Trifluoromethanesulfonic acid, an alternative solvent medium for the direct electrophilic fluorination of DOPA: New syntheses of 6-[18F]fluoro- L-DOPA and 6-[18F]fluoro-D-DOPA

Babak Behnam Azad, Raman Chirakal, Gary J. Schrobilgen

Research output: Contribution to journalArticle

Abstract

Previous work from this laboratory has shown that the direct fluorination of 3, 4-dihydroxy-phenyl-L-alanine (L-DOPA) in anhydrous HF (aHF) or BF 3/HF with F2 is an efficient method for the synthesis of 6-fluoro-L-DOPA. Since then, 18F-labeled 6-fluoro-L-DOPA ([ 18F]6-fluoro-L-DOPA) has been used to study presynaptic dopaminergic function in the human brain and to monitor gastrointestinal carcinoid tumors. This work demonstrates that the reactivity and selectivity of F2 toward L-DOPA in CF3SO3H is comparable with that in aHF. This new synthetic procedure has led to the production of [18F] fluoro-L-DOPA and [18F]fluoro-L-DOPA isomers in 17 ± 2% radiochemical yields (decay corrected with respect to [18F]F 2). The 2- and 6-FDOPA isomers were separated by HPLC and subsequently characterized by 19F NMR spectroscopy. The corresponding [18F]-FDOPA enantiomers have been obtained in clinically useful quantities by a synthetic approach that avoids the use of aHF.

Original languageEnglish (US)
Pages (from-to)1236-1242
Number of pages7
JournalJournal of Labelled Compounds and Radiopharmaceuticals
Volume50
Issue number14
DOIs
StatePublished - Dec 1 2007
Externally publishedYes

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Keywords

  • Cyclotron
  • DOPA
  • Electrophilic fluorination
  • Fluorine-18
  • PET
  • Radiolabeling

ASJC Scopus subject areas

  • Analytical Chemistry
  • Biochemistry
  • Radiology Nuclear Medicine and imaging
  • Drug Discovery
  • Spectroscopy
  • Organic Chemistry

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