Trifluoromethanesulfonic anhydride (0.22 mL) was added to an ice-cooled mixture of benzyl 2-benzyloxy-4-hydroxybenzoate (0.40 g) and pyridine (0.1 mL) in methylene chloride (1.5 mL) with stirring, and the mixture was stirred at room temperature for 30 min. The reaction mixture was poured into a mixture of hydrochloric acid and ethyl acetate, and the mixture was extracted with ethyl acetate. The organic layer was washed with water and brine, and dried over anhydrous magnesium sulfate. The solvent was evaporated under reduced pressure, and the residue was purified by medium-pressure liquid silica gel column chromatography (eluent: n-hexane/ethyl acetate=6/1) to afford benzyl 2-benzyloxy-4-trifluoromethanesulfonyloxybenzoate (0.56 g).
