Asymmetric synthesis of γ-lactams under low-loading N-heterocyclic carbene catalysis

Abstract

Low-loading N-heterocyclic carbene-catalyzed oxidative formal [3 + 2] annulation of enals with N-Ts diethyl aminomalonate has been successfully developed. Diverse γ-lactams were generated in good yields with excellent enantioselectivities using 2 mol% catalyst in most cases. This reaction features a broad substrate scope and good functional group tolerance, and it can be easily scaled up. Importantly, the resulting γ-lactam can be converted into (R)-rolipram.