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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 AFRICURE PHARMA, ROW2TECH, NIPER-G, Department of Pharmaceuticals, Ministry of Chemicals and Fertilizers, Govt. of India as ADVISOR, earlier assignment was with GLENMARK LIFE SCIENCES LTD, as CONSUlTANT, Retired from GLENMARK in Jan2022 Research Centre as Principal Scientist, Process Research (bulk actives) at Mahape, Navi Mumbai, India. Total Industry exp 32 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, 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 32 PLUS year tenure till date Feb 2023, 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 100 million plus hits on Google, 2.5 lakh plus connections on all networking sites, 100 Lakh plus views on dozen plus blogs, 227 countries, 7 continents, 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 38 lakh plus views on New Drug Approvals Blog in 227 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 He has total of 32 International and Indian awards

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RAMOSETRON


RAMOSETRON, Antiemetics

Ramosetron (INN),(1-methylindol-3-yl)-[(5R)-4,5,6,7-tetrahydro-3H-benzimidazol-5-yl]methanone,  132036-88-5 cas no

  C17H17N3O 
  279.33 g/mol

(1-methyl-1H-indol-3-yl)[(5R)-4,5,6,7-tetrahydro-1H-benzimidazol-5-yl]methanone

YM060

  • Nasea
  • Nor-YM 060
  • Ramosetron
  • UNII-7ZRO0SC54Y

…………………………………………………………………………………..

HYDROCHLORIDE SALT

2D image of a chemical structure

hyrochloride salt, cas no 132907-72-3

C17-H17-N3-O.Cl-H
315.8022
Yamanouchi (Originator)
GASTROINTESTINAL DRUGS, Irritable Bowel Syndrome, Agents for, Nausea and Vomiting, Treatment of, NEUROLOGIC DRUGS, 5-HT3 Antagonists
Launched-1996 JAPAN

 (−)-(R)-5-[(1-methyl-1H-indol-3-yl)carbonyl]-4,5,6,7-tetrahydro-1H-benzimidazole monohydrochloride (yield 78.8%, 99.5% e.e.). FAB-MS (m/z): 280 [M+H+]

1H NMR (DMSO-d6, 30° C.): δ ppm (TMS internal standard): 1.82-1.95 (1H, m), 2.12-2.22 (1H, m), 2.66-2.94 (4H, m), 3.63-3.72 (1H, m), 3.88 (3H, s), 7.24 (1H, t, J=8.0 Hz), 7.30 (1H, t, J=8.0 Hz), 7.56 (1H, d, J=8.0 Hz), 8.22 (1H, d, J=8.0 Hz), 8.53 (1H, s), 8.90 (1H, s), 14.42 (1H, br)

…………………………………………………………………………………….

Ramosetron (INN) is a serotonin 5-HT3 receptor antagonist for the treatment of nausea and vomiting.[1] Ramosetron is also indicated for a treatment of “diarrhea-predominant irritable bowel syndrome in males”.[2] In India it is marketed under the brand name of“IBset”.
It is only licensed for use in Japan and selected Southeast Asian countries. In Japan it is sold under the tradename Iribo (イリボー). [3] Elsewhere it is commonly sold under the tradename Nasea and in India as Nozia (300 mcg/ml Inj. & 100 mcg Tab.) [4]

  1.  Fujii Y, Saitoh Y, Tanaka H, Toyooka H (February 2000). “Ramosetron for preventing postoperative nausea and vomiting in women undergoing gynecological surgery”.Anesth. Analg. 90 (2): 472–5. doi:10.1097/00000539-200002000-00043.PMID 10648342.
  2. http://www.astellas.com/en/corporate/news/detail/astellas-launches-irribow-for.html
  3.  Summary in Japanese. Retrieved on September 4, 2012.
  4.  Abridged prescribing information – Nasea (MIMS Philippines). Retrieved on June 13, 2008.
  5. Synthesis and 5-HT3 antagonistic activities of 4,5,6, 7-tetrahydrobenzimidazole derivatives
    200th ACS Natl Meet (August 26-31, Washington DC) 1990, Abst MEDI 39
1-27-2010
Process for producing ramosetron or its salt
11-20-1996
Intrabuccally dissolving compressed moldings and production process thereof
3-6-1996
5-substituted tetrahydrobenzimidazole compounds
11-15-1995
Intrabuccally disintegrating preparation and production thereof
9-7-1994
Tetrahydrobenzimidazole derivatives and pharmaceutical compositions containing same
6-24-1994
NEW USE OF 5-HT3 RECEPTOR ANTAGONISTS

AU 9048890; EP 0381422; JP 1991223278; US 5344927

CN1696128A Nov 2, 2004 Nov 16, 2005 天津康鸿医药科技发展有限公司 New method for synthesizing Ramosetron Hydrochloride
CN1765896A Oct 28, 2004 May 3, 2006 北京博尔达生物技术开发有限公司 Novel preparation method of ramosetron hydrochloride
US5496942 * 14 Feb 1994 5 Mar 1996 Yamanouchi Pharmaceutical Co., Ltd. 5-substituted tetrahydrobenzimidazole compounds
US5677326 * 30 Sep 1994 14 Oct 1997 Tokyo Tanabe Company Limited Indoline compound and 5-HT.sub.3 receptor antagonist containing the same as active ingredient
US7358270 28 Jan 2005 15 Apr 2008 Astellas Pharma Inc. Treating agent for irritable bowel syndrome
US7683090 18 Oct 2006 23 Mar 2010 Astellas Pharma Inc. Treating agent for irritable bowel syndrome
US7794748 27 Aug 2004 14 Sep 2010 Yamanouchi Pharmaceutical Co., Ltd. Stable oral solid drug composition

WO 2010024306

WO 2013005760

WO 2013100701

WO 2011001954

The chemical name of ramosetron is (−)-(R)-5-[(1-methyl-1H-indol-3-yl)carbonyl]-4,5,6,7-tetrahydro-1H-benzimidazole, and it has the structure represented by the formula (II).

Figure US07652052-20100126-C00002

It is known that ramosetron or a salt thereof has a potent 5-HTreceptor antagonism (Patent Reference 1, Non-patent references 1 and 2), and it is on the market as a preventive or therapeutic agent for digestive symptoms (nausea, emesis) caused by administration of an anti-malignant tumor agent (cisplatin or the like). In addition, a possibility has been reported that ramosetron or a salt thereof may be useful as an agent for treating diarrheal-type irritable bowel syndrome or an agent for improving diarrheal symptoms of irritable bowel syndrome (Patent Reference 1), and its clinical trials are now in progress as an agent for treating diarrheal-type irritable bowel syndrome or an agent for improving diarrheal symptoms of irritable bowel syndrome.

As a process for producing ramosetron or a salt thereof, the following production methods are known.

Patent Reference 1 describes a production method shown by the following Production method A, namely a method for producing a tetrahydrobenzimidazole derivative (V) by allowing a heterocyclic compound (III) to react with a carboxylic acid represented by a formula (IV) or its reactive derivative.

(Production Method A)

Figure US07652052-20100126-C00003

(In the formula, Xis a single bond and binds to a carbon atom on the heterocyclic ring represented by Het.)

As an illustrative production method of ramosetron, Patent Reference 1 describes a production method (Production method A-1) in which racemic ramosetron are obtained by using 1-methyl-1H-indole as the compound (III), and N,N-diethyl-4,5,6,7-tetrahydrobenzimidazole-5-carboxamide or N-[(4,5,6,7-tetrahydrobenzimidazol-5-yl)carbonyl]pyrrolidine, which are acid amides, as the reactive derivative of compound (IV), and allowing them to undergo treatment with phosphorus oxychloride (Vilsmeyer reaction), and then their optical resolution is carried out by fractional crystallization using (+)-dibenzoyltartaric acid.

In addition, the Patent Reference 1 exemplifies an acid halide as one of the reactive derivatives of the compound (IV), and also describes another production method of the compound (V) (Production method A-2) in which the heterocyclic compound (III) is condensed with an acid halide of the compound (IV) by the Friedel-Crafts acylation reaction using a Lewis acid as the catalyst. However, illustrative production example of ramosetron by the Friedel-Crafts acylation reaction is not described therein.

Also, a method similar to the Production example A-1 is described in Non-patent References 1 and 2 as a production method of ramosetron.

In addition, Non-patent Reference 3 describes a method for producing ramosetron labeled with 11C, represented by a Production method B. However, it discloses only the methylation step, and does not disclose a production method of nor-YM060 as the starting material.

(Production Method B)

Figure US07652052-20100126-C00004

(In the formula, nor-YM060 means (R)-5-[(1H-indol-3-yl)carbonyl]-4,5,6,7-tetrahydro-1H-benzimidazole which was provided by the present applicant, DMF means dimethylformamide.)

  • Non-patent Reference 1: Chemical Pharmaceutical Bulletin, 1996, vol. 44, no. 9, p. 1707-1716
  • Non-patent Reference 2: Drugs of the Future, 1992, vol. 17, no. 1, p. 28-29
  • Non-patent Reference 3: Applied Radiation and Isotopes, 1995, vol. 46, no. 9, p. 907-910
  • Patent Reference 1: JP-B-6-25153

LIU Qing-wen, XU Hao, TIAN Hua, ZHENG Liang-yu, ZHANG Suo-qin
Chemoenzymatic Synthesis of Ramosetron Hydrochloride

2012 Vol. 28 (1): 70-72 [Abstract] ( 1143 ) [HTML 1KB] [PDF 206KB] ( 1052 )
doi:http://www.cjcu.jlu.edu.cn/hxyj/EN/abstract/abstract13356.shtml

…………………………………………………………………………..

The Vilsmeier-type reaction of 1-methylindole (I) with 5 – (1-pyrrolidinocarbonyl) -4,5,6,7-1 H-tetrahydrobenzimidazole hydrochloride (II) and phosphorous oxychloride in 1,2-dichloroethane gives (-5? -. [(1-methyl-3-indolyl) carbonyl] -4,5,6,7-tetrahydro-1H-benzimidazol e (III) Optical resolution of (III) with (+)-dibenzoyltartaric acid (DIBTA) in DMF -H2O, followed by exchange of the salt affords YM060.

………………………………………………….

Ondansetron: 1,2,3 ,9-Tetrahydro-9-methyl-3-[(2-methyl1-H-imidazole-1-yl)methyl]-4H-carbazol-4-one

Figure US06451808-20020917-C00005

Granisetron: Endo-1-methyl-N-(9-methyl-9-azabicyclo[3.3.1]non-3-yl)-1H-indazole-3-carboxamide

Figure US06451808-20020917-C00006

Tropisetron: Endo-1H-indole-3-carbocylic acid8-methyl-8-azabicyclo[3.2.1]oct-3-yl ester

Figure US06451808-20020917-C00007

Dolasetron: 1H-Indole-3 -carboxylic acid (2a, 6a, 8a, 9up)-octahydro-3-oxo-2,6-methano-2H-quinolizin-8-yl Ester

Figure US06451808-20020917-C00008

Azasetron: (±)-N-Azabicyclo[2.2.2]oct-3-yl-6-chloro-3,4-dihydro-4-methyl-3-oxo-1,4-benzoxazine-8-carboxamide

Figure US06451808-20020917-C00009

Alosetron: 2,3,4,5-Tetrahydro-5-methyl-2-[(5-methyl- 1H-imidazol-4-yl)methyl]-1H-pyrido[4,3-b]indol-1-one

Figure US06451808-20020917-C00010

Ramosetron

Figure US06451808-20020917-C00011
2D image of a chemical structure
Galdansetron hydrochloride [USAN]
156712-35-5

