The general procedure for the synthesis of 2,5-dibromo-1-methoxybenzene from methanol and 1,4-dibromo-2-fluorobenzene was as follows: to a mixture of 1,4-dibromo-2-fluorobenzene (25.0 g, 98.5 mmol) in a solution of tetrahydrofuran (492 mL) and methanol (40 mL, 984.7 mmol) was added slowly and dropwise potassium tert-butoxide (118.2 mL, 118.2 mmol, 1 M hexane solution). The reaction mixture was stirred at room temperature, then warmed to 70 °C and kept overnight. Upon completion of the reaction, the reaction was quenched with water (50 mL) and the reaction mixture was diluted with ether (400 mL) and subsequently washed once with saturated ammonium chloride solution (300 mL). The aqueous layer was back-extracted with ether (200 mL) and all organic phases were combined and dried over anhydrous sodium sulfate. After filtration, the organic phase was concentrated under reduced pressure to give the crude product. The crude product was purified by fast column chromatography using 5-10% ethyl acetate/hexane as eluent to give 22.0 g (84% yield) of 2,5-dibromo-1-methoxybenzene. The product was analyzed by gas chromatography and the m/z (79Br16Br) was 266 [M]+.
