18F-Labelling of electron rich iodonium ylides: application to the radiosynthesis of potential 5-HT2A receptor PET ligands

Abstract

¹⁸F-Labelling of aromatic moieties was limited to electron deficient aromatic systems for many years but recent developments have provided access to the direct labelling of electron rich aromatic systems. Herein we report the synthesis and ¹⁸F-labelling of iodonium ylide precursors in the pursuit of ¹⁸F-labelled 5-HT_2A receptor agonist PET-ligands. Subsequent evaluation in pigs showed high brain uptake of the PET ligands but a blocking dose of ketanserin did not significantly reduce the signal in relevant brain regions – indicating that the ligands do not interact specifically with the 5-HT_2A receptor in vivo.