申请人:Mitsui Toatsu Chemicals, Inc.
公开号:US05302743A1
公开(公告)日:1994-04-12
Disclosed is an improved process for the preparation of an N-protected .alpha.-L-aspartyl-L-phenylalanine methyl ester from an N-protected L-aspartic anhydride and L-phenylalanine methyl ester, the improvement which comprises employing the L-phenylalanine methyl ester in the form of a mineral acid salt thereof and conducting the reaction either (a) in an organic solvent and in the presence of a salt of an organic carboxylic acid, or (b) in an organic solvent comprising an organic carboxylic acid and in the presence of at least one member of the group consisting of an alkali metal or an alkaline earth metal inorganic base, an ammonium alkali metal or alkaline earth metal salt of an organic carboxylic acid and ammonium carbonate. The starting N-protected aspartic anhydride, e.g., N-benzyloxycarbonyl-L-aspartic anhydride, can be produced by the reaction of N-protected aspartic acid with phosgene. When the N-protecting group sibenzyloxycarbonyl and the solvent is acetic acid, the desired product can be isolated from the reaction mixture in crystalline form in high purity by adding water thereto.
本发明公开了一种改进的方法,用于从N-保护的L-天冬氨酸酐和L-苯丙氨酸甲酯制备N-保护的α-L-天冬氨酸-L-苯丙氨酸甲酯,其改进包括采用以矿酸盐形式存在的L-苯丙氨酸甲酯,并在有机溶剂中进行反应,同时存在有机羧酸盐的盐类(a),或在包含有机羧酸的有机溶剂中进行反应,并存在于由碱金属或碱土金属无机碱、有机羧酸的铵盐和碳酸铵组成的至少一个成员的存在下(b)。起始的N-保护的天冬氨酸酐,例如N-苄氧羰基-L-天冬氨酸酐,可以通过N-保护的天冬氨酸与光气反应而产生。当N-保护基为苄氧羰基且溶剂为乙酸时,可以通过添加水从反应混合物中以结晶形式高纯度地分离所需的产物。