Table . Optimization of PMB-R deprotection / fluorination Switching to NFSI or addition of TEMPO resulted in little to no product confirming a radical-based mechanism involving the 1,4diazoniabicyclo[2.2.2]octane (TEDA) radical cation (See Supporting Information for a plausible mechanism). No reaction occurred in the absence of selectfluor and light (entry 8 and 12, respectively).