Silver-promoted (radio)fluorination of unsaturated carbamates via a radical process.

The intramolecular fluorocyclization of unsaturated carbamates is described here using a hypervalent iodine reagent in the presence of a silver catalyst. Both (hetero)aryl-substituted olefins and acrylamides can be utilized as effective substrates. Preliminary mechanistic investigations suggest that the reaction proceeds via a cyclization/1,2-(hetero)aryl migration/fluorination cascade involving an unusual radical process. Furthermore, starting from no-carrier-added [18F]TBAF, a simple one-pot, two-step cascade method was developed for the generation of 18F-labeled heterocycles with high radiochemical purity.