Hydrogen-Bonding-Assisted α-F Elimination from Cu-CF3 for in Situ Generation of R3N·HF Reagents: Reaction Design and Applications.

We report herein a strategy of ammonium hydrogen-bonding-assisted α-F elimination from Cu-CF3 compounds that generates R3N·HF reagents in situ. Combining this strategy and Cu(III)-CF3 chemistry with alkynes, dual fluorination and trifluoromethylation of terminal alkynes is enabled by a single Cu(III)-CF3 compound assisted by a tertiary amine with excellent regio- and stereoselectivity. This strategy also enables the development of other reaction types involving trapping of the in situ-formed R3N·HF reagents by other electrophilic groups and can be used for the late-stage functionalization of estrone derivatives.