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

Numerous strategies employing prosthetic groups for the radiosynthesis of 18 F‐fluorinated peptides for positron emission tomography have been investigated in recent years. We have previously reported a novel [ 18 F]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‐[ 18 F]fluoroethoxy)ethyl]‐ N ‐methyl‐ N ‐hydroxylamine, [ 18 F]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 [ 18 F]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.