Direct vinylogous aldol addition of #gamma#-butyrolactones and #gamma#-butyrolactams

摘要

Deprotonation of N-benzyl-3-phenylselenylpyrrol-2(5H)-one 3 and furan-2-(5H)-one 4 and reaction with aldehydes affords regioselectively 5-(1'-hydroxy)-#gamma#-butyrolactones and the aza-analogous butyrolactams with good diastereoisomeric exceeses. The presence of Lewis acids enhances the diastereoisomeric ratios.This methodology is an alternative to Lewis acid mediated silyloxydiene condensation.