Recent advances in transition metal-mediated/ catalyzed radiofluorination of arenes and heteroarenes for positron emission tomography

Abstract

Positron emission tomography (PET) imaging endows the possibility of precise diagnosis and effective treatment of diseases. Aromatic (hetero)cycle is one of the most fundamental groups in pharmaceuticals as well as in the development of PET tracers. In particular, incorporation of ¹⁸F to aromatic (hetero)cycles has accelerated the progress of nuclear medicine tracers. Current trend indicates a rapid progress in ¹⁸F-labeling of aromatic (hetero)cycles for PET imaging. Transition metal-catalyzed ¹⁸F-labeling method speeds up the reaction by lowering the activation energy of the substrate by the metal complex. The reaction conditions are mild, and a wide range of substrates can be used. In this article we systematically reviewed the methods of radioactive ¹⁸F-labeling of aromatic (hetero)cycles with different precursors mediated by transition metals‑copper, ruthenium, nickel, palladium, silver, and titanium. The precursors, radiolabeling conditions, catalytic efficiency, catalytic mechanism, optimization of transition metal-catalyzed ¹⁸F-labeling methods, and corresponding frontier applications of ¹⁸F-labeled molecular probes were discussed.