Asymmetric transformation of l-homoserine lactone to an optically active 2-substituted pyrrolidine for clemastine
作者:Seung Jin Kim、Minsun Chang、Hee-Doo Kim
DOI:10.1016/j.tetasy.2011.11.005
日期:2011.11
The asymmetric transformation of l-homoserine lactone to (R)-ethyl 2-(2-chloroethyl)pyrrolidine-1-carboxylate for clemastine has been accomplished by a combination of regioselective N-allylation and ring-closing metathesis. A key feature associated with the synthesis involved the racemization-minimized N-allylation of carbamate version of an amino ester by using P4-phosphazene as a base. This method
通过区域选择性N-烯丙基化和闭环复分解的结合,实现了L-高丝氨酸内酯不对称转化为clemastine的(R)-乙基2-(2-氯乙基)吡咯烷-1-羧酸酯。与合成有关的一个关键特征是,以P4-磷腈为碱,使氨基甲酸酯形式的氨基甲酸酯的消旋最小化N-烯丙基化。该方法可能提供了另一种途径,可从α-氨基酯获得旋光的2取代的吡咯烷,这是不容易从基于脯氨酸的不对称转化中获得的。