Regio- and Diastereoselective Cascade Reactions of Bicyclo[1.1.0]butanes: Access to gem-Difluorinated Carbocyclic Rings

gem -Difluorinated carbocyclic rings are attractive motifs in drug development. Herein, we report the transition-metal free cascade reaction of bicyclo[1.1.0]butanes (BCBs) with gem -difluorocyclopropenes for the synthesis of gem -difluorinated carbocyclic rings with excellent regio- and diastereoselectivity. This method was successfully applied to provide a broad range of gem -difluorinated cyclopentenes and cyclopropanes, which could undergo a variety of difluoromethylene (CF 2 ) retaining transformations.