Hydrazine → 4-chloro-1H-pyrazolo[4,3-c]pyridine

Participants

Reaction Steps

To a mixture of 2-chloro-4-iodonicotinaldehyde (1.0 g, 3.7 mmol) in ethanol (6.0 mL) was added 3.0 mL of hydrazine (excess). The mixture was stirred at room temperature for 15 h and then concentrated under reduced pressure. The residue was diluted with water (30 mL) and extracted with dichloromethane (300 mL). The organic extract was washed with brine, dried over Na2SO4, and concentrated under reduced pressure. The residue was dissolved in dichloromethane (5 mL) and stirred for 5 min. The precipitated solid was isolated by filtration and dried to give the desired intermediate 4-chloro-1H-pyrazolo[4,3-c]pyridine as a grey solid (110 mg, 19% yield), which was used in the next step without further purification. LCMS(ESI) m/z: 154.1 [M+H+]

Provenance & Evidence