6-Chloro-1H-pyrazolo[4,3-c]pyridine

Used as a pharmaceutical intermediate for laboratory research and development.

4,6-Dichloropyridine-3-carbaldehyde (3.7 g, 32 mmol), hydrazine (3.5 mL, 110 mmol) and N,N-diisopropylethylamine (20 mL) were combined in DMA (100 mL) and stirred at 80° C. for four hours. Then, the solution was cooled to room temperature, diluted with EtOAc, and washed three times with water and then with brine. The organic solution was concentrated and the resulting mixture was precipitated from dichloromethane to give 6-chloro-1H-pyrazolo[4,3-c]pyridine. Yield 2 g (41%). LCMS (ESI): calc. C6H4ClN3=153; obs. M+H=154.