Radiosynthesis of three [11C]ureido-substituted benzenesulfonamides as PET probes for carbonic anhydrase IX in tumors

Three ureido-substituted benzenesulfonamides 1a-c have been developed as potent inhibitors for carbonic anhydrase IX, which is overexpressed in hypoxic tumors. In this study, we labeled these unsymmetrical ureas 1a-c using [C-11]phosgene ([C-11]COCl2) as a labeling agent with the expectation that [C-11]1a-c could become promising positron tomography probes for imaging carbonic anhydrase IX in tumors. The strategy for radiosynthesis of [C-11]1a-c was to react hydrochloride of anilines 2a-c with [C-11]COCl2 to give isocyanate [C-11]4a-c, followed by a reaction with 4-aminobenzenesulfonamide (3). (C) 2011 Elsevier Ltd. All rights reserved.