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.