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DABIGATRAN PART 2/3
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Dabigatran etexilate (a compound of formula (I)) is the international commonly accepted non-proprietary name for ethyl 3-{[(2-{[(4-{[(hexyloxy)carbonyl]carbamimidoyl}phenyl)amino]methyl}-1-methyl-1H-benzimidazol-5-yl)carbonyl](pyridin-2-yl)amino}propanoate, which has an empirical formula of C34H41N7O5 and a molecular weight of 627.73.
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Dabigatran etexilate is the pro-drug of the active substance, dabigatran, which has a molecular formula C25H25N7O3 and molecular mass 471.51. The mesylate salt (1:1) of dabigatran etexilate is known to be therapeutically useful and is commercially marketed as oral hard capsules in the United States and in Europe under the trade mark Pradaxa™ for the prevention of stroke and systemic embolism in patients with non-valvular atrial fibrillation. Additionally, it is also marketed in Europe under the same trade mark for the primary prevention of venous thromboembolic events in adult patients who have undergone elective total hip replacement surgery or total knee replacement surgery.
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Dabigatran etexilate was first described in U.S. Patent No. 6,087,380 , according to which the synthesis of dabigatran etexilate was carried out in three synthetic steps (see Scheme 1). Example 58 describes the condensation between ethyl 3-{[3-amino-4-(methylamino)benzoyl](pyridin-2-yl)amino}propanoate (compound II) and N-(4-cyanophenyl)glycine (compound III) in the presence of N,N‘-carbonyldiimidazole (CDI) in tetrahydrofuran to give the hydrochloride salt of ethyl 3-{[(2-{[(4-cyanophenyl)amino]methyl}-1-methyl-1H-benzimidazol-5-yl)carbonyl](pyridin-2-yl)amino}propanoate (compound IV), which is subsequently reacted with ethanolic hydrochloric acid, ethanol and ammonium carbonate to give the hydrochloride salt of ethyl 3-{[(2-{[(4-carbamimidoylphenyl)amino]methyl}-1-methyl-1H-benzimidazol-5-yl)carbonyl](pyridin-2-yl)amino}propanoate (compound V). Finally, example 113 describes the reaction between compound V and n-hexyl chloroformate (compound VI), in the presence of potassium carbonate, in a mixture of tetrahydrofuran and water, to give dabigatran etexilate after work-up and chromatographic purification. However, no information is given about the purity of the isolated dabigatran etexilate.
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U.S. Patent No. 7,202,368 describes an alternative process for the synthesis of dabigatran etexilate (see Scheme 2). Example 3 describes the condensation between ethyl 3-{[3-amino-4-(methylamino)benzoyl](pyridin-2-yl)amino}propanoate (compound II) and 2-[4-(1,2,4-oxadiazol-5-on-3-yl)phenylamino]acetic acid (compound VII) in the presence of a coupling agent such as N,N‘-carbonyldiimidazole (CDI), propanephosphonic anhydride (PPA), or pivaloyl chloride, to give ethyl 3-{[(2-{[(4-{1,2,4-oxadiazol-5-on-3-yl}phenyl)amino]methyl}-1-methyl-1H-benzimidazol-5-yl)carbonyl](pyridin-2-yl)amino}propanoate (compound VIII), which is subsequently hydrogenated (Example 4) in the presence of a palladium catalyst to give ethyl 3-{[(2-{[(4-carbamimidoylphenyl)amino]methyl}-1-methyl-1H-benzimidazol-5-yl)carbonyl](pyridin-2-yl)amino}propanoate (compound V). Then, Example 5 describes the acylation of compound V with n-hexyl chloroformate (compound VI) to give dabigatran etexilate. Finally, Example 6 describes the conversion of dabigatran etexilate into its mesylate salt. Although the patent describes the HPLC purities of intermediate compounds II, VII, VIII and V, no information is given neither about the purity of the isolated dabigatran etexilate nor about its mesylate salt.
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European Patent Applications EP 1966171A and EP 1968949Adescribe similar processes for the synthesis of dabigatran etexilate to that depicted in Scheme 2, but without isolating some of the intermediate compounds. HPLC purities higher than 99% are described for both dabigatran etexilate (see Examples 6B and 6C ofEP 1966171A ) and its mesylate salt (see Example 9 ofEP 1966171A and Example 7 ofEP 1968949A). However, no information is given about the structure of the impurities present in dabigatran etexilate and / or its mesylate salt.
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PCT Patent Application WO 2010/045900 describes the synthesis of dabigatran etexilate mesylate with 99.5% purity by HPLC (Examples 3 and 4) by following a similar synthetic process to that described in Scheme 1. However, no information is given about the structure of the impurities present in the mesylate salt of dabigatran etexilate.
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The Committee for Medicinal Products for Human use (CHMP) assessment report for Pradaxa (i.e. dabigatran etexilate mesylate salt 1:1) reference EMEA/174363/2008, as published in the European Medicines Agency website on 23/04/2008, describes (page 8) that the proposed specifications for impurities in the active substance are for some specified impurities above the qualification threshold of the ICH guideline “Impurities in new drug substances”, i.e. above 0.15%. However, no information is given about the structure of the impurities present in the mesylate salt of dabigatran etexilate.
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Patent
http://www.google.com/patents/EP2522662A1?cl=en
There is still further provided by the present invention a process of preparing dabigatran etexilate mesylate, which process comprises the following synthetic steps:
wherein X is a leaving group, such as chloro.
Typically, intermediate (I) is prepared, preferably as a hydrochloride salt, by the following intermediate steps.
Example 1: Synthesis of dabigatran etexilate mesylate
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The overall synthetic scheme, and associated reagents, is as follows.
a) 4-(Methylamino)-3-nitrobenzoic acid
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300 g (1.49 mol) of 4-chloro-3-nitrobenzoic acid were suspended in 769 g of a 25-30% aqueous solution of methylamine. After heating to reflux temperature, a clear solution was obtained. The solution was kept at reflux temperature for 2 hours and total consumption of 4-chloro-3-nitrobenzoic acid was checked by TLC. The solution was cooled to room temperature, and pH was adjusted to about 1 by addition of 2M aqueous sulphuric acid. Precipitation of a yellow solid was observed, which was isolated by filtration. The filtered cake was washed with water and subsequently with methanol to obtain 331 g of wet 4-(methylamino)-3-nitrobenzoic acid as a yellow powder. Purity (HPLC, method 2): 99.1 %.
b) Ethyl 3-(2-pyridylamino)propanoate
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75.2 g (0.80 mol) of 2-aminopyridine and 88.0 g (0.88 mol) of ethyl acrylate were dissolved in 20 mL of acetic acid. The mixture was heated to 80°C and stirred for 24 hours at the same temperature. Solvent was removed under vacuum, and the title compound was isolated by vacuum distillation (b.p. 160-172°C, 10-15 mmHg) to obtain 77.0 g of ethyl 3-(2-pyridylamino)propionate as a white solid. Yield: 49.6 %.
c) Ethyl 3-{[{1-(methylamino)-2-nitrophen-4-yl}carbonyl](pyridyn-2-yl)aminolpropanoate hydrochloride
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50 g (0.25 mol) of 4-(methylamino)-3-nitrobenzoic acid as obtained in step (a) were suspended in a mixture of 459.2 g of thionyl chloride and 3 mL of N,N-dimethylformamide. The mixture was stirred at reflux temperature for 45 minutes. Excess thionyl chloride was removed by vacuum distillation. The residue was dissolved in 300 mL of toluene, which was subsequently removed by vacuum distillation to remove completely any residual thionyl chloride. The brownish crystalline residue obtained was dissolved in 280 mL of tetrahydrofuran at 60°C. At this point, 35.1 g of triethylamine were added to the solution. Then, a solution of 45 g (0.23 mol) of ethyl 3-(2-pyridylamino)propanoate as obtained in step (b) in 95 mL of tetrahydrofuran was added dropwise over the reaction mixture, keeping the temperature at about 30°C. The resulting mixture was stirred overnight at room temperature. Solvent was removed by vacuum distillation, and the residue was dissolved in 1 L of dichloromethane. The resulting solution was washed with 500 mL of water, 500 mL of 2M hydrochloric acid, 500 mL of saturated sodium bicarbonate and 500 mL of water. The organic phase was dried with anhydrous sodium sulfate and concentrated under vacuum. The residue was dissolved with 600 mL of ethyl acetate, and dry hydrogen chloride was bubbled into the solution until precipitation was completed. The solid was isolated by filtration and dried to obtain 63 g of the title compound, which was recrystallized in a mixture of 450 mL of ethanol and 50 mL of acetonitrile at reflux temperature. After cooling to 10°C, solid was isolated by filtration and dried to yield 44.7 g of ethyl 3-{[{1-(methylamino)-2-nitrophen-4-yl}carbonyl](pyridyn-2-yl)amino}propanoate hydrochloride as a yellow solid. Yield: 47.2 %. Purity (HPLC, method 1): 97.6 %.
