Automated Synthesis of 5-HT_1A Receptors Antagonists ¹¹C-WAY-100635

A fully automated synthesis of ¹¹C-labeled-N-2-4-(2-methoxyphenyl)-1-piperazinylethyl-N-2-pyridinylcyclohexanecarboxamide maleate (¹¹C-WAY-100635) for imaging 5-HT_1A receptors was performed on a module system. ¹¹C-WAY-100635 was obtained based on the methylation reaction of the precursor (O-demethyl)-WAY-100635, purification with HPLC and subsequent removal of organic solvents using a Sep-Pak Plus C18. The results revealed that fully automated synthesis of ¹¹C-WAY-100635 was completed within the total synthesis time of about 40 min. The uncorrected radiochemical yield was between 10% and 20%, and the radiochemical purity was over 97%. After the intravenous injection of ¹¹C-WAY-100635 (about 111 MBq), the uptake in the brain tissues of the white rabbit was significantly higher than the other tissues of head. This method provides simple synthesis of ¹¹C-WAY-100635 with relatively short radiosynthesis time and a high radiochemical yield for clinical need.