Photoinduced Enantioselective α-Alkylation of Active Methines with Nonactivated Alkenes Using a Chiral Ytterbium Lewis Acid

Abstract

Catalytic enantioselective alkylation is a fundamental strategy for constructing molecular frameworks bearing chiral carbon centers. Herein, we report a photoinduced highly enantioselective catalytic α-alkylation of active methine compounds with nonactivated alkenes to construct chiral quaternary stereocenters. Cooperative catalysis using an organophotocatalyst and a chiral ytterbium Lewis acid bearing an Indapybox ligand efficiently promotes the alkylation of open-chain 2-substituted β-ketoesters, affording the desired products in high yields with high enantioselectivities (up to 96% yield and 96% ee). The reaction exhibits a broad substrate scope with respect to both the alkene and β-ketoesters components. Furthermore, the resulting products can be readily transformed into optically active 5-pyrazolone and 5-isoxazolone derivatives while maintaining high optical purity.