Highly Enantioselective Direct Vinylogous Michael Addition of γ-Butenolide to Enals
摘要:
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.
2-position, gave a synergistic effect leading to two powerful complementary organocatalysts. They show excellent enantiocontrol in the -functionalization of a wide range of linear/branched aldehydes and ketones, including Michael additions to ethenediyl disulfones or nitrostyrene and -amination. We obtained ees up to 98.5 % with low catalyst loadings (down to 1 mol-%). As a proof of efficiency, TOFs of up to