N,N'-dioxide-scandium (III)-catalyzed asymmetric Michael addition of β,γ-unsaturated butenolides to α,β-unsaturated γ-keto esters

Abstract

A highly efficient N,N'-dioxide-scandium-(III) complex catalytic system has been developed for the asymmetric vinylogous Michael reaction of a-angelica lactone and its derivatives to α,β-Unsaturated γ-Keto esters, affording the corresponding γ,γ-disubstituted butenolide products in moderate to good yields (up to 93%) with high dr (up to >19:1) and ee values (up to 97%) under mild reaction conditions. © 2013 Wiley-VCH Verlag GmbH&Co. KGaA, Weinheim.