97640-15-8

24638-20-8

97640-15-8

Step 1004b: Preparation of 3H-imidazo[4,5-b]pyridine-2-carboxylic acid. To a boiling aqueous solution of KMnO4 (0.38 g, 2.4 mmol) (8 mL), an aqueous solution of 3H-imidazo[4,5-b]pyridine-2-methanol (0.20 g, 1.4 mmol) and Na2CO3 (0.19 g, 1.5 mmol) (6 mL) was slowly added. The reaction mixture was heated to reflux for 4 hours. The reaction mixture was filtered while hot and the filtrate was cooled to room temperature and the pH was adjusted with concentrated hydrochloric acid to 2. The precipitate precipitated was collected by vacuum filtration to afford 3H-imidazo[4,5-b]pyridine-2-carboxylic acid in 100% yield. Mass spectrometry (MS) analysis results: C7H5N3O2, m/z 164 (M + H)+.