Syntheses of novel N‐([18F]fluoroalkyl)‐N‐nitroso‐4‐methyl‐benzenesulfonamides and decomposition studies of corresponding 19F‐ and bromo‐analogues: potential new compounds for the 18F‐labelling of radiopharmaceuticals

Abstract

AbstractN‐([18F]fluoroalkyl)‐N‐nitroso‐4‐methyl‐benzensulfonamides [n‐alkyl = (−CH2)[18,19F]F, n=2–4)] were synthesized in radiochemical yields ranging from 75–90% to provide new secondary labelling precursors for the syntheses of 18F‐labelled compounds. Preliminary decomposition studies utilizing the corresponding non‐radioactive 19F‐compounds as well as the bromo containing analogous compounds were performed to evaluate their stability regarding temperature and basicity of the labelling medium. Furthermore, initial difficulties in labelling these compounds led to the development of a modified labelling procedure applying nearly solvent‐free conditions. Extensive decomposition experiments of the new fluoro‐ as well as the bromo‐compounds were conducted under various conditions in order to get experimental data about their stability and reactivity. As a result, different trends for the stability of the bromo as well as the fluoro compounds could be observed. Copyright © 2003 John Wiley & Sons, Ltd.