Synthesis of carbon-11-labeled piperidine ring of N-[ω-(6-methoxynaphthalen-1-yl)alkyl] derivatives as new selective PET σ1 receptor probes

Carbon-11-labeled piperidine ring of N-[ω-(6-methoxynaphthalen-1-yl)alkyl] derivatives were first designed and synthesized as new selective PET σ1 receptor probes. The target tracers were prepared by O-[11C]methylation of their corresponding phenolic hydroxyl precursors using [11C]CH3OTf under basic conditions and isolated by a simplified SPE method in 40-50% radiochemical yields based on [11C]CO2 and decay corrected to EOB. The overall synthesis time from EOB was 15-20 min, the radiochemical purity was >99%, and the specific activity at EOS was 111-185 GBq/μmol.