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 β dual inhibitors based on the N ‐phenyl‐ N ′‐4‐(4‐quinolyloxy)‐phenyl‐urea was labelled with 11 C ( β + , 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 [ 11 C]carbon monoxide. Starting with 10.7±0.5 GBq of [ 11 C]carbon monoxide, 1‐[4‐(6,7‐dimethoxy‐quinolin‐4‐yloxy)‐3‐fluoro‐phenyl]‐3‐(4‐fluoro‐phenyl)‐[ 11 C]‐urea (2.1 GBq) was isolated after total reaction time of 45 min with a specific activity of 92±4 GBq µmol −1 .