To a solution of 6-fluoro-4-hydroxy-naphthalene-2-carboxylic acid methyl ester (3.7 g, 16.8 mmol) in dry DMF (40 mL) was added K2CO3 (3.25 g, 23.5 mmol), benzyl bromide (3.44 g, 20.2 mmol) and Bu4NI (0.02 g) simultaneously at room temperature under nitrogen. The reaction mixture was stirred for 3 hours at room temperature. The mixture was diluted with water (60 mL) and extracted with ethyl acetate (2×100 mL). The combined organic extracts were washed with water (30 mL), brine (30 mL), dried over anhydrous sodium sulfate and concentrated in vacuo to obtain the crude product. Silica gel column chromatography (2%-5% ethyl acetate in hexanes) afforded 4-benzyloxy-6-fluoro-naphthalene-2-carboxylic acid methyl ester (4.6 g, 88%) as an off-white solid. MS cald. for C19H16FO3 [(M+H)+]: 311, obsd. 311.0.
