Cu-Mediated C-H 18 F-Fluorination of Electron-Rich (Hetero)arenes.

This communication describes a method for the nucleophilic radiofluorination of electron-rich arenes. The reaction involves the initial C(sp ² )-H functionalization of an electron-rich arene with MesI(OH)OTs to form a (mesityl)(aryl)iodonium salt. This salt is then used in situ in a Cu-mediated radiofluorination with [ ¹⁸ F]KF. This approach leverages the stability and availability of electron-rich arene starting materials to enable mild late-stage radiofluorination of toluene, anisole, aniline, pyrrole, and thiophene derivatives. The radiofluorination has been automated to access a 41 mCi dose of an ¹⁸ F-labeled nimesulide derivative in high (2800 ± 700 Ci/mmol) specific activity.