Controllable Double Difluoromethylene Insertions into S-Cu Bonds: (Arylthio)tetrafluoroethylation of Aryl Iodides with TMSCF 2 Br.

A new method of constructing "ArSCF 2 CF 2 Cu" from ArSCu and TMSCF 2 Br (TMS=trimethylsilyl) has been developed. The cross-coupling reactions of the obtained "ArSCF 2 CF 2 Cu" with diverse aryl iodides (Ar'I) provide an efficient access to Ar'CF 2 CF 2 SAr. Mechanistic studies demonstrate that the "ArSCF 2 CF 2 Cu" species were generated through controllable double difluoromethylene insertions into ArS-Cu bonds rather than the 1,2-addition of ArSCu to tetrafluoroethylene.