Co(salen)-mediated enantioselective radiofluorination of epoxides. Radiosynthesis of enantiomerically enriched [18F]F-MISO via kinetic resolution

The first example of transition metal mediated enantioselective radiofluorination of epoxides is reported. The procedure utilizes gaseous [18F]HF in a combination with (−)tetramisole and (R,R)-Co(salen), giving the corresponding (S,S)-18F-fluorohydrines in 78–93% radiochemical yield (RCY) and 20–46% enantioselectivities (ee). The use of this methodology allowed for a single step radiosynthesis of [18F]F-MISO, which took 1.5 h and after solid phase-based purification delivered [18F]F-MISO in 81%/45% analytical/preparative RCY and 55% ee.