Medicinal Chemistry International: FILIBUVIR


Medicinal Chemistry International: FILIBUVIR

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

FILIBUVIR
PFIZER
PF-868554 is an anti-hepatitis C drug candidate which had been in phase II clinical trials at Pfizer; however this research has been discontinued.
Li, H.; Tatlock, J.; Linton, A.; et al
Discovery of (R)-6-cyclopentyl-6-(2-(2,6-diethylpyridin-4-yl)ethyl)-3-((5,7-dimethyl-(1,2,4)triazolo(1,5-a)pyrimidin-2-yl)methyl)-4-hydroxy-5,6-dihydropyran-2-one (PF-00868554) as a potent and orally available hepatitis C virus polymerase inhibitor
J Med Chem 2009, 52(5): 1255
Johnson, S.; Drowns, M.; Tatlock, J.; et al.
Synthetic route optimization of PF-00868554, an HCV polymerase inhibitor in clinical evaluation
Synlett (Stuttgart) 2010, 2010(5): 796
WO 2012016995
WO 2013101550
WO 2011072370
WO 2007023381
WO 2006018725
WO2003095441A1 * 7 mei 2003 20 nov 2003 Melwyn A Abreo Inhibitors of hepatitis c virus rna-dependent rna polymerase, and compositions and treatments using the same
WO2006018725A1 * 5 aug 2005 23 feb 2006 Pfizer Inhibitors of hepatitis c virus rna-dependent rna polymerase, and compositions and treatments using the same
US20050176701 * 19 nov 2003 11 aug 2005 Agouron Pharmaceuticals, Inc. Inhibitors of hepatitis C virus RNA-dependent RNA polymerase, and compositions and treatments using the sameWO2007023381A1
Example 1 : Preparation of the glycolate salt of (5-amino-1H-1,2,4-triazol-3-yl)methanol
Figure imgf000055_0001
glycolate salt
Glycolic acid (1 L, 70% in water, 11.51 mol) was added to a 5 L flask. To the solution was slowly added aminoguanidine bicarbonate (783.33 g, 5.755 mol) in portions to control significant bubbling. As solids are added, the solution cools due to endothermic dissolution. The solution was gently heated to maintain an internal temp of 25 °C during addition. Ten minutes after complete addition of aminoguanidine bicarbonate, cone. Nitric acid (6.8 ml_) was carefully added. The solution was heated to an internal temperature of 104-108 0C (mild reflux) for 22 h. The heating was discontinued and the solution allowed to cool, with stirring. At an internal temp of aboutδi °C, solids began to crystallize. After the internal temperature was just below 80 0C, ethanol (absolute, 375 mL) was slowly added to the mixture. After the internal temp had cooled to aboutδδ 0C1the cooling was sped up by the use of an ice/water bath. After cooling below rt, the solution became very thick but remained stirrable at all times. The slurry was stirred for 2h at T<10 0C, then filtered and the solids rinsed with ethanol (900 mL cold, then 250 mL rt). The solids were dried overnight in a vacuum oven (about25 mmHg, 45-50 0C) to provide 815.80 g (75%) of (5-amino-1H-1 ,2,4-triazol-3-yl)methanol as the glycolate salt. 1H (300 MHz, de-DMSO): 3.90 (s, 2), 4.24 (s, 2).
Example 2: Preparation of (5,7-dimethyl[1,2,4]triazolo[1,5-a]pyrimidin-2-yl)methanol
Figure imgf000056_0001
To a 2L, 3-neck flask was charged glycolate salt of (5-amino-1tf-1 ,2,4-triazol-3-yl)methanol (99.93 g, 0.526 mol), 2,4 pentanedione (0.578 mols, 60 mL), acetic acid (6.70 mL), and EtOH (550 mL). The mixture was heated to a slight reflux. One hour after adding the reagents, the resulting solution was cooled to ambient temperature, and CH2CI2 (500 mL) and Celite (25.03 g) were added. After stirring for 1 h, the mixture was filtered through a 4″ Buchner funnel packed with celite (20 g) and rinsed with EtOH (100 mL). The solution was distilled to 5 vols then cooled to 0 °C for 1-2 hours. The slurry was filtered and the cake was rinsed with cold EtOH (2×100 mL). The solids were dried to provide 76.67 g (81.7%) of the title compound.
1H NMR (300 MHz, d6-DMSO): 2.57 (s, 3), 2.71 (d, 3, J=0.8), 4.63 (uneven d, 2, J=5.7), 5.49
(t, 1 , J=6.2), 7.13 (d, 1 , J=0.8).
Example 3: Preparation of 5,7-dimethyl[1 ,2,4]triazolo[1 ,5-a]pyrimidine-2-carbaldehyde
Figure imgf000056_0002
To a 10 L reactor was sequentially charged CH2CI2 (5.1 L)1 (5,7- dimethyl[1 ,2,4]triazolo[1 ,5-a]pyrimidin-2-yl)methanol (680 g, 3.816 mol), and iodobenzene diacetate (1352 g, 4.197 mol). As the iodobenzene diacetate dissolves, there is a significant endotherm (typically down to 15-16 0C). The jacket was set to 23 0C. The mixture was warmed to ambient temperature and Tempo (2,2,6,6-tetramethyl-1-piperidinyloxy, free radical, 43.75 g, 0.28 mol) added in a single charge. The reaction was stirred until 5% of the starting alcohol remained by HPLC. Once the starting material is adjudged to be less than about about5%, the over-oxidized product begins to be observed. Allowing the reaction to run to further completion leads to an overall diminished yield of the desired product. For this reaction, the desired reaction completion was reached in 2.75 h. MTBE (5.1 L) was then slowly charged to the reactor, causing the product to precipitate, and the slurry stirred for an additional 30 mins. The mixture was filtered, washed twice with 1 :1 DCM/MTBE (2 x 1 L), and dried in a vacuum oven overnight at 50 0C to provide 500.3 g (74%) of 5,7- dimethyl[1,2,4]triazolo[1 ,5-a]pyrimidine-2-carbaldehyde as an off-white solid. 1H NMR (300 MHz, ds-DMSO): 2.64 (s, 3), 2.78 (d, 3, J=0.8), 7.36 (d, 1 , J=0.9), 10.13 (s, 1). Example 4: Preparation of the dibenzoyl-L-tartaric acid salt of 1-cyclopentyl-3-(2,6- diethylpyridin-4-yl)propan-1-one
Figure imgf000057_0001
DMAC
L-DBTA NEt3-HOTs + LiBr + NEt3-HBr THF/MTBE
Figure imgf000057_0002
A nitrogen-purged, 5-L, 3-neck flask containing 4-bromo-2,6-diethylpyridine (250.0 g, 0.6472 mol) was sequentially charged with LiBr (112.42 g, 1.2944 mol), 1-cyclopentyl-prop-2- en-1-ol ( 89.84 g, 0.7119 mol), DMAc (625 mL), and H2O (55.0 mL). The mixture was cooled to 5-10 0C and was then purged (subsurface) with N2 for 30 minutes. The flask was charged with Et3N (198.5 mL, 1.4242 mol) and Pd(OaC)2 (3.63 g, 0.0162 mol), followed by a careful purge of the headspace. The reaction was heated until the internal temperature reached 95 0C. After stirring at 95 °C for three hours, an aliquot was removed and analyzed by HPLC, showing >99% conversion to 1-cyclopentyl-3-(2,6-diethylpyridin-4-yl)propan-1-one. The reaction was then cooled to 30 0C over 20 min. The flask was charged with H2O (1500 mL), and MTBE (1500 mL). The solution was stirred well for 5 minutes before the mixture was allowed to settle and the aqueous layer was removed. To the organic layer was charged Celite (62.5Og), and Darco G-60 (6.25g). The slurry was stirred for 20 minutes at 20-25 0C. The slurry was then filtered using a Buchner funnel dressed with Celite. The filter cake was rinsed with MTBE (250 mL). The organic layer was extracted with 5% sodium bicarbonate solution (500 mL) and the phases separated. The organic layer was transferred to a 5 L, three-neck flask, and MTBE added to achieve a total reaction volume of 1750 mL. Additional MTBE (1500 mL) was added and atmospherically distilled until an internal volume of 1750 mL was reached. After cooling below 40 0C, a sample was removed for analysis of water content. After cooling to 20-25 0C, MTBE (250 mL) was added to bring the total volume to 2000 mL and the solution was seeded with crystals of the dibenzoyl-L-tartaric acid salt of 1-cyclopentyl-3-(2,6- diethylpyridin-4-yl)propan-1-one (130 mg), which were prepared according to this procedure. A solution of dibenzoyl-L-tartaric acid (231.89 g, 0.6472 mol) in THF (900 mL) was added over 25 minutes. The slurry was granulated for 1 hour, the mixture was filtered, and the cake rinsed with MTBE (450 mL). The solids were dried in a vacuum oven at 50 0C for 12 h to provide 366.70 g (92% yield) of the title compound. 1H NMR (300 MHz, d6-DMSO): 1.19 (t, 6, J=7.6), 1.47-1.81 (m, 8), 2.73 (q, 4, J=7.6), 2.73-2.98 (m, 5), 5.86 (s, 2), 7.00 (S1 2), 7.55-7.63 (m, 4), 7.68-7.75 (m, 2), 7.98-8.04 (m, 4).
Example 5: Preparation of 3-cyclopentyl-5-(2,6-diethylpyridin-4-yl)-3-hydroxypentanoic acid
Figure imgf000058_0001
A 3-L, 3-neck flask was charged with the dibenzoyl-L-tartaric acid salt of 1- cyclopentyl-3-(2,6-diethylpyridin-4-yl)propan-1-one (174.95 g, 0.2832 mol), MTBE (875 mL), water (875 mL), and triethanolamine (113.0 mL, 0.8513 mol). After stirring for 2 h at rt, an aliquot of the aqueous phase was removed and analyzed by HPLC, showing no detectable starting material. The solution was transferred to a separatory funnel and the layers separated. The lower aqueous phase was discarded and the upper org. phase was washed with water (150 mL). The organic layer was added to a flask set up for distillation. The solution was distilled down to approx. 183 mL and an aliquot was removed and analyzed for water content. The dry solution of 1-cyclopentyl-3-(2,6-diethylpyridin-4-yl)propan-1-one (th. Wt = 73.47 g) in MTBE was used directly in the next step.
A clean 2-L, 3-neck flask was charged with LiHMDS (1.0 M in THF, 355 mL, 0.355 mol) and purged with nitrogen. The flask was cooled to -34 0C. An addition funnel was then charged with EtOAc (35 mL, 0.3583 mol) and this reagent was slowly added to the reaction vessel at such a rate that the low temperature of the vessel could be maintained. After complete EtOAc addition another addition funnel was charged with the 1-cyclopentyl-3-(2,6- diethylpyridin-4-yl)propan-1-one solution (crude MTBE soln from prior reaction, theor. 73.47 g, 0.2832 mol) and rinsed over with THF (anhydrous, 5 ml_). The 1-cyclopentyl-3-(2,6- diethylpyridin-4-yl)propan-1-one solution was slowly added to the reaction flask at such a rate that the low internal temperature could be maintained. Five minutes after complete addition, a reaction aliquot was removed and analyzed by HPLC, showing less than 1% 1-cyclopentyl-3- (2,6-diethylpyridin-4-yl)propan-1-one. Ten minutes after complete ketone addition, the bath was switched to O 0C. Once the internal temperature had warmed to -10 0C, 1 M NaOH (510 mL) was added. After complete NaOH soln addition, the reaction was heated to 50 0C. After 21 hours the reaction solution was cooled below 30 0C and an aliquot of both layers was removed and analyzed for completion. The mixture was added to a separatory funnel with MTBE (350 mL) and the phases were mixed well and separated. An aliquot of the organic phase was analyzed by HPLC, verifying no significant product, and this layer was discarded. The aqueous phase was added to a flask with CH2CI2(350 mL). Concentrated aqueous HCI (about 100 mL) was slowly added to the aqueous phase until the pH = 5. The mixture was added back to a separatory funnel and mixed well. The phases were separated and the aqueous layer was extracted a second time with CH2CI2 (150 mL). The organic layers were combined and charged to a clean flask set up for distillation. The solution was distilled down to 370 mL then displaced with THF by addition of solvent portions followed by continued distillation down to 370 mL after each addition. When the distillation head temp, held steady at 65 °C for 30 min an aliquot was removed and analyzed by 1H NMR, showing a 12.5:1 ratio of THF:CH2CI2. The solution of 3-cyclopentyl-5-(2,6-diethylpyridin-4-yl)-3-hydroxypentanoic acid in THF was used directly in the next step.
Example 6a: Preparation of the (1R,2R)-(-)-2-amino-1-(4-nitrophenyl)-1,3-propanedioI salt of ®-3-cyclopentyl-5-(2,6-diethylpyridin-4-yl)-3-hydroxypentanoic acid
Figure imgf000059_0001
