Oxonium, trimethyl-, tetrafluoroborate(1-) (1:1) → methyl 5-bromo-6-chloro-2-methyl-2H-indazole-4-carboxylate

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Reaction Steps

To a solution of methyl 5-bromo-6-chloro-1H-indazole-4-carboxylate (390 mg, 1.35 mmol) in ethyl acetate (27 mL) was added trimethyloxonium tetrafluoroborate (260 mg, 1.76 mmol) at room temperature, and the mixture was stirred for 2 hr. The reaction solution was diluted with ethyl acetate, washed with saturated aqueous sodium hydrogen carbonate solution, and dried over anhydrous sodium sulfate. The solvent was evaporated under reduced pressure, and the residue was purified by silica gel column chromatography (NH, ethyl acetate/hexane=10/90→40/60) to give the title compound (336 mg, yield 82%).

Provenance & Evidence