Dong, FuguiDu, JieMiao, CaihongJia, LimengLi, WeiWang, MinZheng, Qi-HuangXu, Zhidong2019-12-302019-12-302019-12Dong, F., Du, J., Miao, C., Jia, L., Li, W., Wang, M., … Xu, Z. (2019). Radiosynthesis of carbon-11 labeled PDE5 inhibitors as new potential PET radiotracers for imaging of Alzheimer’s disease. Applied Radiation and Isotopes, 154, 108873. https://doi.org/10.1016/j.apradiso.2019.108873https://hdl.handle.net/1805/21621To develop PET tracers for imaging of Alzheimer's disease, new carbon-11 labeled potent and selective PDE5 inhibitors have been synthesized. The reference standards (5) and (12), and their corresponding desmethylated precursors (6) and (13) were synthesized from methyl 2-amino-5-bromobenzoate and (4-methoxyphenyl)methanamine in multiple steps with 2%, 1%, 1% and 0.2% overall chemical yield, respectively. The radiotracers ([11C]5) and ([11C]12) were prepared from their corresponding precursors 6 and 13 with [11C]CH3OTf through O–11C-methylation and isolated by HPLC combined with SPE in 40–50% radiochemical yield, based on [11C]CO2 and decay corrected to EOB. The radiochemical purity was >99%, and the molar activity (Am) at EOB was in a range of 370–740 GBq/μmol.enPublisher PolicyPhosphodiesterase 5 (PDE5)Carbon-11 labeled PDE5 inhibitorsradiosynthesisArticle