d) Ethyl 3-{[{2-amino-1-(methylamino)phen-4-yl}carbonyl](pyridyn-2-yl)amino}propanoate (compound II)
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82.2 g (0.20 mol) of ethyl 3-{[{1-(methylamino)-2-nitrophen-4-yl}carbonyl](pyridyn-2-yl)amino}propanoate hydrochloride as obtained in step (c) were suspended in 1.1 L of isopropanol, in the presence of 126.7 g of ammonium formate and 17.5 g of a 5 % Pd/C catalyst (55% water content). The reaction mixture was stirred at reflux temperature for 2.5 hours. After cooling to room temperature, the catalyst was removed by filtration, the filtrate was concentrated under vacuum, and the residue was dissolved in 1.5 L of ethyl acetate. The resulting solution was washed with 800 mL of saturated sodium bicarbonate and with 800 mL of water. The organic phase was dried with anhydrous sodium sulfate and was concentrated under vacuum to yield 44 g of ethyl 3-{[{2-amino-1-(methylamino)phen-4-yl}carbonyl](pyridyn-2-yl)amino}propanoate as a dark oil. Yield: 63.9 %. Purity (HPLC, method 2): 90.8 %.
e) 2-(4-Cyanophenylamino)acetic acid (compound III)
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54.0 g (0.46 mol) of 4-aminobenzonitrile and 106.5 g (0.92 mol) of sodium chloroacetate were suspended in 750 mL of water, and the resulting mixture was stirred at reflux temperature for 4 hours. After cooling to room temperature, pH was adjusted to 8-9 with sodium bicarbonate. The resulting solution was washed with 2 x 200 mL of ethyl acetate, and 5M hydrochloric acid was added to the aqueous phase until pH=3. The precipitated solid was isolated by filtration, washed with 100 mL of water and dried to yield 57.1 g of 2-(4-cyanophenylamino)acetic acid as an off-white solid. Yield: 70.9 %. Purity (HPLC, method 3): 88.4 %.
f) Ethyl 3-{[(2-{[(4-cyanophenyl)amino]methyl}-1-methyl-1H-benzimidazol-5-yl)carbonyl](pyridin-2-yl)amino}propanoate oxalate (salt of compound IV)
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[0081]
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25.7 g (0.15 mol) of 2-(4-cyanophenylamino)acetic acid as obtained in step (e) and 22.8 g (0.14 mol) of 1,1′-carbonyldiimidazole were suspended in 720 mL of tetrahydrofuran. The mixture was stirred at reflux temperature for 1 hour. Then, a solution of 44.0 g (0.13 mol) of ethyl 3-{[{2-amino-1-(methylamino)phen-4-yl}carbonyl](pyridyn-2-yl)amino}propanoate as obtained in step (d) in 180 mL of tetrahydrofuran was added dropwise over the reaction mixture. The resulting mixture was stirred overnight at reflux temperature, and the solvent was removed by distillation under vacuum. The resulting residue was dissolved in 486 mL of acetic acid and heated to reflux temperature for 1 hour. After cooling to room temperature, solvent was removed by distillation under vacuum. The resulting residue was dissolved in 450 mL of ethyl acetate, and the solution was washed with 450 mL of water. The organic phase was dried with anhydrous sodium sulfate and heated to 50-60°C. At this temperature, 15.1 g (0.17 mol) of oxalic acid were added, and the resulting mixture was stirred for 1 hour at 50-60°C. After cooling to room temperature, the precipitated solid was filtered and dried under vacuum, to yield 47.7 g of ethyl 3-{[(2-{[(4-cyanophenyl)amino]methyl}-1-methyl-1H-benzimidazol-5-yl)carbonyl](pyridin-2-yl)amino}propanoate oxalate as a brownish solid. Yield: 64.8 %. Purity (HPLC, method 1): 87.9 %
g) Ethyl 3-{[(2-{[(4-{carbamimidoyl}phenyl)amino]methyl}-1-methyl-1H-benzimidazol-5-yl)carbonyl](pyridin-2-yl)amino}propanoate (compound V)
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[0084]47.7 g (83 mmol) of ethyl 3-{[(2-{[(4-cyanophenyl)amino]methyl}-1-methyl-1H-benzimidazol-5-yl)carbonyl](pyridin-2-yl)amino}propanoate oxalate as obtained in step (f) and 21.8 g of p-toluenesulfonic acid were suspended in 142 g of a 10M hydrogen chloride solution in ethanol. The mixture was stirred at room temperature for 24 hours. At this point, 400 mL of ethanol were added and the resulting mixture was cooled to 0°C. Ammonia gas was bubbled at this temperature until formation of precipitate was completed. The mixture was stirred at 10°C for 2 hours, and then was stirred at room temperature overnight. Solvent was removed by distillation under vacuum. The residue was dissolved in a mixture of 400 mL of ethanol, 400 mL of water and 2.3 g of sodium hydroxide at 55°C, and was stirred at this temperature for 45 minutes. After cooling to 10°C, the mixture was stirred at this temperature for 1 hour. The solid was removed by filtration and discarded. The mother liquors were concentrated under vacuum to remove ethanol. The precipitated solid was isolated by filtration, washed with 200 mL of water and with 2 x 100 mL of acetone, to yield 34.7 g of ethyl 3-{[(2-{[(4-{carbamimidoyl}phenyl)amino]methyl}-1-methyl-1H-benzimidazol-5-yl)carbonyl](pyridin-2-yl)amino}propanoate as an off-white solid. Yield: 83.4 %. Purity (HPLC, method 3): 83 %.
h) Dabigatran etexilate
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33.7 g (67 mmol) of ethyl 3-{[(2-{[(4-{carbamimidoyl}phenyl)amino]methyl}-1-methyl-1H-benzimidazol-5-yl)carbonyl](pyridin-2-yl)amino}propanoate as obtained in step (g) and 24.7 g of potassium carbonate were suspended in a mixture of 280 mL of water and 1.4 L of tetrahydrofuran. After stirring at room temperature for 15 minutes, 9.2 g (56 mmol) of hexyl chloroformate were added dropwise. The resulting mixture was stirred at room temperature for 1 hour. The organic phase was extracted, washed with 400 mL of brine and dried with anhydrous sodium sulfate. The solvent was removed under vacuum, and the resulting solid was purified by column chromatography eluting with ethyl acetate, to yield 24.9 g of dabigatran etexilate as an off-white solid. Yield: 71.0 %. Purity (HPLC, method 1): 96.3 %.
i) Dabigatran etexilate mesylate
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18.7 g (30 mmol) of dabigatran etexilate as obtained in step (h) were suspended in 103 g of acetone. The mixture was heated to 45°C. After cooling to 36°C, a solution of 2.83 g of methanesulfonic acid in 11.6 g of acetone at 0°C was added dropwise over the reaction mixture. The reaction was stirred at 23-33°C for 90 minutes and at 17-23°C for 60 minutes. The resulting solid was isolated by filtration, washed with 97 mL of acetone and dried at 50°C under vacuum, to yield 18.7 g of dabigatran etexilate mesylate as a pale yellow solid. Yield: 86.7 %. Purity (HPLC, method 1): 98.8 %.
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PATENT
http://www.google.com/patents/WO2010045900A1?cl=en
One of the advanced intermediates during the production of dabigatran is the substance of formula VI.
