反应详情

A hot solution of silver nitrate (4.7 g, 27.4 mmol) in ethanol (15 mL) and water (4 mL) was added to a stirring solution of 4-dichloromethyl-1-methyl-5-nitro-1H-pyrazole (1.44 g, 6.85 mmol) in ethanol (50 mL) at 50° C. The mixture was stirred vigorously under reflux for 1 h, cooled to room temperature, and diluted with water (14 mL). The aqueous layer was extracted with chloroform and filtered through a layer of celite. Concentration and chromatography on a silica gel column with hexane and ethyl acetate (6:1) gave 1-methyl-5-nitro-1H-pyrazole-4-carbaldehyde (0.42 g, 41%): 1H NMR (300 MHz, CDCl3) δ 9.93 (s, 1H), 8.08 (s, 1H), 4.36 (s, 3H).

1. temperatureunder reflux for 1 h
2. extractionThe aqueous layer was extracted with chloroform
3. filtrationfiltered through a layer of celite
4. concentrationConcentration and chromatography on a silica gel column with hexane and ethyl acetate (6:1)