Highly Enantioselective Conjugate Addition of Malonate and β-Ketoester to Nitroalkenes: Asymmetric C−C Bond Formation with New Bifunctional Organic Catalysts Based on Cinchona Alkaloids

Abstract

The development of readily accessible bifunctional chiral catalysts is a desirable yet challenging goal in catalytic asymmetric synthesis. In this communication, we describe the development of a new class of readily accessible chiral bifunctional organic catalysts that could be derived in one or two steps in high yield from either quinidine or quinine. These catalysts have been shown to catalyze a highly enantioselective conjugate addition of methyl and ethyl malonates and β-ketoesters to a broad range of β-substituted nitroalkenes, an synthetically important C−C bond-forming reaction utilizing readily available starting materials. This new catalytic asymmetric reaction proceeds in 91−98% ee and 71−99% yield.