A mixture of 7.5 g of 1-(1-naphthyl)-1-(tetrahydropyran-2-yloxy)-2-[2-(p-toluenesulfonyloxy)ethoxy]ethane, 2.65 ml of N-methylpiperazine, 3.96 g of potassium carbonate and 38 ml of N,N-dimethylformamide was stirred for 2 hours at 90°-100° C. The reaction mixture was cooled and added to a mixture of 100 ml of diethyl ether and 100 ml of ice water. The organic layer was separated. The aqueous layer was extracted twice each with 25 ml of diethyl ether. The extracts were combined with the previously separated organic layer. The combined organic layer was washed with water and a saturated aqueous sodium chloride solution in this order, and dried over anhydrous magnesium sulfate. The solvent was removed by distillation under reduced pressure. The residue thus obtained was purified by column chromatography (eluant: chloroform/ethanol=10/1) to obtain 3.36 g of colorless, oily 2-[2-(4-methylpiperazin-1-yl)ethoxy]-1-(1-naphthyl)-1-(tetrahydropyran-2-yloxy)ethane (compound No. 258).
