Aminohydroxyphosphine ligand for the copper-catalyzed enantioselective conjugate addition of organozinc reagents

An alanine-derived aminohydroxyphosphine ligand was developed for copper-catalyzed asymmetric conjugate addition of organozinc reagents to α,β-unsaturated carbonyl compounds. This new tridentate ligand induces consistently high enantioselectivity in reactions of a variety of acyclic substrates. Theoretical mechanistic analysis suggests that the C-C bond formation takes place through a highly ordered transition state by the coordination of the phosphorus and nitrogen atoms to the copper(III) and zinc(II) atoms, respectively, and of the oxygen anion to both the metal centers.