VI
The compound of formula VI is prepared by a reaction of substance IV with reagent V as shown in Scheme 1.
Scheme 1
The procedure described in WO 9837075 produces compound VI in the form of its base or acetate. Both these products require chromatographic purification, which is very difficult to apply in the industrial scale. This purification method burdens the process economy very much and has a negative impact on the yield.
In the next stage acidic hydrolysis of the nitrile function of compound VI and a reaction with ammonium carbonate is performed to produce the substance of formula VII. The reaction is shown in Scheme 2.
Vl VII
Scheme 2 The procedure in accordance with WO 9837075 produces substance VII in the monohydro chloride form.
When reproducing the procedure of WO 9837075 we found out, in line with WO 9837075, that compound VII prepared by this method required subsequent chromatographic purification as it was an oily substance with a relatively high content of impurities. We did not manage to find a solvent that would enable purification of this substance by crystallization.
The last stage is a reaction of intermediate VII with hexyl chloroformate producing dabigatran and its transformation to a pharmaceutically acceptable salt; in the case of the above mentioned patent application it is the methanesulfonate.
Scheme 3.
EtOH
DABIGATRAN
Example 3: Preparation of dabigatran mesylate
To 9.1 g of compound VII-2HC1 (0.016 mol) 270 ml of chloroform and 9 ml (0.064 mol) of triethylamine are added. Then, a solution of 3.1 ml (0.018 mol) of hexyl chloroformate in chloroform is added dropwise at the laboratory temperature. After one hour the reaction mixture is shaken with brine and the organic layer is separated, which is dried with sodium sulfate and concentrated. The obtained evaporation residue is crystallized from ethyl acetate. Yield: 8.6 g (86%)
This product is dissolved in acetone and an equimolar amount of methanesulfonic acid is added dropwise. The separated precipitate is aspirated and dried at the laboratory temperature. Yield: 75%; content according to HPLC: 99.5%. 27
Example 4:
Preparation of dabigatran mesylate
9 g of compound VII-HCl (0.017 mol) were dissolved in 300 ml of chloroform. 6, ml of triethylamine were added to this solution and then a solution of 3.4 ml (0.02 mol) of hexyl chloroformate in chloroform was added dropwise. After one hour the reaction mixture is shaken with brine, the organic layer is separated, which is dried with sodium sulfate and concentrated. The obtained evaporation residue is crystallized from ethyl acetate. Yield: 9.6 g (90%)
This product is dissolved in acetone and an equimolar amount of methanesulfonic acid is added dropwise. The separated evaporation residue is aspirated and dried at the laboratory temperature. Yield: 73%; content according to HPLC: 99.5%.
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PATENT
http://www.google.com/patents/WO2014009966A2?cl=en
DabigatranEtexilateMesylate chemically know as N-[[2-[[[4-[[[(hexyloxy) carbonyl] amino]-iminomethyl] phenyl] amino] . methyl]-l -methyl-lH- benzimidazol-5-yl] carbonyI]-N-2- pyridinyl-beta-Alanine ethyl ester methanesulfonate having the formula I as provided below,
Formula I
is a direct thrombin inhibitor having anti – coagulant activity when administered orally.
DabigatranEtexilate is first time reported in the US patent 6087380 (hereinafter referred as US’380) in which the process fo the preparation of DabigatranEtexilate is disclosed in the Example 49, 58a and Example 59, said process for the preparation of DabigatranEtexilate is depicted below:
Dabigatran etexilate
In accordance to the process in the Patent US’380 the substance requires complex purifying operations, such as chromatography for the production of high- quality API. Further the chromatographic purification is expensive and difficult to implement in large scale. The impurity in the Dabigatran single prodrug and Dabigatran Etexilate affects the purity of the final product DabigatranEtexilateMesylate.. Hence there is a necessity to maintain the purity level of every intermediate involved in the preparation of DabigatranEtexilateMesylate.
The patent application US201 1082299 discloses a process for the preparation Dabigatran from 3- ([2-[(4-cyanophenyl amino)-methyl]- l-methyl- l H-benzimidazole-5-carbonyl]-pyridin-2-yl-amino) ethyl propionate oxalate as one of the intermediate in order to overcome the problem of the process depicted in the product pate
The patent US81 19810 discloses the process for the preparation Dabigatran from 3- ([2-[(4-cyanophenylamino)-methyl]-l-methyl-lH- benzimidazole-5-carbonyl]-pyridin-2-yl-amino) ethyl propionate hydro bromide as one of the intermediate in order to overcome the problem of the process depicted in the product patent.
The single prodrug of Dabigatran having the formula-II,
and double
which is DabigatranEtexilate are exemplified in the examples of the patent US’380. The patent US’380 has no information about the solid state properties of the single prodrug of Dabigatran and DabigatranEtexilate. However, a similar process described in a publication of Hauel et al in Journal of Medicinal Chemistry, 2002, 45, .1757 – 1766, wherein DabigatranEtexilate is characterized by 128 – 129°C.
The PCT publication WO2006131491 discloses the anhydrous form [ of DabigatranEtexilate having the melting point 135°C, anhydrous form II of DabigatranEtexilate having the melting point 150°C, and hydrate form of DabigatranEtexilate having the melting point 90°C.
The PCT publication WO2008059029 discloses anhydrous form III of DabigatranEtexilate having melting point 128°C, anhydrous form IV of DabigatranEtexilate having the melting point 133°C, and mono hydrate form I of DabigatranEtexilate having melting point 128°C and mono hydrate form II of DabigatranEtexilate having melting point 123°C.
The different forms of the single prodrug of Dabigatran and/or the DabigatranEtexilate are disclosed in the patent applications of WO2012027543, WO2012004396 and WO 2012044595.
The patent application US2007185333 discloses the process ; for the preparation of DabigatranEtexilateMesylate from the DabigatranEtexilate by adding acetone solution of , methanesulfonic acid in an acetone solution of DabigatranEtexilate.
The patent application US 200601 83779 discloses the process for the preparation of DabigatranEtexilateMesylate from the DabigatranEtexilate by adding ethylacetate solution of methanesulfonic acid in an ethylacetate solution of DabigatranEtexilate.
Example-9: Process for the preparation of DabigatranEtexilateMesylate from DabigatranEtexilate
[0086] The DabigatranEtexilate (0.04 mol) was dissolved in acetone (250.0 ml) and added Methanesulfonic acid (0.04 mol) in Ethyl acetate (25 ml) at 25-30°C. Stirred the reaction mass for 3 hrs at the same temperature, the isolated solid was filtered and washed with acetone, dried under vacuum to get the DabigatranEtexilateMesylate. Yield: 85 %, Purity: Not less than 99.0%
Example 10: Process for the preparation of DabigatranEtexilateMesylate
[0087] To a solution of DabigatranEtexilate (0.04 mol) in Acetone (8 volumes) and Ethanol (2 volumes), Methanesulfonic acid solution [Methanesulfonic acid (0.04 mol) was dissolved in Ethyl acetate (25 ml) was added at 25-30°C and stirred for 3 hrs at the same temperature. After completion of the reaction, the resultant solid was filtered, washed with acetone and dried under vacuum. Yield: 93%
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http://www.google.com/patents/WO2013150545A2?cl=en
l-methyl-2-|Tvi-[4-(TSi-n-hexyloxycarbonylamidino)phenyl]aminomethyl]benzimidazole- 5-yl-carboxylicacid-N-(2-pyridyl)-N-(2-ethoxycarbonylethyl)amide is commonly known as Dabigatran etexilate. Dabigatran is an anticoagulant from the class of the direct thrombin inhibitors developed by Boehringer Ingelheim and is used for the treatment of thrombosis, cardiovascular diseases, and the like. Dabigatran etexilalte mesylate was approved in both US and Europe and commercially available under the brand name Pradaxa.
Dabigatran etexilate and process for its preparation was first disclosed in WO 98/37075.
