Synthesis and in vitro characterization of trans- and cis-[¹⁸F]-4-methylbenzyl 4-[(pyrimidin-2-yl-amino)methyl]-3-fluoro-piperidine-1-carboxylates as new potential PET radiotracer candidates for the NR2B subtype N-methyl-D-aspartate receptor

Dia-stereoisomeric compounds [¹⁸F]cis- and [¹⁸F]trans-4-methylbenzyl 4-[(pyrimidin-2-yl-amino)methyl]-3-fluoro-piperidine-1-carboxylates were successfully synthesized as new subtype-selective PET radiotracers for imaging the NR2B subunit containing NMDA receptors. Rat brain section auto-radiographies demonstrated a high specific binding in NR2B/NMDA receptor rich regions for both radioligands. The measured logD_7.4 values as well as B_max/K_d ratios indicated that both radiotracers possess the adequate properties required for PET radiotracers. (authors)