Radiosynthesis of [11C]SL25.1188 via [11C]CO2 fixation for imaging monoamine oxidase B

Carbon‐11‐labelled (S)‐5‐methoxymethyl‐3‐6‐(4,4,4‐trifluorobutoxy)benzod]isoxazol‐3‐yl]oxazolidin‐2‐¹¹C]‐one (¹¹C]SL25.1188), a promising reversibly binding radiotracer for imaging central monoamine oxidase B, was rapidly prepared via an intramolecular cyclization reaction in an automated one‐pot procedure directly from ¹¹C]CO₂, thereby precluding the use of ¹¹C]COCl₂. Formulated ¹¹C]SL25.1188 was isolated in 12 ± 1% uncorrected radiochemical yield, based on starting ¹¹C]CO₂, with a specific activity of 37 ± 2 GBq/µmol at the end of synthesis (30 min; n = 3). Radiochemical and enantiomeric purities were both >99%. The methodology described herein offers an efficient production of ¹¹C]SL25.1188 at ambient temperature and is suitable for human imaging studies.