R. (KBr) (cm−1) 3400; 1620; 1460; 1380. These analytical data, with the exception of the unreported melting point, are the same as those indicated in the cited patent documents describing a mixture of (2R,4R)-4methyl-[4N2-(3S-methyl-1,2,3,4-tetrahydro-8-quinolinesulphonyl)-L-arginyl]-2-piperidine carboxylic acid and (2R,4R)-4methyl-1-[N2-(3R-methyl-1,2,3,4-tetrahydro-8-quinolinesulphonyl)-L-arginyl]-2-piperidine carboxylic acid isomers of argatroban, but do not correspond to the melting point given in the publication, being the only document that identifies the monohydrate form of argatroban.

More recently, patent application CN 1,951,937 (filing date 10 Nov. 2006) described a method for preparing hydrated argatroban by treating argatroban with large quantities of water (more than 60 and up to 80 volumes of distilled water per gram of argatroban) at a temperature of 80-100° C. for a time of 0.5-1 hour and crystallization by cooling. The water content reported is comprised between 3.3 and 3.8% and the ratio of dextroisomer R to levoisomer S is R:S=63-67: 37-33.

Argatroban is a compound of wide therapeutic use, for which reason the need still exists to provide a compound of pharmaceutically acceptable quality obtained by easily industrialized and economically convenient methods. With regard to the monohydrate, this form is preferable for the applicative purpose since the anhydrous form is unstable and tends to become hydrated and/or wet. Moreover it crystallizes only with difficulty at the correct ratio between the diastereoisomers.

Figure US08378106-20130219-C00001

…..

the protection of 4-methylpiperidine (I) with (Boc)2O gives the carbamate (II), which is condensed with benzyl chloroformate by means of sec-butyl lithium and TMEDA in ethyl ether to yield (?-trans-1-(tert-butoxycarbonyl)-4-methylpiperidine-2-carboxylic acid benzyl ester (III). Deprotection of the NH group of (III) with HCl in ethyl acetate affords (?-trans-4-methylpiperidine-2-carboxylic acid benzyl ester (IV), which is condensed with the protected arginine derivative (V) by means of isobutyl chloroformate and TEA to provide the corresponding amide as a diastereomeric mixture. Resolution of this mixture by flash chromatography furnishes the desired diastereomer (VI), which is treated with HCl in ethyl acetate in order to remove the Boc-protecting group to yield compound (VII). Condensation of compound (VII) with 3-methylquinoline-8-sulfonyl chloride (VIII) by means of TEA in dichloromethane affords the expected sulfonamide (IX). Finally, this compound is submitted to hydrogenation with H2 over Pd/C in AcOH/ethanol in order to produce debenzylation, cleavage of the NO2 group and hydrogenation of the pyridine ring to yield argatroban.

………….

Argatroban, i.e., (2R,4R)-1-((2S)-5-((Aminoiminomethyl)amino)-1-oxo-2-((1,2,3,4-tetrahydro-3-methyl-8-quinolinyl)sulfonyl)amino) pentyl)-4-methyl-2-piperidine carboxylic acid, has two diastereoisomers: 21(R) and 21(S). Usually the ratio of 21(R) to 21(S) is 64-65: 36-35 (U.S. Pat. No. 6,440,417, Cossy. J., et al, Bioorganic & Medicine Chemistry Letters, 11 (2001), 1989-1992, Journal of pharmaceutical Sciences, Vol. 82, No. 6, 672 (1993)).

The structure formula of Argatroban is reported below:

Figure US20120202850A1-20120809-C00001
    • 21(S) Argatroban, X=CH3, Y═H;
    • 21(R) Argatroban, X=H, Y=CH3;
    • Argatroban, 21(S): 21 (R)=35:65.

