Pentaethylene glycol (10.8 g, 57.8 mmol) was slowly added to a stirred mixture of potassium hydroxide (7.8 g, 139.3 mmol) and ethylene glycol (60 mL) under nitrogen protection and the reaction was carried out at room temperature. Subsequently, the reaction mixture was heated to reflux temperature and stirred continuously for 36 hours. Upon completion of the reaction, it was cooled to room temperature, the reaction mixture was filtered and concentrated by depressurization to obtain a viscous oily substance. This viscous oily substance was dissolved with sodium hydroxide (4.8 g, 120 mmol) in a solution of tetrahydrofuran/water (v/v = 1/1, 40 mL) and cooled under nitrogen protection to 0°C. At this temperature, p-toluenesulfonyl chloride (22 g, 115 mmol) was slowly added. After addition, stirring was continued for 3 hours. At the end of the reaction, water (100 mL) was added to dilute the reaction mixture and the product was extracted with dichloromethane (20 mL × 3). The organic phase was washed with brine (20 mL × 3), and the combined organic layers were dried with anhydrous magnesium sulfate, followed by evaporation to remove the dichloromethane. The crude product was purified by column chromatography (petroleum ether:ethyl acetate = 3:1) to give a yellow oily pure product (8.1 g) in 27.5% yield. The product was characterized by 1H NMR (CDCl3, 500 MHz) with chemical shifts of δ 2.44 (3H, s), 3.57 (4H, s), 3.59 (2H, s), 3.67 (2H, t, J = 4.8 Hz), 4.14 (2H, t, J = 4.8 Hz), 7.33 (2H, d, J = 8.1 Hz), 7.78 (2H, d , J = 8.2 Hz).
