N,O,P-Ligand for Cu(II)-Catalyzed Enantioselective Conjugate Additions

Significance

Using a tridentate N,O,P-ligand, copper(II)-catalyzed addition of organozinc nucleophiles to acyclic enones gave uniformly high enantioselectivities (÷98% ee). The method is important as the acyclic enones are known to be challenging substrates for enantioselective 1,4-additions of cuprate nucleophiles. The reaction tolerated a wide variety of substituents at the β-position (R¹). A significant advantage is the ease with which the ligand can be varied, as it is synthesized in one step from configurationally stable amino aldehyde derivatives (M. T. Reetz Chem. Rev. 1999, 99, 1121-1162).