Recent progress in aromatic radiofluorination

Abstract

Fluorine-18 is considered to be the radionuclide of choice for positron emission tomography (PET). Thus, the development of small molecule-based radiopharmaceuticals for use in diagnostic imaging relies heavily on efficient radiofluorination techniques. Until the early 2000s, diaryliodonium salts and aryliodonium ylides were widely employed as labeling precursors to yield aromatic PET radiotracers with cyclotron-produced [18F]fluoride ion. Rapid recent progress in the development of efficient borylation methods has led to a paradigm shift in 18F-labeling methods. In addition, deoxyfluorination has attracted a great deal of interest as an alternative approach to aryl ring activation with 18F-. In this review, methods for radiolabel development are discussed with a specific focus on the progress made in the last 5 years. Other interesting 18F-based protocols are also briefly introduced. New methods for exploiting 18F- are expected to increase the number of 18F-labeling methods, to allow applications in a range of chemical environments.