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.
Wu et al. (2026) studied this question.