ChemInform Abstract: Highly Enantioselective Direct Allylic Alkylation of Butenolides with Morita—Baylis—Hillman Carbonates Catalyzed by Chiral Squaramide‐Phosphine.

Abstract

An efficient asymmetric vinylogous allylic alkylation of β,γ-butenolides with Morita–Baylis–Hillman carbonates has been developed. With a chiral cyclohexane-based squaramide-phosphine catalyst 5e, optically active γ,γ-disubstituted butenolides containing adjacent quaternary and tertiary chiral centers have been constructed in good-to-excellent yields (up to 98%) and excellent stereoselectivities (87 : 13–99 : 1 dr, 96–99% ee).