Synthesis of [11C-carbonyl]hydroxyureas by a rhodium-mediated carbonylation reaction using [11C]carbon monoxide

[C-11]Hydroxyurea has been successfully labelled using [C-11]carbon monoxide at low concentration. The decay-corrected radiochemical yield was 38 +/- 3%, and the trapping efficiency of [C-11]carbon monoxide in the order of 90 +/- 5%. This synthesis was performed by a rhodium-mediated carbonylation reaction starting with azidotrimethylsilane and the rhodium complex being made in situ by chloro(1,5-cyclooctadiene)rhodium(l) dimer ([Rh(cod)C]12) and 1,2-bis(diphenylphosphino)ethane (dppe). (13 C)Hydroxyurea was synthesized using this method and the position of the labelling was confirmed by C-13-NMR. In order to perform accurate LC-MS identification, the derivative 1-hydroxy-3-phenyl[C-11]urea was synthesized in a 35 +/- 4% decay-corrected radiochemical yield. After 13 mu A h bombardment and 21 min synthesis, 1.6 GBq of pure 1-hydroxy-3-phenyl[C-11]urea was collected starting from 6.75 GBq of [C-11]carbon monoxide and the specific radioactivity of this compound was in the order of 686 GBq/mu mol (3.47 nmol total mass). [C-11]Hydroxyurea could be used in conjunction with PET to evaluate the uptake of this anticancer agent into tumour tissue in individual patients. Copyright (c) 2006 John Wiley & Sons, Ltd.