Copper-catalyzed enantioselective 1, 4-reduction of α, β-unsaturated ketones using some air and moisture stable Cu (II) pre-catalysts

Abstract

Some air and moisture stable Cu (II) salts were successfully used as catalyst precursors in asymmetric conjugate reduction of α, β-unsaturated ketones. There into, highly effective copper precatalysts were CuF2, Cu (OAc)2•H2O, Cu (acac)•1/2H2O, Cu (CF3COO)2•H2O and some other copper carboxylates. Compared with previous catalyst precursor (CuCl/NaOt-Bu), these catalyst precursors are not only easier to handle but also capable of avoiding the use of NaOt-Bu. In addition, it was founded that the addition of H2O could inhibit 1, 2-reduction and enhance the selectivity of 1, 4- reduction. An alcohol acceleration effect was also observed in the asymmetric conjugate reduction of α, β-unsaturated ketones.