The radiosynthesis of NCA [O-methyl-11C]viqualine, through an N-trityl-protected intermediate, as a potential PET radioligand for 5HT re-uptake sites

C. Pascali, V. W. Pike, D. R. Turton

Research output: Contribution to journalArticle

Abstract

Vioqualine, {4-[3-[3(R)-ethenyl-4(R)-piperidinyl]propyl]-6-methoxyquinoline}, has been labelled in the O-methyl position with no-carrier-added (nca) carbon-11 (t( 1/2 ))=20.4 min; β+=99.8%) to provide a potential radioligand for PET studies of 5HT re-uptake sites. Direct treatment of desmethyl-viqualine with nca [11C]iodomethane gave [O-methyl-11C]viqualine as only a minor product. NMR data suggested that the dominant product is that from the [11C]alkylation of the competing piperidino-nitrogen. Protection of this nitrogen with the trityl group, followed by treatment with nca [11C]iodomethane in dimethyl sulphoxide with sodium hydroxide as base, and then rapid deprotection by mild acid hydrolysis gave nca [O-methyl-11C]viqualine as the main crude product (27% radiochemical yield, decay-corrected from [11C]iodomethane). Radiochemically and chemically pure nca [O-methyl-11C]viqualine was obtained by work up on C18 Sep-pak followed by reverse phase HPLC. The radiosynthesis, including final formulation for i.v. administration, takes 56 min after producing the carbon-11 as [11C]carbon dioxide by the 14N(p,α)11C reaction. This radiosynthesis illustrates the potential utility of the trityl group for the protection of nitrogen in rapid carbon-11 radiochemistry.

Original languageEnglish
Pages (from-to)1341-1350
Number of pages10
JournalJournal of Labelled Compounds and Radiopharmaceuticals
Volume28
Issue number11
Publication statusPublished - 1990

ASJC Scopus subject areas

  • Analytical Chemistry
  • Drug Discovery
  • Organic Chemistry
  • Clinical Biochemistry
  • Molecular Medicine
  • Pharmacology

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