A process for preparing an optically active 3-hydroxybutanoic acid represented by formula (I): ##STR1## wherein: R.sup.1 represents a protective group of carboxylic acid, and R.sup.2 represents a hydrogen atom; a lower alkyl group which may be substituted with a halogen atom; a lower alkoxy group; a phenyl group which may be substituted with a lower alkyl group or a lower alkoxy group; or a benzyloxy group which may be substituted with a lower alkyl group or a lower alkoxy group, is disclosed, comprising asymmetrically hydrogenating a 3-oxobutanoic acid ester represented by formula (II): ##STR2## wherein R.sup.1 and R.sup.2 are as defined above, in the presence of a ruthenium-optically active phosphine complex as a catalyst. The compound of formula (I) which is useful for synthesizing a 4-acetoxyazetidin-2-one derivative, a useful intermediate for obtaining penem antibiotics, can be prepared economically.
本发明公开了一种制备光学活性3-羟基
丁酸的方法,其
化学式为(I):##
STR1## 其中:R.sup.1表示
羧酸的保护基,R.sup.2表示
氢原子;可以被卤素原子取代的较低烷基基团;较低烷
氧基团;可以被较低烷基基团或较低烷
氧基团取代的
苯基;或者可以被较低烷基基团或较低烷
氧基团取代的苄
氧基团。该方法包括在
钌-光学活性膦配合物
催化剂的存在下,不对称
氢化
化学式为(II)的
3-氧代丁酸酯:##
STR2## 其中R.sup.1和R.sup.2如上所定义。该化合物可以经济地制备出用于合成4-乙酰
氧基
氮杂
环戊二烯-2-
酮衍
生物的化合物,后者是获得青霉烷类
抗生素的有用
中间体。