反応 #9293

反応方程式

water

acetic acid

7-(2,4-Dichlorophenyl)-2-ethyl-3-nitropyrazolo[1,5-a]pyridine

→

[7-(2,4-dichlorophenyl)-2-ethylpyrazolo[1,5-a]pyridin-3-yl]amine

収率 89.8%

溶媒

ethanol

反応条件

後処理

1. 1
   温度the mixture was heated
2. 2
   ろ過The reaction mixture was filtered
3. 3
   workup.ADDITIONwater was added to the filtrate, extraction
4. 4
   洗浄the extract was washed with saturated aqueous sodium hydrogencarbonate and brine
5. 5
   乾燥After drying over anhydrous magnesium sulfate and filtration
6. 6
   濃縮the solvent was concentrated under reduced pressure

実験手順

7-(2,4-Dichlorophenyl)-2-ethyl-3-nitropyrazolo[1,5-a]pyridine (110 mg) was suspended in ethanol (6 mL), and then water (3 mL), acetic acid (1 mL) and zinc powder (220 mg) were added and the mixture was heated and stirred at 60° C. for 1 hour. The reaction mixture was filtered, water was added to the filtrate, extraction was performed with ethyl acetate and the extract was washed with saturated aqueous sodium hydrogencarbonate and brine. After drying over anhydrous magnesium sulfate and filtration, the solvent was concentrated under reduced pressure to obtain [7-(2,4-dichlorophenyl)-2-ethylpyrazolo[1,5-a]pyridin-3-yl]amine (90 mg) as crude crystals. These were dissolved in tetrahydrofuran (1 mL), and after adding propionaldehyde (0.059 mL) and 3 M aqueous sulfuric acid (0.294 mL), sodium borohydride (22.2 mg) was added in five portions while vigorously stirring on ice, and stirring was continued for 30 minutes. Water was added to the reaction mixture, extraction was performed with diethyl ether and the extract was washed with saturated sodium hydrogencarbonate and brine. After drying over anhydrous magnesium sulfate and filtration, the solvent was concentrated under reduced pressure, the residue was purified by silica gel column chromatography, and the title compound (59 mg) was obtained from the n-hexane:ethyl acetate (100:1) fraction as a yellow oil.

出典