Wittig olefination and thiol mediated 7-endo-trig radical cyclization: novel synthesis of oxepin derivatives

Thiophenol-mediated 7- endo radical cyclization for the synthesis of seven-membered cyclic ethers is described. This method can be successfully applied to synthesize various benzoxepin derivatives, which are present in many natural products as building blocks. Alkenyl radicals are generated from easily available terminal alkynes and thiophenol.