Asymmetric Michael addition of alpha-hydroxyketones to nitroolefins catalyzed by chiral diamine.
[reaction: see text] 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.
Andrey
Olivier
O
Chimie Organique, Sciences II, University of Geneva, Quai Ernest Ansermet, CH-1211, Geneva, Switzerland.
Alexakis
Alexandre
A
Bernardinelli
Gérald
G