Single C-F Bond Activation of the CF 3 Group with a Lewis Acid: CF 3 -Cyclopropanes as Versatile 4,4-Difluorohomoallylating Agents

The selective activation of one C-F bond (single activation) of the CF group on cyclopropanes was achieved for the first time. When (trifluoromethyl)cyclopropanes were treated with arenes, allylsilanes, silyl enol ethers, or hydrosilanes in the presence of Me AlCl, fluoride elimination and the subsequent ring opening proceeded to afford 4,4-difluorohomoallylated products. In the absence of external nucleophiles, an alkyl group of AlR was effectively introduced to provide the corresponding 1,1-difluoroalkenes.