Boron tribromide → 4-methyl-1H-indazol-5-ol

Beteiligte Stoffe

Reaktionsschritte

A solution of boron tribromide (0.513 ml, 5.43 mmol) in dichloromethane (5 ml) was added dropwise to a solution of the 5-methoxy-4-methyl-1H-indazole (400 mg, 2.47 mmol) obtained in Example 401 in dichloromethane (5 ml) at 0° C. After 1 hour, the reaction solution was poured onto ice (50 ml), adjusted to pH 4 to 5 with a saturated aqueous sodium hydrogencarbonate solution, and then extracted with chloroform (20 ml×2) and ethyl acetate (20 ml×2), and the organic layer was dried over anhydrous magnesium sulfate. The organic layer dried was concentrated under reduced pressure and the resulting residue was purified by a silica gel column chromatography (eluent: chloroform/ethyl acetate) to obtain 4-methyl-1H-indazol-5-ol (149 mg, 41%).

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