5-CHLORO-1H-PYRAZOLO[3,4-C]PYRIDINE

5-Chloro-1H-pyrazolo[3,4-C]pyridine is a pyrazolo aromatic heterocyclic compound and an important organic synthesis intermediate. And it is widely used in the preparation of medicines, pesticides and other compounds.

2-Chloro-5-fluoro-4-aldolpyridine (0.49 mol, 75.0 g), methoxyamine hydrochloride (0.51 mol, 42.6 g) and potassium carbonate (0.59 mol, 81.5 g) were combined at room temperature were respectively added to the reactor containing 1L of tetrahydrofuran solution. After stirring overnight at room temperature, it was filtered and the filtrate was concentrated to give a residue. 85 wt% aqueous hydrazine hydrate solution (1.47 mol) was added dropwise to the residue, and the residue was refluxed overnight, and the progress of the reaction was monitored by LC-MS until the reaction was completed. After evaporating off excess hydrazine, 1 L of water was added to the mixture, and after a precipitate was deposited, it was filtered, washed with water and dried to obtain a gray powder. The gray powder was dissolved in tetrahydrofuran, 10 mL of trifluoroacetic acid was added to reflux for 1 hour, the reaction mixture was concentrated, washed three times with water and tert-butyl methyl ether to obtain a light gray powder of pyrazoloheterocyclic compound (5-Chloro-1H-pyrazolo[3,4-c]pyridine) powder, yield 86%, and purity ≥95%. 1H-NMR (CD3OD-d4, 400MHz) δ: 7.82 (s, 1H), 8.15 (s, 1H), 8.80 (s, 1H).