Scope of sydnone-mediated 18F fluorination. Reaction conditions: precursor (25 μmol), Et4NHCO3 (50 μmol), DMSO (200 μL), [18F]fluoride (300 μCi), 150 °C, 5 min. RCC was determined by radio-TLC. The identity of each labeled product was confirmed by radio-HPLC; a10 min. b15 min. c20 min. dRCC reported as radio-TLC conversion multiplied by radio-HPLC fraction of identified product.