Stereocontrolled creation of all-carbon quaternary stereocenters by organocatalytic conjugate addition of oxindoles to vinyl sulfone

Abstract

Multifunctional catalysts in operation: A novel class of trifunctional thiourea catalysts containing natural amino acid residues have been prepared (see scheme), and found to be very effective towards the asymmetric addition of 3-alkyl-oxindoles to 1,1-bis(benzenesulfonyl)ethylene. This synthetic protocol has led to the enantioselective synthesis of 3-alkyl-3-aryl-disubstituted oxindoles and indolines with an all-carbon quaternary stereogenic center. © 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.