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.