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

Diastereoisomeric compounds [(18)F]cis- and [(18)F]trans-4-methylbenzyl 4-[(pyrimidin-2-ylamino)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 autoradiographies 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.