Masayasu Igarashi

Pd/C-catalyzed cross-coupling reaction of benzyloxysilanes with halosilanes for selective synthesis of unsymmetrical siloxanes

A new protocol for the nonhydrolytic synthesis of unsymmetrical siloxanes has been developed. The cross-coupling reaction of benzyloxysilanes with halosilanes catalyzed by Pd/C afforded various unsymmetrical siloxanes with co-production of benzyl halides.

Non-aqueous selective synthesis of orthosilicic acid and its oligomers

Orthosilicic acid (Si(OH)4) and its small condensation compounds are among the most important silicon compounds but have never been isolated, due to their instability. These compounds would be highly useful building blocks for advanced materials if they became available at high purity. Here we show a simple procedure to selectively synthesize orthosilicic acid and its dimer, cyclic trimer and tetramer in organic solvents. Isolation of orthosilicic acid, the dimer and the cyclic tetramer as hydrogen-bonded crystals with tetrabutylammonium halides and the cyclic trimer as solvent-containing crystals is also described. The solid-state structures of these compounds are unambiguously clarified by single crystal X-ray and neutron diffraction studies. The usefulness of orthosilicic acid and its oligomers prepared by the new procedure is demonstrated by the synthesis of functionalized oligosiloxanes.Orthosilicic acid is essential to many natural and synthetic materials but notoriously difficult to isolate, limiting its use in materials synthesis. Here, the authors successfully synthesize and stabilize orthosilicic acid and its oligomers, making available a new family of building blocks for silicon oxide-based materials.