The chemical names of the two diastereoisomers mentioned above are:

  • 21(S) Argatroban: (2R,4R)-1-((2S)-5-((Aminoiminomethyl)amino)-1-oxo-2-((((3S)-1,2,3,4-tetrahydro-3-methyl-8-quinolinyl)sulfonyl)amino)pentyl)-4-methyl-2-piperidine carboxylic acid (121785-72-6); and
  • 21(R) Argatroban: (2R,4R)-1-((2S)-5-((Aminoiminomethyl)amino)-1-oxo-2-((((3R)-1,2,3,4-tetrahydro-3-methyl-8-quinolinyl)sulfonyl)amino)pentyl)-4-methyl-2-piperidine carboxylic acid (121785-71-5).

In 1978, S. Akamoto et al from Japanese Mitsubishi Chemical Corporation first disclosed the anti-thrombin activity of Argatroban monohydrate (U.S. Pat. No. 4,101,653). In the next 20 years, numerous researchers had in-depth studies on Argatroban about its biological activity and medicine values. In 1981, S. Akamoto compared Argatroban with heparin in vivo (Okamoto, S. et al., Biochem. Biophys. Res. Commun. 101, 440 (1981)); T. Kumoto disclosed its three-dimensional selective activity (Kumada, T. et al., Thromb. Res. 24, 285 (1981)). In 1984, R. Kumato made a clinical evaluation of hemodialysis of Argatroban (Kikumoto, R. et al., Biochemistry 23, 85 (1984)), and in 1986, he further disclosed that Argatroban can inhibit the thrombin activity of mammals, and can be used as active ingredient to treat and prevent thrombosis and as an inhibitor of platelet aggregation. Argatroban monohydrate can be used as a selective anti-thrombosis agent for treatment of chronic arterial blockage and cerebral thrombosis, etc (JP 61-48829). In 1992 and 1993, Taparelli and Jakubowski separately disclosed the reversibility of Argatroban in anti-thrombin (Taparelli, C., Trends Pharmacol. Sci., 1993, 14, 366, Jakubowski, J. A. et al, Rep. Med. Chem., 1992, 27, 99). In 1990s, many researchers such as L. R. Buch reported other related research (Buch, L. R., Cadiosvasc. Drug Rev., 1991, 9, 247, Strupcnewski, J. D. et al., Academic: San Diego, 1991; Vol. 26, p 299, Brundish, D. et al., J. Med. Chem. 1999; 42, 4584, Shebuski, R. J., Academic: San Diego, 1999; Vol. 26, p 98). In 1992, Argatroban monohydrate was first approved as an anti-thrombin medicine in Japan (Hijikata-Okunomiya, A., et al, Thromb. Hemostasis, 1992, 18, 135).

Updated in sept 2015, reader there may be duplication

Argatroban.svg

Argatroban
AC1L99H9; AC-15185; TL8005144; C04931;
Molecular Formula: C23H36N6O5S
Molecular Weight: 508.63414 g/mol

(2R,4R)-1-[5-(diaminomethylideneamino)-2-[(3-methyl-1,2,3,4-tetrahydroquinolin-8-yl)sulfonylamino]pentanoyl]-4-methylpiperidine-2-carboxylic acid, cas 74863-84-6

Patent Submitted Granted
Prodrugs of (2R)-2-Propyloctanoic Acid For the Treatment of Stroke [US7495029] 2008-06-05 2009-02-24

Tomiya Mano, Jin Shiomura, “Argatroban preparations for ophthalmic use.” U.S. Patent US5506241, issued October, 1986.

US5506241

Argatroban is an anticoagulant that is a small molecule direct thrombin inhibitor.[1] In 2000, argatroban was licensed by the Food and Drug Administration (FDA) for prophylaxis or treatment of thrombosis in patients with heparin-induced thrombocytopenia (HIT). In 2002, it was approved for use during percutaneous coronary interventions in patients who have HIT or are at risk for developing it. In 2012, it was approved by the MHRA in the UK for anticoagulation in patients with Heparin-Induced Thrombocytopenia Type II (HIT) who require parenteral antithrombotic therapy.[2]

Argatroban is given intravenously and drug plasma concentrations reach steady state in 1-3 hours.[3] Argatroban is metabolized in the liver and has a half-life of about 50 minutes. It is monitored by PTT. Because of its hepatic metabolism, it may be used in patients with renal dysfunction. (This is in contrast to lepirudin, a direct thrombin inhibitor that is primarily renally cleared).

