Enantioselective [3 + 2] annulation of 3-hydroxymaleimides with quinone monoimines

Abstract

Enantioselective [3 + 2] annulation of 3-hydroxymaleimides with quinone monoimines was realized using a chiral phosphoric acid as a catalyst. Various novel succinimide fused dihydrobenzofurans bearing two continuous quaternary stereocenters were obtained in moderate to excellent yields (up to 99%) with moderate to excellent enantioselectivities (up to 99% ee). The absolute configuration of one product was assigned by X-ray crystal structural analysis and a plausible reaction mechanism was proposed.