Process for the preparation of intermediates of perindopril
A process for the preparation of (2S, 3aS, 7aS)perhydroindole-2-carboxylic acid is provided comprising (a) esterifying a cis-perhydroindole-2-carboxylic acid with a first alcohol of the formula ROH and a suitable free acid to provide the acid salt (AS) of Formula V: (b) reacting the acid salt of Formula V with a first base to provide a compound of Formula VI: (c) treating the product of step (b) with an L-tartaric containing acid in a second alcohol of the formula ROH to precipitate a compound of Formula VII: (d) reacting the compound of Formula VII with a second base to provide a compound of Formula II (e) hydrolyzing the compound of Formula II to provide the (2S, 3aS, 7aS)perhydroindole-2-carboxylic acid.
1 . A process for the preparation of (2S,3aS,7aS)perhydroindole-2-carboxylic acid of Formula III
the process comprising:
(a) esterifying cis-perhydroindole-2-carboxylic acid of Formula IV:
with a first alcohol of the formula ROH and a suitable free acid to provide the acid salt (AS) of formula V:
wherein R is an alkyl, aryl or aralkyl group;
(b) reacting the acid salt of Formula V with a first base to provide a compound of Formula VI:
(c) treating the product of step (b) with an L-tartaric containing acid in a second alcohol of the formula ROH to precipitate a compound of Formula VII:
wherein R has the aforestated meaning;
(d) reacting the compound of Formula VII with a second base to provide a compound of Formula II
wherein R has the aforestated meaning; and
(e) hydrolyzing the compound of Formula II to provide the compound of Formula III.
2 . The process of claim 1 , wherein the first alcohol is benzyl alcohol.
3 . The process of claim 1 , wherein the first alcohol is selected from the group consisting of methanol, ethanol, isopropanol, propanol, butanol and mixtures thereof.
4 . The process of claim 1 , wherein the free acid is selected from the group consisting of p-toluenesulfonic acid, hydrochloric acid and mixtures thereof.
5 . The process of claim 1 , wherein the first base is organic amine base.
6 . The process of claim 1 , wherein the first base is selected from the group consisting of a primary amine, secondary amine, tertiary amine, aliphatic amine, aromatic amine, ammonia and mixtures thereof.
7 . The process of claim 1 , wherein the first base is selected from the group consisting of a tertiary amine, heterocyclic amine and mixtures thereof.
8 . The process of claim 1 , wherein the first base is selected from the group consisting of a trialkylamine, heterocyclic amine and mixtures thereof.
9 . The process of claim 8 , wherein the trialkylamine contains from about 3 to about 20 carbon atoms.
10 . The process of claim 1 , wherein the first base is selected from the group consisting of trimethylamine, triethylamine, tripropylamine, tributylamine and mixtures thereof.
11 . The process of claim 1 , wherein the first base is selected from the group consisting of an alkali metal carbonate, alkali earth metal carbonate and mixtures thereof.
12 . The process of claim 1 , wherein the first base is selected from the group consisting of sodium carbonate, potassium carbonate and mixtures thereof.
13 . The process of claim 1 , wherein the L-tartaric containing acid is dibenzoyl L-tartaric acid or L-tartaric acid.
14 . The process of claim 1 , wherein the second alcohol is benzyl alcohol.
15 . The process of claim 1 , wherein the second alcohol is selected from the group consisting of methanol, ethanol, isopropanol, propanol, butanol and mixtures thereof.
16 . The process of claim 1 , wherein the second base is selected from the group consisting of an alkali metal hydroxide, alkali earth metal hydroxide and mixtures thereof.
17 . The process of claim 1 , wherein the second base is selected from the group consisting of sodium hydroxide, potassium hydroxide and mixtures thereof.
18 . The process of claim 1 , wherein in step (e) the compound of Formula II is hydrolyzed with an alkali metal hydroxide.
19 . The process of claim 1 , wherein the compound of Formula III is thereafter converted to perindopril or a pharmaceutically acceptable salt thereof.
20 . Perindopril erbumine obtained from the process of claim 19.