-imidazoline (IV). A racemization rate of the alanine residue was measured from an optical rotation of 2,4-dinitrophenyl derivative obtained from the acid hydrolyzate and from hydrogen-deuterium exchange reaction at α-carbon atom. All these compounds were found to be racemized very easily particularly in the presence of proton source. From the experimental results, a plausible mechanism for racemization
                                    为研究
噻唑啉、
恶唑啉或
咪唑啉环的外次次甲基碳原子的外消旋化,从
氨基酸亚
氨基醚合成了以下四种化合物:2-(1-苄氧羰基
氨基乙基)-2-
噻唑啉(I)、甲基2- (1-benzyloxycarbonylaminoethyl)-2-thiazoline-4-carboxylate (II)、2-(1-benzyloxycarbonylaminoethyl)-2-oxazoline-4-carboxylate (III) 和 2-(1-benzyloxycarbonylaminoethyl)-2-imidazoline (四)。丙
氨酸残基的外消旋化率由酸
水解产物的2,4-
二硝基苯基衍
生物的旋光度和α-碳原子的氢-
氘交换反应测定。发现所有这些化合物都非常容易外消旋化,尤其是在质子源的存在下。从实验结果来看,