Difluorocarbene‐Derived Trifluoromethylthiolation and [ 18 F]Trifluoromethylthiolation of Aliphatic Electrophiles

The first trifluoromethylthiolation and [ 18 F]trifluoromethylthiolation of alkyl electrophiles with in situ generated difluorocarbene in the presence of elemental sulfur and external (radioactive) fluoride ion is described. This transition‐metal‐free approach is high yielding, compatible with a variety of functional groups, and operated under mild reaction conditions. The conceptual advantage of this exogenous‐fluoride‐mediated transformation enables unprecedented syntheses of [ 18 F]CF 3 S‐labeled molecules from most commonly used [ 18 F]fluoride ions. The rapid radiochemical reaction time (≤1 min) and high functional‐group tolerance allow access to a variety of aliphatic [ 18 F]CF 3 S compounds in high yields.