5-(5-Chloropentylsulfonyl)-1,1,1,2,2-pentafluoropentane (27 mg, 0.082 mmol), potassium carbonate (34 mg, 0.25 mmol) and 18-crown-6 (21 mg, 0.08 mmol) were added to benzene-dimethylformamide (1:1) solution (2 ml) of (3RS,4RS)-4-(4-hydroxyphenyl)-7-methoxymethyloxy-3-[4-(methoxymethyloxy)phenyl]-3-methylthiochroman (37 mg, 0.082 mmol) and then stirred for 8 hours at 100° C. under argon atmosphere. After adding water, the reaction solution was extracted with ethyl acetate. The organic layer was washed with saturated saline, dried over anhydrous magnesium sulfate and distilled under reduced pressure to remove the solvent. The crude product thus obtained was purified using silica gel plate (ethyl acetate:hexane=1:2) to obtain 41 mg (yield: 67%) of the title compound.
