N-bromobutanimide → (4-Benzyloxy-1-bromo-6-fluoro-naphthalen-2-yl)-acetic acid methyl ester

To a stirred solution of (4-benzyloxy-6-fluoro-naphthalen-2-yl)-acetic acid methyl ester (350 mg, 1.08 mmol) in acetonitrile (10 mL) was added N-bromosuccinimide (385 mg, 2.16 mmol). After being stirred at room temperature for 1 hour, the resulting mixture was diluted with water (20 mL), and extracted with ethyl acetate (20 mL×2). The combined organic layers were washed with water (15 mL) and brine (20 mL), dried over sodium sulfate and concentrated in vacuo. The residue was purified by column chromatography (gradient elution with 0-20% ethyl acetate in hexanes) to afford (4-benzyloxy-1-bromo-6-fluoro-naphthalen-2-yl)-acetic acid methyl ester (400 mg, 92%) as a white solid.