Phosphine-catalyzed enantioselective γ-addition of 3-substituted oxindoles to 2,3-butadienoates and 2-butynoates: Use of prochiral nucleophiles

Abstract

The first phosphine-catalyzed enantioselective γ-addition with prochiral nucleophiles and 2,3-butadienoates as the reaction partners has been developed. Both 3-alkyl- and 3-aryl-substituted oxindoles could be employed in this process, which is catalyzed by a chiral phosphine that is derived from an amino acid, thus affording oxindoles that bear an all-carbon quaternary center at the 3-position in high yields and excellent enantioselectivity. The synthetic value of these γ-addition products was demonstrated by the formal total synthesis of two natural products and by the preparation of biologically relevant molecules and structural scaffolds. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.