substrates having a bulky substituent, such as a tert-Bu group, at the beta-position give high yields. Bulkiness is also required in cyclic alpha,beta-unsaturated ketones, but the effect is small. In alkyl vinyl ketones, the reactivity decreased with the steric bulk of the alkyl group. In aryl vinyl ketones, the presence of an electron-donating group on the aromatic ring decreases the reactivity. The