Indium-Catalyzed Radical Reductions of Organic Halides with Hydrosilanes

The In(OAc)3-catalyzed reaction of bromo- and iodoalkanes with PhSiH3 in THF at 70 degrees C gave dehalogenated alkanes in good to high yields. In the presence of Et3B and air, the reduction proceeded smoothly at 30 degrees C. When 2,6-lutidine and air were used as additives, the In(OAc)3-catalyzed system enabled an efficient reduction of simple and functionalized iodoalkanes in EtOH. Catalytic use of GaCl3 was found to be effective in the reduction of haloalkanes with poly(methylhydrosiloxane) (PMHS). These catalytic reductions probably involve a radical chain mechanism in which indium or gallium hydride species work as the actual reductants.