Fluorine-18-labeled diethylaminosulfur trifluoride (DAST): an F-for-OH fluorinating agent

A new fluorinating agent was developed by incorporation of 18F into diethylaminosulfur trifluoride (DAST), a reagent capable of replacing hydroxyl and carbonyl oxygen with fluorine. The DAST was synthesized using sulfur tetrafluoride and trimethylsilyldiethylamine in a freon-11 solvent at -78 degrees C and purified by reduced-pressure distillation. Labeling was then accomplished by exchange with anhydrous 18F-hydrofluoric acid, which caused more than 80% of the available activity to be incorporated into the DAST. Fluorine-18-labeled methyl fluoride, ethyl fluoride, and 2-fluoroethanol were prepared from methanol, ethanol, and ethylene glycol, with yields of 20%, 25%, and 12%, respectively.