Patent ID: 6979736

Claim:
A process for the preparation of benazepril hydrochloride (2), comprising the following steps: a) reacting (3S)-3-amino-1-t-butoxycarbonylmethyl-2,3,4,5-tetrahydro-1H-benzazepin-2-one (11) with a 3-benzoyl acrylic acid ester (13) in which R is a straight or branched C 1 –C 6 alkyl group or a benzyl group, to give a Michael adduct of formula (14) in which R has the meanings as defined above; b) transforming compound (14) into 3-[[1-(ethoxycarbonyl)-3-hydroxy-3-phenyl-propyl]amino]-1-t-butoxycarbonylmethyl-2,3,4,5-tetrahydro-1H-benzazepin-2-one (15) c) crystallizing the S,S isomer of compound (15); d) esterifying compound (15) to give 3-[[1-(ethoxycarbonyl)-3-phenyl-propyl]amino]-1-t-butoxycarbonylmethyl-2,3,4,5-tetrahydro-1H-benzazepin-2-one (12); and e) treating compound (12) with hydrochloric acid gas to give benazepril hydrochloride (2).