Diastereo- and Enantioselective Conjugate Addition of α-Ketoesters to Nitroalkenes Catalyzed by a Chiral Ni(OAc)2 Complex under Mild Conditions

A highly efficient, catalytic, diastereo- and enantiosetective conjugate addition of aketoesters to nitroatkenes has been devised. The reaction was applicable to various substrates. Notably, the combination of endogenous and exogenous bases was effective, allowing a small amount of the catalyst (0.1-1 mol % Ni) to promote the reaction efficiently. The synthetic utility of this reaction was demonstrated in the synthesis of substituted pyrrolidine derivatives, whose stereochemistry is closely related to biologically important natural products such as kainic acid.