title: Dramatic improvement of the enantiomeric excess in the asymmetric conjugate addition reaction using new experimental conditions.
abstract: The asymmetric conjugate addition of dialkylzincs is usually performed with Cu(OTf)(2) in toluene. We show that by using a copper carboxylate in Et(2)O, THF, or EtOAc, we strongly improve the enantioselectivity with a given ligand. Ee values up to 99.1% could be reached with new ligands based on the induced atropisomerism of a simple biphenol unit. In addition, we show that the Lewis acid effect of Cu(OTf)(2) is not a significant.
authors: Department of Organic Chemistry, University of Geneva, 30, Quai Ernest Ansermet, 1211 Geneva 2, Switzerland.
authors: A
authors: A
authors: Alexakis
authors: C
authors: C
authors: Benhaim
authors: S
authors: S
authors: Rosset
authors: M
authors: M
authors: Humam