[Br:1][C:2]1[CH:10]=[CH:9][C:8]2[NH:7][N:6]=[CH:5][C:4]=2[C:3]=1[C:11]([O:13][CH3:14])=[O:12].F[P-](F)(F)(F)(F)F.[CH2:22]([O+](CC)CC)[CH3:23]>C(OCC)(=O)C.C(=O)([O-])O.[Na+]>[Br:1][C:2]1[CH:10]=[CH:9][C:8]2[C:4](=[CH:5][N:6]([CH2:22][CH3:23])[N:7]=2)[C:3]=1[C:11]([O:13][CH3:14])=[O:12]To a solution of methyl 5-bromo-1H-indazole-4-carboxylate (2.00 g, 7.84 mmol) in ethyl acetate (80 mL) was added triethyloxonium hexafluorophosphate (2.92 g, 11.8 mmol), and the mixture was stirred under nitrogen atmosphere at room temperature for 15 hr. The reaction solution was diluted with ethyl acetate, saturated aqueous sodium hydrogen carbonate solution was added, and the mixture was extracted with ethyl acetate. The extract was dried over anhydrous sodium sulfate and the solvent was evaporated under reduced pressure. The residue was purified by silica gel column chromatography (NH, ethyl acetate/hexane=5/95→50/50) to give the title compound (2.03 g, yield 91%).
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