A 2-L, 3-neck flask was sequentially charged with a solution of 3-cyclopentyl-5-(2,6- diethylpyridin-4-yl)-3-hydroxypentanoic acid (crude from last step, theoretical 95.28 g, 0.1792 mol, in about300 mL), (1 R,2R)-(-)-2-amino-1-(4-nitrophenyl)-1 ,3-propanediol (38.03 g, 0.1792 moles) and THF (415 mL). A seed crystal of the (1R,2R)-(-)-2-amino-1-(4-nitrophenyl)-1 ,3- propanediol salt of ®-3-cyclopentyl-5-(2,6-diethylpyridin-4-yl)-3-hydroxypentanoic acid, prepared according to this procedure, was added and the mixture was stirred and heated to 65 0C, then held at this temperature for 16 h. The slurry was cooled slowly to rt and stirred for at least 1 h. The slurry was filtered and the cake rinsed with THF (100 mL). The filtrate (solution of (S)-3-cyclopentyl-5-(2,6-diethylpyridin-4-yl)-3-hydroxypentanoic acid in THF) was used directly in the next procedure. The solids were dried to provide 67.09 g (42 %) of the (1R,2R)-(-)-2-amino-1-(4-nitrophenyl)-1 ,3-propanediol salt of ®-3-cyclopentyl-5-(2,6- diethylpyridin-4-yl)-3-hydroxypentanoic acid as an off-white crystalline solid. Chiral HPLC analysis of the product showed a 92.1:7.9 ratio of the (1R,2R)-(-)-2-amino-1-(4-nitrophenyl)- 1 ,3-propanediol salt of ®-3-cyclopentyl-5-(2,6-diethylpyridin-4-yl)-3-hydroxypentanoic acid to (S)-3-cyclopentyl-5-(2,6-diethylpyridin-4-yl)-3-hydroxypentanoic acid. HPLC conditions: The solid was dissolved in methanol. HPLC conditions: Chirobiotic TAG column, 4.6 x 250 mm, 40 0C column chamber, flow rate = 0.5 mL/min, mobile phase = 100% MeOH (0.05% TEA, 0.05% HOAc). Gradient: Initial flow rate = 0.5 mL/min; 10 min flow rate = 0.5 mL/min; 10.10 min flow rate = 2.00 mL/min; 35 min flow rate = 2.00 mL/min; 36 min flow rate = 0.5 mLΛnin. Percentages reported are at 265 nm. Retention times: (1 R,2R)-(-)-2- amino-1-(4-nitrophenyl)-1 ,3-propanediol = >30 min; (S)-3-cyclopentyl-5-(2,6-diethylpyridin-4- yl)-3-hydroxypentanoic acid = 5.8 min; ®-3-cyclopentyl-5-(2,6-diethylpyridin-4-yl)-3- hydroxypentanoic acid = 7.2 min. 1H NMR (300 MHz, d6-DMSO): 1.19 (t, 6, J=7.6), 1.38-1.62 (m, 8), 1.65-1.75 (m, 2), 1.93-2.07 (m, 1), 2.23 (d, 1 , J=14.4), 2.31 (d, 1 , J=14.4), 2.56 (m, 2), 2.64 (q, 4, J=7.6), 2.91-2.99 (m, 1), 3.22 (dd, 1 , J=5.8, 11.1), 3.42 (dd, 1 , J=4.8, 11.1), 4.77 (d, 1 , J=6.2), 6.0 (br s, 6), 6.84 (s, 2), 7.62 (d, 2, J=8.7), 8.20 (d, 2, J=8.8). Example 6b: Recrystallization of the (1R,2R)-(-)-2-amino-1-(4-nitrophenyl)-1 ,3- propanediol salt of ®-3-cyclopentyl-5-(2,6-diethylpyridin-4-yl)-3-hydroxypentanoic acid
A 2-L, 3-neck flask was charged with the (1R,2R)-(-)-2-amino-1-(4-nitrophenyl)-1 ,3- propanediol salt of ®-3-cyclopentyl-5-(2,6-diethylpyridin-4-yl)-3-hydroxypentanoic acid (66.20 g, 0.1245 moles) and 2B EtOH (970 mL absolute EtOH + 5 mL toluene). The slurry was stirred and heated to reflux. After holding at reflux for 40 min, all the solids had dissolved and the solution was cooled to an internal temp of about 65 0C over 30 min, and the solution was then seeded with crystals of the title compound. The solution was allowed to cool to 50 0C and held for an additional 2h. The solution was then cooled slowly to room temperature over about 2 hours. The cooled solution was stirred at rt for an additional 10 h. The mixture was then filtered and the solids rinsed with 2B EtOH (75 mL). The solids were dried to provide 52.72 g (80%) of product as an off-white crystalline solid that was then dried under vacuum (30 mm Hg) with a nitrogen bleed at 50 0C for 12 h. Chiral HPLC analysis showed product with 96% ee. For determination of e.e., the solid was dissolved in MeOH. HPLC conditions: Chirobiotic TAG column, 4.6 x 250 mm, 40 0C column chamber, flow rate = 0.5 ml_/min, 100% MeOH (0.05% TEA, 0.05% HOAc). Gradient: Initial flow rate = 0.5 mL/min; 10 min flow rate = 0.5 mL/min; 10.10 min flow rate = 2.00 mL/min; 35 min flow rate = 2.00 mL/min; 36 min flow rate = 0.5 mL/min. Percentages reported are at 265 nm. Retention times: (1 R,2R)-(-)-2- amino-1-(4-nitrophenyl)-1 ,3-propanediol = >30 min, (S)-3-cyclopentyl-5-(2,6-diethylpyridin-4- yl)-3-hydroxypentanoic acid = 5.8 min, ®-3-cyclopentyl-5-(2,6-diethylpyridin-4-yl)-3- hydroxypentanoic acid = 7.2 min.
Example 7: Preparation of 1-cyclopentyl-3-(2,6-diethylpyridin-4-yl)propan-1-one from (S)-3-cyclopentyl-5-(2,6-diethylpyridin-4-yl)-3-hydroxypentanoic acid
Figure imgf000061_0001
A flask was charged with a solution of (S)-3-cyclopentyl-5-(2,6-diethylpyridin-4-yl)-3- hydroxypentanoic acid (crude from last step, theoretical 15 g, 0.0470 mol, in about 200 mL THF) and ethanol (100 ml_, 1.7126 mol). To the solution, H2SO4 (5.0 ml_, 0.0938 mol) was added slowly. The solution was heated at reflux for 18 h. When the reaction was judged to be complete by HPLC, the solution was cooled and added to a separatory funnel with 0.5M NaOH (400 mL) and then extracted with MTBE (200 mL). The phases were separated and the organic layer was washed with aqueous acetic acid H2O (100 mL H2O + 3.0 mL HOAc). The phases were separated and the organic layer was washed with 0.5 M NaOH (100 mL). The phases were separated and the organic layer was washed with saturated aqueous NaCI solution (25 mL). The organic layer was distilled at atmospheric pressure down to an internal volume of 150 mL. The solvent was displaced by toluene via atmospheric distillation by adding toluene (100 mL), distilling down to 200 mL internal volume, and repeating this procedure two more times. The final solution was distilled down to an internal volume of 130 mL. An aliquot was removed and analyzed by KF titration. The solution was cooled to rt and a solution of KotBu (1.0M in THF, 4.7 mL, 0.0047 mol) was added in one portion. After 5 min, an aliquot was removed and analyzed by HPLC. The solution was added to a separatory funnel with 1M HCI (60 mL). The phases were mixed well and separated, transferring the product to the aqueous phase. The organic phase was extracted once with water (10 mL) and the aqueous phases combined. The organic phase was discarded. To the aqueous phase was added MTBE (60 mL) and 1 M NaOH (70 mL) and the phases mixed well. The phases were separated and the organic phase extracted with saturated aqueous NaCI solution (25 mL). MTBE was added to bring the volume up to 125 mL. The solution was cooled to rt and seeded with crystals of the dibenzoyl-L-tartaric acid salt of 1-cyclopentyl-3-(2,6-diethylpyridin- 4-yl)propan-1-one (prepared according to Example 4). In a separate vessel, L-DBTA (16.89 g, 0.0471 mol) was dissolved in THF (65 ml_). The solution of L-DBTA was added to the 1- cyclopentyl-3-(2,6-diethylpyridin-4-yl)propan-1-one solution over 45 min, and the slurry granulated for 1 h. The slurry was filtered and the cake washed with MTBE (50 mL). The solids were dried to provide 19.54 g of the dibenzoyl-L-tartaric acid salt of 1-cyclopentyl-3- (2,6-diethylpyridin-4-yl)propan-1-one (67 %) as an off-white solid. Example 8a: Preparation of the dibenzoyl-L-tartaric acid salt of ®-6-cyclopentyl-6-(2- (2,6-diethylpyridin-4-yl)ethyl)-4-hydroxy-5,6-dihydropyran-2-one
Figure imgf000062_0001
i. CDI, DWIAP O O
Ii. KO-^^OEt MgCI2
Figure imgf000062_0002
A nitrogen-purged flask containing the (1R,2R)-(-)-2-amino-1-(4-nitrophenyl)-1 ,3- propanediol salt of ®-3-cyclopentyl-5-(2,6-diethylpyridin-4-yl)-3-hydroxypentanoic acid (20.00 g, 0.0376 mol) was charged with CH2CI2 (200 mL) and H2O (100 mL). The pH of the mixture was adjusted to pH 4.75 with 40% aqueous citric acid (10 mL) and was stirred for 60 minutes. The layers were allowed to settle for 30 minutes and separated. The upper (aqueous) layer was charged CH2CI2 (50 mL), stirred 15 minutes, and was then allowed to settle. The organic layer was combined with the first organic layer and dried with sodium sulfate. The dried organic was concentrated under reduced pressure. The ®-3-cyclopentyl-5-(2,6-diethylpyridin- 4-yl)-3-hydroxypentanoic acid residue was dissolved in THF (47 mL) and this solution added to a slurry of carbonyl diimidazole (9.00 g, 0.0555 mol) and 4-N,N-dimethylaminopyridine (DMAP, 0.45 g, 0.0037 mol) in THF (106 mL) over 5 minutes. Upon complete acyl-imidazole formation, the solution was added to a slurry of potassium ethyl malonate (12.57 g, 0.0738 mol) and magnesium chloride (7.38 g, 0.0775 mol) in 106 mL THF over 5 minutes. The slurry was allowed to stir at 20-25 0C for 30 hours. An aliquot was removed and analyzed by HPLC, showing 96% conversion to ©-ethyl 5-cyclopentyl-7-(2,6-diethylpyridin-4-yl)-5-hydroxy-3- oxoheptanoate. The flask was charged with H2O (64 mL), and MTBE (118 mL). The mixture was stirred well for 5 minutes before it was allowed to settle and the aqueous (lower) layer was removed. To the organic layer was charged brine (52 mL). The mixture was stirred well for 5 minutes before it was allowed to settle and the aqueous (lower) layer was removed. The organic layer was then displaced via atmospheric distillation with methanol (2 x 210 mL) until a total volume of 140 mL was achieved. MTBE (105 mL) was added followed by powdered potassium carbonate (7.65 g, 0.0554 mol), and the slurry heated to reflux for 12 hours. After cooling to 40 °C, MTBE (140 mL) and water (140 mL) were added. The mixture was stirred well for 5 minutes before it was allowed to settle and the aqueous (lower) layer was isolated. The organic layer was extracted with water (30 mL) and the aqueous layers were combined. CH2CI2 (140 mL) was added to the aqueous layer and the pH adjusted to 6.4 with 40% aqueous citric acid (29 mL). The aqueous layer was extracted a second time with CH2CI2 (25 mL). The combined organic layers were then displaced fully into MTBE (140 mL final volume) via atmospheric distillation, cooled, and added slowly to a solution of dibenzoyl-D-tartaric acid (9.92 g, 0.0277 mol) in MTBE (100 mL). The slurry was heated to reflux for 1 hour, then allowed to cool to 20-25 0C. The mixture was filtered, and the cake rinsed with MTBE (50 mL). The solids were dried in a vacuum oven at 50 0C for 12 h to provide 16.40 g (62%) of the title compound.
Example 8b: Preparation of the dibenzoyl-L-tartaric acid salt of ®-6-cyclopentyl-6-(2- (2,6-diethylpyridin-4-yl)ethyl)-4-hydroxy-5,6-dihydropyran-2-one
