[F:1][C:2]1[C:11]([O:12]C)=[C:10]([F:14])[CH:9]=[CH:8][C:3]=1[C:4]([O:6][CH3:7])=[O:5].B(Br)(Br)Br.C(OCC)(=O)C.O>C(Cl)Cl>[F:1][C:2]1[C:11]([OH:12])=[C:10]([F:14])[CH:9]=[CH:8][C:3]=1[C:4]([O:6][CH3:7])=[O:5]In 20 ml of methylene chloride was dissolved 2.00 g of methyl 2,4-difluoro-3-methoxy-benzoate, and to the solution was added 12.8 ml of a 1 M solution of boron tribromide in methylene chloride at -30° C., after which the resulting mixture was stirred under ice-cooling for 2 hours. The reaction mixture was added to a mixed solvent of 150 ml of ethyl acetate and 150 ml of water and the organic layer was separated. The organic layer obtained was washed with a saturated aqueous sodium chloride solution, dried over anhydrous magnesium sulfate, and then distilled under reduced pressure to remove the solvent. The resulting residue was purified by a column chromatography (eluent; n-exane:ethyl acetate=3:1) to obtain 1.35 g of methyl 2,4-difluoro-3-hydroxybenzoate as colorless crystals.
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