The disclosed process involves the reaction of ethyl 3-(3-amino-4-(methylamino)-N-(pyridin-2- yl)benzamido)propanoate with 2-(4-cyanophenylamino) acetic acid in the presence of N,N- carbonyldiimidazole in tetrahydrofuran to provide ethyl 3-(2-((4-cyanophenylamino)methyl)-l- methyl-N-(pyridin-2-yl)-lH-benzo[d] imidazole-5-carboxamido)propanoate, which is further converted into l-methyl-2-[N-[4-amidinophenyl]aminomethyl]benzimidazol-5-ylcarboxylicacid- N-(2-pyridyl)-N-(2-ethoxycarbonylethyl)amide hydrochloride by reacting with ammonium carbonate in ethanol, followed by treating with ethanolic hydrochloric acid. The obtained compound was reacted with n-hexyl chloroformate in presence of potassium carbonate in tetrahydrofuran/water provides Dabigatran etexilate and further conversion into its mesylate salt was not disclosed. The purity of Dabigatran etexilate prepared as per the disclosed process is not satisfactory, and also the said process involves chromatographic purification which is expensive and difficult to implement in the large scale. Hence the said process is not suitable for commercial scale up.
Moreover, the said process proceeds through the l-methyl-2-[N-[4-amidinophenyl] aminomethyl]benzimidazol-5-ylcarboxylicacid-N-(2-pyridyl)-N-(2-ethoxycarbonylethyl)amide hydrochloride (herein after referred as “Dabigatran hydrochloride”), which degrades to form impurities and resulting in the formation of Dabigatran etexilate with low purity. In view of intrinsic fragility of Dabigatran hydrochloride, there is a need in the art to develop a novel salt form of 1 -methyl-2-[N-[4-amidinophenyl]aminomethyl]benzimidazol-5-ylcarboxylicacid-N-(2- pyridyl)-N-(2-ethoxycarbonyl ethyl)amide, which enhances the purity of the final compound.
The prior reported processes disclosed in WO2012004396 and WO2008095928 Al involves the usage of inorganic salts like hydrochloride and hydrobromide salts of ethyl 3-(2-((4- cyanophenylamino)methyl)- 1 -methyl -N-(pyridin-2-yl)- 1 H-benzo[d]imidazole-5-carboxamido) propanoate (herein after referred as “cyano intermediate”) and ethyl 3-(2-((4-carbamimidoyl phenylamino)methyl)- 1 -methyl -N-(pyridin-2-yl)- 1 H-benzo[d]imidazole-5-carboxamido) propanoate (herein after referred as “amidino intermediate”). The inorganic acid addition salts are less stable when compared to the organic acid addition salts and also the process for the preparation of organic acid addition salts is very much easy when compared to inorganic acid addition salt. Inorganic acid addition salts of amidine intermediate seem to be hygroscopic in nature. Therefore, organic acid addition salts are always preferable to synthesize stable salts which in-turn enhances the purity of the final compound.
The oxalate salt of cyano intermediate was disclosed in WO2009111997. However as on date, there is no other organic acid addition salts of cyano intermediate were reported in the prior art for preparing pure Dabigatran etexilate. Henceforth, there is a need to develop a novel organic acid addition salt of cyano intermediate compound which is very much efficient when compared to its corresponding oxalate salt and that result in the formation of final compound with high purity and yield.
The process disclosed in WO 98/37075 also involves the reduction of, ethyl 3-(4- (methylamino)-3-nitro-N-(pyridin-2-yl)benzamido)propanoate (herein after referred as “nitro compound”) using Pd-C in a mixture of dichloromethane and methanol under hydrogen pressure to provide ethyl 3-(3-amino-4-(methylamino)-N-(pyridin-2-yl)benzamido)propanoate (herein after referred as “diamine compound”).
The reduction of nitro compound through catalytic hydrogenation in the presence of tertiary amine under hydrogen pressure was also disclosed in WO2009153214; and in presence of inorganic base under hydrogen pressure was also disclosed in WO2012004397.
However, most of the prior art processes proceed through catalytic hydrogenation which involves the pressure reactions. Handlings of these pressure reactions are not suitable for the large scale process. Therefore, there is a significant need in the art to provide a simple reduction process which avoids the difficulties associated with catalytic hydrogenation.
JMC, 2002, 45(9), 1757-1766 disclosed a process for the preparation of ethyl 3-(3-amino- 4-(methylamino)-N-(pyridin-2-yl)benzamido)propanoate starting from 4-(methylamino)-3- nitrobenzoic acid. The disclosed process involves the conversion of 4-(methylamino)-3- nitrobenzoic acid into its acid chloride using thionyl chloride and the obtained compound was reacted with ethyl 3-(pyridin-2-ylamino)propanoate to provide nitro compound, followed by catalytic reduction using Pd-C to provide diamine compound.
However, particularly in large scale synthesis the reduction reaction occasionally stops due to catalyst poisoning which leads to incomplete reaction and requires additional catalyst to complete the reaction. Moreover the sulfur impurities which are present in nitro compound formed due to the reaction with thionyl chloride in the previous stages of the synthesis of diamine compound are strongly influence the reaction time, quality and catalyst consumption in the manufacturing process.
Surprisingly, the problem associated with the catalytic hydrogenation and catalyst poisoning is solved by the present invention by adopting a suitable reducing agent such as Fe- acetic acid and Fe-hydrochloric acid.
The crystalline forms-I, II, V and VI of Dabigatran etexilate oxalate were disclosed in WO2008043759 and WO2011110876.
The crystalline forms-Ill, IV and V of Dabigatran etexilate fumarate were disclosed in WO2008043759 and WO2011110876.
Various different salts for Dabigatran etexilate and their polymorphs were reported in WO98/37075, WO03074056, WO2005028468, WO2006114415, WO2008043759, WO2011110876, WO2012027543 and WO2012044595.
The process for the preparation of crystalline form-I of Dabigatran etexilate mesylate was described in WO2005028468 and WO2012027543.
HPLC analysis of Innovator Tablet
The present inventors has also analyzed the Pradaxa 110 mg tablet having Lot no: 808809 and compared with dabigatran etexilate mesylate obtained from the present invention and found that, the impurity profile of both the products are similar to each other i.e., amide impurity, despyridyl ethyl ester etc. are well present even in Pradaxa tablet. Henceforth, we can presume that these impurities are known from the art.
Amide Impurity: 0.31%; Despyridyl ethyl ester: 0.10%; Deshexyl Impurity: 0.08%. HPLC Method of Analysis:
a) Dabigatran etexilate (Formula-1) and Dabigatran etexilate mesylate (Formula-la):
Apparatus: A liquid chromatographic system is to be equipped with variable wavelength
UV-detector; Column: Zorbax Eclipse XDB CI 8, 100 X 4.6mm, 3.5 μιη θΓ Equivalent; Flow Rate: 1.0 mL/min; Wavelength : 300 nm; Column temperature: 25°C; Injection volume: 5 μΐ,; Run time: 50 minutes; Auto sampler temperature: 5°C; Buffer: Dissolve 0.63gm of Ammonium formate in lOOOmL of Milli-Q- Water and mix well. Adjust its pH to 8.2 with Ammonia and filtered through 0.22 μιη nylon membrane and degas it. Mobile phase-A: Buffer; Mobile phase- B: Acetonitrile: Water (80:20) v/v; Diluent: N,N-Dimethylformamide; Needle wash: Diluent; Elution: Gradient. b) Ethyl 3-(2-((4-cyanophenylamino)methyl)-l-methyl-N-(pyridin-2-yl)-lH-benzo[d] imidazole-5-carboxamido)propanoate methanesulfonate (Formula-10)
Apparatus : A liquid chromatograph is equipped with variable wavelength UV- Detector; Column: Zorbax SB CN 150 x 4.6mm, 5μπι (or) Equivalent (Make: Agilent and PNo: 883975- 905); Flow Rate: 1.0 mL / min; Column temperature: 25°C; Wave length: 290 nm; Injection volume: 5 μΐ-.; Run time: 60 minutes; Elution: Gradient; Diluent: Water: Acetonitrile (70:30) v/v; Needle wash: Diluent; Buffer: Weigh accurately about 2 g of 1 -Octane sulphonic acid sodium salt anhydrous and add 5 mL of Ortho phosphoric acid in 1000 mL of Milli-Q- Water and mix well, filter this solution through 0.22 μηι^ΐοη membrane and sonicate to degas; Mobile Phase- A: Buffer(100%);Mobile Phase- B: Acetonitrile: Methanol (90: 10) v/v. c) Ethyl 3-(2-((4-carbamimidoylphenylamino)methyl)-l-methyl-N-(pyridin-2-yl)-lH- benzo[d] imidazole-5-carboxamido)propanoate methanesulfonate (Formula-11)
Apparatus : A liquid chromatographic system is to be equipped with variable wavelength UV- Detector and Integrator; Column : Zodiac CI 8 250 X 4.6 mm, 5 μηι (or) equivalent (Make: Zodiac and PNo. ZLS.C18.46.250.0510 ); Flow Rate: 1.0 mL/min; Wavelength: 290 nm; Column temperature: 25°C; Injection Volume: 5μί; Run time: 55 min; Elution: Gradient;
Buffer: Take 5 mL of Ortho phosphoric acid(85%) and 2 g of 1 -Octane sulfonic acid sodium salt anhydrous in 1000 mL of Milli-Q-water and adjust its pH to 2.5 with Triethyl amine filter, through 0.22 μπι Nylon membrane filter paper and sonicate to degas it; Mobile Phase-A: Buffer(l 00%) Mobile Phase-B: Acetonitrile: Water (90: 10) v/v; Diluent : Water: Acetonitrile (80:20) v/v.
