Patent ID: 7202365
Filing Date: 2007-04-10
Classification: C07D

Abstract:
1. A process for the preparation of S-(−)-amlodipine, which comprises: (i) reacting (R,S)-amlodipine with L-(+)-tartaric acid in dimethyl sulfoxide (DMSO); (ii) filtering off the resulting precipitate of the step (i); (iii) precipitating (S)-(−)-amlodipine-hemi-L-tartrate-¼-DMSO-solvate by adding methylene chloride to the filtrate of the step (ii); (iv) optionally forming (S)-(−)-amlodipine-hemi-L-tartrate-monohydrate by adding an alcohol to (S)-(−)-amlodipine-hemi-L-tartrate-¼-DMSO-solvate obtained in the step (iii); and (v) treating with a base (S)-(−)-amlodipine-hemi-L-tartrate-¼-DMSO-solvate obtained in the step (iii) or (S)-(−)-amlodipine-hemi-L-tartrate-monohydrate obtained in the step (iv); wherein said (R,S)-amlodipine is 3-ethyl 5-methyl-(±) 2-[(2-aminoethoxy)methyl]-4-(2-chlorophenyl)-1,4-dihydro-6-methylpyridine-3,5-dicarboxylate, and wherein said S-(−)-amlodipine is 3-ethyl 5-methyl-(−) 2-[(2-aminoethoxy)methyl]-4-(2-chlorophenyl)-1,4-dihydro-6-methylpyridine-3,5-dicarboxylate.