| 摘要 |
<p>Process for the preparation of unsymmetrical 1,4-dihydro-pyridinedicarboxylic esters Process for the preparation of unsymmetrical 1,4dihydropyridines of the formula I I in which R represents a phenyl radical which is optionally substituted once or twice by nitro and/or chlorine and R1 represents a C1-C4-alkyl radical which is optionally substituted by a C1-C4-alkoxy group, and R2 represents a C1-C12-alkyl radical which is optionally substituted by a C1-C4-alkoxy group, a trifluoromethyl group or the radical ¢C6H5CH2! ¢CH3!N, the radicals R1 and R2 not being identical, by reaction of an ylidene compound of the formulae II or III II III with an enamine compound of the formulae IV or V IV V Le A 22 262 characterised in that the ylidene compound of the formulae II or III is prepared by reaction of a ketocarboxylic ester of the formula VI or VII CH3-?-CH2-COOR1 VI CH3-?-CH2-COOR2 VII with an aldehyde of the formula RCHO, in a solvent, in the presence of catalytic amounts of acetate salts of amines, at temperatures from -10.degree.C and up to 100.degree.C. Le A 22 262</p> |
