Cupration of C2F5H: isolation, structure, and synthetic applications of [K(DMF)2][(t-BuO)Cu(C2F5)]. Highly efficient pentafluoroethylation of unactivated aryl bromides.

Pentafluoroethane, C2F5H (HFC-125), is smoothly cuprated with preisolated or in situ-generated [K(DMF)][(t-BuO)2Cu] to give [K(DMF)2][(t-BuO)Cu(C2F5)] (1) in nearly quantitative yield. Complex 1 has been isolated, structurally characterized, and demonstrated to be an exceedingly versatile pentafluoroethylating reagent for a variety of substrates, including unactivated aryl bromides.