Catalytic asymmetric vinylation of ketones

ORGN 96

Hongmei Li and Patrick J. Walsh. Department of Chemistry, University of Pennsylvania, 231 S. 34th St., 221, philadelphia, PA 19104
Catalytic asymmetric 1, 2-addition of vinylzinc reagents to aromatic α,β-unsaturated, and dialkyl ketones gave good enantionselectivies between 79-97% and good yields ranging from 84-98%. The reaction involves hydrozirconation of a terminal alkyne, transmetallation to zinc, and addition to a ketone in the presence of a chiral titanium-based Lewis acid catalyst. The reactions proceed smoothly at room temperature under 20 h. The products of these reactions are tertiary allylic alcohols with chiral quaternary centers that are useful in organic synthesis.