A nitrogen-purged flask containing the (1 R,2R)-(-)-2-amino-1-(4-nitrophenyl)-1 ,3-propanediol salt of ®-3-cyclopentyl-5-(2,6-diethylpyridin-4-yl)-3-hydroxypentanoic acid (50.00 g, 0.0940 mol) was charged with CH2CI2 (500 mL) and H2O (250 mL). The pH of the resulting suspension was adjusted to pH 4.6 to 4.8 (a measured pH of 4.75 is preferred) with 40% aqueous citric acid (21 mL) and was stirred for 30 minutes. The layers were allowed to settle for 30 minutes and separated. The upper (aqueous) layer was charged with CH2CI2 (100 mL), stirred 15 minutes, and allowed to settle. The organic layer was combined with the first organic layer. The upper (aqueous) layer was again charged with CH2CI2 (100 mL), stirred 15 minutes, and allowed to settle. This organic layer was also combined with the first organic layer. A sample of each of the combined organic layers and the aqueous layer was taken for HPLC analysis. The combined organic layers were atmospherically distilled until a total volume of 120 mL was reached. THF (100 mL) was charged and atmospheric distillation continued until a total volume of 120 mL was reached. The THF charge and displacement was repeated 3 times. A sample was removed and analyzed by NMR and KF. The resulting solution was added to a slurry of CDI (22.86 g, 0.1410 mol) and DMAP (1.15 g, 0.0094 mol) in THF (250 mL) over 15 minutes. The addition funnel was then rinsed with 10 mL THF which was then added to the CDI slurry. After stirring 15 minutes, a sample was removed and analyzed by HPLC. Upon complete acyl-imidazole formation, the solution was added to a slurry of potassium ethyl malonate (32.00 g, 0.1880 mol) and magnesium chloride (18.80 g, 0.1974 mol) in 250 mL THF at 20-25 0C over 25 minutes. The slurry was allowed to stir at 20-25 0C for 21 hours. An aliquot was removed and analyzed by HPLC, showing 96% conversion to ®- ethyl 5-cyclopentyl-7-(2,6-diethylpyridin-4-yl)-5-hydroxy-3-oxoheptanoate. The flask was charged with H2O (162 mL), and MTBE (300 mL). The mixture was stirred well for 5 minutes before it was allowed to settle and the yellow aqueous (lower) layer was removed. To the organic layer was charged brine (100 mL). The mixture was stirred well for 5 minutes before it was allowed to settle and the aqueous (lower) layer was removed. The organic layer was then atmospherically distilled down to 350 mL total volume. MTBE (250 mL) was charged and the solution distilled to 350 mL total volume. Additional MTBE (250 mL) was charged and the solution distilled at a temperature of at least 55 0C to 350 mL total volume. A sample was removed for KF titration. Methanol (250 mL) was charged and the solution was then atmospherically distilled until a total volume of 350 mL was achieved. Methanol (250 mL) was charged and then the solution was atmospherically distilled until a total volume of 350 mL was achieved and a temperature of ~66 0C was achieved. Powdered potassium carbonate (19.49 g, 0.1410 mol) was added and the slurry heated to reflux for 4 hours. A sample was removed for HPLC analysis showing >99% completion. After cooling to 22 0C, MTBE (350 mL) and water (350 mL) were added. The mixture was stirred well for 5 minutes before it was allowed to settle and the product rich aqueous (lower) layer was isolated. The organic layer was extracted with water (100 mL) and the aqueous layers were combined. To the combined aqueous layers was charged MTBE (100 mL). The mixture was stirred well for 5 minutes before it was allowed to settle and the product rich aqueous (lower) layer was isolated. CH2CI2 (350 mL) was added to the aqueous layer and the pH adjusted to 6.0-6.4 with 40% aqueous citric acid (75 mL). The aqueous layer was extracted a second time with CH2CI2 (100 mL). The combined organic layers were then atmospherically distilled to 250 mL total volume. MTBE (400 mL) was charged and the solution was atmospherically distilled at a temperature of at least 55 0C until 250 mL final volume was reached. After cooling the solution to 20-25 0C, a prepared solution of dibenzoyl-D-tartaric acid (23.58 g, 0.0658 mol) in MTBE (125 mL) was added over 10 minutes. The resulting slurry was heated to reflux for 4 hours, then allowed to cool to 20-25 0C and stirred an additional 4 hours. The slurry was filtered, and the cake rinsed with MTBE (125 mL). The solids were dried in a vacuum oven at 50 0C for 12 h to provide 38.19 g (58%) of the title compound. HPLC conditions: aliquots were withdrawn and dissolved in CH3CN/H2O (40:60). HPLC conditions: Kromasil C4 column, 5 μm, 4.6x150mm, 40 0C column chamber, flow rate= 1.0 mL/min, 40% CHsCN/60% aqueous (1.OmL 70% HcIO4 in 1 L H2O) isocratic. Percentages reported are at 254 nm. Approximate retention times: ®-3- cyclopentyl-5-(2,6-diethylpyridin-4-yl)-3-hydroxypentanoic acid = 3.4 min; ©-ethyl 5- cyclopentyl-7-(2,6-diethylpyridin-4-yl)-5-hydroxy-3-oxoheptanoate = 7.3 min; ®-6-cyclopentyl- 3-(2-(2,6-diethylpyridin-4-yl)ethyl)-4-hydroxy-5,6-dihydropyran-2-one = 3.9 min; D-DBTA = 5.5 min. Example 9a: Preparation of ®-6-cyclopentyl-6-(2-(2,6-diethylpyridin-4-yl)ethyl)-3-((5,7- dimethyl-ri^.^triazoloII.S-alpyrimidini-Z-yOmethylH-hydroxy-S.e-clihyclropyran^-one
Figure imgf000065_0001
BHe-pyridine
Figure imgf000065_0002
A flask was charged with the dibenzoyl-L-tartaric acid salt of ®-6-cyclopentyl-6-(2- (2,6-diethylpyridin-4-yl)ethyl)-4-hydroxy-5,6-dihydropyran-2-one (this material contained 1.5 eq DBTA counterion, 4.00 g, theor. 0.00454 mol), 2-MeTHF (40 ttiL), MTBE (40 mL), and water (20 mL). A solution of 5% aq NaHCO3 (about 20 mL) was added until the pH was 7.4. The solution pH was back-adjusted to pH = 7.2 with a small amount of 40% citric acid solution. The phases were separated and the aqueous layer was extracted with 2-MeTHF (25 mL). The combined organic layers were dried with Na2SO4 and concentrated to an oil. The oil was used directly in the subsequent condensation. To the crude ®-6-cyclopentyl-6-(2-(2,6- diethylpyridin-4-yl)ethyl)-4-hydroxy-5,6-dihydropyran-2-one was added methanol (32 mL) and the solution cooled to -40 0C. To the cold solution was added pyridine-borane complex (1.30 mL, 0.01287 mol) and 5,7-dimethyl-[1 ,2,4]triazolo[1 ,5-a]pyrimidine-2-carbaldehyde (1.41 g, 0.00800 mol). The solution was warmed to 0 0C over 45 min then stirred for an additional 2 h. The reaction was quenched by the addition of water (10 mL) and the mixture stirred at rt overnight. To the mixture was added 1M HCI (10 mL), and the solution was stirred for 3 h. lsopropyl acetate (57 mL) was added and the pH adjusted to 7 by the addition of 1 M NaOH. The phases were separated and the organic layer extracted with water (25 mL x 2). The aqueous phases were extracted further with CH2CI2 (100 ml, 2 x 25 mL). The combined IPAc and CH2CI2 layers were dried (Na2SO4), filtered, and concentrated to yield 3.41 g of crude ®-6- cyclopentyl-6-(2-(2,6-diethylpyridin-4-yl)ethyl)-3-((5,7-dimethyl-[1 ,2,4]triazolo[1 ,5-a]pyrimidin-2- yl)methyl)-4-hydroxy-5,6-dihydropyran-2-one. To the residue was added isopropyl acetate (46 mL) and EtOH (2.5 mL) and the mixture heated to reflux until homogeneous. The solution was allowed to cool slowly to rt and stirred overnight. The slurry was filtered, the solids rinsed with IPAc (13 mL), and dried to provide 1.74 g (76 %) of ®-6-cyclopentyl-6-(2-(2,6- diethylpyridin-4-yl)ethyl)-3-((5J-dirnethyl-[1 ,2,4]triazolo[1 ,5-a]pyrimidin-2-yl)methyl)-4-hydroxy-
5,6-dihydropyran-2-one as an off-white solid.
Example 9b: Preparation of ®-6-cyclopentyl-6-(2-(2,6-diethylpyridin-4-yl)ethyl)-3-((5,7- dimethyl-[1,2,4]triazolot1,5-a]pyrimidin-2-yl)methyl)-4-hydroxy-5,6-dihydropyran-2-one
A 500 mL flask was charged with the dibenzoyl-L-tartaric acid salt of ®-6-cyclopentyl-
6-(2-(2,6-diethylpyridin-4-yl)ethyl)-4-hydroxy-5,6-dihydropyran-2-one (15.00 g, 0.02137 moles), THF (75 mL), MeOH (75 mL), pyridine-borane (4.25 mL, 0.034 moles), and 5,7- dimethyl-[1 ,2,4]triazolo[1 ,5-a]pyrimidine-2-carbaldehyde (5.65 g, 0.03207 moles) was added last. The resulting mixture was stirred at rt and an aliquot was removed after 1.25 h and analyzed by HPLC showing 13.5% ®-6-cyclopentyl-6-(2-(2,6-diethylpyridin-4-yl)ethyl)-4- hydroxy-5,6-dihydropyran-2-one. Stirring was continued for an additional 2 h, and HPLC analysis of an aliquot then showed 4.8% of ®-6-cyclopentyl-6-(2-(2,6-diethylpyridin-4-yl)ethyl)-
4-hydroxy-5,6-dihydropyran-2-one remaining. The reaction solution was charged with CH2CI2
(150 mL) and water (150 mL), and the phases were stirred overnight. The lower organic layer was removed and to the upper aqueous layer was charged CH2CI2 (25 mL), the phases were mixed well and separated and the aqueous layer was discarded. The organic layers were combined and charged to a flask containing water (150 mL) and triethanolamine (7.1 mL,
0.0535 mol), mixed well then separated. The lower organic layer was removed and to the upper aqueous layer was charged CH2CI2 (25 mL), the phases were mixed well, separated, and the aqueous layer was discarded. To the combined organic layers was charged water
(100 mL) and 1M NaOH (25 mL), the phases were mixed well, separated, and the lower organic layer was discarded. To the upper aqueous layer was charged CH2CI2 (75 mL) and
1N HCI was added until the pH=6.91 (~25 mL added), the phases were mixed well, separated, and the aqueous layer was discarded. The combined organic layers were extracted with water (3.2 volumes). The layers were separated and the organic layer was transferred to a
;lean flask marked with a 75 mL volume line. The organic layer was distilled atmospherically
0 75 mL. To the flask was charged isopropyl acetate (75 mL x 2) followed by distillation down
0 75 mL total volume after each addition. The flask was seeded and cooled to rt and stirred
)vemight. The reaction was filtered and the cake was washed with isopropyl acetate (25 ml).
he solids were dried to provide 7.20 g (67%) of ®-6-cyclopentyl-6-(2-(2,6-diethylpyridin-4-
‘l)ethyl)-3-((5,7-dimethyl-[1 ,2,4]triazolo[1 ,5-a]pyrimidin-2-yl)methyl)-4-hydroxy-5,6- lihydropyran-2-one as an off-white powder, which was dried in a vacuum oven (~25 inHg at
0C) for 12 h. For HPLC monitoring, aliquots were withdrawn and dissolved in CH3CN/H2O
1-0:60). HPLC conditions: Kromasil C4 column, 5 μm, 4.6×150 mm, 40 0C column chamber, ow rate= 1.0 mL/min, 40% CH3CN/60% aqueous (1.0 mL 70% HcIO4 in 1L H2O) isocratic.
‘ercentages reported are at 254 nm. Retention times: ®-6-cyclopentyl-6-(2-(2,6- iethylpyridin-4-yl)ethyl)-4-hydroxy-5,6-dihydropyran-2-one = 3.85 min; ®-6-cyclopentyl-6-(2- (2,6-diethylpyridin-4-yl)ethyl)-3-((5,7-dimethyl-[1 ,2,4]triazolo[1 ,5-a]pyrimidin-2-yl)methyl)-4- hydroxy-5,6-dihydropyran-2-one = 3.56 min; DBTA= 5.14 min; BH3 «pyr=3.36 min.
Example 10: Recrystallization of ®-6-cyclopentyl-6-(2-(2,6-diethylpyridin-4-yl)ethyl)-3-
((5,7-dimethyl-[1,2,4]triazolo[1,5-a]pyrimidin-2-yl)methyl)-4-hydroxy-5,6-dihydropyran-2- one
A 200 mL flask was charged with ®-6-cyclopentyl-6-(2-(2,6-diethylpyridin-4-yl)ethyl)-3- ((5,7-dimethyl-[1 ,2,4]triazolo[1 ,5-a]pyrimidin-2-yl)methyl)-4-hydroxy-5,6-dihydropyran-2-one (10.05 g, 0.01995 mol) and THF (70 mL). The mixture was stirred and heated to 30 to 35 0C to provide a homogeneous solution. The solution was filtered through a 0.45 μm Teflon filter, and rinsed with THF (10 mL). The filtrate was added to a flask set up for atmospheric distillation and isopropyl acetate (IPAC, 50 mL) was added. The solution was concentrated by distillation to an internal volume of 100 mL. Isopropyl acetate (50 mL) was added and distillation continued at atmospheric pressure until the internal volume reached 100 mL. The solution was seeded with ®-6-cyclopentyl-6-(2-(2,6-diethylpyridin-4-yl)ethyl)-3-((5,7-dimethyl- [1 ,2,4]triazolo[1 ,5-a]pyrimidin-2-yl)methyl)-4-hydroxy-5,6-dihydropyran-2-one and additional IPAC (30 mL) was added. The solution was again distilled to an internal volume of 100 mL and was cooled over about 1 h to 50 0C. The solution was held at 50 0C for an additional 1.5 h, cooled over about 2 h to rt, and stirred overnight. The resulting slurry was filtered and rinsed with IPAC (30 mL). The resulting solids were dried to provide 9.41 g (94%) of the title compound as an off-white powder that was vacuum dried (~25 in Hg, 50 0C) for 12 h.
CAS 877130-28-4
 FILIBUVIR
(R)-6-Cyclopentyl-6-[2-(2,6-diethylpyridin-4-yl)ethyl]-3-[(5,7-dimethyl-[1,2,4]triazolo[1,5-a]pyrimidin-2-yl)methyl]-4-hydroxy-5,6-dihydro-2H-pyran-2-one
Filibuvir;Pf-00868554;Unii-198J479Y2l;(6R)-6-Cyclopentyl-6-(2-(2,6-diethylpyridin-4-yl)ethyl)-3-((5,7-dimethyl(1,2,4)triazolo(1,5-A)pyrimidin-2-yl)methyl)-4-hydroxy-5,6-dihydro-2H-pyran-2-one;(R)-6-Cyclopentyl-6-[2-(2,6-diethylpyridin-4-yl)ethyl]-3-[(5,7-dimethyl-[1,2,4]triazolo[1,5-a]pyrimidin-2-yl)methyl]-4-hydroxy-5,6-dihydro-2H-pyran-2-one;2H-Pyran-2-one, 6-cyclopentyl-6-(2-(2,6-diethyl-4-pyridinyl)ethyl)-3-((5,7-dimethyl(1,2,4)triazolo(1,5-A)pyrimidin-2-yl)methyl)-5,6-dihydro-4-hydroxy-, (6R)-
MF C29H37N5O3
MW 503.64

