Enantioselective Michael addition of malonates to beta,gamma-unsaturated alpha-ketoesters catalysed by Cu(ii) complexes bearing binaphthyl-proline hybrid ligands

High yields (up to 96%) and high ee (up to 92%) were achieved for chiral copper(ii) complex-catalysed enantioselective Michael addition of malonates to beta,gamma-unsaturated-alpha-ketoesters. The chiral ligands took advantage of both the binaphthyl and the proline moieties, and substituents with different electronic and steric features could be tolerated. The reactions could be carried out under mild conditions, and a gram scale reaction could be realised without the loss of yield and enantioselectivity.