Intramolecular Radical Oxidative Cyclization: Access to Fused-Bicyclo[3.1.0] Hexanes from <i>gem</i>-Dihalo Olefins

Bicyclo[3.1.0] hexanes are valuable compounds due to their significant biological and pharmaceutical importance. Herein, we report a general transition-metal-free approach for the synthesis of benzo-fused bicyco[3.1.0] hexanes using <i>gem</i>-dihaloolefins. The developed protocol involves the intramolecular radical oxidative cyclization of 1-(2,2-dibromovinyl)-2-(phenylethynyl)benzenes using diphenyl diselenide and TBHP. This method avoids the need for expensive transition metal catalysts, external ligands, and prolonged reaction times. This developed protocol facilitates the formation of multiple bonds (two C─C bonds and one C═O bond) in a broad range of substrates including menthol-derived natural products. Mechanistic studies suggest that the reaction proceeds via a radical pathway.