ANTHONY MELVIN CRASTO

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Medicinal Chemistry International: NARLAPREVIR


Medicinal Chemistry International: NARLAPREVIR

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NARLAPREVIR

NARLAPREVIR
An antiviral agent that inhibits hepatitis C virus NS3 protease.
M.Wt: 707.96
Formula: C36H61N5O7S
CAS No.: 865466-24-6
SCH 900518;SCH900518;SCH-900518
3-Azabicyclo[3.1.0]hexane-2-carboxamide, N-[(1S)-1-[2-(cyclopropylamino)-2-
oxoacetyl]pentyl]-3-[(2S)-2-[[[[1-[[(1,1-dimethylethyl)sulfonyl]methyl]cyclohexyl]
amino]carbonyl]amino]-3,3-dimethyl-1-oxobutyl]-6,6-dimethyl-, (1R,2S,5S)-
2. (1R,2S,5S)-N-{(1S)-1-[2-(cyclopropylamino)-2-oxoacetyl]pentyl}-3-[(2S)-2-{[(1-{[(1,1-
dimethylethyl)sulfonyl]methyl}cyclohexyl)carbamoyl]amino}-3,3-dimethylbutanoyl]-6,6-
dimethyl-3-azabicyclo[3.1.0]hexane-2-carboxamide
3. (1R,2S,5S)-3-{N-[({1-[(tert-butylsulfonyl)methyl]cyclohexyl}amino)carbonyl]-3-methyl-L-
valyl}-N-{(1S)-1-[(cyclopropylamino)(oxo)acetyl]pentyl}-6,6-dimethyl-3-
azabicyco[3.1.0]hexane-2-carboxamide
Narlaprevir is a potent, Second Generation HCV NS3 Serine Protease Inhibitor.Narlaprevir is useful for Antiviral
Merck & Co. (Originator)
SCH-900518 had been in phase II clinical trials by Merck & Co. for the treatment of genotype 1 chronic hepatitis C; however, no recent development has been reported for this indication.
A potent oral inhibitor of HCV NS3 protease, SCH-900518 disrupts hepatitis C virus (HCV) polyprotein processing. When added to the current standard of care (SOC), peginterferon-alfa plus ribavirin, SCH-900518 is likely to increase the proportion of patients achieving undetectable HCV-RNA levels and sustained virologic response (SVR).
In 2012, the product was licensed by Merck & Co. to R-Pharm in Russia and the Commonwealth of Independent States (CIS) for the development and commercialization as treatment of hepatitis C (HCV)
PATENTS
WO 2011014494
WO 2010068714
(1 R,5S)-N-[1 (S)-[2-(cyclopropylamino)-1 ,2-dioxoethyl]pentyl]-3-[2(S)- [[[[1-[[1.1-dimethylethyl)sulfonyl]methyl]cyclohexyl]amino]carbonyl]amino]-3,3- dimethyl-1-oxobutyl]-6,6-dimethyl-3-azabicyclo[3.1.0]hexane-2(S)-carboxamide.
Figure imgf000003_0001
Identification of any publication in this section or any section of this application is not an admission that such publication is prior art to the present invention.
The compound of Formula I is generically and specifically disclosed in
Published U.S. Patent No.2007/0042968, published February 22, 2007 (the ‘968 publication), incorporated herein by reference.
Processes suitable for making the compound of Formula I are generally described in the ‘968 publication. In particular, the ‘968 publication discusses preparing a sulfone carbamate compound, for example, the compound of Formula 837 comprising a cyclic sulfone substituent (paragraphs [0395] through [0403]). The following reaction scheme describes the procedure:
Figure imgf000004_0001
The process disclosed in the ‘968 publication produces the intermediate alcohol in step S7 as a mixture of diastereomers at the hydroxyl group; while this chiral center is lost in the final step of the disclosed process, the alcohol intermediate as a mixture of isomers cannot be crystallized and required a volumetrically inefficient precipitative isolation that did not remove any impurities
,………………………………………………………………………………………………………………………
Figure imgf000048_0001
……………………………………………………………………………………………………………………
Preparation of Compound VIJ
Figure US20120178942A1-20120712-C00062
LDA was made by slowly charging n-butyl lithium (2.5 M, 159 kg) to diisopropyl amine (60 kg) dissolved in THF (252 kg), keeping the temperature at about −20° C., followed by agitation at this temperature for about 30 min. To this solution was charged cyclohexane carboxylic acid, methyl ester (70 kg), keeping the temperature below −10° C. The mixture was agitated at this temperature for about 2 h. To the resulting enolate was charged TMSCI (64.4 kg). The mixture was agitated at −10 to −20° C. for about 30 min, and then heated to about 25° C. and held at this temperature to allow for conversion to the silylenol ether Compound VIH. The reaction mixture was solvent exchanged to n-heptane under vacuum, keeping the temperature below 50° C., resulting in the precipitation of solids. The solids were filtered and washed with n-heptane, and the wash was combined with the n-heptane reaction mixture. The n-heptane mixture of Compound VIH was concentrated under vacuum and diluted with CH2Cl2.
In a separate reactor was charged CH2Cl(461 kg) and anhydrous ZnBr(14.5 kg). The temperature of the zinc slurry was adjusted to about 20° C. To the zinc slurry was simultaneously charged the solution of Compound VIH and 2-chloromethylsulfanyl-2-methyl-propane (63.1 kg, ref: Bioorg. Med. Chem. Lett, 1996, 6, 2053-2058), keeping the temperature below 45° C. After complete addition, the mixture was agitated for about 1.5 h at 35 to 45° C., after which the reaction mixture was cooled to 10 to 15° C. A solution of dilute aqueous HCl was then charged, keeping the temperature between 0 and 15° C., followed by a separation of the aqueous and organic layers (desired compound in organic layer). The organic layer was washed with aqueous NaHCOand water. The organic layer was solvent exchanged to methanol by vacuum distillation, keeping the temperature below 35° C., and kept as a solution in methanol for further processing to Compound VIK. Active Yield of Compound VIJ=69.7 kg (molar yield=57.9%).
Preparation of Compound VIK
Figure US20120178942A1-20120712-C00063
To a fresh reactor was charged Compound VIJ (99.8 kg active in a methanol solution), water (270 kg), NaOH (70 kg), and methanol (603 kg). The mixture was heated to −70° C. and agitated at this temperature for about 16 h. Upon conversion to the sodium salt of Compound VIK, the reaction mixture was concentrated under vacuum, keeping the temperature below 55° C., and then cooled to about 25° C. Water and MTBE were then charged, agitiated, and the layers were separated (product in the aqueous layer). The product-containing aqueous layer was further washed with MTBE.
CH2Clwas charged to the aqueous layer and the temperature was adjusted to ˜10° C. The resultant mixture was acidified to a pH of about 1.5 with HCl, agitated, settled, and separated (the compound was in the organic layer). The aqueous layer was extracted with CH2Cl2, and the combined organic layers were stored as a CH2Clsolution for further processing to Compound VID. Active yield of Compound VIK=92.7 kg (molar yield=98.5 kg). MS Calculated: 230.13; MS Found (ES−, M−H): 229.11.
Preparation of Compound VID
Figure US20120178942A1-20120712-C00064
To a reactor was charged water (952 kg), Oxone® (92.7 kg), and Compound VIK (92.7 kg active as a solution in CH2Cl2). The reaction mixture was agitated for about 24 h at a temperature of about 15° C., during which time Compound VIK oxidized to sulfone Compound VID. The excess Oxone® was quenched with aqueous Na2S2O5, the reaction mixture was settled and the layers separated; the aqueous layer was back-extracted with CH2Cl2, and the combined product-containing organic layers were washed with water.
The resultant solution was then concentrated under vacuum. To precipitate Compound VID, n-heptane was charged, and the resulting slurry was agitated for about 60 min at a temperature of about 30° C. The reaction mixture was filtered, and the wet cake was washed with n-heptane. The wet cake was redissolved in CH2Cl2, followed by the addition of n-heptane. The resultant solution was then concentrated under vacuum, keeping the temperature below 35° C., to allow for product precipitation. The resultant solution was cooled to about 0° C. and agitated at this temperature for about 1 h. The solution was filtered, the wet cake was washed with n-heptane, and dried under vacuum at about 45° C. to yield 68.7 kg Compound VID (molar yield=65.7%). MS Calculated: 262.37; MS Found (ES−, M−H): 261.09
Preparation of Compound VI
Figure US20120178942A1-20120712-C00065
To a reactor was charged Compound VID (68.4 kg), toluene (531 kg), and Et3N (31 kg). The reaction mixture was atmospherically refluxed under Dean-Stark conditions to remove water (target KF <0.05%). The reaction temperature was adjusted to 80° C., DPPA (73.4 kg) was charged over 7 h, and the mixture was agitated for an additional 2 h. After conversion to isocyanate Compound VIE via the azide, the reaction mixture was cooled to about 0 to 5° C. and quenched with aqueous NaHCO3. The resultant mixture was agitated, settled and the layers were separated. The aqueous layer was extracted with toluene, and the combined isocyante Compound VIE organic layers were washed with water.
In a separate vessel was charged L-tert- Leucine (L-Tle, 30.8 kg), water (270 kg), and Et3N (60 kg). While keeping the temperature at about 5° C., the toluene solution of Compound VIE was transferred to the solution of L-Tle. The reaction mixture was stirred at 0 to 5° C. for about 5 h, at which time the mixture was heated to 15 to 20° C. and agitated at this temperature for 2 h to allow for conversion to urea Compound VI.
The reaction was quenched by the addition of aqueous NaOH, keeping the temperature between 0 and 25° C. The reaction mixture was separated, and the organic layer was extracted with water. The combined Compound VI-containing aqueous layers were washed with toluene, and acidified to pH 2 by the addition of HCl, at which time the product precipitated from solution. The reaction mixture was filtered, washed with water and dried under vacuum at 65 to 70° C. to yield 79.7 kg crude Compound VI (molar yield 52.7%). MS Calculated: 390.54; MS Found (ES−, M−H): 389.20.
Compound VI is further purified by slurrying in CH3CN at reflux (about 80° C.), followed by cooling to RT. Typical recovery is 94%, with an increase in purity from about 80% to 99%.
Preparation of Compound Va
Figure US20120178942A1-20120712-C00066
To a reactor was charged Compound VI (87.6 kg), Compound VII-1 (48.2 kg), HOBt (6 kg) and CH3CN (615 kg). The reaction mixture was cooled to about 5° C., and NMM (35 kg) and EDCi (53.4 kg) were charged. The reaction was heated to 20 to 25° C. for about 1 h, and then to 35 to 40° C., at which time water was charged to crystallize Compound Va. The reaction mixture was cooled to 5° C. and held at this temperature for about 4 h. Compound Va was filtered and washed with water. XRD data for the hydrated polymorph of Va is as follows:
The Compound Va wet cake was charged to a fresh vessel and was dissolved in ethyl acetate at 25 to 30° C. The solution was washed with an aqueous HCl solution, aqueous K2COsolution, and brine. The solution was then concentrated under vacuum, keeping the temperature between 35 to 50° C. Additional ethyl acetate was charged, and the solution was heated to 65 to 70° C. While keeping the temperature at 65 to 70° C., n-heptane was charged, followed by cooling the resultant solution to 0 to 5° C. Compound Va was filtered and washed with an ethyl acetate/n-heptane mix.
The wet cake was dried under vacuum between 55 to 60° C. to yield 96.6 kg crystalline Compound Va (molar yield 79.2%). MS Calculated: 541.32; MS Found (ES+, M+H): 542.35.
Preparation of Compound IUB
Figure US20120178942A1-20120712-C00067
Pyridine (92 L) was charged to the reactor and was cooled to 5° C. To the cooled pyridine was slowly charged malonic acid (48.5 kg) and valeraldehyde (59 L), keeping the temperature below 25° C. The reaction was stirred between 25 to 35° C. for at least 60 h. After this time, H2SOwas charged to acidify, keeping the temperature below 30° C. The reaction mixture was then extracted into MTBE. The organic layer was washed with water. In a separate reactor was charged water and NaOH. The MTBE solution was charged to the NaOH solution, keeping the temperature below 25° C., and the desired material was extracted into the basic layer. The basic layer was separated and the organic layer was discarded. MTBE was charged, the mixture was agitated, settled, and separated, and the organic layer was discarded. To the resultant solution (aqueous layer) was charged water and H2SOto acidify, keeping the temperature between 10 to 15° C. To the acidified mixture was charged MTBE, keeping the temperature below 25° C. The resultant solution was agitated, settled, and separated, and the aqueous layer was discarded. The product-containing organic layer was washed with water and was concentrated under vacuum, keeping the temperature below 70° C., to yield 45.4 kg Compound IIIB (molar yield=76.2%) as an oil. Compound Reference: Concellon, J. M.; Concellon, C J. Org. Chem., 2006, 71, 1728-1731
Preparation of Compound IIIC
Figure US20120178942A1-20120712-C00068
To a pressure vessel was charged Compound IIIB (9.1 kg), heptane (9 L), and H2SO(0.5 kg). The pressure vessel was sealed and isobutylene (13.7 kg) was charged, keeping the temperature between 19 to 25° C. The reaction mixture was agitated at this temperature for about 18 h. The pressure was released, and a solution of K2COwas charged to the reaction mixture, which was agitated and settled, and the bottom aqueous layer was then separated. The resultant organic solution was washed with water and distilled under vacuum (temp below 45° C.) to yield 13.5 kg Compound IIIC (molar yield=88.3%) as a yellow oil.
Preparation of Compound IIID
Figure US20120178942A1-20120712-C00069
To a reactor capable of maintaining a temperature of −60° C. was charged (S)-benzyl-1-phenyl ethylamine (18 kg) and THF (75 L). The reaction mixture was cooled to −60° C. To the mixture was charged n-hexyl lithium (42 L of 2.3 M in heptane) while maintaining a temperature of −65 to −55° C., followed by a 30 min agitation within this temperature range. To the in situ-formed lithium amide was charged Compound IIIC over 1 h, keeping the temperature between −65 to −55° C. . The reaction mixture was agitated at this temperature for 30 min to allow for conversion to the enolate intermediate. To the resultant reaction mixture was charged (+)-camphorsulfonyl oxaziridine (24 kg) as a solid, over a period of 2 h, keeping the temperature between −65 to −55° C. . The mixture was agitated at this temperature for 4 h.
The resultant reaction mixture was quenched by the addition of acetic acid (8 kg), keeping the temperature between −60 to −40° C. The mixture was warmed to 20 to 25° C., then charged into a separate reactor containing heptane. The resultant mixture was concentrated under vacuum, keeping the temperature below 35° C. Heptane and water were charged to the reaction mixture, and the precipitated solids were removed by filtration (the desired compound is in the supernatant). The cake was washed with heptane and this wash was combined with the supernatant. The heptane/water solution was agitated, settled, and separated to remove the aqueous layer. An aqueous solution of H2SOwas charged, and the mixture was agitated, settled, and separated. The heptane layer was washed with a solution of K2CO3.
The heptane layer was concentrated under reduced pressure, keeping the temperature below 45° C., and the resulting oil was diluted in toluene, yielding 27.1 kg (active) of Compound IIID (molar yield=81.0%). MS Calculated: 411.28; MS Found (ES+, M+H): 412.22.
A similar procedure for this step was reported in: Beevers, R, et al, Bioorg. Med. Chem. Lett. 2002, 12, 641-643.
Preparation of Compound IDE
Figure US20120178942A1-20120712-C00070
Toluene (324 L) and a toluene solution of Compound IIID (54.2 kg active) was charged to the reactor. TFA (86.8 kg) was charged over about 1.5 h, keeping the temperature below 50° C. The reaction mixture was agitated for 24 h at 50° C. The reaction mixture was cooled to 15° C. and water was charged. NaOH was slowly charged, keeping the temperature below 20° C., to adjust the batch to a pH between 5.0 and 6.0. The reaction mixture was agitated, settled, and separated; the aqueous layer was discarded. The organic layer was concentrated under vacuum, keeping the temperature below 40° C., and the resulting acid intermediate (an oil), was dissolved in 2-MeTHF.
In a separate reactor, 2-MeTHF (250 L), HOBt (35.2 kg), and EDCi-HCl (38.0 kg) were charged and the mixture was adjusted to a temperature between 0 to 10° C. DIPEA (27.2 kg) was charged, keeping the mixture within this temperature range. The mixture was agitated for 5 min, followed by the addition of cyclopropyl amine (11.4 kg), keeping the temperature between 0 to 10° C.
To this solution was charged the 2-MeTHF/ acid intermediate solution, keeping the resultant solution between 0 to 10° C. The resultant mixture was heated to 25 to 35° C., and was agitated at this temperature for about 4 h. The reaction mixture was cooled to about 20° C., and was washed with aqueous citric acid, aqueous K2CO3, and water. The solvent was exchanged to n-heptane, and the desired compound was crystallized from a mix of n-heptane and toluene by cooling to 0° C. The crystalline product was filtered, washed with n-heptane, and dried to yield 37.1 kg Compound IIIE (molar yield=70.7%). MS Calculated: 394.26; MS Found (ES+, M+H): 395.22.
Preparation of Compound III
Figure US20120178942A1-20120712-C00071
To a pressure reactor was charged acetic acid (1.1 kg), methanol (55 kg), and Compound IIIE (10.9 kg). In a separate vessel, Pd/C (50% water wet, 0.5 kg) was suspended in methanol (5 kg). The Pd/C suspension was transferred to the solution containing Compound IIIE. The resultant mixture was pressurized to 80 psi with hydrogen, and agitated at 60° C. for 7 h. The reaction mixture was then purged with nitrogen, and the Pd/C catalyst was filtered off. The resultant solution was concentrated under vacuum and adjusted to about 20° C. MTBE was charged, and the resultant solution was brought to reflux. Concentrated HCl (3 L) was charged and the product was crystallized by cooling the reaction mixture to about 3° C. The desired compound was filtered, washed with MTBE, and dried under vacuum, keeping the temperature below 40° C. to yield 5.5 kg Compound III (molar yield=83.0%). MS Calculated (free base): 200.15; MS Found (ES+, M+H): 201.12.
Preparation of Compound II
Figure US20120178942A1-20120712-C00072
Compound Va (119.3 kg) was dissolved in 2-MeTHF (720 kg) and water (180 kg). To this solution was charged 50% NaOH (21.4 kg) while maintaining a temperature between 20 and 30° C. The reaction mixture was then agitated for about 7 h at a temperature between 50 and 60° C. The reaction mixture was cooled to a temperature between 20 and 30° C.
The pH of the reaction mixture was adjusted to 1.5-3.0 with dilute phosphoric acid, maintaining a temperature between 20 and 30° C. The resultant mixture was agitated for 10 min, settled for 30 min, and the bottom aqueous layer was separated and removed. The top organic layer was washed with water, followed by concentration by atmospheric distillation.
The concentrated solution was solvent exchanged to CH3CN by continuous atmospheric distillation, and crystallized by cooling to 0° C. The crystalline product was filtered, washed with CH3CN, and dried under vacuum at a temperature between 45 and 55° C. to yield 97.9 kg Compound II (molar yield=83.7%). MS Calculated: 527.30; MS Found (ES+, M+H): 528.29.
Preparation of Compound IV
Figure US20120178942A1-20120712-C00073
Compound II (21.1 kg), Compound III (9.9 kg), HOBt (3.2 kg) and EDCi (11.2 kg) were charged to the vessel, followed by CH3CN (63 kg), ethyl acetate (20 kg) and water (1.5 kg). The reaction mixture was agitated and the heterogeneous mixture was cooled to −5 to +5° C. DIPEA (11.2 kg) was charged to the reaction mixture, maintaining a temperature between −5 to +5° C. and the mixture was agitated at a temperature of −5 to +5° C. for 1 h. The resultant reaction mixture was warmed to 20 to 30° C. and agitated for 2 to 3 h.
The resultant product was extracted with aqueous HCl, aqueous K2CO3, and water.
The desired product was crystallized from ethyl acetate by cooling from reflux (78° C.) to about 0° C. The crystalline product was filtered and dried at 30° C. under vacuum to yield 23.1 kg Compound IV (molar yield=81.3%). MS Calculated: 709.44; MS Found (ES+, M+H): 710.47.
Preparation of Compound I
Figure US20120178942A1-20120712-C00074
Compound IV (22.5 kg), TEMPO (5 kg), NaOAc (45 kg), methyl acetate (68 L), MTBE (158 L), water (23 L) and acetic acid (22.5 L) were charged to the reactor. The reaction mixture was stirred at 20-30° C. to allow for dissolution of the solids, and was then cooled to 5-15° C. NaOCl solution (1.4 molar equivalents) was charged to the reaction mixture, keeping the temperature at about 10° C. After complete addition of NaOCl, the reaction mixture was agitated at 10° C. for 2 h.
The reaction was quenched by washing with a buffered sodium ascorbate/HCl aqueous solution, followed by a water wash.
The reaction mixture was solvent exchanged to acetone under vacuum, keeping the temperature below 20° C.; the desired product was crystallized by the addition of water, and dried under vacuum, keeping the temperature below 40° C. to yield 18.6 kg Compound I (molar yield=82.7%). MS Calculated: 707.43: MS Found (ES+, M+H): 708.44.

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ANTHONY MELVIN CRASTO

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World Drug Tracker: Degarelix …NICE backs Ferring’s Firmagon for prostate cancer subgroup


World Drug Tracker: Degarelix …NICE backs Ferring’s Firmagon for prostate cancer subgroup

TAVABOROLE, AN 2690, 他伐硼罗 Таваборол تافابورول


TAVABOROLE

  • AN 2690
  • AN-2690
  • AN2690
  • UNII-K124A4EUQ3

5-Fluoro-1,3-dihydro-1-hydroxy-2,1-benzoxaborole

5-Fluoro-2,1-benzoxaborol-1(3H)-ol;

1,3-Dihydro-5-fluoro-1-hydroxy-2,1-benzoxaborole

MOLECULAR FORMULA C7H6BFO2

MOLECULAR WEIGHT 151.9

SPONSOR Anacor Pharmaceuticals, Inc.

CAS REGISTRY NUMBER 174671-46-6Fine

Mp 118-120° C…..US20070265226

1H NMR (300 MHz, DMSO-d6) δ (ppm) 4.95 (s, 2H), 7.15 (m, 1H), 7.24 (dd, J=9.7, 1.8 Hz, 1H), 7.74 (dd, J=8.2, 6.2 Hz, 1H), 9.22 (s, 1H)

FDA APPROVED JULY 2 2014………..“FDA Approves Anacor Pharmaceuticals’ KERYDIN™ (Tavaborole) Topical Solution, 5% for the Treatment of Onychomycosis of the Toenails”. Market Watch. July 8, 2014.

Has antifungal activity.

The US Food and Drug Administration (FDA) 2014 JULY 8 ratified the Anacor’s Kerydin (5% Tavaborole solution) for the topical treatment of nail fungal infections. Tavaboroleindications of toenail fungus Trichophyton rubrum or Trichophyton rubrum infections.Instructions recommended once a day for toenail infections, treatment for 48 weeks, on the recommendation of Anacor, and do not need to nail debridement.

I tis an oxaborole antifungal used topically, as a 5% w/w solution, for the treatment of onychomycosis of the toenails due to Trichophyton rubrumor T. mentagrophytes. It is applied to the affected toenail once daily for 48 weeks.

Ingrowing toenails and application site reactions including exfoliation, erythema, and dermatitis have been reported during use.Stock market

1H NMR FROM NET

tavaborole nmr 1h

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COSY NMR prediction (14)

Tavaborole (AN2690, trade name Kerydin) is a topical antifungal medication for the treatment of onychomycosis, a fungal infectionof the nail and nail bed. Tavaborole began its Phase 3 trials in December 2010[1] and was approved in July 2014.[2] Tavaborole inhibits an essential fungal enzyme, Leucyl-tRNA synthetase, or LeuRS, required for protein synthesis. The inhibition of protein synthesis leads to termination of cell growth and cell death, eliminating the fungal infection. No treatment-related systemic side effects were observed in any of its clinical trials.Passing

Tavaborole is the first oxygen boron used to treat toenail infections dioxolane (oxaborole) antifungal agents, located in Palo Alto, Anacor focuses on boron-based drug development and production, according to the latest news, Tavaborole future also be used to infect fingernails. Wedbush Securities analyst predicts that next year the drug sales in the United States for $ 16 million, by 2021 will reach peak sales of $ 347 million.

