Metal ion-complexes of α,β-unsaturated ketones acting as actual reactive species in Michael addition of ketene silyl acetal

The Michael addition of β,β-dimethyl-substituted ketene silyl acetal [Me₂C=C(OMe)OSiMe₃] with α,β-unsaturated ketones occurs efficiently in the presence of magnesium perchlorate or lutetium trifluoromethanesulfonate in acetonitrile at 298 K via the 1 : 1 complexes between α,β-unsaturated ketones and the metal ion, in which the coordination of the metal ion enhances the electrophilicity of α,β-unsaturated ketones to accelerate the reaction rate.