Synthesis of (+/-)-oxohexahydrofuro[3,2-b]pyrroles (pyrrolidine-trans-lactones) via a reduction - Alkylation protocol

A synthesis of pyrrolidine-trans-lactones is described commencing from 1-(b enzyloxycarbonyl)-3-oxo-2-pyrrolidineacetic acid ethyl eater cis-Reduction of the oxo-pyrrolidine followed by hydroxyl inversion with benzoic acid in a Mitsunobu reaction gave the trans-benzoate eater which was converted into its corresponding silyl ether. After allylation a to ethyl eater, silyl de protection, saponification and trans-lactonisation gave pyrrolidine-trans-l actones. Stereoselective allylation of trans-1-(benzyloxycarbonyl)-3-hydrox y-2-pyrrolidineaceticacid ethyl eater is feasible to give predominantly the desired diastereomer.