Studies on fluoroalkylation and fluoroalkoxylation. Part 33. Direct trifluoromethylation of aryl halides with fluorosulphonyldifluoromethyl iodide in the presence of copper: an electron transfer induced process

Aryl halides are readily trifluoromethylated with fluorosulphonyldifluoromethyl iodide (1) in the presence of copper in DMF in high yield. A single electron transfer (s.e.t.) scavenger, p-dinitrobenzene, and free radical inhibitor, hydroquinone, partly suppress the reaction. Addition of 2,3-dimethylbut-2-ene to the reaction mixture gives a free radical addition-elimination product and difluorocarbene derivatives besides the trifluoromethyl displaced compound. A copper SET-induced mechanism is proposed.