Direct arene C–H fluorination with 18 F − via organic photoredox catalysis

A metal-free route to PET probes Positron emission tomography (PET) is a widely used imaging technique for medical diagnostics and pharmaceutical development. As the name implies, it requires tracers that emit positrons, typically through labeling with fluorine or carbon radioisotopes. W. Chen et al. devised a versatile technique to incorporate radioactive fluoride into aromatic rings. The metal-free photochemical method directly substitutes aryl carbon-hydrogen bonds with [ 18 F]fluoride and so is particularly well suited to late-stage transformation of complex molecules into tracers. Science , this issue p. 1170