反应 #470433

反应方程式

3-bromo-2-methyl aniline

potassium acetate

isoamyl nitrite

acetic anhydride

18-Crown-6

→

4-bromo-1H-indazole

收率 40.0%

溶剂

chloroform

反应条件

后处理

1. 1
   温度The mixture was cooled with ice-water bath
2. 2
   其他Ice-water bath was then removed
3. 3
   其他formed
4. 4
   温度The mixture was then heated
5. 5
   温度under reflux for 18 hours
6. 6
   温度to cool
7. 7
   其他was partitioned between chloroform (3×10 mL) and saturated aqueous sodium hydrogen carbonate (10 mL)
8. 8
   洗涤The combined organic extracts were washed with brine (10 mL)
9. 9
   干燥dried over Na2SO4
10. 10
    过滤filtered
11. 11
    其他evaporated
12. 12
    其他to give a crude product which
13. 13
    其他was purified by column chromatography (ethyl acetate in petroleum ether, 10% v/v)

实验过程

To a solution of 3-bromo-2-methyl aniline (0104) (0.50 g, 2.69 mmol) in chloroform (5 mL) was added potassium acetate (0.28 g, 2.82 mmol). The mixture was cooled with ice-water bath and then acetic anhydride (0.50 mL, 5.37 mmol) was added to it. Ice-water bath was then removed and the resulting mixture was stirred at room temperature for 10 minutes after which time a white gelatinous solid formed. 18-Crown-6 (0.14 g, 0.54 mmol) was then added followed by isoamyl nitrite (0.80 mL, 5.90 mmol). The mixture was then heated under reflux for 18 hours. The reaction mixture was allowed to cool, and was partitioned between chloroform (3×10 mL) and saturated aqueous sodium hydrogen carbonate (10 mL). The combined organic extracts were washed with brine (10 mL), dried over Na2SO4, filtered and evaporated to give a crude product which was purified by column chromatography (ethyl acetate in petroleum ether, 10% v/v) to give 1-(4-bromoindrazol-1-y1)-ethanone (0105) as an orange solid (0.31 g, 49%), and 4-bromo-1H-indazole (0106-3) as a pale orange solid (0.21 g, 40%). Compound 0105: LCMS: 239 [M+1]+; 1H NMR (400 Hz, CDCl3) δ 2.80 (s, 3H), 7.41 (t, J=6.8 Hz, 1H), 7.50 (d, J=6.0 Hz, 1H), 8.15 (s, 1H), 8.40 (d, J=6.8 Hz, 1H). Compound 0106: LCMS: 197 [M+1]+; 1H NMR (400 Hz, CDCl3) δ 7.25 (t, J=6.0 Hz, 1H), 7.34 (d, J=6.4 Hz, 1H), 7.46 (d, J=6.8 Hz, 1H), 8.12 (s, 1H).

来源