In a round-bottomed flask equipped with a magnetic stirrer, 1.6 g (10.0 mmol) of 1,6-dihydroxynaphthalene (compound 39, purchased from Tokyo Chemical Industry Co., Ltd.) was dissolved in 15 mL of N,N-dimethylformamide (DMF). Subsequently, 14.2 g (100.0 mmol) of iodomethane (purchased from Wako Pure Chemical Industries, Ltd.) and 13.8 g (100.0 mmol) of potassium carbonate (purchased from Wako Pure Chemical Industries, Ltd.) were added to the solution. The reaction mixture was stirred at room temperature for 2 hours. After completion of the reaction, the reaction mixture was extracted by adding dichloromethane and water to the reaction mixture and the organic layer was separated and washed with distilled water. The solvent was removed by distillation under reduced pressure to give 1.7 g (yield: 90%) of 2,5-dimethoxynaphthalene (compound 40) as a colorless liquid.
