Process for the preparation of 2- (N-benzyl-N-methylamino) -ethylmethyl-2,6-dimethyl-4- (m-nitrophenyl) -1,4-dihydro-pyridine-3,5-dicarboxylate or its hydrochloride

摘要

A new, technologically easily feasible process for the preparation of 2-(N-benzyl-N-methylamino)ethyl methyl 2,6-dimethyl-4(m-nitrophenyl)-1,4-dihydropyridine-3,5-dicarboxylate, comprising a partrial hydrolysis of dimethyl 2,6-dimethyl-4-(m-nitrophenyl)-1,4-dihydropyridine-3,5-dicarboxylate in an inert organic solvent at a temperature between room temperature and the reflux temperature of the reaction mixture with an aqueous solution of alkali hydroxide and the reaction of the obtained 3-methoxycarbonyl-2,6-dimethyl-4-(m-nitrophenyl)-1,4-dihydropyridine-5 -carboxylic acid either with N-(2-hydroxyethyl)-N-benzyl-methylamine in the presence or absence of an organic solvent in the presence of N,N'-dicyclohexylcarbodiimide at a temperature of between 25 DEG and 120 DEG C. or with N-(2-haloethyl)-N-benzyl-methylamine in the presence of an inert organic solvent and of a proton acceptor at a temperature of between 25 DEG and 140 DEG C., to yield the title compound, which can be, if desired, converted to its hydrochloride salt. The hydrochloride salt is known under the generic name "nicardipine hydrochloride" and is used as a valuable therapeutic in the therapy of cerebral insufficiency.