Recently a novel method for the preparation of (18)F-labeled arenes via oxidative [(18)F]fluorination of easily accessible and sufficiently stable nickel complexes with [(18)F]fluoride under exceptionally mild reaction conditions was published. The suitability of this procedure for the routine preparation of clinically relevant positron emission tomography (PET) tracers, 6-[(18)F]fluorodopamine (6-[(18)F]FDA), 6-[(18)F]fluoro-l-DOPA (6-[(18)F]FDOPA) and 6-[(18)F]fluoro-m-tyrosine (6-[(18)F]FMT), was evaluated. The originally published base-free method was inoperative. However, a "low base" protocol afforded protected radiolabeled intermediates in radiochemical conversions (RCCs) of 5-18 %. The subsequent deprotection step proceeded almost quantitatively (>95 %). The simple one-pot two-step procedure allowed the preparation of clinical doses of 6-[(18)F]FDA and 6-[(18)F]FDOPA within 50 min (12 and 7 % radiochemical yield, respectively). In an unilateral rat model of Parkinsons disease, 6-[(18)F]FDOPA with high specific activity (175 GBq mumol(-1)) prepared using the described nickel-mediated radiofluorination was compared to 6-[(18)F]FDOPA with low specific activity (30 MBq mumol(-1)) produced via conventional electrophilic radiofluorination. Unexpectedly both tracer variants displayed very similar in vivo properties with respect to signal-to-noise ratio and brain distribution, and consequently, the quality of the obtained PET images was almost identical.
Zlatopolskiy, B. D., Zischler, J., Urusova, E. A., Endepols, H., Kordys, E., Frauendorf, H., Mottaghy, F. M., & Neumaier, B. (2015). A Practical One-Pot Synthesis of Positron Emission Tomography (PET) Tracers via Nickel-Mediated Radiofluorination. Chemistry Open, 4(4), 457-462. https://doi.org/10.1002/open.201500056