Argatroban is a direct, selective thrombin inhibitor. The American College of Cardiologists (ACC) recommend using bivalirudin or argatroban in patients who have had, or at risk for, heparin induced thrombocytopenia (HIT) and are undergoing percutaneous coronary intervention. Argatroban is a non-heparin anticoagulant shown to both normalize platelet count in patients with HIT and prevent the formation of thrombi. Parental anticoagulants must be stopped and a baseline activated partial thromboplastin time must be obtained prior to administering argatroban.

argatroban.png

Transitioning to warfarin in individuals with heparin induced thrombocytopenia

Argatroban is used as an anticoagulant in individuals with thrombosis and heparin induced thrombocytopenia. Often these individuals require long term anticoagulation. If warfarin is chosen as the long term anticoagulant, this poses particular challenges due to the falsely elevated prothrombin time and INR caused by argatroban. The combination of argatroban and warfarin may raise the INR to greater than 5.0 without a significant increased risk of bleeding complications.[4] One solution to this problem is to measure the chromogenic factor X level. A level < 40-45% typically indicates that the INR will be therapeutic (2-3) when the argatroban is discontinued.

http://www.google.com/patents/WO2009124906A2?cl=en

………….

NMR paper

Complete 1H and 13C assignments of (21R) and (21S) diastereomers of argatroban

  1. Diego Colombo1,*,
  2. Patrizia Ferraboschi1,
  3. Paride Grisenti2 and
  4. Laura Legnani3

Article first published online: 20 DEC 2007

DOI: 10.1002/mrc.2122, http://onlinelibrary.wiley.com/doi/10.1002/mrc.2122/abstract

nmr1 nmr2 nmr3

click on image for clear view

1H NMR PREDICT

1h nmr gr molbase 1h nmr val molbase

13C NMR PREDICT

13c nmr gr molbase 13c nmr val molbase

References

1 Di Nisio M, Middeldorp S, Buller HR. Direct thrombin inhibitors. N Engl J Med 2005;353:1028-40. PMID 16148288

2http://www.pharmatimes.com/Article/12-07-03/UK_launch_for_Mitsubishi_s_blood_thinner_Exembol.aspx

3Dhillon S. Argatroban: A Review of its Use in the Management of Heparin-Induced Thrombocytopenia. Am J Cardiovasc Drugs 2009; 9 (4): 261-82. Link text

  1. Hursting MJ, Lewis BE, Macfarlane DE. (2005). “Transitioning from argatroban to warfarin therapy in patients with heparin-induced thrombocytopenia.”. Clin Appl Thromb Hemost 11 (3): 279–87. doi:10.1177/107602960501100306. PMID 16015413.

External links

EP0823430A1 * Aug 4, 1997 Feb 11, 1998 Mitsubishi Chemical Corporation Method for preparing n2-arylsulfonyl-l-argininamides
US4201863 * Aug 31, 1978 May 6, 1980 Mitsubishi Chemical Industries, Limited N2 -Arylsulfonyl-L-argininamides and the pharmaceutically acceptable salts thereof
1 None
2 * OKAMOTO S ET AL: “Potent inhibition of thrombin by the newly synthesized arginine derivative No. 805. The importance of stereo-structure of its hydrophobic carboxamide portion” BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS, ACADEMIC PRESS INC. ORLANDO, FL, US, vol. 101, no. 2, 30 July 1981 (1981-07-30), pages 440-446, XP024844713 ISSN: 0006-291X [retrieved on 1981-07-30] cited in the application
3 * SONG H: “Method for preparing argatroban monohydrate in pure water” CASREACT,, 25 April 2007 (2007-04-25), XP002493272 & CN 1 951 937 A (TIANJIN WEIJIE TECHNOLOGY CO L [CN]) 25 April 2007 (2007-04-25)
WO2012136504A1 Mar 26, 2012 Oct 11, 2012 Lundbeck Pharmaceuticals Italy S.P.A. Method for the preparation of process intermediates for the synthesis of argatroban monohydrate
CN102408468A * Sep 20, 2011 Apr 11, 2012 海南灵康制药有限公司 Argatroban compound and preparation method thereof
EP2752412A1 Mar 26, 2012 Jul 9, 2014 Lundbeck Pharmaceuticals Italy S.p.A. Intermediates for the synthesis of Argatroban monohydrate

