BigPatents India

A process for the preparation of benazepril hydrochloride in high yield with high purity. A chiral tert-butyl ester of 3(S)-amino-2,3,4,5-tetrahydro-2-oxo-1H-1-benazazepin-1-acetic acid is prepared by treating ester of 3-amino-2,3,4,5-tetrahydro-2-oxo-1H-1-benzazepine-1-acetic acid with chirally active organic acids such as L(+) tartaric acid in the presence of aldehyde in an organic solvent to obtain a chiral protected (S,S) distereomeric tartarate salt of tert butyl ester of 3-(S)-amino-2,3,4,5-tetrahydro-2-oxo-1H-1-benzazepine-1-acetic acid followed by treatment with base such as liquid ammonia in an organic solvent such as halogenated hydrocarbons selected from dichloromethane, dichloroethane or chloroform at pH in the range of 9 to 11 to obtain chiral tert butyl ester of 3-amino-2,3,4,5-tetrahydro-2-oxo-1H-1-benzazepine-1-actic acid which is further condensed with ethyl(+)-R-2-(4-nitrobenzenesulfonyloxy)-4-phenyl butyrate in the presence of base such as of n-methyl morpholine and an organic solvent to obtain benazepril. The benazepril is further converted into its hydrochloride salt. No. of Pages : 24 No. of Claims : 09