Morphology: Method of analysis: Samples were mounted on aluminium stubs using double adhesive tape, coated with gold using HUS-5GB vacuum evaporation and observed in Hitachi S-3000 N SEM at an acceleration voltage of 10KV.
Following are the impurities observed during the preparation of Dabigatran etexilate mesylate.
Deshexyl Impurity Despyridyl Ethyl Ester
Methyl Carbamate Ethyl Carbamate
The present invention is schematically represented as follows:
Formula-2 ene
Formula-6
Fe-AcOH
Formula-7
Dabigatran etexilate Dabigatran etexilate Mesylate The process described in the present invention was demonstrated in examples illustrated below.
Example-13: Preparation of Dabigatran etexilate (Formula-1)
n-hexanol (30.8 g) was added to a solution of N, N-carbonyldiimidazole (61.15 g) and dichloromethane (360 ml) at 15-25°C and stirred for 3 hours. The organic layer was washed with water followed by sodium chloride solution. Distilled off the solvent from the organic layer completely under reduced pressure to get amide compound. Acetonitrile (157.5 ml) was added to the obtained amide compound. This was added to a mixture of ethyl 3-(2-((4- carbamimidoylphenylamino)methyl)-l-methyl-N-( yridin-2-yl)-lH-benzo[d]imidazole-5- carboxamido)propanoate mesylate compound of formula- 11 (90 g), potassium carbonate (62.5 g), acetonitrile (378 ml) and water (252 ml) at 25-35°C. The reaction mixture was heated to 40- 50°C and stirred for 8 hours. After completion of the reaction, both the organic and aqueous layers were separated; the organic layer was cooled to -5 to +5°C and stirred for 2 hours. Filtered the precipitated solid washed with acetonitrile and water. The obtained compound was dissolved in a mixture of acetone (270 ml) and acetonitrile (270 ml) at 45-50°C. Cooled the reaction mixture to 25-30°C and water (360 ml) was added to it. Filtered the obtained solid and dissolved in the mixture of dichloromethane and sodium chloride solution at 35-40°C. Both the organic and aqueous layers were separated; the organic layer was distilled under reduced pressure and then co-distilled with ethyl acetate. The obtained crude compound was dissolved in ethyl acetate (540 ml) by heating it to 70-80°C and stirred for 30 minutes. Filtered the reaction mixture, the filtrate was cooled to 35-45°C and ethanol (8 ml) was added to the reaction mixture. The reaction mixture was again cooled to 25-35°C and stirred for 3 hours. Filtered the precipitated solid and then dried to get pure title compound.
Yield: 44 g; MR: 128-131 °C. Purity by HPLC: 99.63%.
……………….
http://www.google.com/patents/WO2014020555A2?cl=en
EXAMPLE 6
Preparation of dabigatran etexilate mesylate: l-methyl-2-[N-[4-( -n-hexyloxycarbonylamidino)phenyl] amino methyl]benzimidazol-5- yl-carboxylicacid-N-(2-pyridyl)-N-(2-ethoxycarbonyl ethyl) amide (100 gm) was dissolved acetone (1000 ml) under heating at 25-35 °C. A solution of methane sulfonic acid (13.77 gm) in acetone (100 ml) was added to the reaction mixture. The solution is filtered and after the addition of acetone cooled to approximately 20° C. The precipitated product was filtered and washed with acetone then dried at 50° C under reduced pressure.
Wet weight : 0.120-0.140 kg
Dry weight : 0.90-1.0 kg
Yield (W/W) : 0.90-1.0
Theoretical Yield (w/w) : 1.15
Percentage Yield : 78.2-86.9%
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| US20050095293 * | Sep 3, 2004 | May 5, 2005 | Boehringer Ingelheim Pharma Gmbh Co. Kg | Administration form for the oral application of poorly soluble drugs |
| US20070185173 * | Dec 21, 2006 | Aug 9, 2007 | Georg Zerban | Process for the Preparation of the Salts of 4-(Benzimidazolylmethylamino)-Benzamides |
| Citing Patent | Filing date | Publication date | Applicant | Title |
|---|---|---|---|---|
| WO2014020555A2 * | Jul 31, 2013 | Feb 6, 2014 | Alembic Pharmaceuticals Limited | An improved process for the preparation of dabigatran etexilate mesylate |
| WO2014009966A2 * | Jul 5, 2013 | Jan 16, 2014 | Rao Davuluri Ramamohan | An improved process for the preparation of dabigatran etexilate mesylate and its intermediates thereof |
| WO2014009966A3 * | Jul 5, 2013 | Mar 6, 2014 | Rao Davuluri Ramamohan | An improved process for the preparation of dabigatran etexilate mesylate and its intermediates thereof |
| EP1966171A1 | Dec 20, 2006 | Sep 10, 2008 | Boehringer Ingelheim International GmbH | Improved process for the preparation of 4-(benzimidazolylmethylamino)-benzamides and the salts thereof |
| EP1968949A1 | Dec 20, 2006 | Sep 17, 2008 | Boehringer Ingelheim International GmbH | Improved process for the preparation of the salts of 4-(benzimidazolylmethylamino)-benzamides |
| US6087380 | Feb 18, 1998 | Jul 11, 2000 | Boehringer Ingelheim Pharma Kg | Disubstituted bicyclic heterocycles, the preparations and the use thereof as pharmaceutical compositions |
| US7202368 | Jun 9, 2005 | Apr 10, 2007 | Boehringer Ingelheim International Gmbh | Process for the preparation of 4-(benzimidazolymethylamino) benzamidines |
| WO2000005207A1 * | Jul 20, 1999 | Feb 3, 2000 | Boehringer Ingelheim Pharma | Substituted phenylamidines with antithrombotic action |
| WO2007071742A1 * | Dec 20, 2006 | Jun 28, 2007 | Boehringer Ingelheim Int | Improved process for the preparation of 4-(benzimidazolylmethylamino)-benzamides and the salts thereof |
| WO2010045900A1 | Oct 26, 2009 | Apr 29, 2010 | Zentiva, K.S. | A method for the preparation of dabigatran and its intermediates |
| Reference | ||
|---|---|---|
| 1 | * | European Medicines Agency (EMEA): “CHMP ASSESSMENT REPORT FOR Pradaxa“, , 1 January 2008 (2008-01-01), pages 1-36, XP55003938, London Retrieved from the Internet: URL:http://www.ema.europa.eu/docs/en_GB/document_library/EPAR_-_Public_assessment_report/human/000829/WC500041062.pdf [retrieved on 2011-08-01] |
| 2 | * | HAUEL N H ET AL: “STRUCTURE-BASED DESIGN OF NOVEL POTENT NONPEPTIDE THROMBIN INHIBITORS“, JOURNAL OF MEDICINAL CHEMISTRY, AMERICAN CHEMICAL SOCIETY, US, vol. 45, no. 9, 1 January 2002 (2002-01-01), pages 1757-1766, XP001098844, ISSN: 0022-2623, DOI: DOI:10.1021/JM0109513 |
| CN103058920A * | Jan 21, 2013 | Apr 24, 2013 | 上海应用技术学院 | Preparation method of 3-(2-pyridineamino)ethyl propionate |
| CN1861596A * | May 18, 2006 | Nov 15, 2006 | 复旦大学 | Process for synthesizing antithrombin inhibitor of non-asymmetric non-peptide kind |
| CN101875626A * | Nov 6, 2009 | Nov 3, 2010 | 广东光华化学厂有限公司;北京理工大学 | Method for synthesizing N-benzyl maleimide from immobilized supported acid catalyst |
| EP2522662A1 * | May 11, 2011 | Nov 14, 2012 | Medichem, S.A. | Dabigatran etexilate and related substances, processes and compositions, and use of the substances as reference standards and markers |
| JP2004315371A * | Title not available |
See full gatran series at………………http://apisynthesisint.blogspot.in/p/argatroban.html
OLANZEPINE VISITED PART 2/3
PART 1…..https://newdrugapprovals.org/2015/04/08/olanzepine/
PART 2….https://newdrugapprovals.org/2015/04/09/olanzepine-visited-part-22/
PART 3…….https://newdrugapprovals.org/2015/04/09/olanzepine-visited-part-33/
WATCHOUT………..