Argatroban is a synthetic direct thrombin inhibitor and the chemical name is 1-[5[(aminoiminomethyl)amino]1-oxo-2-[[(1,2,3,4-tetrahydro-3-methyl-8-quinolinyl)sulfonyl]amino]pentyl]-4methyl-2-piperidinecarboxylic acid, monohydrate. Argatroban has 4 asymmetric carbons. One of the asymmetric carbons has an R configuration (stereoisomer Type I) and an S configuration (stereoisomer Type II). Argatroban consists of a mixture of R and S stereoisomers at a ratio of approximately 65:35.

The molecular formula of argatroban is C23H36N6O5S•H2O. Its molecular weight is 526.66 g/mol. The structural formula is:

Argatroban - Structural Formula Illustration

Argatroban Injection is a sterile, non-pyrogenic, clear, colorless to pale yellow isotonic solution. It is supplied in a single use polyolefin bag containing 250 mg of argatroban in 250 mL sodium chloride solution (1 mg/mL). Each mL contains 1 mg argatroban, 9 mg sodium chloride, USP, and 3 mg sorbitol, NF in water for injection, USP. The pH of the solution is between 3.2 to 7.5.

Argatroban
Argatroban.svg
Systematic (IUPAC) name
(2R,4R)-1-[(2S)-5-(diaminomethylideneamino)-2-
[[(3R)-3-methyl-1,2,3,4-tetrahydroquinolin-8-yl]
sulfonylamino]pentanoyl]-4-methyl-piperidine-2-
carboxylic acid
Clinical data
Trade names Argatroban
AHFS/Drugs.com monograph
Routes of
administration
intravenous
Pharmacokinetic data
Bioavailability 100% (intravenous)
Protein binding 54%
Metabolism hepatic
Biological half-life 39 and 51 minutes
Identifiers
CAS Registry Number 74863-84-6 Yes
ATC code B01AE03
PubChem CID: 440542
DrugBank DB00278 Yes
ChemSpider 389444 Yes
UNII OCY3U280Y3 Yes
KEGG C04931 Yes
ChEMBL CHEMBL1166 
Chemical data
Formula C23H36N6O5S
Molecular mass 508.635 g/mol

//////

Drug spotlight- Zafirlukast


Zafirlukast.svg

ZAFIRLIKAST 

cyclopentyl 3-{2-methoxy-4-[(o-tolylsulfonyl)carbamoyl]benzyl}-1-methyl-1H-indol-5-ylcarbamate 107753-78-6

Matassa, V.G. et al, J. Med. Chem., v. 33, 1781 (1990);

U. S. Patent No. 4,859,692;

U. S. Patent No. 5,993,859;

http://www.accessdata.fda.gov/drugsatfda_docs/label/2011/020547s031lbl.pdf

Zafirlukast is an oral leukotriene receptor antagonist (LTRA) for the maintenance treatment of asthma, often used in conjunction with an inhaled steroid and/or long-acting bronchodilator. It is available as a tablet and is usually dosed twice daily. Another leukotriene receptor antagonist is montelukast (Singulair), taken once daily. Zileuton (Zyflo), also used in the treatment of asthma via its inhibition of 5-lipoxygenase, is taken four times per day.

