Accessing CF3-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 enabled access to highly-substituted trifluoromethylated cyclopropanes, difluoromethylene cyclopropanes and non-cyclic trifluoromethylated compounds.