Highly Selective Synthesis of Hydrosiloxanes by Au-Catalyzed Dehydrogenative Cross-Coupling Reaction of Silanols with Hydrosilanes

We report a highly selective synthesis of siloxane building blocks containing SiH2 or SiH functionalities. AuCl(PPh3)/PPh3 or AuCl(PPh3)/PnBu3 system catalyzed the reaction of trihydrosilanes with silanols giving SiH2-containing siloxanes exclusively. On the other hand, a highly selective reaction of dihydrosilanes with silanols to afford SiH-containing siloxanes was achieved by simply changing the phosphine ligand to a bidentate one, xantphos. Usefulness of SiH2-containing siloxanes was demonstrated by the synthesis of a trisiloxane, Et3SiOSi(Ph)(H)OSitBuMe2, and a pentasiloxane, Ph2Si(OSiHPhOSiEt3)2, bearing SiH functionalities.