Zafirlukast blocks the action of the cysteinyl leukotrienes on the CysLT1 receptors, thus reducing constriction of the airways, build-up of mucus in the lungs andinflammation of the breathing passages.

Zafirlukast is marketed by Astra Zeneca with the brand names AccolateAccoleit, and Vanticon. It was the first LTRA to be marketed in the USA and is now approved in over 60 countries, including the UK, Japan, Taiwan, Italy, Spain, Canada, Brazil, China and Turkey

Healthy young men who received a single oral 40 mg dose attained peak plasma zafirlukast concentrations that averaged 607 μg/L at 3.4 hours. The elimination half-life ranged from 12 to 20 hours. In another study involving a 20 mg single oral dose in healthy men, the elimination half-life averaged 5.6 hours.[1][2]

A letter was submitted to the FDA by Zeneca Pharmaceuticals on July 22, 1997, notifying them of a change in product labeling that includes the following potential reaction in patients undergoing a dosage reduction of oral steroids who are currently taking zafirlukast:

PRECAUTIONS-Eosinophilic Conditions: The reduction of the oral steroid dose, in some patients on ACCOLATE therapy, has been followed in rare cases by the occurrence of eosinophilia, vasculitic rash, worsening pulmonary symptoms, cardiac complications, and/or neuropathy sometimes presenting as Churg–Strauss syndrome, a systemic eosinophilic vasculitis. Although a causal relationship with ACCOLATE has not been established, caution is required when oral steroid reduction is being considered.1

 NDA..020547  26/09/1996, ACCOLATE, ASTRAZENECA, 20MG TABLET

US Patent No Expirey Date patent use code
5482963 Jan 9, 2013
5612367 Mar 18, 2014 U-189

Brief background information

Salt ATC Formula MM CAS
R03DC01 C 31 H 33 N 3 O 6 S 575.69 g / mol 107753-78-6
monohydrate R03DC01 C 31 H 33 N 3 O 6 S · H 2 O 593.70 g / mol 143052-93-1
calcium (2: 1) R03DC01 C 62 H 64 CaN 6 O 12 S 2 1189.43 g / mol 107753-86-6

Application

  • antihistamine effect
  • LTD4-antagonist

Classes of substances

  • Benzenesulfonamide (s -imidy), as well as their derivatives
    • Esters of carbamic acid
      • Cyclopentanes
        • Hydroxybenzoic acid amides, and hydroxy acids alkoksibenzoynyh
          • Indoles

Zafirlukast is a synthetic, selective peptide leukotriene receptor antagonist (LTRA), with the chemical name 4(5-cyclopentyloxy-carbonylamino-1-methyl-indol-3ylmethyl)-3-methoxy-N-o-tolylsulfonylbenzamide. The molecular weight of zafirlukast is 575.7 and the structural formula is:

Zafirlukast, a fine white to pale yellow amorphous powder, is practically insoluble in water. It is slightly soluble in methanol and freely soluble in tetrahydrofuran, dimethylsulfoxide, and acetone.The empirical formula is: C31H33N3O6S

  1.  Fischer JD, Song MH, Suttle AB, Heizer WD, Burns CB, Vargo DL, Brouwer KL. Comparison of zafirlukast (Accolate) absorption after oral and colonic administration in humans. Pharmaceut. Res. 17: 154-159, 2000.
  2.  Bharathi DV, Naidu A, Jagadeesh B, Laxmi KN, Laxmi PR, Reddy PR, Mullangi R. Development and validation of a sensitive LC-MS/MS method with electrospray ionization for quantitation of zafirlukast, a selective leukotriene antagonist in human plasma: application to a clinical pharmacokinetic study. Biomed. Chromatogr. 22: 645-653, 2008.

