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.