"Ligandless" Pentafluoroethylation of Unactivated (Hetero)aryl and Alkenyl Halides Enabled by the Controlled Self-Condensation of TMSCF-Derived CuCF.

Pentafluoroethylation of unactivated C(sp)-X bonds (X = I, Br) using a storable, "ligandless" CuCF reagent prepared by controlled self-condensation of ready available TMSCF-derived CuCF has been developed. A thorough analysis by F NMR and ESI-MS revealed the nature of this reagent in solution. The operational simplicity and robustness of this system enables the efficient, late-stage incorporation of CF units into a variety of (hetero)aryl and complex alkenyl halides such as glycals, nucleosides, and nucleobases.