反应详情

Concentrated sulfuric acid (1 mL) was added to a suspension of 5-bromo-1H-indazole-3-carboxylic acid (CXV) (1.30 g, 5.39 mmol) in dry MeOH (50 mL) and heated to reflux for 4 h under argon. The solution was cooled to room temperature and the MeOH was evaporated under vacuum. The residue was dissolved in EtOAc and washed with water. The organic phase was dried over Na2SO4, filtered and concentrated to afford methyl 5-bromo-1H-indazole-3-carboxylate (CXVI) as a white solid (1.35 g, 5.29 mmol, 98% yield). 1H NMR (DMSO-d6) δ ppm 14.13 (s, 1H), 8.21 (d, J=1.6 Hz, 1H), 7.67 (d, J=7.2 Hz, 1H), 7.59 (dd, J=7.2, 1.2 Hz, 1H), 3.92 (s, 3H); ESIMS found for C9H7BrN2O2 m/z 256.0 (M+H).

1. temperatureheated
2. temperatureto reflux for 4 h under argon
3. customthe MeOH was evaporated under vacuum
4. dissolutionThe residue was dissolved in EtOAc
5. washwashed with water
6. dry with materialThe organic phase was dried over Na2SO4
7. filtrationfiltered
8. concentrationconcentrated