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Updated: Dec 19, 2025

Enhancing Efficiency and Radiolabeling Yields of Carbon-11 Radioligands for Clinical Research Using the Loop Method
Published on: December 20, 2024
Radiosynthesis of a carbon-11 labeled PDE5 inhibitor [11C]TPN171 as a new potential PET heart imaging agent
Zhidong Xu1, Limeng Jia2, Wenqing Liu3
1College of Chemical & Pharmaceutical Engineering, Key Laboratory of Molecular Chemistry for Medicine of Hebei Province, Hebei University of Science & Technology, Shijiazhuang, Hebei, 050018, China; Key Laboratory of Medicinal Chemistry and Molecular Diagnosis of Ministry of Education, College of Chemistry & Environmental Science, Hebei University, Baoding, Hebei, 071002, China.
Abstract:
To develop PET tracers for imaging of heart disease, a new carbon-11 labeled potent and selective PDE5 inhibitor [11C]TPN171 ([11C]9) has been synthesized. The reference standard TPN171 (9) and its corresponding precursor desmethyl-TPN171 (11) were synthesized from methyl 3-oxovalerate and 2-hydroxybenzonitrile in 9 and 10 steps with 31% and 25% overall chemical yield, respectively. The radiotracer [11C]TPN171 was prepared from desmethyl-TPN171 with [11C]CH3OTf through N-11C-methylation and isolated by HPLC purification followed by SPE formulation in 45-55% 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.
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