Excess phosphine ligand plays a critical role in the asymmetric copper(I) iodide-catalyzed conjugate addition of grignard reagents to α,β- unsaturated esters

The role of excess ligand in the asymmetric 1,4-conjugate addition (ACA) of Grignard reagents to α,β-unsaturated esters compounds catalyzed by copper(I) iodide-2,2′-bis(di-p-tolylphosphino)-1,1′-binaphthyl (CuI-Tol-BINAP) is explored herein. In addition, this methodology allows asymmetric induction to be carried out using a non-chiral phosphine copper complex with excess of a chiral phosphine ligand.