 

File:Zafirlukast.svg

Zafirlukast
Zafirlukast.svg
Zafirlukast 3D ball-and-stick.png
Systematic (IUPAC) name
cyclopentyl 3-{2-methoxy-4-[(o-tolylsulfonyl)carbamoyl]benzyl}-1-methyl-1H-indol-5-ylcarbamate
Clinical data
Trade names Accolate
AHFS/Drugs.com monograph
MedlinePlus a697007
Pregnancy cat. B1 (Australia), B (United States)
Legal status POM (UK)
Routes Oral
Pharmacokinetic data
Bioavailability Unknown
Protein binding 99%
Metabolism Hepatic (CYP2C9-mediated)
Half-life 10 hours
Excretion Biliary
Identifiers
CAS number 107753-78-6 Yes
ATC code R03DC01
PubChem CID 5717
IUPHAR ligand 3322
DrugBank DB00549
ChemSpider 5515 Yes
UNII XZ629S5L50 Yes
KEGG D00411 Yes
ChEBI CHEBI:10100 Yes
ChEMBL CHEMBL603 Yes
Chemical data
Formula C31H33N3O6S 
Mol. mass 575.676 g/mol

Trade Names

Country Trade name Manufacturer
United Kingdom Akkolat AstraZeneca
Italy Akkoleit – “-
Zafirst Chiesi
Japan Akkolat AstraZeneca
USA – “- Zeneca
Ukraine No No

Formulations

  • Tablets of 20 mg, 40 mg
Zafirlukast, cyclopentyl 3 – [2-methoxy-4- [(o-tolylsulfonyl)carbamoyl]- benzyl]-l-methyIindole-5-carbamate, having the formula:
Figure imgf000002_0001

is a first anti-asthmatic leukotriene antagonist (Matassa, V.G. et al, J. Med. Chem., v. 33, 1781 (1990); U. S. Patent No. 4,859,692 and The Merck Index, 12th Edition, 10241). Methods for the preparation of Zafirlukast are described in J. Med. Chem., v. 33, 1781 (1990), U. S. Patent 4,859,692 and U.S. Patent 5,993,859 starting from methyl 3-methoxy-4-(l-methyl-5-nitroindol-3-ylmethyl)benzoate [la]

Figure imgf000003_0001
Alkyl (l-alkylindol-3-ylmethyl)benzoates of formula [lb] are useful as chemical intermediates in the pharmaceutical industry.
Figure imgf000003_0002
These compounds may be obtained by a process described in J. Med. Chem., v. 33, 1781 (1990) and U. S. Patent 4,859,692. This process comprises the steps of:
(a) reacting an alkyl (halomethyl)benzoate of formula [2] with an equivalent amount of an indole of formula [3]
Figure imgf000003_0003

in the presence of an equivalent quantity of silver(I) oxide,

(b) isolating the alkyl (indol-3-ylmethyl)benzoates of formula [4] from the reaction mixture obtained in step (a) above,
(c) reacting the compound [4] with an alkylating agent of formula [6],
Figure imgf000003_0004

The above process has serious disadvantages in the isolation of the product [4] in step (b) which is due to the fact that alkylation of indole, that is unsubstituted at positions 1-, 2- and 3-, at the 3-position, is accompanied by the undesired process of poly alkylation, to form polysubstituted indoles of formula [7] and/or formula [8] :

Figure imgf000004_0001

while at the same time some quantity of the starting unreacted indole remains in the reaction mixture. Most common methods for the separation of alkyl (indol-3-ylmethyl)benzoate of formula [4] from by-products of polyalkylation and starting unreacted indole, which are all covalent compounds with similar physical properties, include column chromatography that is an unpractical method for industrial scale applications.

Formula (I) compound for the synthesis of an important intermediate of zafirlukast.Reported in the patent EP199543 synthesized compound (I) of the conventional method, the following formula:

Figure CN101104601BD00032

(A) (I)

 In this method, Intermediate A and 5 – nitro-indole silver oxide in the presence of a catalyst, for docking composite formula (I) compound. Reported only 45% of the reaction yield, the reaction is difficult to complete the reaction and post-treatment using chromatographic methods, resulting in product purification more difficult. And the use of more expensive silver oxide catalysts, high cost.

