Accessing CF ₃ -Cyclopropenes ─ A Platform for the Synthesis of Trifluoromethylated Building Blocks

Cyclopropenes are the smallest unsaturated carbocycles. They possess exceptionally high ring strain, resulting in unique reactivity, enabling C═C bond functionalization and ring-opening transformations. Herein, we report a copper-mediated trifluoromethylation of cyclopropenyl benziodoxole (CpBX) reagents, providing access to previously inaccessible, yet highly useful, sp²-trifluoromethylated cyclopropenes. Subsequent functionalizations of these novel strained ring building blocks enable access to highly substituted trifluoromethylated cyclopropanes, difluoromethylene cyclopropanes and noncyclic trifluoromethylated compounds.