Radical C-H Fluorination Using Unprotected Amino Acids as Radical Precursors.

We report a unique example of utilizing unprotected amino acids for benzylic C-H fluorination via a radical process. α-Aminoalkyl radicals are readily generated via oxidative decarboxylation of unprotected amino acids using a simple silver(I) catalyst and Selectfluor, which serves as both a mild oxidant and source of electrophilic fluorine. Mechanistic investigation shows that coordination of the unprotected amino acid plays a crucial role in lowering the oxidation potential of Ag(I), enabling oxidation under mild conditions. Mono- or difluorination is possible by controlling the stoichiometry of amino acid and fluorine source.