Synthesis of18F-radiolabeled organophosphine fluorides for thiol-chemoselective peptide conjugation

Two(18)F-radiolabeled organofluorophosphine fluorides ([F-18]4and [F-18]7) for chemoselective thiol-conjugation were designed and synthesized via(18)F-F-19 isotopic exchange reaction. This simple and rapid radiofluorination produced both(18)F-radiolabeled fluorides in excellent radiochemical yields (>94%) and radiochemical purity. The optimal reaction conditions are 0.05-mg substrate, 0.69 mg of potassium carbonate, and dried [F-18]F(-)were mixed in 100-mu l anhydrous acetonitrile at room temperature for 5 min. Both of [F-18]4and [F-18]7showed specificity for thiol-conjugation with cysteine and have been used in the radiosynthesis of c (RGDfC). The [F-18]7with an adamantanyl-hindered substituent displayed superior in vitro and in vivo stability.