Asymmetric Michael addition of α-hydroxy aldehydes to nitroolefins catalyzed by chiral diamine

The regio-, stereo-, and enantioselective direct Michael addition of alpha-hydroxyketones to beta-arylnitroolefins catalyzed by N-iPr-2,2'-bipyrrolidine is described. The formation of an internal hydrogen bond between the OH group of alpha-hydoxyacetone and the tertiary nitrogen of the catalyst leads to the formation of a rigid cis enamine intermediate that explains the inversion of the expected diastereoselectivity and the very high ee's