摘要:
Urea subunits are common components of various pharmaceuticals' core structure. Since in most cases the design and development of PET biomarkers is based on approved or potential drugs, there is a growing need for a general labeling methodology of urea-containing pharmacophores. As a part of research in the field of molecular imaging of angiogenic processes, we synthesized several highly potent VEGFR-2/PDGFR dual inhibitors as potential PET biomarkers. The structure of these inhibitors is based on the N-phenyl-N'-{4-(4-quinolyloxy)phenyl} urea skeleton. A representative inhibitor was successfully labeled with fluorine-18 by a three-step process. Initially, a two-step radiosynthesis of 4-[F-18]fluoro-aniline from 1,4- dinitrobenzene (60 min, EOB decay corrected yield: 63%) was performed. At the third and final step, the 4-[F-18]fluoro-aniline synthon reacted for 30 min at room temperature with 4-(2-fluoro-4-isocyanato-phenoxy)-6,7-dimethoxy-quinoline to give complete conversion of the labeled synthon to 1-[4-(6,7-dimethoxyquinolin-4-yloxy)-3-fluoro-phenyl]-3-(4-[F-18]fluoro-phenyl)-urea.The desired labeled product was obtained after total radiosynthesis time of 3 h including HPLC purification with 46 +/- 1% EOB decay corrected radiochemical yield, 99% radiochemical purity, 99% chemical purity, and a specific activity of 400 +/- 37 GBq/mmol (n = 5). (C) 2008 Elsevier Ltd. All rights reserved.