Optically active threo-dihydroxyphenylserine derivatives represented by the forumla:
wherein R₁ and R₂ each represents or form together a protecting group for the phenolic hydroxyl group, R₃ represents a protecting group for the amino group and R₄ represents a protecting group for the carboxyl group, which are intermediates for L-threo-3-(3,4-dihydroxyphenyl)-serine, are prepared by asymmetrical hydrogenation of ketones represented by the formula:
wherein R₁, R₂, R₃ and R₄ are as defined above, in a solvent in the presence of optically active ruthenium phosphine complexes represented by the formula:
wherein X represents a chlorine atom, a bromine atom or an acetoxy group, R₅ represents a lower alkyl group of 1 - 5 carbon atoms, Z represents a phenyl group or a p-tolyl group and n is 0 or 1.
具有光学活性的三-二羟基
苯基丝氨酸衍
生物,由以下式子表示:
其中R₁和R₂各自代表或共同组成
酚羟基的保护基团,R₃代表
氨基的保护基团,R₄代表羧基的保护基团,它们是L-苏-3-(3,4-二羟基苯基)-
丝氨酸的中间体,通过式代表的酮的不对称氢化制备:
其中 R₁、R₂、R₃ 和 R₄ 如上文所定义:
其中 X 代表
氯原子、
溴原子或乙酰氧基,R₅ 代表 1-5 个碳原子的低级烷基,Z 代表苯基或
对甲苯基,n 为 0 或 1。