Highly Enantioselective Direct Vinylogous Michael Addition of γ-Butenolide to Enals

An unprecedented and simple direct vinylogous addition of deconjugated butenolide to enals has been developed in excellent stereoselectivities (> 95% ee), with Aminal-PYrrolidine (APY) catalyst. This methodology allows for the efficient preparation of complex gamma-butenolide from readily available renewable resources. Furthermore, preliminary mechanistic investigations have allowed for the better understanding of the origin of both stereoselectivities and of the observed high reactivities.