…………………….
PATENT
http://www.google.com/patents/US7459449
Olanzapine is a pharmaceutically active compound that can be represented by formula (1).
It was disclosed in EP 454436 and corresponding U.S. Pat. No. 5,229,382 as a useful antipsychotic agent. Olanzapine acts as a serotonin (5-HT2) and dopamine (D1/D2) receptor antagonist with anticholinergic activity. In commercially available final forms, the active substance is marketed as a free base, which is a white to yellow crystalline solid that is insoluble in water; i.e., solubility at pH 6.8=0.02 mg/ml.
The olanzapine base is known to exist in various crystalline modifications and in various hydrated forms that are generally stable at ambient conditions; see for example EP 733635 and corresponding U.S. Pat. No. 5,736,541; WO 98-11893; and EP 831098. Having so many different forms is considered to be a disadvantage as repeated production of olanzapine substance may give rise to unpredictable amounts of the respective modifications in the product, which in turn can influence the properties of the product such as in tabletting and/or releasing of the active from the tablets after ingestion.
WO 99-16313 discloses olanzapine pamoate as a pharmaceutical agent. It is a compound that is also insoluble in water and is useful particularly in intramuscular depot forms. However, like the free base, the pamoate salt exists in several forms including hydrates, solvates, and in different counter ion ratios.
WO 03-007912 discloses an amorphous lyophilized olanzapine in a reconstitutable parenteral formulation. The olanzapine is “intimately mixed” with a stabilizer and a solubilizer. The stabilizer is preferably lactose and the solubilizer includes organic acids and most preferably tartaric acid. The composition is formed by lyophilizing, i.e. a type of freeze drying, a solution of olanzapine, the stabilizer and the solubilizer to form the intimate mixture. The resulting lyophilized amorphous product can be reconstituted with parenteral diluents to make an injectable composition. Whether the tartaric acid salt of olanzapine is present in the lyophilized product is unclear.
For instance, the “des-methyl olanzapine” (2) may be methylated by formic acid/formaldehyde (Chinese Journal of Pharmaceuticals 2001, 32, 391-393) to form an olanzapine reaction mixture.
Similarly, the “des-piperazine olanzapine” (3) can be treated with N-methylpiperazine in DMSO under conditions of olanzapine formation to produce a reaction mixture containing olanzapine.
In a third process, the “formyl-olanzapine” (4) is reduced by a reducing agent, for instance by a borohydride agent (WO 2004/000847) or by hydrogen under the presence of a hydrogenation catalyst.
The starting compounds (2), (3), and (4) are known compounds and may be obtained by procedures known in the art.
EXAMPLE 16A
Olanzapine Benzoate by Methylation of Desmethyl Olanzapine
In a 100 ml flask, equipped with a magnetic stirrer, 0.5 g desmethyl olanzapine was dissolved in 5 ml DMSO. Then, 0.142 g formic acid (37% in water) and 0.082 g formic acid (98%) were added and the resulting mixture was heated at 80° C. for 2 hours. After cooling to room temperature, 20 ml ethyl acetate and 20 ml water were added. The organic layer was washed with 2*20 ml water and 20 ml saturated aqueous NaCl, dried (Na2SO4) and concentrated at reduced pressure to a volume of about 10 ml. Then, 0.200 g benzoic acid dissolved in 2 ml ethyl acetate was added dropwise to the crude olanzapine solution. An off-white/yellow solid formed which was isolated by filtration and dried over weekend at 40° C. in vacuo. Isolated yield: 0.58 gram (80%). 1H-NMR: expected compound; trace of ethyl acetate present.
EXAMPLE 16B
Synthesis of Olanzapine and Isolation of Olanzapine as the Benzoate Salt
In a 250 ml flask, equipped with a magnetic stirrer, 4.3 g of N-desmethylpiperazine-olanzapine was refluxed in a mixture of 15 ml N-methylpiperazine, 20 ml DMSO, and 20 ml toluene under a nitrogen atmosphere for 20 hours. The mixture was cooled and 50 ml water was added. The aqueous layer was extracted three times with 150 ml ethyl acetate and the combined organic layers were washed 3 times with 100 ml water and once with 100 ml aqueous saturated sodium chloride. After drying over Na2SO4, the organic layer was concentrated to about 100 ml and 1.6 g benzoic acid was added. After a few minutes, a yellow solid was formed. Stirring was continued at 4° C. for 1 hour. The solid material was isolated by filtration, washed with 5 ml ethyl acetate and 10 ml diethyl ether, and dried overnight at 40° C. in vacuum. Isolated yield: 4.61 g (80%; based on benzoic acid).
EXAMPLE 16C
Synthesis of Olanzapine and Isolation of Olanzapine as the Benzoate Salt
In a 2000 ml flask, 50 g of desmethyl olanzapine was dissolved in 450 ml of DMSO. Then, 13.04 g of formaldehyde (37% in water) and 7.59 g of formic acid (98%) were added and the resulting mixture was heated at 80° C. for 2 hours. The crude reaction mixture was poured into a mixture of 1000 ml of ethyl acetate and 1000 ml of ice-cooled water. The aqueous layer was separated and extracted with 2×500 ml of ethyl acetate. The combined organic layers were washed with 3×500 ml of water and 500 ml of saturated aqueous NaCl, dried (Na2SO4) and concentrated at reduced pressure to a volume of about 1000 ml. To the warm solution, 20.4 g of benzoic acid was added in one portion under stirring. An off-white/yellow solid was formed. Stirring was continued overnight at room temperature and subsequently for 2 hours at 4 C. The yellow solid was isolated by filtration, washed with 30 ml of cold ethyl acetate and 100 ml of diethyl ether and dried overnight at 60° C. in vacuo. Isolated yield: 60.25 g. Assay (HPLC): 99.1%.
EXAMPLE 16D
Synthesis of Olanzapine and Isolation of Olanzapine as the Benzoate Salt
In a 3000 ml flask, 86 g of desmethylpiperazine-olanzapine hydrochloride was refluxed in a mixture of 300 ml of N-methylpiperazine, 400 ml of DMSO, and 400 ml of toluene under a nitrogen atmosphere for 5 hours. The mixture was cooled to 50° C. and poured into a mixture of 2000 ml of ethyl acetate and 2000 ml of ice-cooled water. The aqueous layer was extracted with 2×500 ml of ethyl acetate and the combined organic layers were washed with 3×500 ml of water and with 500 ml of aqueous saturated sodium chloride. After drying over Na2SO4, the organic layer was concentrated to about 1500 ml and 39.6 g of benzoic acid was added in one portion. After a few minutes, a yellowish solid was formed. Stirring was continued overnight at room temperature. The solid material was isolated by filtration, washed with 50 ml of ethyl acetate and 200 ml of diethyl ether, and dried overnight at 60° C. in vacuum. Yield: 86.35 gram.
