Propargyl 4-[F]fluorobenzoate: A Putatively More Stable Prosthetic group for the Fluorine-18 Labeling of Biomolecules via Click Chemistry.

Faster and more efficient approaches for radiolabeling biomolecules with short-lived (18)F are in dire need. Herein we report a new (18)F-labeled prosthetic group containing an acetylene function that permits the labeling of biomolecules via click chemistry. This template, propargyl 4-[(18)F]fluorobenzoate ([(18)F]PFB) was synthesized from a quaternary salt precursor in decay-corrected radiochemical yields of 58 +/- 31%. Several model compounds containing an azide moiety-benzyl azide, two lysine derivatives and a transglutaminase-reactive peptide-were labeled using [(18)F]PFB via a click reaction in decay-corrected radiochemical yields of 88 +/- 4%, 79 +/- 33%, 75 +/- 5%, and 37 +/- 31%, respectively. Our results suggest that the novel agent [(18)F]PFB is a potentially useful template for the (18)F-labeling of biomolecules via click chemistry.