Sequential Conversion of Vinyl Triflates to 1,2-Disilanes via Technical Control of Magnesium and Calcium Reducibility Differences.

Reductive direct substitution of α-arylvinyl triflates on the sp carbon atom by magnesium in the presence of chlorosilane proceeded to give the corresponding α-silylstyrenes, which could not be reduced further, and the reaction completely stopped because the reduction potential of α-silylstyrenes lies out of the reducible field of magnesium. The subsequent reduction of α-silylstyrenes by calcium brought about the second introduction of another silyl group to the vicinal carbon atom to lead a selective and simple route to a variety of 1,2-disilanes from vinyl triflates by cooperative works of magnesium and calcium with different reduction potentiality.