The first radiosynthesis of 2-amino-5-[<sup>18</sup>F]fluoropyridines <i>via</i> a “minimalist” radiofluorination/palladium-catalyzed amination sequence from anisyl(2-bromopyridinyl)iodonium triflate
synthesis of 2-amino-5-[18F]fluoropyridines was achieved in 8-85% yields by palladium-catalyzed reaction of 2-bromo-5-[18F]fluoropyridine with piperidine, dimethylamine, butylamine, methylpiperazine, benzylamine, aniline and 3-aminopyridine. 2-Bromo-5-[18F]fluoropyridine was obtained by radiofluorination of anisyl(2-bromopyridinyl-5)iodonium triflate (88% yield). The radiofluorination step was performed
Development, Optimization, and Scope of the Radiosynthesis of 3/5-[<sup>18</sup>F]Fluoropyridines from Readily Prepared Aryl(pyridinyl) Iodonium Salts: The Importance of TEMPO and K<sub>2</sub>CO<sub>3</sub>
A robust process for the radiosynthesis of 3/5-[F-18]fluoropyridines has been developed by radiofluorination of iodonium triflates using (KF)-F-18/(KCO3)-C-2/K-222 complex in the presence of TEMPO. Both electronically deficient and enriched iodonium salts were readily obtained from the corresponding 3/5-iodopyridines and afforded the corresponding 3/5-[F-18]fluoropyridines in 6-78% yields. The concentrations of K2CO3 and TEMPO were found to be crucial for the radiofluorination efficiency. The process was validated using two automated systems for the F-18-radiolabeling of 2-chloro and 2-carboxamido-5-fluoropyridines carried out in 10-20% yields.