Asymmetric Carbonyl-Ene Reaction Catalyzed by Chiral N,N′-Dioxide-Nickel(II) Complex: Remarkably Broad Substrate Scope

Highly enantioselective carbonyl-ene reaction of glyoxal derivatives and glyoxylate with various alkenes was accomplished using a novel nickel (II)-N,N'-dioxide complex under mild conditions, which facilitated the asymmetric synthesis of biologically interesting a-hydroxy carbonyl compounds. Various aromatic, aliphatic, and heteroaromatic glyoxal derivatives, as well as glyoxylate, could be tolerated in this system and afforded the corresponding adducts in excellent enantioselectivities (97->99% ee) with high yields. Moreover, the catalyst loading could even be decreased to 1 mol%, while the enantioselectivity was basically maintained.