Synthesis of a 125I labelled azido-substituted glibenclamide analogue for photoaffinity labelling of the sulfonylurea receptor

N-{4-(2-{4-Azido-2-hydroxy-5-[125I]iodobenzamido}ethyl)benzenesul]-N′-cyclohexylurea has been prepared as a novel photoaffinity ligand for the sulfonylurea receptor. This involved synthesis of a 4-azidosalicyloyl analogue of glibenclamide and treatment of the analogue with Na125I and chloramine-T. Purification by HPLC gave the radiolabelled sulfonylurea in 56% radiochemical yield and high specific activity (2130 Ci/mmol).