Evaluation of aromatic radiobromination by nucleophilic substitution using diaryliodonium salt precursors
Radiobromine‐labeled compounds can be used for positron emission tomography (PET) imaging (ie, 76 Br) and for radiation therapy (ie, 77 Br). 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 [ 76 Br]/[ 77 Br]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.
- Research Organization:
- Washington Univ., St. Louis, MO (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC); National Institutes of Health (NIH)
- Grant/Contract Number:
- SC0008432; CA025836
- OSTI ID:
- 1533183
- Alternate ID(s):
- OSTI ID: 1401796
- Journal Information:
- Journal of Labelled Compounds and Radiopharmaceuticals, Vol. 60, Issue 9; ISSN 0362-4803
- Publisher:
- WileyCopyright Statement
- Country of Publication:
- United States
- Language:
- English
Web of Science
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journal | December 2018 |
The first radiosynthesis of 2-amino-5-[ 18 F]fluoropyridines via a “minimalist” radiofluorination/palladium-catalyzed amination sequence from anisyl(2-bromopyridinyl)iodonium triflate
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journal | January 2019 |
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