Remarkable enhancement of Lewis acidity of chlorosilane by the combined use of indium(III) chloride

A combination of InCl3 and R3SiCl provided a strong Lewis acid catalyst for such reactions as allylation, hydrosilation and Friedel–Crafts alkylation. Especially, catalytic Sakurai–Hosomi-type allylation was accomplished with high yield and selectivity. The silicon atom is assumed to be the acidic center of the combined system, and the catalytic activity largely depends on the substituents on the silicon center.