Gram-negative bacteria cause approximately 70% of the infections in intensive care units. A growing number of bacterial isolates responsible for these infections are resistant to currently available antibiotics and to many in development. Most agents under development are modifications of existing drug classes, which only partially overcome existing resistance mechanisms. Therefore, new classes of Gram-negative antibacterials with truly novel modes of action are needed to circumvent these existing resistance mechanisms. We have previously identified a new a way to inhibit an aminoacyl-tRNA synthetase, leucyl-tRNA synthetase (LeuRS), in fungi via the oxaborole tRNA trapping (OBORT) mechanism.Irrigation

Herein, we show how we have modified the OBORT mechanism using a structure-guided approach to develop a new boron-based antibiotic class, the benzoxaboroles, which inhibit bacterial leucyl-tRNA synthetase and have activity against Gram-negative bacteria by largely evading the main efflux mechanisms in Escherichia coli and Pseudomonas aeruginosa. The lead analogue,  is active against Gram-negative bacteria, including Enterobacteriaceaebearing NDM-1 and KPC carbapenemases, as well as P. aeruginosa. This novel boron-based antibacterial,  has good mouse pharmacokinetics and was efficacious against E. coli and P. aeruginosa in murine thigh infection models, which suggest that this novel class of antibacterials has the potential to address this unmet medical need.

Anacor continued development on that drug, tavaborole, and filed for FDA approval in July. The FDA will review the phase 3 trial data and issue a decision on July 29, 2014.

If approved, Anacor hopes tavaborole’s ability to clear onychomycosis in 10% of treated patients will be enough to win market share away from generic Lamisil and generic topical Pentac. While Lamisil cleared the fungus in 38% of patients, it’s been associated with rare cases of liver failure. And Pentac requires frequent debridement of the nail and only clears the fungus in 5.5% to 8.5% of patients.

Tavaborole is a novel, topical antifungal medication being developed for the topical treatment of onychomycosis, a nail fungus infection, which affects seven to ten percent of the U.S. population. Early studies show AN-2690 penetrates the nail effectively and has robust activity against dermatophytes, which cause onychomycosis.Top

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ARTICLEGrab spaces

July 18, 2013

Anacor Pharmaceuticals to Present Pivotal Phase 3 Data of Tavaborole for the Topical Treatment of Toenail Onychomycosis
Abstract Accepted for Oral Presentation at the 2013 American Podiatric Medical Association Annual Scientific Meeting

PALO ALTO, Calif.–(BUSINESS WIRE)– Anacor Pharmaceuticals (NASDAQ:ANAC) announced today that its abstract “Pivotal Phase 3 Safety and Efficacy Results of Tavaborole (Formerly AN2690), a Novel Boron-Based Molecule for the Topical Treatment of Toenail Onychomycosis” was accepted for oral presentation at the 2013 APMA Annual Scientific Meeting (The National) to be held in Las Vegas, Nevada. Max Weisfeld, DPM, will present the data from tavaborole’s Phase 3 studies on Monday, July 22, 2013 during the Evidence-Based Medicine and Oral Abstracts session.

As announced earlier this year, tavaborole achieved statistically significant and clinically meaningful results on all primary and secondary endpoints in two Phase 3 pivotal studies without concomitant debridement. Anacor is seeking approval for tavaborole from the Food and Drug Administration (FDA) and will file a New Drug Application imminently. Currently, there is only one FDA-approved topical treatment for onychomycosis, a fungal infection of the nail and nail bed, which affects approximately 35 million people in the United States.Mildew

“I’m impressed with tavaborole’s safety and efficacy data. There is no FDA-approved topical treatment for onychomycosis with tavaborole’s range of efficacy and ability to penetrate the nail to reach the site of the infection,” said Dr. Weisfeld. “Tavaborole’s Phase 3 results demonstrate its ability to clear the nail and eliminate the infection which is important to both patients and the physicians who treat them. In addition, tavaborole is easy to apply and dries quickly which makes it convenient for patients to use.”

“We are pleased to present these positive data at the APMA’s Annual Scientific Meeting, the leading annual meeting of podiatrists. As we seek FDAapproval for tavaborole, we look forward to developing relationships with podiatrists to potentially offer them a new treatment option for the large number of patients who seek treatment for onychomycosis,” said David Perry, Chief Executive Officer of Anacor Pharmaceuticals.

About the StudiesHappy

Anacor conducted two separate Phase 3 studies of tavaborole on patients with distal subungual onychomycosis affecting 20 to 60 percent of the target great toenail. Approximately 600 patients aged 18 years and older with no upper age limit (the oldest subject was 88 years old) were enrolled in each study and randomized two-to-one to receive either tavaborole or the vehicle control. Patients were instructed to apply tavaborole solution or the vehicle to the toenail once daily for 48 weeks.

A copy of the presentation will be available on Anacor’s website following the oral session.

About Anacor Pharmaceuticals

Anacor is a biopharmaceutical company focused on discovering, developing and commercializing novel small-molecule therapeutics derived from its boron chemistry platform. Anacor has discovered eight compounds that are currently in development. Its two lead product candidates are topically administered dermatologic compounds — tavaborole, a topical antifungal for the treatment of onychomycosis, and AN2728, a topical anti-inflammatory PDE-4 inhibitor for the treatment of atopic dermatitis and psoriasis. In addition to its two lead programs, Anacor has discovered three other wholly-owned clinical product candidates — AN2718 and AN2898, which are backup compounds to tavaborole and AN2728, respectively, and AN3365 an antibiotic for the treatment of infections caused by Gram-negative bacteria. We have discovered three other compounds that we have out-licensed for further development — two compounds for the treatment of animal health indications that are licensed to Eli Lilly and Company and AN5568, also referred to as SCYX-7158, for human African trypanosomiasis (HAT, or sleeping sickness), which is licensed to Drugs for Neglected Diseases initiative, or DNDi. We also have a pipeline of other internally discovered topical and systemic boron-based compounds in development. For more information, visit http://www.anacor.com.

 

Patents赞

WO 1995033754

WO 2004009578….

WO 2006089067

WO 2008025543

…………………………..

SYNTHESIS

APX1

 

APX1

APX1

 

 

 

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Reference:

ELI LILLY AND COMPANY Patent: WO2004/9578 A2, 2004 ; Location in patent: Page 36-37 ; WO 2004/009578 A2

 

APX1

 

PATENT

Anacor Pharmaceuticals Patent: US2007/265226 A1, 2007 ; Location in patent: Page/Page column 59 ;

http://www.google.com/patents/US20070265226

Figure US20070265226A1-20071115-C00072

1,3-Dihydro-5-fluoro-1-hydroxy-2,1-benzoxaborole (19b)

To a solution of 5b (73.2 g, 293 mmol) in dry THF (400 mL) was added n-butyllithium (1.6 M in hexanes; 200 mL) over 45 min at −78° C. under nitrogen atmosphere. Anion precipitated. After 5 min, (i-PrO)3B (76.0 mL, 330 mmol) was added over 10 min, and the mixture was allowed to warm to room temperature over 1.5 h. Water and 6 N HCl (55 mL) were added, and the solvent was removed under reduced pressure to about a half volume. The mixture was poured into ethyl acetate and water. The organic layer was washed with brine and dried over anhydrous Na2SO4. The solvent was removed under reduced pressure. To a solution of the residue in tetrahydrofuran (360 mL) was added 6 N HCl (90 mL), and the mixture was stirred at 30° C. overnight. The solvent was removed under reduced pressure to about a half volume. The mixture was poured into ethyl acetate and water. The organic layer was washed with brine and dried over anhydrous Na2SO4. The solvent was removed under reduced pressure, and the residue was treated with i-Pr2O/hexane to give 19b (26.9 g, 60%) as a white powder:

mp 118-120° C.;

1H NMR (300 MHz, DMSO-d6) δ (ppm) 4.95 (s, 2H), 7.15 (m, 1H), 7.24 (dd, J=9.7, 1.8 Hz, 1H), 7.74 (dd, J=8.2, 6.2 Hz, 1H), 9.22 (s, 1H);

ESI-MS m/z 151 (M−H);

HPLC purity 97.8%; Anal (C7H6BFO2) C, H.

Stock market

…………………

Gunasekera, Dinara S.; Gerold, Dennis J.; Aalderks, Nathan S.; Chandra, J. Subash; Maanu, Christiana A.; Kiprof, Paul; Zhdankin, Viktor V.; Reddy, M. Venkat Ram Tetrahedron, 2007 , vol. 63, # 38 p. 9401 – 9405

…………………….

Baker, Stephen J.; Zhang, Yong-Kang; Akama, Tsutomu; Lau, Agnes; Zhou, Huchen; Hernandez, Vincent; Mao, Weimin; Alley; Sanders, Virginia; Plattner, Jacob J. Journal of Medicinal Chemistry, 2006 , vol. 49, # 15 p. 4447 – 4450

………………..

Ding, Charles Z.; Zhang, Yong-Kang; Li, Xianfeng; Liu, Yang; Zhang, Suoming; Zhou, Yasheen; Plattner, Jacob J.; Baker, Stephen J.; Liu, Liang; Duan, Maosheng; Jarvest, Richard L.; Ji, Jingjing; Kazmierski, Wieslaw M.; Tallant, Matthew D.; Wright, Lois L.; Smith, Gary K.; Crosby, Renae M.; Wang, Amy A.; Ni, Zhi-Jie; Zou, Wuxin; Wright, Jon Bioorganic and Medicinal Chemistry Letters, 2010 , vol. 20, # 24 p. 7317 – 7322

…………..

PATENT

US20050261277

PREPARATION 13 5-Fluoro-3H-benzo[c][1,2)oxaborol-1-ol

Figure US20050261277A1-20051124-C00027
Dissolve 1-bromo-2-(1-ethoxy-ethoxymethyl)-4-fluoro-benzene(5.4 g, 19.5 mmol) in dry THF (100 mL) and cool to −78° C. under nitrogen. Add butyl lithium (2.5M in Hexanes, 10.2 mL, 25.4 mmol) dropwise at −78° C. Upon complete addition, stir the reaction at −78° C. for 10 minutes and then add trimethyl borate (4.4 mL, 39 mmol) and warm the reaction to room temperature. Pour the reaction into 1N HCl (100 mL) and stir for 1 hour. Extract the biphasic mixture with ether three times. Dry the combined organic layers with sodium sulfate, filter and concentrate in vacuo. Triturate the oily residue with cold hexanes to yield 2.1 g (70%) of the title compoud as a white solid.

1H NMR (d6-DMSO)

9.18 (s, 1H),

7.70 (dd, J=8.2, 5.8 Hz, 1H),

7.20 (dd, J=9.5, 2.7 Hz, 1H),

7.11 (m, 1H), 4.92 (s, 1H).

…………………

SEE

http://jpet.aspetjournals.org/content/early/2012/11/28/jpet.112.200030.full.pdf

………………………………..

SEETop

Discovery of a new boron-containing antifungal agent, 5-fluoro-1,3-dihydro-1-hydroxy-2,1- benzoxaborole (AN2690), for the potential treatment of onychomycosis.

Baker SJ, Zhang YK, Akama T, Lau A, Zhou H, Hernandez V, Mao W, Alley MR, Sanders V, Plattner JJ.

J Med Chem. 2006 Jul 27;49(15):4447-50.

Boron-containing inhibitors of synthetases.

Baker SJ, Tomsho JW, Benkovic SJ.

Chem Soc Rev. 2011 Aug;40(8):4279-85. doi: 10.1039/c0cs00131g. Epub 2011 Feb 7. Review.

Benzoxaborole antimalarial agents. Part 2: Discovery of fluoro-substituted 7-(2-carboxyethyl)-1,3-dihydro-1-hydroxy-2,1-benzoxaboroles.

Zhang YK, Plattner JJ, Freund YR, Easom EE, Zhou Y, Ye L, Zhou H, Waterson D, Gamo FJ, Sanz LM, Ge M, Li Z, Li L, Wang H, Cui H.

Bioorg Med Chem Lett. 2012 Feb 1;22(3):1299-307. doi: 10.1016/j.bmcl.2011.12.096. Epub 2011 Dec 28.

Tavaborole Market Opportunity

Anacor is developing tavaborole specifically to address the current limitations of existing treatment options for onychomycosis. This includes designed leaps forward in both the potential safety and efficacy profile aimed to make the drug a best-in-class therapy. Additionally, management has used the company’s expertise in medicinal chemistry to improve delivery of the compound through the nail plate to the nail bed, the site of onychomycosis infection. For example, preclinical studies indicate that tavaborole is able to penetrate the nail plate 250 times more effectively than ciclopirox.

Tavaborole novel mechanism of action inhibits an essential fungal enzyme, leucyl transfer RNA synthetase, or LeuRS required for protein synthesis. The inhibition of protein synthesis leads to termination of cell growth and cell death, eliminating the fungal infection.

Likewise, the topical dosing was designed to eliminate systemic absorption. Previous preclinical and clinical data shows topical treatment with tavaborole resulted in little or no detectable levels of drug in the blood or urine. No treatment related systemic side effects have been observed in any clinical trials to date. Safety data from the company’s studies to date was recently presented at the 100th National APMA meeting in Washington, DC.

Anacor’s topical solution currently in two phase III trials for onychomycosis. Phase II data with tavaborole suggests efficacy superior to ciclopirox with little to no systemic exposure.Top

Data from an open-label phase 2 program with tavaborole showed 50% patients using a 7.5% solution saw 2 mm clear nail growth and negative fungal cultures after six months. Roughly 25% of the patients saw 5 mm clear nail growth and negative fungal cultures after six months.

Anacor and partner Merck (NYSE:MRK) met with the U.S. FDA in 2009 to discuss the phase II data. Merck has since returned the rights to tavaborole to Anacor. The original deal was with Schering-Plough in 2007. Merck most likely felt as though tavaborole clashed with existing products or did not have peak sales potential large enough to continue the partnership with Anacor. We see tavaborole as a specialty promoted product, into podiatrists and dermatologists. For a company like Anacor, it’s an attractive first product.

Anacor’s first phase III trial completed enrollment in November 2011. The second phase III trial completed enrollment in December 2011. Data from these trials are expected around the middle of January 2013. Data from the second study is expected six weeks later. Given the positive phase II data noted above, we think odds favor a positive outcome. A benchmark for the trial is the efficacy of Lamisil, which is a complete cure rate of around 35% to 40%, and a mycological cure of around 70% after a typical course of treatment.

I note that on Anacor’s third quarter conference call management noted that they are pleased with the conduct of the trial to date. Specifically, the compliance rate appears to better than management had expected. The trial was designed with a 20% drop-out rate. It looks as though the drop-out rate is only around 13%, at a minimum suggestive of good safety and tolerability, but potentially also a sign that the drug is working.

I see onychomycosis as a significant market opportunity for Anacor. An estimated 35 million Americans have nail fungus, with about 95% of the infections in the toenail. With efficacy similar to Lamisil, we think Anacor can capture 20% of the market. With a price per course of treatment at around   $1,200, I think peak sales of tavaborole are $500 million.Fine

ChemSpider 2D Image | Tavaborole | C7H6BFO2

Conclusion

I’ll note two more important pieces of information for investors. Firstly, besides optimism for tavaborole, Anacor has apipeline of anti-infectant drugs. For this article I discussed only tavaborole. A second article can be dedicated entirely to AN2728 for the treatment of psoriasis and atopic dermatitis. Anacor also has an animal health collaboration with Eli Lilly (NYSE:LLY).

