1076-74-0

13314-85-7

The general procedure for the synthesis of 5-hydroxy-2-methylindole from 5-methoxy-2-methylindole was as follows: a solution of boron tribromide (32.5 mL, 341 mmol) in dichloromethane (60 mL) was added batchwise to a solution of 5-methoxy-2-methylindole (25 g, 155 mmol) in dichloromethane (250 mL) that had been cooled to -50 °C. After stirring the reaction mixture at -30 °C for 15 min, it was slowly warmed to room temperature and stirring was continued for 1 hour. Subsequently, dichloromethane (300 mL) was added in batches and the reaction mixture was cooled to 0 °C. Water was slowly added and the pH of the mixture was adjusted to 6 with 4N sodium hydroxide solution. the organic layer was separated and the aqueous layer was extracted with dichloromethane. All organic layers were combined, washed sequentially with water and saturated brine and dried over anhydrous magnesium sulfate. The solvent was removed by evaporation under reduced pressure and the resulting crude product was purified by column chromatography with the eluent ethyl acetate/dichloromethane (initial ratio 1:9, subsequently adjusted to 15:85) to give 5-hydroxy-2-methylindole (21.2 g, 93% yield) as a white solid.