The thiazole-based one carbon homologation of four α-amino acids (L-phenylalanine, L-leucine, L-threonine, and L-serine) to the corresponding α-hydroxy β-amino aldehydes and acids in both configurations at Cα, is described. The methodology involves the following key operations: (i) the conversion of an α-amino ester to a 2-thiazolyl α-amino ketone; (ii) the stereocontrolled reduction of a ketone carbonyl to either syn or anti α,β-amino alcohols; (iii) the aldehyde release from the thiazole ring; (iv) the oxidation of the aldehyde to a carboxylic acid. The methodology was only partially applied to L-phenylglycine because of some limitations in operation (i).
描述了四种
α-氨基酸(
L-苯丙氨酸、
L-亮氨酸、
L-苏氨酸和
L-丝氨酸)的
噻唑基单碳同源化,生成相应的α-羟基β-
氨基醛和酸,且在Cα上具有两种构型。该方法论涉及以下关键操作:(i)将α-
氨基酯转化为2-
噻唑基α-
氨基酮;(ii)对酮羰基进行立体选择性还原,生成syn或anti的α,β-
氨基醇;(iii)从
噻唑环中释放醛;(iv)将醛氧化为
羧酸。由于操作(i)的一些限制,该方法论仅部分应用于
L-苯甘氨酸。