Biphenol-Based Phosphoramidite Ligands for the Enantioselective Copper-Catalyzed Conjugate Addition of Diethylzinc

Abstract
Phosphoramidite ligands, based on ortho-substituted biphenols and a chiral amine, induce high enantioselectivities (ee's up to 99%) in the copper-catalyzed conjugate addition of dialkylzinc reagents to a variety of Michael acceptors. Particularly, the best reported ee's were obtained for acyclic nitroolefins.