Radiolabelling of 2-oxoquazepam with electrophilic 18F prepared from [18F]fluoride

✍ Scribed by Jörgen Bergman; Peter Johnström; Merja Haaparanta; Olof Solin; Tim Duelfer; Sharon Stone-Elander

• Book ID: 103989411
• Publisher: Elsevier Science
• Year: 1995
• Tongue: English
• Weight: 709 KB
• Volume: 46
• Category: Article
• ISSN: 0969-8043
• DOI: 10.1016/0969-8043(94)00127-l

✦ Synopsis

Electrophilic radiofluorination reagents with greatly improved specific activity (102-103-fold) were successfully used to radiolabel the chemically labile ligand 2-oxoquazepam. [ISF]Fluorine was synthesized in an electrical discharge chamber by exchanging varying amounts of carrier fluorine with high specific activity [tSF]methyl fluoride. Both [lSF]fluorine and acetyl [tSF]hypofluorite were investigated in the fluoro-destannylation, but the latter was found to give better radiochemical conversions (up to 38%). Isolation procedures were greatly facilitated by the lower masses used. [2'-tSF]-2-Oxoquazepam was obtained with high chemical and radiochemical purity using SepPak precleaning followed by straight phase HPLC in a total synthesis time of ~ 1.3-1.5 h. The specific activities for [~SF]F 2 and the isolated product ranged from 1.5-48.5 (n =7) and 2.6-16.7 (n---5) GBq//zmol at 20min and 80min from end-of-bombardment, respectively. This is the first report of the electrophilic fluorination of a neuroreceptor ligand with high specific activity. This study demonstrates the promising potential of these electrophilic fluorinating agents prepared from high specific activity [~SF]fluoride.