Evaluation of aromatic radiobromination by nucleophilic substitution using diaryliodonium salt precursors

Dong Zhou, Sung Hoon Kim, Wenhua Chu, Thomas Voller, John A. Katzenellenbogen

Research output: Contribution to journalArticle

4 Scopus citations

Abstract

Radiobromine-labeled compounds can be used for positron emission tomography (PET) imaging (ie, 76Br) and for radiation therapy (ie, 77Br). However, the commonly used electrophilic substitution reaction using no-carrier-added radiobromide does not always afford the desired product due to the high reactivity of the brominating intermediate. A nucleophilic substitution by bromide, such as radiobromination of iodonium precursors, provides an alternative route for the synthesis of bromo-radiopharmaceuticals. The applicability of aromatic radiobromination by nucleophilic substitution using diaryliodonium salt precursors was evaluated using iodonium model compounds and [76Br]/[77Br]bromide. Radiobromination was observed under all conditions tested, in up to quantitative yields. A QMA cartridge treatment method and a base-free method have been developed, and no extra base is needed for either methods. The base-free conditions are mild and afford much cleaner reactions. Up to 20% water is tolerated in the reactions without reducing the radiochemical yields. No-carrier-added and carrier-added reactions afforded similar results. 4-Bromobenzaldehyde and 4-bromobenzoate have been radiosynthesized reliably and in good yields. These results indicate that this method is robust and efficient and thus will provide a route for radiobromination of electron-deficient arenes and an alternative route for the synthesis of bromo-radiopharmaceuticals for biological evaluations.

Original languageEnglish
Pages (from-to)450-456
Number of pages7
JournalJournal of Labelled Compounds and Radiopharmaceuticals
Volume60
Issue number9
DOIs
StatePublished - Jul 1 2017

Keywords

  • Auger electron radiation
  • PET imaging
  • bromine-76
  • bromine-77
  • diaryliodonium salts
  • labeling methods
  • radiobromination

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