Rhodium-mediated [11C]Carbonylation: a library of N-phenyl-N′-{4-(4-quinolyloxy)-phenyl}-[11C]-urea derivatives as potential PET angiogenic probes

As part of our ongoing investigation into the imaging of angiogenic processes, a small library of eight vascular endothelial growth factor receptor-2 (VEGFR-2)/platelet-derived growth factor receptor beta dual inhibitors based on the N-phenyl-N'-4-(4-quinolyloxy)-phenyl-urea was labelled with C-11 (beta(+), t(1/2) = 20.4 min) in the urea carbonyl position via rhodium-mediated carbonylative cross-coupling of an aryl azide and different anilines. The decay-corrected radiochemical yields of the isolated products were in the range of 38-81% calculated from [C-11]carbon monoxide. Starting with 10.7+/-0.5 GBq of [C-11]carbon monoxide, 1-[4-(6,7-dimethoxy-quinolin-4-yloxy)-3-fluoro-phenyl]-3-(4-fluoro-phenyl)-[C-11]-urea (2.1 GBq) was isolated after total reaction time of 45 min with a specific activity of 92+/-4 GBq mu mol(-1).