 W00246153 reported a catalyst for the above reaction to zinc bromide, Compound (I), after treatment of the compound (I) with sodium hydroxide hydrolysis of the intermediate (B), separating the product and raw materials purification products.

 

Figure CN101104601BD00041

The method reported in the literature a yield of 60%, but the actual operation is repeated only about 30% yield, and the operation is complicated, cumbersome and costly.

zaafirlukast is a selective and competitive receptor antagonist of leukotriene D4 and E4 (LTD4 and LTE4), components of slow-reacting substance of anaphylaxis (SRSA). Cysteinyl leukotriene production and receptor occupation have been correlated with the pathophysiology of asthma, including airway edema, smooth muscle constriction, and altered cellular activity associated with the inflammatory process, which contribute to the signs and symptoms of asthma.

The cysteinyl leukotrienes (LTCLTD4, LTE4) are the products of arachidonic acid metabolism and are various cells, including mast cells and eosinophills, these eicosinoids bind to cysteinyl leukotriene (CysLT) receptors. The CysLT type-1 (CysLT1) receptor is found in human airway and other pro-inflammatory cells. CysLTs have been correlated with the pathophysiology of asthma.

Zafirlukast is a synthetic, selective peptide leukotriene receptor antagonist (LTRA), useful for the treatment of asthma and is commercially available in products sold under the brand name ACCOLATE™ as 10 and 20 mg tablets for oral administration. ACCOLATE™ is indicated for the prophylaxis and treatment of asthma in adults and children 5 years of age and older.

ACCOLATE™ film coated tablets contain amorphous zafirlukast as the active ingredient and the excipients croscarmellose sodium, lactose, magnesium stearate, microcrystalline cellulose, povidone, hypromellose, and titanium dioxide.

The greatest prevalence of asthma is in preschool children; however, the clinical utility of asthma therapy for this age group is limited by a narrow therapeutic index, long-term tolerability, and frequency and/or difficulty of administration. Asthma treatment requires an immediate perceivable effect. Inhalation therapy is a very common therapy prescribed for young children; inhalation therapy has the disadvantage of high dose variability.

File:Zafirlukast 3D ball-and-stick.png
……………………
Process for the preparation of zafirlukast
US 20040186300 A1
Figure US20040186300A1-20040923-C00015
In comparison, the known process for the preparation of zafirlukast described in J. Med. Chem., v. 33, 1781 (1990) and U.S. Pat. No. 4,859,692 involves separation steps, e.g. column chromatography, that are not practical for industrial scale applications. The known process is summarized in Scheme 3:
Figure US20040186300A1-20040923-C00016
,……………………………………………………..

An Improved and Scalable Process for Zafirlukast: An Asthma Drug

Research and Development, Integrated Product Development, Dr. Reddy’s Laboratories Ltd., Survey No.’s 42, 45, 46, and 54, Bachupally, Qutubullapur, Ranga Reddy District – 500 072, Andhra Pradesh, India, Institute of Science and Technology, Center for Environmental Science, J.N.T. University, Kukatpally, Hyderabad – 500 072, Andhra Pradesh, India, and Research and Development, Inogent Laboratories Private Limited (A GVK BIO Company), 28A, IDA, Nacharam, Hyderabad – 500 076, India
Org. Process Res. Dev.200913 (1), pp 67–72
DOI: 10.1021/op800137b

