Functionalization of Vinyl-Substituted Cyclosiloxane and Cyclosilazane via Ruthenium-Catalyzed Silylative Coupling Reaction

A new type of functionalization of cyclosiloxane and cyclosilazane is reported. Commercially available vinyl-substituted cyclosiloxane and cyclosilazane can be converted chemo- and regioselectively to styryl- and β-alkoxyvinyl-substituted derivatives via respective silylative coupling reactions with styrene and vinyl alkyl ethers catalyzed by RuHCl(CO)(PCy₃)₂. The obtained cis-tristyrylcyclotrisiloxane showed a unique arrangement of the three styryl groups through face-to-face and side-by-side π−π interactions. Pd-catalyzed Hiyama coupling reaction of synthesized β-n-butoxyvinyl-substituted cyclosiloxane with iodobenzene was also performed to afford β-n-butoxystyrene regioselectively.