[S:1]1[CH:5]=[CH:4][C:3]2[CH:6]=[C:7]([CH2:10][CH2:11][O:12][CH2:13][CH2:14][OH:15])[CH:8]=[CH:9][C:2]1=2.[CH3:16][S:17](Cl)(=[O:19])=[O:18].N1C=CC=CC=1.Cl>C(Cl)Cl.O>[CH3:16][S:17]([O:15][CH2:14][CH2:13][O:12][CH2:11][CH2:10][C:7]1[CH:8]=[CH:9][C:2]2[S:1][CH:5]=[CH:4][C:3]=2[CH:6]=1)(=[O:19])=[O:18]In 20 mL of methylene chloride is dissolved 2.10 g of 2-(2-benzo[b]thiophen-5-ylethoxy)-1-ethanol. At an ice-cooled temperature, 1.63 g of methanesulfonyl chloride and 1.47 g of pyridine are added to the solution obtained above, and the mixture thus formed is stirred at the same temperature as above for 30 minutes and then at ambient temperature for 12 hours. Then, methylene chloride and water are added to the reaction mixture, pH is adjusted to 2.0 with 2 mol/L hydrochloric acid, and the organic layer is separated. The organic layer is washed with water and saturated aqueous solution of sodium chloride successively and dried over anhydrous magnesium sulfate, the solvent is distilled off under reduced pressure, and the residue is purified by column chromatography (eluent: n-hexane:ethyl acetate=4:1 to 2:1) to obtain 2.50 g of 2-(2-benzo[b]thiophen-5-ylethoxy)-ethyl methanesulfonate.
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