Synthesis of silafluorenes and silaindenes via silyl radicals from arylhydrosilanes: intramolecular cyclization and intermolecular annulation with alkynes

Intramolecular homolytic aromatic silylation of biphenyl-2-hydrosilanes via silyl radicals has been developed for the synthesis of silafluorenes. Moreover, silaindenes are synthesized via a silyl radical cascade process, assembling internal alkynes with readily available arylhydrosilanes by C-H and Si-H cleavage and C-C and C-Si bond formation in one step. These represent a new simple and efficient approach towards the synthesis of benzosilole derivatives.