133627-45-9

76006-11-6

Step 1: A solution of sodium nitrite (7.36 g, 107 mmol) in water (30 mL) was slowly added dropwise to a solution of 2-chloro-3-amino-4-methylpyridine (10.14 g, 71.1 mmol) and potassium acetate (9.02 g, 92 mmol) in acetic acid (200 mL) while keeping the internal temperature below 13 °C. After the dropwise addition was completed, the reaction mixture was allowed to slowly warm to room temperature and stirred continuously for 66 hours. Upon completion of the reaction, the mixture was concentrated under reduced pressure and the residue was alkalized with saturated sodium bicarbonate solution. Subsequently, the solid product was collected by filtration and washed with distilled water. The resulting solid was stirred in ethyl acetate overnight and filtered again. The filtrate was combined with the organic extract, evaporated to dryness and adsorbed on silica gel, and purified by fast column chromatography (using 120 g silica gel, eluent ethyl acetate: hexane, gradient from 0:1 to 1:1), resulting in a white crystalline solid product, 7-chloro-1H-pyrazolo[3,4-c]pyridine (4.99 g, 46% yield). Mass spectrometry analysis showed m/z = 153.9, 155.9 [M + H]+, which corresponds to the theoretically calculated value of molecular weight 153 for C6H4ClN3.