Into 8 mL of THF was dissolved 115 mg of dimethyl 4-aminoisophthalate, followed by addition of 22 mg of sodium hydride (oily, 60%). After 20 minutes of stirring at room temperature, 130 mg of 5-chloro-2-chlorosulfonyl-3-methylbenzo[b]thiophene was added at the same temperature, followed by 30 minutes of stirring at room temperature. Further, 26 mg of sodium hydride (oily, 60%) was added and the whole was heated under refluxing for 6 hours. After confirmation of disappearance of the starting material, the reaction was terminated by adding saturated aqueous ammonium chloride solution at 0° C., followed by extraction with ethyl acetate. The organic layer was washed with saturated brine and then dried over anhydrous sodium sulfate. The solvent was removed by evaporation and the residue was purified by silica gel column chromatography (ethyl acetate/hexane 1/1) to obtain 62 mg of the title compound as light yellow amorphous.
