A synthesis of pyrrolidine-trans-lactones is described commencing from 1-(benzyloxycarbonyl)-3-oxo-2-pyrrolidineacetic acid ethyl ester. cis-Reduction of the oxo-pyrrolidine followed by hydroxyl inversion with benzoic acid in a Mitsunobu reaction gave the trans-benzoate ester which was converted into its corresponding silyl ether. After allylation α to ethyl ester, silyl deprotection, saponification and trans-lactonisation gave pyrrolidine-trans-lactones. Stereoselective allylation of trans-1-(benzyloxycarbonyl)-3-hydroxy-2-pyrrolidine-acetic acid ethyl ester is feasible to give predominantly the desired diastereomer.
本文描述了一种从1-(苄氧羰基)-3-氧代-
2-吡咯烷乙酸乙酯出发合成
吡咯烷-反向
乳酸的方法。对氧代
吡咯烷进行顺式还原,随后在Mitsunobu反应中与
苯甲酸进行羟基反转,得到反式
苯甲酸酯,并将其转化为相应的
硅醚。在
乙酯的α位进行烯丙基化、去
铵保护、皂化和反向
乳酸化后,最终得到
吡咯烷-反向
乳酸。对反式1-(苄氧羰基)-3-羟基-
2-吡咯烷乙酸乙酯进行立体选择性的烯丙基化是可行的,主要获得所需的二构象异构体。