Regioselective α-addition of vinylogous α-ketoester enolate in organocatalytic asymmetric Michael reactions: enantioselective synthesis of Rauhut-Currier type products.

Abstract

Catalytic asymmetric α-regioselective Michael additions of vinylogous α-ketoester enolate are described herein. With 0.1-1.0 mol% loadings of a chiral bifunctional organocatalyst, the addition of a deconjugated α-keto ester to a series of nitroolefins, including the challenging β-alkylnitroalkenes, efficiently proceed, providing the Rauhut-Currier type products after isomerization of the terminal double bond in good yields (60-88%) with excellent regio- and enantioselectivities (94-99% ee, TON up to 160 with 0.5 mol% of the catalyst).