Site‐specific addition of an 18F‐N‐methylaminooxy‐containing prosthetic group to a vinylsulfone modified peptide

Numerous strategies employing prosthetic groups for the radiosynthesis of 18F-fluorinated peptides for positron emission tomography have been investigated in recent years. We have previously reported a novel [18F]prosthetic group bearing the N-methylaminooxy functionality capable of reacting in a site-selective manner with peptides functionalized with Michael-acceptors. In a further extension of this methodology we demonstrate that O-[2-(2-[18F]fluoroethoxy)ethyl]-N-methyl-N-hydroxylamine, [18F]4, reacts chemoselectively with a vinylsulfone functionalized peptide. The conjugation yields were studied with respect to reaction time, level of radioactivity, peptide concentration and purity of the [18F]prosthetic group used in the conjugation reaction. Incubation at 70°C gave conjugation yields of around 80% with high radiochemical purity after 70 min at pH 5 in acetate buffer. Copyright © 2009 John Wiley & Sons, Ltd.