Asymmetric conjugate addition of α-keto esters to nitroolefins catalyzed by chiral CuII hydroxo complexes

As a part of our research project on hard anion-late transition metal complexes as mild acid-base catalysts, we describe herein that Cu-II hydroxo complexes having chiral N-substituted-diaminocyclohexanes are mild and selective catalysts, which are applicable to the catalytic asymmetric conjugate addition of alpha-keto esters to nitroolefins. The reaction proceeded diastereoselectively without the detectable formation of self-aldol products, affording the corresponding coupling products with anti-stereochemistry in an enantioselective manner. (C) 2010 Elsevier Ltd. All rights reserved.