F-Trifluoromethanesulfinate Enables Direct C-H F-Trifluoromethylation of Native Aromatic Residues in Peptides.

F labeling strategies for unmodified peptides with [F]fluoride require F-labeled prosthetics for bioconjugation more often with cysteine thiols or lysine amines. Here we explore selective radical chemistry to target aromatic residues applying C-H F-trifluoromethylation. We report a one-step route to [F]CFSONH from [F]fluoride and its application to direct [F]CF incorporation at tryptophan or tyrosine residues using unmodified peptides as complex as recombinant human insulin.