A new synthesis of 3-chloro-2-(thiazol-4-yl)propenoic acid and its application to cephalosporins.
作者:KIYOHARU NISHIDE、MARIKO YAMAMURA、MAYUMI YAMAZAKI、TAKEO KOBORI、DAIEI TUNEMOTO、KIYOSI KONDO、KIYOSHI SATO
DOI:10.1248/cpb.36.2346
日期:——
Three step transformations of α-formylation, chlorination and hydrolysis starting from ethyl 4-thiazoleacetate (1) afforded a new cephem 7-side chain acid, (E)-3-chloro-2-(thiazol-4-yl)propenoic acid (4-(E)). The presence of the corresponding 4-(Z) derived from photoisomerization of 4-(E) was confirmed by nuclear magnetic resonance analysis. Acylation of several 7-aminocephalosporins was conducted by two routes involving the photoisomerization of 4-(E) to 4-(Z) (method A) or the isomerization of the activated intermediate (formula III) of the carboxylic acid 4-(E) with Vilsmeier reagent by heating (method B). The synthesis and the antibacterial activities of a new series of geometrical isomers of 7-[3-chloro-2-(thiazol-4-yl)propenamido] cephalosporins (formula II) are described.
从 4-噻唑乙酸乙酯(1)开始,经过α-甲酰化、氯化和水解三个步骤的转化,得到了一种新的头孢 7 侧链酸,即(E)-3-氯-2-(噻唑-4-基)丙烯酸(4-(E))。核磁共振分析证实了 4-(E)光异构化产生的相应 4-(Z)的存在。几种 7-氨基头孢菌素的酰化有两种途径,一种是 4-(E)光异构化成 4-(Z)(方法 A),另一种是羧酸 4-(E)的活化中间体(式 III)与 Vilsmeier 试剂加热异构化(方法 B)。本文介绍了 7-[3-氯-2-(噻唑-4-基)丙烯酰胺基]头孢菌素(式 II)的一系列新几何异构体的合成和抗菌活性。