An Efficient Organocatalytic Method for Highly Enantioselective Michael Addition of Malonates to Enones Catalyzed by Readily Accessible Primary Amine-Thiourea

Abstract

A practical and highly enantioselective Michael addition of malonates to enones catalyzed by simple and readily available bifunctional primary amine-thiourea derived from 1,2-diaminocyclohexane is reported. The addition of weak acids and elevated temperature (ca. 50 °C) improved the efficiency of the Michael reaction. This approach enables the efficient synthesis of 1,5-ketoesters with good yields, excellent enantioselectivities (up to 99% ee), and low loading (0.5-5 mol %) of simple chiral primary amine-thiourea catalysts, and is applicable in multigram scale synthesis.