Synthesis of a radiotracer for studying serotonin uptake sites with positron emission tomography: [11C]McN‐5652‐Z

The highly potent serotonin (5‐HT) uptake blocker, McN‐5652‐Z (trans‐1,2,3,5,6,10b ‐ hexahydro ‐ 6 ‐ [4 ‐ (methylthio)phenyl] pyrrolo ‐ [2,1‐a]‐isoquinoline) was labeled with 11C for studying serotonin uptake sites using positron emission tomography (PET). [11C]McN‐5652‐Z was synthesized by S‐methylation of the normethyl precursor with [11C]iodomethane in DMF at 30 ‐ 35° C. The radiosyntheses including purification by HPLC and formulation for injection were completed in an average of 16 minutes following the end of bombardment (E.O.B.) with an overall radiochemical yield of 12%. The average specific activity determined at the end of synthesis (E.O.S.) was approximately 4250 mCi/μmole; this corresponds to approximately 7350 mCi/μmole at E.O.B. [11C]McN‐5655‐Z, a less potent blocker, was also prepared by the same procedure.