139022-25-6

1314777-15-5

139022-25-6

Step 2. Imidazo[1,2-a]pyridine-6-carboxylic acid hydrochloride (170 g) was dissolved in water (600 mL) and heated until completely dissolved to form a clarified solution. Subsequently, the pH was adjusted to 5-6 by slowly adding 2 M NaOH aqueous solution. the reaction mixture was cooled to 0 °C in an ice-water bath. The precipitate precipitated was collected by vacuum filtration, washed with ethanol and dried under vacuum to afford the target product imidazo[1,2-a]pyridine-6-carboxylic acid (107.2 g, 77% yield) as a light yellow powder. The structure of the product was confirmed by 1H NMR (400 MHz, DMSO-d6) and mass spectrometry (ESI+): 1H NMR δ 13.76-12.82 (br, 1H), 9.28 (s, 1H), 8.10 (s, 1H), 7.68 (s, 1H), 7.64-7.56 (m, 2H); MS (ESI+) m/z: 163 [M + H]+.