反应详情

A suspension of methyl 5-bromo-1H-indazole-3-carboxylate (CXVI) (1.35 g, 5.29 mmol), pyridinium p-toluenesulfonate (0.143 g, 0.56 mmol) and 3,4 dihydro-2H-pyran (1.02 mL, 11.90 mmol) in anhydrous dichloroethane (20 mL) was refluxed 5 h under argon. The suspension was turned into the clear solution. The solution was cooled and the excess solvent was evaporated under vacuum. The residue was dissolved in EtOAc and washed with dilute NaHCO3 solution (satd. NaHCO3 soln/H2O: 1:9). The organic layer was dried over Na2SO4, filtered and concentrated. The residue was purified by column chromatography (100% hexanes→5:95 EtOAc:hexanes) to get methyl 5-bromo-1-(tetrahydro-2H-pyran-2-yl)-1H-indazole-3-carboxylate (CXVII) as a white solid (1.47 g, 4.34 mmol, 82% yield). 1H NMR (DMSO-d6) δ ppm 8.22 (d, J=1.4 Hz, 1H), 7.89 (d, J=7.2 Hz, 1H), 7.68 (dd, J=7.2, 1.6 Hz, 1H),), 6.02 (dd, J=8.0, 2.4 Hz, 1H), 3.94 (s, 3H), 3.88 (m, 1H), 3.79 (m, 1H), 2.37-2.31 (m, 1H), 2.05-1.96 (m, 2H), 1.77-1.73 (m, 1H). 1.60-1.58 (m, 2H); ESIMS found for C14H15BrN2O3 m/z 340.0 (M+H).

1. temperaturewas refluxed 5 h under argon
2. temperatureThe solution was cooled
3. customthe excess solvent was evaporated under vacuum
4. dissolutionThe residue was dissolved in EtOAc
5. washwashed with dilute NaHCO3 solution (
6. dry with materialThe organic layer was dried over Na2SO4
7. filtrationfiltered
8. concentrationconcentrated
9. customThe residue was purified by column chromatography (100% hexanes→5:95 EtOAc:hexanes)