Abstract
The radiosynthesis of a new [^18^F]fluoroalkylating agent, [^18^F]fluoroacetaldehyde, is described. It was produced using the Kornblum method by oxidation with dimethyl sulphoxide of 2‐[^18^F]fluoroethyl p‐toluenesulphonate ([^18^F]FETos). In these conditions the oxidation proceeds smoothly and rapidly to the selective conversion of tosyl esters of primary alcohols to aldehydes with no carboxylic acids being produced. The chemical identity of [^18^F]fluoroacetaldehyde was determined by comparing its chromatographic properties as well as those of its 2,4‐dinitrophenylhydrazone (2,4‐DNPH) derivative with those of, respectively, the standard fluoroacetaldehyde and its 2,4‐DNPH derivative. Standard fluoroacetaldehyde was prepared by oxidation of fluoroethanol with pyridinium dichromate and characterized as its 2,4‐DNPH derivative by mass spectrometry. To test its reactivity with amines under reductive alkylation conditions, [^18^F]fluoroacetaldehyde was reacted with benzylamine used as model substrate. The chemical identity of the resulting radiolabelled product was determined to be [^18^F]N‐(2‐fluoroethyl)‐benzylamine by comparing its chromatographic properties with those of the synthesized standard N‐(2‐fluoroethyl)‐benzylamine characterized by ^19^F and ^1^H NMR spectroscopy and mass spectrometry. This new fluorine‐18 labelled synthon may find applications in radiolabelling peptide, protein and antibody fragments as well as in aldol condensation or in the Mannich reaction. Copyright © 2008 John Wiley & Sons, Ltd.