An improved method for the synthesis of radiolabeled McN5652 via thioester precursors

Makiko Suehiro, John L. Musachio, Robert F. Dannals, William B. Mathews, Hayden T. Ravert, Ursula Scheffel, Henry N. Wagner

Research output: Contribution to journalArticlepeer-review


An improved procedure that facilitates routine production and increases the radiochemical yield of [11C]McN5652 (trans - 1,2,3,5,6,10b-hexahydro-6-[4-([11C]methylthio)-phenyl]pyrrolo-[2,1-a]-isoquinoline) is presented. Specifically, thiol acetate, butyrate, and benzoate derivatives of McN5652 were prepared as the precursors for the [11C]McN5652 synthesis. These thioesters offer greater stability than the previously used thiol precursor (desmethyl McN5652) and enable a single batch of material to be used for multiple radiolabelings. Hydrolysis of the thioester functionality (tetrabutylammonium hydroxide, 10 min) unmasked the free thiol which, without purification, was reacted with [11C]iodomethane in DMF at 40-45 °C for 1 min. The average decay-corrected radiochemical yield for [11C]McN5652 was 26% with an average specific activity of 2290mCi/μmol (end of synthesis). This facile radiolabeling method, utilizing the butyrate thioester of McN5652, was also employed in the preparation of [3H](+)- and (-)McN5652 [trans-1,2,3,5,6S (or 6R),10bR, (or 10bS)-hexahydro-6-[4-([3H]methylthio)phenyl] pyrrolo-[2,1,a]-iso-quinoline] from [3H]iodomethane.

Original languageEnglish (US)
Pages (from-to)543-545
Number of pages3
JournalNuclear Medicine and Biology
Issue number4
StatePublished - May 1995

ASJC Scopus subject areas

  • Molecular Medicine
  • Radiology Nuclear Medicine and imaging
  • Cancer Research


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