Hydrochloric Acid → 6-(Hydroxymethyl)-2-benzofuran-1(3H)-one

The compound (1.1274 g) obtained in Example 102-1 was dissolved in carbon tetrachloride (19.2 ml). The reaction solution was added with N-bromosuccinimide (2.417 g) and benzoyl peroxide (147.2 mg), and the whole was refluxed under heating for 6.5 hours. After having been cooled to room temperature, the reaction solution was concentrated under reduced pressure. The resultant residue was purified through silica gel column chromatography (hexane/ethyl acetate), thereby obtaining a mixture (2.4003 g) containing 2,5-bis-bromomethyl-benzoic acid methyl ester. The resultant mixture was dissolved in a 50% 1,4-dioxane aqueous solution (48 ml). The reaction solution was added with calcium carbonate (3.4823 g) and the whole was stirred at 100° C. for 16.5 hours. After having been cooled to room temperature, the reaction solution was cooled to 0° C. and concentrated hydrochloric acid was gradually added thereto to make the pH of the solution to 2. After that, the whole was stirred at room temperature for 20 minutes. The reaction solution was subjected to extraction with ethyl acetate. The organic layer was washed with a saturated aqueous sodium hydrogen carbonate solution and a saturated saline solution and then dried with anhydrous sodium sulfate. After the drying agent was filtrated out, the filtrate was concentrated under reduced pressure. The resultant residue was purified through silica gel column chromatography (chloroform/ethyl acetate), thereby obtaining the subject compound (372.0 mg) as a white crystal.