Stereocontrolled Construction of Quaternary Stereocenters by Inter‐ and Intramolecular Nitro‐Michael Additions Catalyzed by Bifunctional Thioureas

Abstract

Abstract A highly diastereo‐ and enantioselective conjugate addition of β‐keto esters to nitroolefins, catalyzed by a chiral thiourea prepared from L ‐valine is described. The formation of two contiguous tertiary and quaternary stereocenters occurs in high yield and excellent diastereo‐ and enantioselection with only 2 mol% of catalyst loading. The reaction is general and different β‐keto esters and aryl‐ and alkylnitroolefins have been tested. The same catalyst has been used to promote the first intramolecular conjugate addition leading to the cyclic adduct in moderate diastereoselectivity and good enantioselectivity.