EFFECT OF LEAVING GROUP SUBSTITUENTS ON THE MICROFLUIDIC SYNTHESIS OF [18F]3-FLUORO-5-[(PYRIDIN-3-YL)ETHYNYL]BENZONITRILE ([18F]FPEB)

A commercial microfluidic reactor system has been used to synthesize the mGLUR5 receptor imaging agent [F-18]FPEB. To study the effect of leaving group substituents on the synthesis of the desired compound, the chloro-, bromo-, iodo-, and nitro-substituted precursors for FPEB were evaluated. Precursor concentrations of 4 - 10 mg/mL were evaluated in various solvents, with temperature ranges between 120 and 220 degrees C, and total processing times of less than five minutes. Optimized incorporation yields ranged from 5% to 69.4% depending on the precursor used.