Dual-function cinchona alkaloid catalysis: Catalytic asymmetric tandem conjugate addition-protonation for the direct creation of nonadjacent stereocenters

Catalytic tandem asymmetric reactions constitute a powerful strategy for the asymmetric construction of nonadjacent stereocenters in acyclic molecules directly from achiral precursors. In this Communication, we report a highly enantioselective and diastereoselective addition of trisubstituted carbon donors to 2-chloroacrylonitrile catalyzed by bifunctional cinchona alkaloid catalysts. This represents the first asymmetric tandem conjugate addition-protonation with efficient catalytic control of two nonadjacent stereocenters. As demonstrated in a concise and highly stereoselective formal total synthesis of (-)-manzacidin A, this asymmetric tandem reaction establishes a new and versatile catalytic approach for the enantioselective and diastereoselective creation of 1,3-tertiary-quaternary stereocenters. Copyright © 2006 American Chemical Society.