The synthesis of a benzamidine‐containing NR2B‐selective NMDA receptor ligand labelled with tritium or fluorine‐18

A novel tritium or flourine‐18‐labelled benzamidine‐containing NR2B‐selective NMDA receptor ligand has been synthesized. This compound was designed to contain the fluoromethoxy group to allow for the synthesis of a high specific activity, fluorine‐18‐labelled PET tracer for imaging studies of the NR2B receptor. In addition to the fluorine‐18‐labelled compound, this compound was also tritium labelled. The tritiated ligand (11 Ci/mmol) was synthesized by a gas tritiation reaction of an aryl bromide precursor. The fluorine‐18 ligand (2916 Ci/mmol), which was deuterated in the fluoromethoxy group to aid in metabolic stability, was synthesized by alkylating a phenolic precursor with [ 18 F]fluoromethylbromide‐ d 2 .