Regiodivergent and Enantioselective Allylic C-H Alkylation of Allyl Ethers: Optimization, Scope, Mechanism and Application.

Abstract

Vinyl ethers and allyl ethers are important motifs in natural products and pharmaceuticals. Among various methods toward their synthesis, direct allylic C-H functionalization of allyl ethers is one of the most efficient approaches. In this study, one of two regioisomers, a vinyl ether or an allyl ether, could be obtained, depending on whether a Lewis acid co-catalyst was present. Furthermore, branched allyl ethers were smoothly prepared in excellent regio- and enantioselectivity (up to 20:1 b/l, 99% ee) by synergistic catalysis with an achiral Pd(0) complex and a chiral Lewis acid catalyst.