Electrochemical no-carrier-added radiofluorination of thioethers

We report a method for no-carrier-added radiofluorination of thioethers, which are promising candidates for new Positron Emission Tomography tracers. For the first time > 100 MBq of 18F-fluorinated thioethers were produced by electrochemical radiofluorination carried out in the absence of non-radioactive fluorination agents. This is an unexpected achievement since multiple previous reports on this topic consistently demonstrated that high amount of stable [19F]fluoride is needed for reasonable radiochemical yields. Here, we show that addition of an auxiliary stabilizing agent eliminates the need for excess [19F]fluoride, thus enabling electrochemical [18F-]radiolabelling of thioethers.