EXAMPLE 16E
Olanzapine Benzoate from Formyl Olanzapine
In a 250 ml flask, 3.0 g of N-formyl olanzapine precursor (compound (4)) was suspended in 45 ml of dry toluene and cooled to 0C. Under nitrogen atmosphere, 5.4 ml of Red-Al™ solution (70 wt % solution of sodium dihydrido-bis(2-methoxyethoxy) aluminate in toluene) was added dropwise under stirring. The resulting mixture was allowed to warm up to room temperature. Then 5.0 ml of Red-Al solution was added dropwise at this temperature. After stirring for 5 hours at room temperature, the reaction mixture was poured into 100 ml of water and immediately 100 ml of ethyl acetate was added. The mixture was filtered over a P3-filter to remove insoluble material. The biphasic filtrate was allowed to stand for separating the layers and the aqueous layer was removed and washed with 2×50 ml of ethyl acetate. The combined organic layers were washed with 2×50 ml of water, dried over anhydrous sodium sulfate and concentrated at reduced pressure to a volume of about 50-60 ml. Then, 1.12 g of benzoic acid was added in one portion and the resulting mixture was stirred at 4° C. for 4 hours. The formed solid was isolated by filtration, washed with 5 ml of cold ethyl acetate and 10 ml of cold diethyl ether, and dried overnight at 40 C under vacuum. Yield: 2.75 gram, purity (HPLC): 94.8%.
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PATENT
http://www.google.com/patents/WO2003101997A1?cl=en
EXAMPLE 1 ULTRA-PURE OLANZAPINE FORM I
A three necked flask, fitted with a nitrogen gas inlet and a water condenser with calcium chloride guard tube, is charged with 4-amino-2-methyl-10H-theino[2,3-b][1 ,5] benzodiazepine HCI (5.0 g, 0.0188 mol), 1-methylpiperazine (13.0 mL, 0.11 mol, 99.0%, Aldrich Chemicals, USA) and anhydrous dimethyl sulfoxide (30.0 mL, Aldrich Chemicals, USA, water< 0.1%). The reaction mixture is stirred at 112-115°C (oil bath temperature 115°C) for 16 hours under continuous flow of nitrogen to drive away the ammonia gas generated during the reaction. The reaction is monitored by HPLC and it is found that within 16 hours 97% product is formed. The reaction mixture is cooled to room temperature (24- 25°C) and added dropwise to a mixture of dichloromethane.water-methanol (190:190:15, 395 mL). After addition, the reaction mixture is stirred for 30 minutes at room temperature. The resulting mixture is yellowish hazy with a dark brown organic layer settled at the bottom of the flask. The dark brown colored dichloromethane layer is separated from the aqueous hazy phase.
After separating the organic layer, the aqueous hazy phase is again extracted with dichloromethane (1×100.0 mL). The combined dichloromethane phases (total volume 290.0 mL) are extracted twice with 50 % aqueous acetic acid solution (1×100 mL, 1×75.0 mL). A dark orange color acetic acid layer is separated. The pH of the acetic acid solution is found to be around 3.0-3.5 when tested by litmus paper. Combined aqueous acetic acid solution is basified, to pH 7.5-8.5, using 40% aqueous sodium hydroxide solution under cold conditions (0-10°C). After attaining the desired pH of the solution, 200 mL dichloromethane is added and stirred. The content is transferred to a separating funnel and is vigorously shaken. The dichloromethane layer is separated and the aqueous phase is again extracted with dichloromethane (1×75.0 mL). The combined dichloromethane extracts are washed with cold saturated sodium chloride solution (1×30.0 mL) and dried over anhydrous sodium sulfate. Removal of solvent on a rotary evaporator with a water bath temperature of 45°C, gives a dark orange brown viscous liquid. To this viscous liquid, 80-85.0 mL dry toluene is added.
The toluene containing crude olanzapine is transferred into a dry 250 mL single necked round bottom flask. Methanolic sodium hydroxide solution (0.32 g sodium hydroxide dissolved in 3.0-4.0 mL methanol by sonication) is added and the mixture is heated in an oil bath at 60°C for 2 hours. After the stipulated time, 20-25 % of the total volume of solvent is evaporated on a rotary evaporator, with a 55-60°C water bath, to ensure the complete removal of dichloromethane and trace amounts of water, resulting in a final volume of between 55-60 mL. The hot solution is removed from the water bath and cooled in an ice bath with stirring. Within 2-3 minutes, the solution is quickly seeded with previously prepared ultra pure olanzapine Form I, as determined by X-Ray and IR, with stirring. Stirring is continued for 40-45 minutes. The yellowish solid obtained in the solution is filtered off, washed with 1.5-2.0 mL dichloromethane and dried on a vacuum pump for 50-60 minutes to give 4.85 g ( 82.4 % yield) of olanzapine Form I. The solid obtained is crushed to a fine powder and air dried to remove traces of dichloromethane. Karl Fisher analysis indicates 5000-8000 ppm water content. The material is dried in an oven at 65°C for 1.5-2.0 hours and analyzed for water (670-860 ppm water). The weight of the title product is 4.80 g (82 % yield), HPLC purity = 99.83%, polymorphic purity is 100% as no detectable polymorph II is observed by X-ray and IR, as shown in Example 3.
The HPLC conditions are as follows: Column: SymmetryC18 , 4.6 x 250 mm λmax 254 nm
Flowrate : 1.0 mL/min. Run Time: 70 minutes
The buffer comprises 5.4 g potassium phosphate; 0.5 g heptanesulfonic acid sodium salt and 0.5 g 1-octanesulfonic acid sodium salt dissolved in 500 mL Dl water and adjusted the pH to 2.6 using cone, phosphoric acid. The mobile phase was 500 mL buffer/300 mL acetonitrile/200 mL methanol. The final pH of the mobile phase is about 3.6. The concentration of the standard is 100μg/mL; the injection volume is 15 μl; and RT = 4.6—4.7 min.
EXAMPLE 2 RECRYSTALLIZATION
From the dried yellowish solid prepared according to Example 1 , 2.0 g (0.0064 mol) is transferred into a single necked round bottom flask provided with a magnetic stirrer. To the solid, 40.0 mL dry toluene and methanolic sodium hydroxide solution (0.052 g sodium hydroxide pellets dissolved in 2.0 L methanol by sonication) are added. To this mixture 3.5-4.0 mL dichloromethane is added.
The mixture is heated for 5-10 minutes in an oil-bath at 60-65°C until a clear solution is obtained. After heating, the solution is transferred into an ice bath and seeded with previously prepared ultra-pure olanzapine Form I. The solution is stirred for 30-35 minutes at 0-10°C. The yellowish solid obtained is filtered on vacuum pump and washed with 2.0-2.5 mL dichloromethane. The solid is dried on a vacuum pump for 40-45 minutes. The solid obtained is crushed into a fine powder and air dried to remove traces of dichloromethane. The air dried material is further dried in the oven at 65°C for 1.5-2.0 hours and analyzed for water content. Karl Fisher study shows 670-860 ppm water content. The weight of olanzapine Forml is 1.93 g (95.0 % crystallization yield) of 99.96 % HPLC purity. EXAMPLE 3 X-RAY POWDER DIFFRACTOMETRY STUDY
Olanzapine Form I prepared according to Example 1 is analyzed by X-ray, IR, and DSC and found to conform to a commercially available reference standard olanzapine Form I. DSC of the olanzapine Form I prepared according to the present invention shows an endotherm peak at 195°C.
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http://www.google.com/patents/CN102268010A?cl=en
Currently, the preparation of olanzapine, mainly in the following three ways:
1.4-amino-2-methyl–10H- thieno [2,3-b] [1,5] – benzodiazepine hydrochloride and N- methylpiperazine, in a nitrogen atmosphere Toluene and DMSO as solvent at reflux for 20h, after-treatment to give the product, recrystallized from acetonitrile to give crystals of olanzapine, a yield of 33% (US5229382).
[0013] The process route fewer steps, simple process, raw materials, but a long reaction time, the use of toxic solvents, pollution, low yield, industrial production adversely.
