反应详情

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).

1. temperatureThe mixture was cooled with ice-water bath
2. customIce-water bath was then removed
3. customformed
4. temperatureThe mixture was then heated
5. temperatureunder reflux for 18 hours
6. temperatureto cool
7. customwas partitioned between chloroform (3×10 mL) and saturated aqueous sodium hydrogen carbonate (10 mL)
8. washThe combined organic extracts were washed with brine (10 mL)
9. dry with materialdried over Na2SO4
10. filtrationfiltered
11. customevaporated
12. customto give a crude product which
13. customwas purified by column chromatography (ethyl acetate in petroleum ether, 10% v/v)