Abstract
The radiofluorination of N-heterocyclic carbene (NHC) boron trifluoride adducts affords novel [(18)F]-positron emission tomography probes which resist hydrolytic fluoride release. The labelling protocol relies on an (18)F-(19)F isotopic exchange reaction promoted by the Lewis acid SnCl4. Modification of the NHC backbone with a maleimide functionality provides access to a model peptide conjugate which shows no evidence of defluorination when imaged in vivo.