Chloroform → 2-(Bromomethyl)-2,3-dihydro-1-benzofuran

340 mg (1.0 mmol) of compound 001B, which had been prepared in Step B, was dissolved in 3 ml of ethanol, followed by cooling to 0° C. To the resultant solution was dropwise added 1.2 ml (1.2 mmol) of a 1N solution of sodium ethoxide in ethanol and then, the resultant mixture was stirred at 0° C. for 2 hours to effect a reaction. To the resultant reaction mixture was added 20 ml of chloroform to obtain a mixture. The obtained mixture was successively washed with 20 ml of a 10% aqueous citric acid solution, 20 ml of water and 20 ml of saturated saline, to thereby form a chloroform layer containing the desired compound 001C, followed by separation of the chloroform layer. The chloroform layer thus separated was dehydrated by means of a Whatman 1PS filter paper and then, concentrated in vacuo to thereby obtain a residue. The obtained residue was purified by silica gel column chromatography. That is, the residue was applied to a column of 10 g of silica gel (Art. 9385, manufactured and sold by E. Merck, Darmstadt, Germany) and eluted with a mixed solvent of hexane-ethyl acetate (30:1), to thereby obtain 140 mg of compound 001C as a transparent oily substance (yield: 66%).