Potassium-Catalyzed Hydrosilylation of Activated Olefins: Evidence for a Silyl Migration Mechanism

The alkali-metal silyl [K­(L)­SiPh3] (1; L = 18-crown-6 ether) catalyzed the hydrosilylation of activated CC double bonds. Isolation and characterization of an addition product is in agreement with the anti-Markovnikov selectivity. Second-order kinetics for the hydrosilylation of 1,1′-diphenylethylene and the kinetic isotope effect of kH/kD = 3.1 indicate that a silyl migration mechanism is operative.