A Versatile Approach to Protected (4S,5R)-4-Hydroxy-5(-hydroxyalkyl)-2-pyrrolidinones

Starting from (S)-N,O-dibenzylmalimide (7), a versatile four-step approach to (4S,5R)-Nbenzyl-4-benzyloxy-5-(-hydroxyalkyl)-2-pyrrolidinones 9 is reported. The method consists of Grignard reagent addition, p-toluenesulfonic acid monohydrate-mediated dehydration, one-pot epoxidation-methanol ring-opening reaction and reductive demethoxylation. 2Pyrrolidinones 9 were obtained with excellent trans-diastereoselectivity in the pyrrolidinone ring and low diastereoselectivity at the carbinol center