[ 18 F]/ 19 F exchange in fluorine containing compounds for potential use in 18 F‐labelling strategies

• Published in: Journal of labelled compounds & radiopharmaceuticals 2009-09, Vol.52 (12), p.504-511
• Main Authors: Blom, Elisabeth, Karimi, Farhad, Långström, Bengt
• Format: Article
• Language: English
• ISSN: 0362-4803; 1099-1344
• DOI: 10.1002/jlcr.1670

Exchange of [ 18 F]fluoride with 19 F in various organofluorine compounds in concentrations ranging from 0.06 to 56 mM was explored. We aimed to explore whether exchange reactions can be a potential useful labelling strategy, when there are no requirement of high specific radioactivity. Parameters such as solvents, temperature, conventional vs microwave heating, and the degree of fluorine load in some aromatic and alkyl compounds were investigated with regard to radiochemical yield and specific radioactivity. A series of fluorobenzophenones (1–6), 1‐(4‐fluorophenyl)ethanone (7), various activated and deactivated fluoro benzenes (8–16), N ‐(pentafluorophenyl)benzamide (17), (pentafluorophenyl)formamide (18), (tridecafluorohexyl)benzene (19) and tetradecafluorohexane (20) were subjected to [ 18 F]/ 19 F exchange. To test this strategy to label biologically active molecules containing fluorine atoms in an aryl group, two analogues of WAY‐100635 (21–22), Lapatinib (23), 2,5,6,7,8‐pentafluoro‐3‐methylnaphthoquinone (24) and 1‐(2,4‐difluorophenyl)‐3‐(4‐fluorophenyl)propan‐1‐one (25) were investigated. The multi‐fluorinated molecules containing an electron‐withdrawing group were successfully labelled at room temperature, whereas the monofluorinated, as well as those containing an electron‐donating group, required heating for the exchange reaction to take place. Copyright © 2009 John Wiley & Sons, Ltd.