Catalytic Enantioselective Conjugate Addition of Dialkylzinc Compounds to Chalcones.

Conjugate addition of diethylzinc to enones is catalyzed by a complex derived from Ni(acac)2 and C2-symmetric 2,2′-bipyridine 3 or chiral pyridines 5–12. The products are obtained with optical purities up to 89% ee. A strong positive nonlinear relationship between the enantiomeric excess of the ligand and the ee of the product has been observed. The factors which govern catalyst activity and enantioselectivity have been investigated.