Catalytic Asymmetric Vinylogous Conjugate Addition of Butenolide to 2-Ester-Substituted Chromones: Access to Chiral Chromanone Lactones via Trapping of a Copper(I) Enolate by Trimethyl Borate

Abstract

A copper-catalyzed asymmetric vinylogous conjugate addition of butenolide to 2-ester-substituted chromones is described, and it delivers syn- or anti-chromanone lactones with high stereoselectivities. The enantioselectivity-determining step varied with the use of B­(OMe)3 as an additive, resulting in enhanced stereoselectivities, as revealed by density functional theory calculations, which also provided theoretical insight into the origin of the ligand-dependent diastereodivergence.

Direct Catalytic Enantioselective Conjugate Addition of α-Substituted Benzyl Nitriles to Alkyl Acrylates

“…With our continuous interest in target-directed catalytic asymmetric reactions, we herein describe the first direct, atom-economic, and highly enantioselective copper-catalyzed conjugate reaction of α-substituted benzyl nitriles with alkyl acrylates to afford high-value chiral quaternary carbon-substituted nitriles (Scheme d).…”