Mg-Cu bimetal system for selective CF bond activation

► Cu(0) deposits on Mg surface in Mg/CuCl/TMS-Cl/DMI system. ► Bimetal of Cu(0) deposited on Mg surface accelerates defluorination of alkyl trifluoroacetates. ► Mg/CuCl/TMS-Cl/ether-THF (9:1) system induces Grignard reaction of 3-chloro(pentafluoroethyl)benzene rather than defluorination from pentafluoroethyl group.