A method of preparing the R- or S- form of the calcium antagonist amlodipine, or of an acid addition salt thereof, which comprises
(i) forming a salt of R,S-2-(2-azidoethoxymethyl)-4-(2-chlorophenyl)-5-methoxycarbonyl-6-methyl-1,4-dihydropyridine-3-carboxylic acid with cinchonidine and separating said salt into its diastereomeric forms by fractional crystallisation;(ii) converting said separated salts into the free acids by acidification;(iii)esterifying the free carboxy groups to ethoxycarbonyl; and(iv) reducing the azido groups to amino, thus producing separated R-(-)- and S-(+)- amlodipine, and isolating the separated forms of amlodipine as such or in acid addition salt form.The invention also includes the novel intermediates obtained by the above process.
制备
氨氯地平的R-或S-形式或其酸加成盐的方法,包括以下步骤:(i) 用
奎宁啶形成R,S-2-(2-
叠氮乙氧甲基)-4-(2-
氯苯基)-5-甲氧羰基-6-甲基-1,4-
二氢吡啶-3-
羧酸盐,并通过分级结晶将该盐分离成其对映异构体形式;(ii) 通过酸化将分离的盐转化为自由酸;(iii) 酯化自由羧基为乙氧羰基;(iv) 还原
叠氮基团为
氨基,从而产生分离的R-(-)-和S-(+)-
氨氯地平,并将分离的
氨氯地平形式作为酸加成盐形式或本身进行分离。该发明还包括通过上述过程获得的新型中间体。