[0014] CN1906201A discloses the use of no solvent or low boiling organic solvent method for preparing olanzapine, pointed N- methylpiperazine with 4-amino-2-methyl -10H- thieno [2,3-b] [l, 5] molar ratio _ benzodiazepine hydrochloride of 3: 1~8: 1,110~145 ° C after the reaction at least polonium, water was added, at least two organic solvents, or water and at least one organic solvent precipitation olanzapine. This improved process reaction time is shortened, reducing energy consumption and cost, but an excess of starting material N- methylpiperazine unrecovered, resource waste problems still exist.
[0015] 2. 4-amino-2-methyl -10H- thieno [2,3_b] [1,5] – benzodiazepine hydrochloride, to generate demethylolanzapine piperazine is reacted with level, and then obtained by methylation of olanzapine, recrystallized from ethanol to obtain refined product yield of 68% (CN1420117A).
[0016]
[0017] The method for preparing olanzapine via a two-step process is relatively complicated and the reaction time is still long; Further, more by-products: The first step is easy to form dimeric product, a second step Iddo methylation.
[0018] 3. 4-amino-2-methyl -10H- thieno [2,3-b] [1,5] – benzodiazepine and N, N- two – (2_ haloethyl ) _ methylamine in alkaline catalyst, solvent reflux 3~IOh obtained crude olanzapine, yield 75% to 92%. Wherein, X = Br or Cl, the catalyst is sodium alkoxide, sodium hydroxide, sodium amide, sodium hydroxide, inorganic bases (CN101168544A).
[0019]
[0020] This method is simple, shorten the reaction time and therefore reduce energy consumption, but the raw material N, N- two – (2-halo-ethyl) _ methylamine not easy, if more raw material preparation is bound to increase the cost of production.
The present invention is olanzapine preparation method:
[0024]
Example 1 olanzapine [0030] Implementation
[0031] To a 250ml three-necked flask of 4-amino-2-methyl -10H- thieno [2,3_b] [1,5] – benzodiazepine hydrochloride 20. OOg (0 075mol.) , N_-methylpiperazine 75. 30g (0. 75mol), nitrogen and stirred and heated to reflux the reaction cell. Under stirring, the reaction mixture was poured into 200ml of water to precipitate a pale yellow solid powder, stirring was continued for lh, filtered and dried to give olanzapine product 23. 30g, yield 99.4%, purity 99. 0% (HPLC).
2 olanzapine refined example [0032] Implementation
[0033] Example 1 was 23. 30g olanzapine product was transferred into 250ml single neck flask was added MOml ethanol, stirred and heated to reflux to make the product the whole solution. 0. 20g of activated carbon was added to the system, reflow bleaching treatment 30min, filtered, and the filtrate cooled to room temperature and crystallization, filtration and dried to give a yellow crystalline powder 16. 32g, yield 70.0%, the purity of 99. 8% (HPLC), high performance liquid phase chromatogram, see photos.
Olanzapine Preparation Example 3 [0034] Implementation
[0035] To a three-necked flask IOOOml 4-amino-2-methyl -10H- thieno [2,3_b] [1,5] – benzodiazepine hydrochloride 150. 03g (. 0 56mol) , N- methylpiperazine 339. 29g (3. 39mol), nitrogen and stirred and heated to reflux the reaction cell. Cooling, vacuum distillation recovery more than 70% excess N- methylpiperazine to give Olanzapine crude solid.
[0036] 400ml of ethanol was added to the three-necked flask and heated to reflux for solid all dissolved. Then dissolved under stirring in ethanol olanzapine solution was poured IOOOml water to precipitate a pale yellow solid powder was filtered and dried to give olanzapine product 173. 87g, yield 99.4%, purity 98. 9% (HPLC).
Preparation 4 olanzapine [0037] Implementation
[0038] To a 250ml three-necked flask of 4-amino-2-methyl -10H- thieno [2,3_b] [1,5] – benzodiazepine hydrochloride 10. OOg (0 038mol.) , N_-methylpiperazine 39. 63g (0. 40mol) and diethylene glycol dimethyl ether 30ml, nitrogen and stirred and heated to reflux the reaction cell. Cooling, vacuum distillation recovery more than 80% excess of N- methylpiperazine and diethylene glycol dimethyl ether mixture to give solid crude olanzapine.
[0039] 40ml of ethanol was added to the three-necked flask and heated to reflux all dissolved solids. Then under stirring to dissolve olanzapine solution was poured into 200ml of water in ethanol, a yellow powder precipitated solid was filtered and dried to give olanzapine product 11.79g, yield 99.3%, purity 98. 7% (HPLC).
Olanzapine Preparation Example 5 [0040] Implementation
[0041] To a 250ml bottle of three 4-amino-2-methyl–10H- thieno [2,3_b] [1,5] – benzodiazepine hydrochloride 20. OOg (0. 075mol) , N_-methylpiperazine 62. 34g (0. 62mol), nitrogen and stirred and heated to reflux the reaction cell. Cooling, vacuum distillation recovery more than 75% excess N- methylpiperazine to give Olanzapine crude solid.
[0042] 60ml of ethanol was added to the three-necked flask and heated to reflux all dissolved solids. Then under stirring to dissolve olanzapine solution was poured into 600ml of ethanol in water to precipitate a pale yellow solid powder was filtered and dried to give olanzapine product 23. 37g, yield 99.7%, purity 99. 0% (HPLC). [0043] Example 6 olanzapine refined
[0044] Example 5 was 23. 37g olanzapine product was transferred into 250ml single neck flask was added ^ Oml ethanol, stirred and heated to reflux to make the product the whole solution. 0. 03g of activated carbon is added to the system and 0. 03g diatomite, reflow bleaching treatment 15min, filtered, and the filtrate cooled to room temperature and crystallization, filtration and dried to give a yellow crystalline powder 16. 76g, yield 71.7%, purity 99.7% ( HPLC).
………………….
http://www.google.com/patents/EP0733635B1?cl=en
Example 1
-
-
In a suitable three neck flask the following was added:
- Dimethylsulfoxide (analytical):
- 6 volumes
- Intermediate 1 :
- 75 g
- N-Methylpiperazine (reagent) :
- 6 equivalents
Intermediate 1 can be prepared using methods known to the skilled artisan. For example, the preparation of the Intermediate 1 is taught in the ‘382 patent.
-
A sub-surface nitrogen sparge line was added to remove the ammonia formed during the reaction. The reaction was heated to 120°C and maintained at that temperature throughout the duration of the reaction. The reactions were followed by HPLC until ≤ 5% of the intermediate 1 was left unreacted.
-
After the reaction was complete, the mixture was allowed to cool slowly to 20°C (about 2 hours). The reaction mixture was then transferred to an appropriate three neck round bottom flask and water bath. To this solution with agitation was added 10 volumes reagent grade methanol and the reaction was stirred at 20°C for 30 minutes. Three volumes of water was added slowly over about 30 minutes. The reaction slurry was cooled to zero to 5°C and stirred for 30 minutes. The product was filtered and the wet cake was washed with chilled methanol. The wet cake was dried in vacuo at 45°C overnight. The product was identified as technical olanzapine.
Yield: 76.7%; Potency: 98.1%
- Technical Grade olanzapine
Example 2
- Form II
-
A 270 g sample of technical grade 2-methyl-4-(4-methyl-1-piperazinyl)-10H-thieno[2,3-b][1,5]benzodiazepine was suspended in anhydrous ethyl acetate (2.7 L) . The mixture was heated to 76°C and maintained at 76°C for 30 minutes. The mixture was allowed to cool to 25°C. The resulting product was isolated using vacuum filtration. The product was identified as Form II using x-ray powder analysis. Yield: 197 g.
-
The process described above for preparing Form II provides a pharmaceutically elegant product having potency > 97%, total related substances < 0.5% and an isolated yield of > 73%.
………………….
Impurities
Olanzapine N-oxide (Olanzapine Impurity D)
…………..
Synthesis and characterization of impurities of an anti-psychotic drug substance, Olanzapine (08-3022UP)
Poornachander Thatipalli, Ramesh Kumar, Chandrasekhar Bulusu, Ramesh Chakka, Pratap R. Padi, Anjaneyulu Yerra and Satyanarayana Bollikonda
Full Text: PDF (226K)
pp. 195 – 201
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