In a three-necked flask equipped with a mechanical stirrer, (3-bromo-5-methylphenyl)boronic acid (15.0 g, 69.8 mmol) was dissolved in an aqueous solution (100 mL) of potassium hydroxide (11.8 g, 209.4 mmol). A 30% hydrogen peroxide solution (57.0 mL) was added slowly and dropwise at room temperature and the reaction lasted for 20 min. Upon completion of the reaction, the pH of the reaction solution was adjusted with 2 mol/L dilute hydrochloric acid to 7. Subsequently, extraction was performed with dichloromethane (50 mL × 3), and the organic phases were combined and dried over anhydrous sodium sulfate. After filtration to remove the desiccant, the solvent was removed by distillation under reduced pressure to afford 3-bromo-5-methylphenol as an oily liquid (11.3 g, 86.5% yield).
