Asymmetric Michael addition reaction of 3-substituted-N-Boc oxindoles to activated terminal alkenes catalyzed by a bifunctional tertiary-amine thiourea catalyst.Org Biomol Chem. 2010 Jan 07; 8(1):77-82.OB
The current article reports an organocatalytic strategy for the asymmetric catalysis of chiral oxindoles bearing 3-position all-carbon quaternary stereocenters. Accordingly, highly enantioselective Michael addition reactions of 3-substituted oxindoles to terminal alkenes have been developed by utilizing a bifunctional tertiary-amine thiourea catalyst. The reactions accommodate a number of Michael donor compounds (different substituted 3-aryl or methyl oxindoles), and Michael acceptor compounds (vinyl ketones and vinyl sulfones) to give the desired oxindole products with moderate to excellent yields (up to 99%) and moderate to excellent enantioselectivities (up to 91% ee).