Boron tribromide → 3-Fluoro-5-methoxyphenol

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Boron tribromide (1M in dichloromethane, 9 mL, 89.985 mmol) was added drop wise to an ice-cooled solution of 3,5-dimethoxy fluorobenzene (3 ml, 22.496 mmol) in dichloromethane (20 mL) and the mixture was stirred at 0° C. to room temperature for 4 hours. The solution was cooled to 0° C., further boron tribromide (4 ml, 44.992 mmol) was added and stirring continued, warming to room temperature for an additional 18 hours. The reaction was quenched with 0.88 ammonia solution and stirred at room temperature for 90 minutes. The organic layer was separated and extracted with 2N sodium hydroxide (30 ml), which was then acidified to pH1 by drop wise addition of concentrated hydrochloric acid. The aqueous layer was then re-extracted with dichloromethane (3×15 mL), the combined organic solution was dried over sodium sulfate and concentrated in vacuo to afford the title compound as a white solid in 54% yield, 1.72 g.