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)benzo[d]isoxazol-3-yl]oxazolidin-2-[C-11]-one ([C-11]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 [C-11]CO2, thereby precluding the use of [C-11]COCl2. Formulated [C-11]SL25.1188 was isolated in 12 +/- 1% uncorrected radiochemical yield, based on starting [C-11]CO2, with a specific activity of 37 +/- 2 GBq/mu mol 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 [C-11]SL25.1188 at ambient temperature and is suitable for human imaging studies.