Site‐Specific Deoxyfluorination of Small Peptides with [18F]Fluoride

Radiolabeled receptor‐binding peptides are an important class of positron emission tomography tracers owing to achievable high binding affinities and their rapid blood clearance. Herein, a method to introduce a 4‐[18F]fluoro‐phenylalanine residue into peptide sequences is reported, by chemoselective radio‐deoxyfluorination of a tyrosine residue using a traceless activating group. The replacement of only one hydrogen atom with [18F]fluoride results in minimal structural perturbation of the peptide, which is desirable in the labeling of tracer candidates.