Organotrifluoroborates as prosthetic groups for Single-Step F18-Labeling of Complex Molecules

To meet the long-standing challenge of a one-step, last-stage aqueous radiofluorination method for labeling large, water-soluble molecules such as peptides, we sought a mild aqueous fluorination reaction that uses organoboron compositions, which are readily fluorinated in mild aqueous acid to give ¹⁸F-labeled organotrifluoroborates. This robust reaction now provides new ¹⁸F-labeled radioprosthetic groups that can be pre-conjugated to peptides and other polar molecules, and then labeled with aqueous no-carrier-added (NCA) [¹⁸F]fluoride ion in a single step. A key application facilitated by this method is the production of ¹⁸F-labeled fluorescent-PET tracers. The development of these radioprosthetics, their elaboration onto peptides, and their extension to fluorescent bioconjugates is the focus of this review.