NEW HIGHLY SELECTIVE PROCESS FOR THE PREPARATION OF ENANTIOMERICALLY PURE PHENYL-SUBSTITUTED 1,4-DIHYDROPYRIDINE-3,5-DICARBOXYLIC ACID DERIVATIVES

摘要

Use of a derivative of an optically active maleimide of the general formula (VII): (see formula VII) wherein: A represents: (i) H or straight-chain or branched alkyl having up to 8 carbon atoms, or (ii) phenyl or benzyl which are optionally up to trisubstituted by identical or different substituents selected from the group consisting of hydroxyl, nitro, a halogen atom, cyano, carboxyl, trifluoromethyl, trifluoromethoxy, straight-chain or branched alkoxy having up to 6 carbon atoms and a group of the general formula: -NR6R7 or -SO2R8, wherein: R6 and R7 are identical or different and represent H, phenyl or straight-chain or branched alkyl having up to 5 carbon atoms, and R8 represents straight-chain or branched alkyl having up to 4 carbon atoms or phenyl, in the preparation of the diastereomerically pure 1,4-dihydropyridines of the general formulae (IVa) and (IVb): (see formulae IVa and IVb) wherein: A is as defined above; R1 represents: (i) straight-chain or branched alkyl having up to 8 carbon atoms which is optionally substituted by straight-chain or branched alkoxy having up to 6 carbon atoms or hydroxyl, or (ii) cycloalkyl having 3 to 7 carbon atoms; and R2 represents the radical (see formula I) wherein R4 and R5 are identical or different and represent: (i) a halogen atom, cyano, ethinyl, trifluoromethoxy, methylthio, nitro or trifluoromethyl, or (ii) straight-chain or branched alkyl, alkenyl, alkinyl or alkoxy having up to 4 carbon atoms, and one of the substituents optionally represents H; and a salt thereof.