Site-Specific Deoxyfluorination of Small Peptides with [18 F]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-[18 F]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 [18 F]fluoride results in minimal structural perturbation of the peptide, which is desirable in the labeling of tracer candidates.