Melting range: 142−145 °C; MS (m/z): 576 (M+ + H); IR (KBr, cm−1): 3326 (NH), 1679 (−C═O), 1H NMR (CDCl3) δ 7.0−8.0 (m, 11H), 3.7 (s, 3H), 4.0 (s, 2H), 3.9 (s, 3H), 2.6 (s, 3H), 1.45−1.8 (s, 9H). ………………………………………………………………..  US 20040186300 A1  http://www.google.com/patents/US20040186300  zafirlukast ethanolate as white powder with mp 132-133° C. (dec.) and 99.8% purity by HPLC. 1H NMR (CDCl3, δ, ppm): 1.22 (t, J 7.05 Hz, 3H), 1.45-1.87 (m, 8H), 2.66 (s, 3H), 3.67 (s, 3H), 3.73 (q, J 7.05 Hz, 4H), 3.79 (s, 3H), 3.98 (s, 2H), 5.08-5.23 (m, 1H), 6.58 (s, 1H), 6.73 (s, 1H), 7.01-7.51 (m, 9H), 8.23 (d, J 7.52 Hz, 1H), 9.67 (s, 1H).

Synthesis pathway

Synthesis a)
Synthesis of b)
  1. Synthesis a)
    • US 4,859,692 (ICI; 08/22/1989; GB -prior. 4/17/1985; 17.10.1985).
    •  EP 199 543 (ICI, Zeneca; appl. 16.4.1986; GB -prior. 4/17/1985).
  2. Synthesis of b)
    • EP 490 649 (ICI, Zeneca; 11.12.1991; GB -prior. 12.12.1990).
    • Matassa, G. et al .: J. Med. Chem. (JMCMAR) 33, 1781 (1990).
    • Srinivas, K. et al .: Org. Process Res. Dev. (OPRDFK) 8 (6), 952 (2004).

added info Asthma is a disease that causes swelling and narrowing the airways of the lungs. Airways are air carriers to and from lungs. Swollen and narrower airways affect the air flow to and from the lungs and this lead to tightness of chest, wheezing, shortness of breath and cough. These symptoms are often occurs in early morning and in night. Asthma is caused by genetic and environmental factors, it was not curable completely but this can be controlled with good medical care. Leukotriene antagonists also known as leukast are the medicaments that are used to reduce leukotrienes, which are produced by several types of cells and causes inflammation in asthma and bronchitis. Leukotriene antagonists that are available in market are Montelukast, Zafirlukast and Pranlukast. Zafirlukast is the first leukast compound approved for management of Asthma. US FDA approved zafirlukast in the form of 10 mg and 20 mg tablet with the brand name of Accolate®.1 Subsequently this was approved and launched by innovator in few other countries. There are many synthetic routes for the preparation of Zafirlukast 4 is well documented in literature. Some of the key approaches are discussed here under. Scientists from ICI Americas Inc2 have reported process for the synthesis of 4, which starts with esterification of 3-methoxy-4-methyl benzoic acid 53 using methanol in presence of acetyl chloride PRODUCT PATENT ROUTE Allylic bromination of methyl ester 54 using bromine in presence of CCl4 resulted bromo compound 55, which was reacted with 5-nitro indole 124 using silver oxide as catalyst to obtain condensed compound 125. N-methylation of 125 utilizing methyl iodide in presence of NaH afforded N-methyl indole derivative 57. Thus obtained 57 was subjected to reduction using palladium carbon (Pd/C) in methanol followed by reacted with cyclopentyl chloroformate to obtain compound 59. Hydrolysis of 59 using LiOH.H2O subsequently reaction with o-toluene sulfonamide (OTSA) in presence of 1-[3-(dimethylamino)propyl]-3-ethyl carbodiimide hydrochloride (DMAPEC) and DMAP furnished zafirlukast 4. Matassa et al3 also reported similar procedure for the synthesis of Zafirlukast 4.

 zafirlukast…….{3-[2-Methoxy-4-(toluene-2-sulfonylaminocarbonyl) benzyl]-1-methyl-1H-indol-5-yl} acetic acid cyclopentyl ester……………………………….Arie, G.; Genndy, N.; Igor, Z.; Victor, P.; Maxim, S. WO 02/46153 A2, 2002. 
 
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