The second important thing to note is Anacor’s cash position. The company reported financial results on November 7, 2012. The company held $36.6 million in cash on the balance sheet as of September 30, 2012. However, in October 2012, the company completed an underwritten public offering of 4.0 million shares of common stock at $6.00 per share to raise net proceeds of $22.7 million. I view the current cash position as sufficient to report data from both phase 3 trials and, if positive, file the new drug application (NDA) around the middle of 2013.

With phase 3 data expected in less than two months, good prior evidence of both safety and efficacy, and a solid cash position, I think Anacor could be an attractive investment at today’s price. The stock is down meaningfully over the past month and investors can buy sizably below the October offering.

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SYNTHESIS

ReferencesFine

Tavaborole
Tavaborole.svg
Tavaborole ball-and-stick model.png
Systematic (IUPAC) name
5-Fluoro-2,1-benzoxaborol-1(3H)-ol
Clinical data
Trade names Kerydin
Legal status
  • (Prescription only)
Routes of
administration
Topical use only
Identifiers
CAS Registry Number 174671-46-6
ATC code None
PubChem CID: 11499245
ChemSpider 9674047
Synonyms AN2690
Chemical data
Formula C7H6BFO2
Molecular mass 151.93 g/mol

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NMR PREDICT

H-NMR spectral analysis
5-fluoro-1-hydroxy-3H-2,1-benzoxaborole NMR spectra analysis, Chemical CAS NO. 174671-46-6 NMR spectral analysis, 5-fluoro-1-hydroxy-3H-2,1-benzoxaborole H-NMR spectrum
CAS NO. 174671-46-6, 5-fluoro-1-hydroxy-3H-2,1-benzoxaborole H-NMR spectral analysis
C-NMR spectral analysis
5-fluoro-1-hydroxy-3H-2,1-benzoxaborole NMR spectra analysis, Chemical CAS NO. 174671-46-6 NMR spectral analysis, 5-fluoro-1-hydroxy-3H-2,1-benzoxaborole C-NMR spectrum
CAS NO. 174671-46-6, 5-fluoro-1-hydroxy-3H-2,1-benzoxaborole C-NMR spectral analysis

more

GSK2251052

BIG TEAM Hernandez, front row, fifth from left, poses during a research meeting at Naeja’s headquarters.Anacor

BIG TEAM Hernandez, front row, fifth from left, poses during a research meeting at Naeja’s headquarters.

Anacor Pharmaceuticals is out to change that. The Palo Alto, Calif.-based biotechnology company is developing a family of boron-containing small-molecule drugs. And with the assistance of Naeja Pharmaceutical, a Canadian contract research organization, Anacor has licensed one of those molecules to GlaxoSmithKline and taken another one into Phase III clinical trials.

Anacor was founded in 2002 to develop technology created by Lucy Shapiro, a Stanford University bacterial geneticist, and Stephen J. Benkovic, a Pennsylvania State University organic chemist. Through a long-standing scientific collaboration, the two researchers had discovered boron-containing compounds that inhibited specific bacterial targets………..https://pubs.acs.org/cen/coverstory/89/8912cover3.html

 UPDATED………….

Click to access NMR.pdf

mp 118-120….http://www.syninnova.com/catalog/product/SL-264

Click to access HPLC.pdf

antifugal AN2690 by Anacor

Tavaborole inhibits an essential fungal enzyme, Leucyl-tRNA synthetase, or LeuRS, required for protein synthesis.
Minimum Inhibitory Concentration: 1, 1, 0.5, 0.25, and 0.25 μg/mL for T.rubrum, T.mentagrophytes, C.albicans, C.neoformans, A.fumigatus, respectivley.

AN2690 is a new boron-containing antifungal agent for the potential treatment of onychomycosis. Onychomycosis is caused mainly by dermatophytes, a class of fungus that dwells on skin, hair, and nails and is the cause of other cutaneous fungal infections such as athlete’s foot.

In vitro: AN2690 showed the most active against fungi and especially against the dermatophytes T. rubrum and T. mentagrophytes, the primary fungal pathogens causing onychomycosis. In addition, AN2690 was identified as having a unique profile of in vitro antidermatophyte activity, maintenance of this activity in the presence of keratin, and exceedingly good penetration of human nails [1].

Ex vivo: AN2690 was found to have superior penetration compared to ciclopirox, and achieves levels within and under the nail plate that suggest it has the potential to be an effective topical treatment for onychomycosis [2].

Clinical trial: The efficacy of tavaborole as a topical treatment for onychomycosis has been evaluated in two identical randomised, double-blind phase III studies, NCT01270971 (301) and NCT01302119 (302), enrolling 593 and 601 patients, respectively. Completely or almost clear nail and negative mycology was achieved in 15.3 and 17.9 % of tavaborole recipients compared with 1.5 and 3.9 % of vehicle recipients [3]

References:
[1] Baker SJ, Zhang YK, Akama T, Lau A, Zhou H, Hernandez V, Mao W, Alley MR, Sanders V, Plattner JJ. Discovery of a new boron-containing antifungal agent, 5-fluoro-1,3-dihydro-1-hydroxy-2,1- benzoxaborole (AN2690), for the potential treatment of onychomycosis. J Med Chem. 2006;49(15):4447-50.
[2] Hui X, Baker SJ, Wester RC, Barbadillo S, Cashmore AK, Sanders V, Hold KM, Akama T, Zhang YK, Plattner JJ, Maibach HI. In Vitro penetration of a novel oxaborole antifungal (AN2690) into the human nail plate. J Pharm Sci. 2007;96(10):2622-31.
[3] Markham A. Tavaborole: first global approval. Drugs. 2014;74(13):1555-8.

UPDATE

 

http://www.google.im/patents/EP1976536A2?cl=en

EXAMPLE 23

Alternative Preparation of 4 from 3

A 22.0 L 3-neck flask was equipped with a stir motor, N2 inlet, addition funnel, heating mantle, and condenser. The flask was charged with 3500 g (17.1 moi) of 2-bromo-5-fluorobenzyl alcohol followed by the addition of 3556 g of tetrahydrofuran and 16.4 g (0.17 mol) of methanesulfonic acid. Next, 400 g (4.7 mol) of 3,4-dihydro-2H-pyran was added at 100C. This step is exothermic so no additional charges should be made until exotherm subsides. The temperature was increased to 27°C, stirred for 15 min and then charged with 400 g (4.7 mol) of 3,4-dihydro-2H- pyran at 240C. Again the temperature increased (24°C to 380C). The mixture was stirred for 15 min. Once the exotherm subsided, the flask was again charged with 40Og (4.7 mol) of 3,4-dihydro-2H-pyran at 350C. The temperature again increased to 470C over a 20 min period. Once the exotherm subsided, the mixture was stirred for 15 min. Finally the remaining 400 g (4.7 mol) of 3,4-dihydro-2H-pyran was added at 440C. The temperature increased to 510C. After stirring for one hour, a sample was removed to check for removal of starting material. Upon reaction completion, contents were cooled to 20 ± 5 0C.

EXAMPLE 24

Figure imgf000215_0001

Alternative Preparation of 5 from 4

To a 22.0 L 3-neck flask equipped with a stir motor, N2 inlet, addition funnel, cooling bath, and condenser was charged 436 g (17.96 mol) of magnesium turnings. 5334 g of tetrahydrofuran was then added followed by 291 g (0.51 mol) of diisobutylaluminum hydride (DIBAL) (25%wt) in toluene. The mixture was stirred for 60 min at 20 ± 5 0C. Some gas evolution was seen. Next, 260-430 g -3-5% (by weight if solution of 4 was dropped to drums) of 4 in THF was added. The mixture was stirred for 15-30 min at which time a slight exotherm should be seen (ΔT = 10- 150C). Once the exotherm was observed, the reaction mixture was cooled to 5 ± 5 0C. To this mixture, the remaining 8.22-8.39 kg of 4 in THF was added at a rate such that the temperature was kept below 300C (t = 3h). The reaction was stirred at 20-25 0C for 30 min, at which time an aliquot was removed, quench with 3 N HCl (10 mL), and analyzed.

Upon completion, the contents were cooled to -25 ± 5°C. A solution of trimethylborate in THF was prepared by mixing 2665 g (25.7 mol) of trimethyl borate and 6666 g of tetrahydrofuran. This solution can be prepared in a drum with stirring. [0618] Next, the 9331 g of trimethyl borate in THF was added at a rate such that the temperature was kept between -35 and -20 °C (t = 2.5h). The mixture became very thick so THF was added. After stirring at -25 ± 5°C for 10 min, 50 mL aliquot was removed, quenched with 25 mL of 3N HCl, and submitted for CoR. Stirring continued at -25 ± 50C for Ih, and then the mixture was allowed to warm to ambient temperature, where it was stirred for at least 12h. Pull two samples (one at 6h and the other at 12h).

Results:

1H-NMR (300 MHz, DMSO-d6) δ (ppm) 1.45-1.75 (m, 6H), 3.53 (s, 6H), 3.45 (m, IH), 3.75 (m, IH), 4.69 (t, J=3 Hz, IH), 4.97 (d, J=14.1 Hz, IH), 5.14 (d, J=14.1 Hz, IH), 7.03 ((td, J=8.4, 2.7 Hz, IH), 7.24 (dd, J=10.8, 2.1 Hz, IH), 7.89 (t, J=7.8 Hz, IH), 8.76 (s, IH).

EXAMPLE 25

Alternative Preparation of I from 5

Figure imgf000216_0001

To the reaction mixture above was added 5.3 kg of USP water. After stirring for 30 min, the mixture was charged 5.3 kg of acetic acid. Gas evolution was seen. After stirring for 30 min, an aliquot was removed for analysis. Mixture was then heated to reflux for 36-48 hours. During the reflux period, 12-13 L of THF were removed.

When the reaction was complete, the contents were cooled by the reactor to <40°C by setting jacket and by charging 10.5 kg of USP water. THF was removed until distillate did not remain. Contents of the reactor were transferred to Rosenmund filter dryer and allowed to cool to 20 ± 5°C. Reactor was rinsed with water, filtered, and then washed again with 10.5 kg of USP water. The flask was charged with 10.5 kg of 10% ACN in water (v/v) and agitated for Ih. After filtering, the cake was washed with 10.5 kg of 10% ACN in water (v/v), and then charged with 10.5 kg 10% ACN in water (v/v). The contents were agitated for Ih. The contents were subsequently washed with 10.5 kg of USP water, charged with 7.0 L of 5% Methyl t- Butyl Ether (MTBE)/Heptane (v/v), agitated for Ih, filtered, charged with 7.0 L of 5% MTBE/Heptanes (v/v) and again agitated for Ih. After filtering, the contents were charged again with 7.0 L of heptane and filtered. Solids were dried at <45°C to constant weight. Solids were recrystallized from toluene :heptane 75:25.

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Medicinal Chemistry International


Medicinal Chemistry International

Vedroprevir


Vedroprevir

GS 9451, GS-9451, 1098189-15-1 USAN ZZ-81

VEDROPREVIR THERAPEUTIC CLAIM Treatment of hepatitis C

CHEMICAL NAMES 1. Cyclopropanecarboxylic acid, N-[[(1α,3β,5α)-bicyclo[3.1.0]hex-3- yloxy]carbonyl]-3-methyl-L-valyl-(4R)-4-[[8-chloro-2-[2-[(1-methylethyl)amino]- 4-thiazolyl]-7-[2-(4-morpholinyl)ethoxy]-4-quinolinyl]oxy]-L-prolyl-1-amino-2- ethyl-, (1R,2R)-

2. N-{[(1R,3r,5S)-bicyclo[3.1.0]hex-3-yloxy]carbonyl}-3-methyl-L-valyl-(4R)-4-[(8- chloro-2-{2-[(1-methylethyl)amino]thiazol-4-yl}-7-[2-(morpholin-4- yl)ethoxy]quinolin-4-yl)oxy]-L-prolyl-(1R,2R)-1-amino-2- ethylcyclopropanecarboxylic acid

MOLECULAR FORMULA C45H60ClN7O9S

MOLECULAR WEIGHT 910.5 daltons

SPONSOR Gilead Sciences, Inc.

CODE DESIGNATION GS-9451

CAS REGISTRY NUMBER1098189-15-1

WHO NUMBER9745

GS-9451 is a NS3 protease inhibitor in phase II clinical trials at Gilead for the oral treatment of hepatitis C.

…………………………………………………………………………

Discovery of GS-9451: An acid inhibitor of the hepatitis C virus NS3/4A protease Bioorg Med Chem Lett 2012, 22(7): 2629   ……………………………………………………………

PATENTS WO 2012087596 WO 2009005676 WO 2013106631 WO2013101550 ……………………….

WO2012087596A1 Compound 3 can be prepared using synthetic methods and intermediates like those described in USSN 12/215,605 (US 20090257978 A1). Compound 3 can also be prepared described in the following Example. Example 3: Preparation of Compound 3

Figure imgf000060_0001

Compound 315 (12 g, 13 mmol) was dissolved in THF (200 ml), LiOH (11g, 260 mmol) in H20 (200 ml) was added, followed by MeOH (200 ml). The mixture was kept stirring at room temperature for 20 hours. Upon completion of the reaction, 4 N HCI in H20 was added to adjust pH to 7 at 0 °C. The mixture was extracted with EtOAc (2 x 400 ml). The combined organic layer was washed with brine, dried (Na2S04) and concentrated in vacuo to give compound 3 as a yellow solid (11 g, 93%). LC/MS = 911.52(M++1 ). 1H NMR (300MHz, CD3OD)57.95 (d, 1H), 7.90 (s, 1H), 7.48 (s, 1H), 7.31 (d, 1H), 5.42 (s, 1H), 4.37 (dd, 1H), 4.20 (m, 2H), 3.83-3.56 (m, 7H), 3.50 (m, 2H), 3.39 (m, 2H), 2.45 (m, 1H), 2.27(m, 1H), 1.62 (m, 2H), 1.50 (m, 1H), 1.33 (m, 2H), 1.18 (m, 1H), 1.05 (m, 8H), 0.90 (m, 3H), 0.76 (m, 11H), 0.14-0.04 (m, 2H) The intermediate compound 315 was prepared as follows.

