反应详情

To a solution of 1H-pyrazole[3,4-b]pyridine-3-carboxylic acid (V) (0.39 g, 2.4 mmol) in dry MeOH (10 mL) was added concentrated H2SO4 (4 drops) and refluxed for 6 h under nitrogen. The solution was cooled and the solvent was evaporated under vacuum. The residue was partitioned between DCM and saturated NaHCO3 solution. The organic layer was separated, dried over MgSO4, filtered and concentrated under reduced pressure. The crude product was purified on a flash silica gel column (100% DCM→100:3 DCM:MeOH) to produce methyl 1H-pyrazolo[3,4-b]pyridine-3-carboxylate (VI) as a white solid (382 mg, 2.16 mmol, 90% yield). 1H NMR (CDCl3) δ ppm 4.08 (s, 3H), 7.38 (m, 1H), 8.63 (dd, J=8.10, 1.51 Hz, 1H), 8.72 (dd, J=4.62, 1.41 Hz, 1H); ESIMS found for C8H7N3O2 m/z 178.2 (M+H).

1. temperaturerefluxed for 6 h under nitrogen
2. temperatureThe solution was cooled
3. customthe solvent was evaporated under vacuum
4. customThe residue was partitioned between DCM and saturated NaHCO3 solution
5. customThe organic layer was separated
6. dry with materialdried over MgSO4
7. filtrationfiltered
8. concentrationconcentrated under reduced pressure
9. customThe crude product was purified on a flash silica gel column (100% DCM→100:3 DCM:MeOH)