Additive‐Free Synthesis of Trifluoromethylated Spiro Cyclopropanes and Their Transformation into Trifluoromethylated Building Blocks

An efficient additive‐free cyclopropanation of 2‐arylideneindane‐1,3‐dione has been realized employing trifluorodiazoethane. This mild protocol displays good functional group tolerance to deliver trifluoromethylated cyclopropanes in high yields. The synthetic potential of the strategy has been explored by the expedient synthesis of CF3‐containing spiro‐pyrrolines and organo‐sulfur scaffolds. Moreover, this protocol provides an interesting substrate for regioselective Friedel‐Crafts alkylation. An efficient additive‐free cyclopropanation of 2‐arylideneindane‐1,3‐dione has been realized employing trifluorodiazoethane. The synthetic potential of the strategy has been explored by transforming these novel cyclopropanes into various CF3‐containing structural units.