Figure imgf000060_0002

301 302 a. Preparation of compound 301. To a dry, argon purged three-neck round bottom flask (1000 mL) were added anhydrous dichloromethane (100 mL) and Et2Zn (28 mL, 273 mmol) at 0 °C. (CAUTION: Source of argon can not be from needle. Use appropriate glass adapter only. A second bubbler can also be attached to the flask to prevent excessive pressure build up.) Cyclopenten-3-ol (10.0 mL, 119 mmol) was then added dropwise (large quantity of ethane gas was produced) to the flask and the reaction mixture was allowed to stir until the evolution of gas had ceased. Diiodomethane (22 mL, 242 mmol) was then added dropwise over a period of 30 minutes. The reaction was allowed to warm to room temperature and continued to stir overnight under a positive flow of argon, at which point TLC analysis had indicated complete disappearance of the starting alcohol. The reaction was then diluted with CH2CI2 and quenched with 2M HCI (white precipitate should be completely dissolved). The biphasic mixture was poured into a separatory funnel and the organic layer was collected. The solvent was removed under reduced pressure until 100 mL of material containing compound 301 remained. b. Preparation of compound 302. Anhydrous dichloromethane (525 mL) was added to the flask followed by the dropwise addition of triethylamine (34 mL, 245 mmol). The reaction continued to stir at room temperature under a positive flow of nitrogen at which point, disuccinimidylcarbonate (40.7 g, 159 mmol) was added to the flask portion wise. The reaction was allowed to stir until TLC analysis indicated complete disappearance of the starting material (2-3 days). Upon completion, the reaction mixture was quenched with 1 M HCI (200 mL x 2) and washed with H20 (200 mL x 2). The desired material was extracted using CH2CI2and the combined organic layers were dried using anhydrous MgS0 and passed through a silica plug. The solvent was removed under reduced pressure and the crude material was purified using flash chromatography (Rf = 0.33, 1 :1 Hex/EtOAc) to provide compound 302 (22 g, 75%): 1H NMR (300 MHz, CDCI3): δ 5. 24 (t, 1 H), 3.82 (s, 4H), 2.24 (m, 2H), 2.03 (d, 2H), 1.38 (m, 2H), 0.48 (m, 1 H), 0.40 (m, 1 H).

Figure imgf000061_0001
Figure imgf000062_0001

c. Preparation of compound 304. N-i-Boc-cis-4-Hydroxy-L-Proline methyl ester 303 (100.0 g, 407.7 mmol) and DABCO (1.5eq, 68.6g, 61 1.6 mmol) were dissolved in anhydrous toluene (200 mL) in a 2 L three necked round bottom flask with a mechanical stirrer and an addition funnel. After cooling the solution to 0 °C under N2, A solution of 4-Bromo-benzenesulfonyl chloride (1.3eq, 135.6g, 530.0 mmol) in 300 mL of toluene was added through addition funnel over 60 minutes. The reaction mixture was stirred and warmed to room temperature overnight (16 hours). The mixture was slowly poured into 2L 1 M Na2C03 (aq.), and the product was extracted with EtOAc (2L). After the organic phase was washed by 0.5 N HCI (2L), H20 (1 L), and brine (1 L), it was dried (MgS04), concentrated to give 195.45 g of a yellow oily brosylate product. To a solution of the above brosylate (407.7 mmol) in dichloromethane (300 mL) was slowly added 4.0 M HCI in dioxane (500 mL, 5eq) and the resulting solution was allowed to stir at room temperature for 2 hours. After ether (500mL) was added to the reaction mixture, the mixture was stirred for 15 minutes and the white precipitate was collected by filtration. The solid was washed with ether and hexane and then dried under vacuum overnight to obtain 153.0 g of the HCI amine salt of compound 304, 381.8 mmol, in 94% yield for two steps. d. Preparation of compound 305. To a solution of Boc-fert-butyl-glycine (97.0g, 420.0 mmol) in DMF (200mL) and DCM (200mL) were added HATU (217.76g, 572.7 mmol) and Hunig’s base (126 mL, 1 145.4 mmol) at room temperature. After the mixture was stirred for 20 minutes at room temperature, a solution of the previous HCI salt (153.0 g, 381.8 mmol) and Hunig’s base (126 mL, 1 145.4 mmol) in DMF (200mL) and dichloromethane (200mL) was added to the above acid mixture in one portion. The reaction mixture was stirred at room temperature for 3h, with monitoring by LCMS. The reaction mixture was concentrated to remove dichloromethane under reduced pressure and the white solid that formed was filtered off. The remaining DMF solution was diluted with ethyl acetate (1 L), washed successively with 3% LiCI (aq) (3x650mL), sat’d NH4CI (2x500mL), 0.5N HCI (aq) (2x600ml_), brine (500ml_), sat’d NaHC03 (3x500mL), and brine (500mL). The resulting organic fraction was dried (MgS04) and concentrated to afford compound 305 (111g). e. Preparation of compound 306. To a solution of the methyl ester 305 (120 g, 207.8 mmol) in THF (300 ml_), MeOH (75 mL) was added a solution of LiOH (26.18 g, 623.4 mmol) in H20 (150 ml_). The solution was allowed to stir at room temperature for 4 hours. The mixture was cooled in an ice-bath while acidifying with 3N HCI to pH about 5.5, stirred for 10minut.es, and the resulting white solids were collected by filtration. The solids were washed with more water, ether and hexane. The solids were dried under vacuum at 40°C overnight to give 95.78g (82%) of the acid 306. f. Preparation of compound 307. To a solution of the carboxylic acid 306 (81.4 g, 144.27 mmol) in DMF (200ml_) and dichloromethane (200mL) was added HATU (82.3g, 216.4 mmol) and Hunig’s base (47.5 mL, 432.8 mmol) at room temperature. After the mixture was stirred for 20 minutes at room temperature, a solution of amine (158.7 mmol) and Hunig’s base (47.5 mL, 1145.4 mmol) in DMF (200mL) and dichloromethane (200mL) was added to the above acid mixture in one portion. The reaction mixture was stirred at room temperature for 3 hours and monitored by LCMS. After the mixture was concentrated under reduced pressure to remove dichloromethane, the white solids that formed were filtered off. The remaining DMF solution was diluted with ethyl acetate (600mL) and successively washed with 3% LiCI (aq) (2x550mL), sat’d NH4CI (500mL), 1 N HCI (aq) (500mL), sat’d NaHC03(500mL), and brine (300mL). The resulting organic fraction was dried (Na2S04) and concentrated to afford compound 307 (111 g). g. Preparation of compound 308. Compound 307 was dissolved in 4N HCI in dioxane (300 mL) at room temperature and stirred for 2 hours. It was then concentrated under vacuum, and co-evaporated with dichloromethane (2 x 200mL) to dryness. The residue was dissolved in EtOAc (600mL) and sat’d aq. NaHC03 (1 L). It was stirred vigorously. After 10 minutes, carbonic acid bicyclo[3.1.0]hex-3-yl ester 2,5-dioxo-pyrrolidin-1-yl ester 302 (41.4 g, 173.1 mmol) was added in one portion. After the resulting mixture was stirred for another 30 minutes, the organic layer was collected and washed with brine (500mL), dried (Na2S04), and concentrated. The crude product was purified by flash chromatography on silica gel with ethyl acetate/hexane to afford 94.44 g (92%) of compound 308.

Figure imgf000064_0001
Figure imgf000064_0002
Figure imgf000064_0003

h. Preparation of compound 310.1-(2-Amino-3-chloro-4-hydroxy-phenyl)-ethanone 309 (70.7 g, 354 mmol) was stirred in 48% aq. HBr (500 mL) at 110 °C for 72 hours. After the mixture was cooled to 0 °C with stirring, the solids were filtered and washed with water. The resulting solids were triturated with a saturated NaHC03 solution (-350 mL), filtered, washed with water, and dried under vacuum to give – 40 g (61%) of crude 310 as a dark brown solid. LC/MS = 186 (M++1). i. Preparation of compound 311. 1-(2-Amino-3-chloro-4-hydroxy-phenyl)-ethanone 310 (40 g, 215 mmol) was dissolved in DMF (360 ml). Cesium carbonate (140 g, 430 mmol) was added, followed by bromoacetaldehyde dimethyl acetal (54.5 g, 323 mmol). The mixture was then vigorously stirred at 65 °C for 24 hours. Upon cooling to room temperature, EtOAc (1 L) and H20 (1 L) were added to the mixture. The organic layer was extracted with EtOAc (1 x 400 ml). The combined organic layer was washed with aqueous 3% LiCI solution (2 x 1 L), brine, dried (Na2S04) and concentrated in vacuo. The residue was purified by silica gel chromatography to give compound 311 as a white solid (39 g, 67%). j. Preparation of compound 312. To a mixture of 1-[2-Amino-3-chloro-4-(2,2-dimethoxy-ethoxy)-phenyl]-ethanone 311 ( 13 g, 47.5 mmol) and isopropylaminothiazole-4-carboxylic acid hydrobromide (12.64 g, 47.5 mmol) in pyridine (150 ml) was slowly added phosphorus oxychloride (9.47 g, 61.8 mmol) at -40 °C. The mixture was then stirred at 0 °C for 4 hours. Upon completion of the reaction, H20 (30 ml) was added dropwise to the mixture. The mixture was then stirred at 0 °C for another 15 minutes. The mixture was concentrated in vacuo. The residue was diluted with EtOAc, washed with a sat. NaHC03 aqueous solution. The organic layer was dried (Na2S04) and concentrated in vacuo. The residue was dissolved in CH2CI2, hexanes were added slowly to the solution, and a yellow solid started to crash out. More hexanes were added until not much product was left in the mother liquid to provide compound 312 (18 g, 85%). k. Preparation of compound 313. 2-lsopropylamino-thiazole-4-carboxylic acid [6-acetyl-2-chloro-3-(2,2-dimethoxy-ethoxy)- phenyl]-amide 312 (18 g, 40.7 mmol) was suspended in toluene (400 ml). NaH (2.4 g, 61 mmol) was added to the vigorously stirred mixture while monitoring H2evolution. The mixture became a clear solution during heating to reflux. The reaction was complete after refluxing for 3 hours. The mixture was cooled to room temperature. A solution of AcOH (69.2 mmol) in H20 (3 vol) was added to the mixture. After vigorous agitation for 1 hour at 0 °C, the solids were collected by filtration, rinsed forward with H20. The wet cake was dried under high vacuum to a constant weight to provide compound 313 ( 5 g, 86%). I. Preparation of compound 314. To a mixture of brosylate intermediate 303 (15 g, 35 mmol) and compound 313 (27.5 g, 38.5 mmol) in NMP (200 ml) was added cesium carbonate (25.1 g, 77 mmol). The mixture was stirred at 65 °C for 5 hours. The reaction was cooled to room temperature and EtOAc (600 ml) and an aqueous solution of 3% LiCI (600 ml) were added to the mixture. The organic layer was washed with aqueous 3% LiCI (1 x 600 ml), brine, dried (Na2S04) and concentrated in vacuo. The residue was purified by silica gel chromatography to give the desired methyl ester as a yellow solid (23.6 g, 75%). LC/MS = 900. 1 3(M++ 1 ) . m. Preparation of compound 315. Methyl ester 314 (23.6 g, 26 mmol) was dissolved in glacial acetic acid (200 ml), 1.4 N HCI in H20 (75 ml) was added to the solution. The mixture was stirred at 60 °C for 1 hour. Upon completion of the reaction, the mixture was concentrated to remove the solvents, coevaporated with toluene (x 2) to remove residual acetic acid. The residue was then dissolved in EtOAc (500 ml) and sat. NaHC03 aqueous solution (enough to neutralize the mixture) while monitoring C02 evolution. The organic layer was washed with brine, dried (Na2S04) and concentrated in vacuo. The residue was further dried under high vacuum for 1 h and used as is for the next step. The crude was dissolved in CH2CI2 (360 ml), morpholine (3.4 g, 39 mmol) and sodium triacetoxyborohydride (7.2 g, 34 mmol) were added to the mixture at 0 °C. Then glacial acetic acid (0.47 g, 7.8 mmol) was added dropwise to the mixture. The reaction was complete in 10 minutes at 0 °C. Sat. NaHC03 aqueous solution was added to quench the reaction. After stirring for another 20 minutes, the organic layer was washed with brine, dried (Na2S04) and concentrated in vacuo. The residue was purified by silica gel chromatography to give the desired amine product 315 as a yellow solid (12 g, 50%). LC/MS = 924.63(M++ 1 )

Preparation of 8-chloro-4-hydroxy-7-methoxyquinoline-2-carboxylic acid 215. To a solution of methyl 8-chloro-4-hydroxy-7-methoxyquinoline-2-carboxylate 214 (36.5g, 0.145 mol) in a mixture of 1 :1 of MeOH: THF (160 mL total) was added a solution of LiOH (30.5 g, 0.725 mol) in H20 (80 mL). The mixture was stirred at room temperature for an hour when LCMS analysis showed complete conversion to the carboxylic acid. The reaction was worked up by removal of the volatiles and adjusting the pH of the solution to 6 using aqueous 6N HCI. The resulted gummy residue was filtered and dried on the lyophilizer for 2 days to provide 34.4 g (99.6 %) of compound 215 as a white solid. El MS (mlz) 253.9 [M+H]. j. Preparation of 2-(2-diazo-l-oxo)-8-chloro-7-methoxyquinolin-4-yl isobutyl carbonate 216. To a solution of 8-chloro-4-hydroxy-7-methoxyquinoline-2-carboxylic acid 215 (10.2 g, 0.04 mol) in THF (400 mL) was added triethyl amine (12.3 mL, 0.088 mol) and /-Butylchloroformate (11.6 mL, 0.088 mol) at 0°C under an argon atmosphere. The mixture was stirred at 0°C for 1 hour when LCMS analysis demonstrated completion of the reaction to provide the desired mixed anhydride. El MS (mlz) 454.0 [M+H]. To the reaction mixture of the anhydride was added a 1 M solution of diazomethane (121 mL, 0.121 mol) in diethyl ether via a plastic funnel at 0°C. This mixture was allowed to stir while warming up to room temperature for additional 2 hours. Analysis of the mixture by LCMS demonstrated completion of the reaction. The septum was removed and the reaction was stirred for additional 20 minutes before removal of the solvent. The residue was dried further under high vacuum to provide compound 216, which was carried on to the next step. El MS (m/z) 377.9 [M+H]. k. Preparation of 8-chloro-2-(2-(isopropylamino)thiazol-4-yl)-7-methoxyquinoiin-4-ol 207. To a cooled solution of 2-(2-diazo-l-oxo)-8-chloro-7-methoxyquinolin-4-yl isobutyl carbonate 216 (15.2 g, 0.040 mol) at 0°C in THF (268 mL) was added 48% HBr (23 mL, 0.201 mol) slowly over 15 minutes. The solution was stirred at 0°C for an additional 40 minutes when LCMS analysis demonstrated complete reaction. The reaction was worked up by addition of aqueous 1 N NaOH (180 mL) at 0° C to adjust the pH of the aqueous layer to 9. The layers were separated and the aqueous layer was washed with EtOAc (2 x 200 mL). Combined organic extracts were washed with brine and dried over MgS04. The solvent was removed in vacuo to provide 17.7 g of a yellow solid. El MS (m/z) 431.9 [M+H]. The solution of the bromoketone obtained from the previous reaction was suspended in i-propanol (270 mL) and isopropylisourea (9.4 g, 0.080 mol). The reaction mixture was heated at 72 °C for 32 hours. LCMS analysis of the reaction demonstrated complete conversion to the desired- product. The reaction was allowed to cool to room temperature to allow for the product to precipitate out of the solution. The reaction was further cooled to 0°C for 12 hours before filtration. The filtrate was washed with ether and dried on lyopholizer to provide 8.03 g of compound 207 as an orange solid. 1H NMR (500 MHz, CDCI3): δ 8.21 (d, J= 9 Hz, 1 H), 7.74 (s, 1 H), 7.44 (d, J= 10Hz), 1 H), 7.07 (s, 1 H), 4.05 (s, 3H), 3.92 (pentet, J=6 Hz, 1 H), 1.25 (d, J= 7 Hz, 6H): El MS (m/z) 350.0 [M+H].

Medicinal Chemistry International: NARLAPREVIR


Medicinal Chemistry International: NARLAPREVIR

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