Highly enantioselective 1,4-conjugate addition of diethylzinc to acyclic enones with chiral phosphite–pyridine ligands derived from H8-NOBIN

A series of new phosphite–pyridine ligands, based on the H₈-binaphthyl backbone, were synthesized and employed in the copper-catalyzed enantioselective 1,4-conjugate addition of diethylzinc to acyclic enones. Ligands derived from (S)-H₈-NOBIN provided better results than their parent ligands in the reaction. Ligand L1 provided excellent ees for trans-4-aryl-3-buten-2-ones (up to 97.8% ee) as substrates. Ligand L2 was very efficient for various para-chalcones, and up to 97.2% ee was achieved.