Ortho-[18F]Fluoronitrobenzenes by no-carrier-added nucleophilic aromatic substitution with K[18F]F–K222—A comparative study

✍ Scribed by M. Karramkam; F. Hinnen; Y. Bramoullé; S. Jubeau; F. Dollé

• Publisher: John Wiley and Sons
• Year: 2002
• Tongue: French
• Weight: 108 KB
• Volume: 45
• Category: Article
• ISSN: 0022-2135
• DOI: 10.1002/jlcr.628

✦ Synopsis

Abstract

The scope of the nucleophilic aromatic ortho‐fluorinations from the corresponding ortho‐halonitrobenzene precursors (halo‐to‐fluoro substitutions) with no‐carrier‐added [^18^F]fluoride ion as its activated K[^18^F]F–K~222~ complex has been evaluated via the radiosynthesis of ortho‐[^18^F]fluoronitrobenzene, chosen as a model reaction. The parameters studied include the influence of the leaving group in the ortho position of the phenyl ring (–Cl, –Br, –l), the quantity of precursor used, the type of activation (conventional heating or microwave irradiations), the solvent, the temperature and the reaction time. The iodo‐precursor was completely unreactive and the bromo‐precursor gave only low incorporation (<10%) in the optimal conditions used (conventional heating at 145°C or microwave activation, 100 W for 120 s). Only the chloro‐precursor was found reactive in the conditions described above and up to 70% yield was observed for the formation of ortho‐[^18^F]fluoronitrobenzene ([^18^F]‐1). In all the experiments, the unwanted ortho‐[^18^F]fluoro‐halobenzenes, potentially resulting from the nitro‐to‐fluoro substitution, could not be detected. These results will be applied for the radiosynthesis of 5‐[^18^F]fluoro‐6‐nitroquipazine, a potent radioligand for the imaging of the serotonin transporter with PET. Copyright © 2002 John Wiley & Sons, Ltd.