反应详情

t-BuLi (27 mL, 1.7 M in pentane) was added to 100 mL of THF at −78° C. 5-bromo-1H-pyrazolo[3,4-c]pyridine (3.0 g, 15 imol) was added dropwise to the solution in 50 ml of THF via addition funnel. The resulting mixture was stirred for 1 h, at which point DMF (6.0 mL, 76 mmol) was added dropwise. The reaction mixture was allowed to warm to room temperature and stirred 2 h. The reaction was then carefully quenched with aq. NH4Cl and diluted with EtOAc. The resulting biphasic mixture was partitioned in a separatory funnel. The aqueous portion was extracted three tines with EtOAc, and the combined organic extracts were washed with brine and dried over MgSO4. Filtration and concentration under reduced pressure, followed by flash chromatography on silica gel (100% CH2Cl2 to 7.5% MeOH/CH2Cl2), afforded the desired 1H-pyrazolo[3,4-c]pyridine-5-carbaldehyde (1.1 g, 50% yield) as a white solid. H1 NMR (MeOD, 400 MHz) keto tautomer: 10.17 (s, 1H), 9.19 (s, 1H), 8.56 (s, 1H), 8.46 (s, 1H); enol tautomer: 9.00 (s, 1H), 8.25 (s, 1H), 8.05 (s, 2H), 5.73 (s, 1H). MS (API-ES) m/z (%): 141 (100%, M++1).

1. additionwas added dropwise
2. customThe reaction was then carefully quenched with aq. NH4Cl
3. additiondiluted with EtOAc
4. customThe resulting biphasic mixture was partitioned in a separatory funnel
5. extractionThe aqueous portion was extracted three tines with EtOAc
6. washthe combined organic extracts were washed with brine
7. dry with materialdried over MgSO4
8. filtrationFiltration and concentration under reduced pressure