The invention relates to a process for the preparation of a physiologically hydrolyzable ester of formula I
wherein R² is hydrogen, R³ is hydrogen or methyl, and R⁴ is a physiologically hydrolyzable ester group which comprises
(1) providing an O-protected acid of Formula I wherein R⁴ is hydrogen and R² is an O-protecting group of the type commonly used in the synthesis of cephalosporin compounds, and R³ is as defined above;
(2) introducing the said R⁴ physiologically hydrolyzable ester group; and (3) replacing said R² O-protecting group with hydrogen.
本发明涉及一种制备式 I 生理可
水解酯的工艺
其中 R² 是氢,R³ 是氢或甲基,R⁴ 是生理上可
水解的酯基,包括
(1) 提供式 I 的 O-保护酸,其中 R⁴ 是氢,R² 是
头孢菌素化合物合成中常用的 O-保护基团,R³ 如上定义;
(2) 引入所述 R⁴ 生理上可
水解的酯基;以及 (3) 用氢取代所述 R² O-保护基。