DIHYDROPYRIDINE-3,5-DICARBOXYLIC ACID ESTER DERIVATIVES

摘要

This invention relates to a process for producing the dextro-rotary optical isomer of diastereoisomer A of 2,6dimethyl-4-(3-nitrophenyl)-1,4-dihydropyridine-3,5-dicarboxylic acid 3-(1-benzylpyrrolidin-3-yl)ester 5-methyl ester or pharmaceutically acceptable acid addition salts thereof. The process comprises subjecting a mixture of optical isomers of 2,6-dimethyl-4-(3-nitrophenyl)-1,4-dihydropyridine-3,5-dicarboxylic acid 3-(1-benzylpyrrolidin -3-yl) ester to column chromatography using silica gel as a carrier and a mixture of ethyl acetate and acetic acid as an eluent to separate the acetate of the dextro-rotatory optical isomer of diastereoisomer A, or reacting said mixture with L-(-)-malic acid to deposit the L-(-)-malate of the dextro-rotatory optical isomer of diastereoisomer A, or treating the resulting salt with a base, or further treating the resulting dextro-rotatory optical isomer with a pharmaceutically acceptable acid.