189102-97-4

97941-89-4

122-51-0

189102-97-4

General procedure for the synthesis of 5,6-dichloro-3H-imidazo[4,5-b]pyridine from 5,6-dichloropyridine-2,3-diamine and triethyl orthoformate: To a solution of 5,6-dichloropyridine-2,3-diamine (28.1 g, 158 mmol) in methanol (840 mL) was added sulfamic acid (765 mg, 7.88 mmol) and triethyl orthoformate sequentially. ethyl ester (39.3 mL, 236 mmol) and the reaction mixture was stirred. The reaction was carried out at room temperature for 7.5 hours. The reaction suspension was filtered, the filter cake was washed with methanol and the combined filtrates were concentrated under reduced pressure. Hexane was added to the concentrated residue, filtered, and the resulting solid was washed with hexane to afford 5,6-dichloro-3H-imidazo[4,5-b]pyridine (24.3 g, 82%) as a gray solid.1H-NMR (DMSO-d6) δ: 8.40 (s, 1H), 8.58 (s, 1H).