Conjugate addition of diethylzinc to enones catalyzed by homogeneous and supported chiral Ni-complexes. Cooperative effect of the support on enantioselectivity

Chiral t-butylaminocarbonylpyrrolidine acetylacetonate Ni(II) hexafluorophosphate and the corresponding supported complexes on silica and on a modified USY-zeolite are readily prepared. The application of these free and supported complexes as catalysts in the addition of diethylzinc to a series of different substituted enones affords chiral β-ethylated ketones in high yields with an enantiomeric excess up to 95%.