Wavelength-Dependent C−H/C−F Chemoselectivity in Photo-Mediated Silacyclizations

Abstract We report a wavelength-dependent photo-mediated silacyclization of allylbenzenes with dihydrosilanes that enables selective C–F or C–H bonds functionalization to synthesize six-membered benzosilacycles. Blue-light irradiation promotes defluorosilacyclization, whereas UV light triggers an acceptorless dehydrosilacyclization accompanied by hydrogen gas evolution. This tunable platform offers broad substrate scope, operational simplicity, and access to diverse benzosilacyclic frameworks via photocatalytic C–Si bond formation.