General procedure for the synthesis of 3-methyl-6-hydroxyindazole from 6-methoxy-3-methyl-1H-indazole: 6-methoxy-3-methyl-1H-indazole (620 mg, 3.82 mmol) was dissolved in dichloromethane (25 mL) and cooled to 0°C. Under stirring, a dichloromethane solution of boron tribromide (1 M, 17 mL) was slowly added. The ice bath was removed and the reaction mixture was allowed to gradually warm to room temperature and stirred overnight. Upon completion of the reaction, the reaction solution was quenched by slowly pouring it into a pre-cooled saturated aqueous sodium bicarbonate solution. The organic and aqueous phases were separated and the aqueous phase was extracted with ethyl acetate (3 x 25 mL). The organic phases were combined and concentrated to give the crude product. The crude product was purified by a Biotage fast chromatography system (40S silica gel column, eluent 45-60% acetone/heptane) to give 3-methyl-1H-indazol-6-ol (458 mg, 81% yield).
