Hydrazine → 6-Chloro-4-fluoro-1H-indazole

Participants

Reaction Conditions

Reaction Steps

4-Chloro-2,6-difluoro-benzaldehyde (15 g, 85 mmol) was dissolved in 1,2-dimethoxyethane 170 ml). O-Methyl-hydroxylamine hydrochloride (7.1 g, 85 mmol) and potassium carbonate (12.9 g, 93.5 mmol) were then added and the mixture was stirred at 35° C. for 24 h. The reaction was filtered, rinsed with dichloromethane, evaporated and redissolved in DMF (170 ml). Hydrazine (2.9 ml 93.5 mmol) was added and the reaction was stirred at 100° C. for 1 h. After cooling, water and ethyl acetate were added. The layers were separated and the aqueous layer was extracted twice more with ethyl acetate. The combined organic layers were washed with water and sodium chloride solution then dried over sodium sulfate. The solvent was evaporated to leave a solid which was purified by silica gel chromatography (diethyl ether/hexanes) to give 7 g (49%) of 6-chloro-4-fluoro-1H-indazole. (M+H)+=171.

Provenance & Evidence