(1) Synthesis of 3-(2-(2-(2-(2-methoxyethoxy)ethoxy)ethoxy)thiophene (Compound 9): In a dry 250 mL two-necked round-bottomed flask assembled with a condenser tube and a magnetic stirrer, potassium tert-butanolate (10.5 g, 94 mmol) and cuprous iodide (2.34 g, 12 mmol) were added in sequence. Subsequently, a solvent mixture consisting of 10 mL of pyridine and 100 mL of toluene was added and stirred until the solids were completely dissolved, then 15 mL of triethylene glycol monomethyl ether was added. The reaction mixture was stirred at room temperature for 30 min. Subsequently, 3-bromothiophene (5.8 mL, 62 mmol) was added in a single addition and the reaction system was heated to 110 °C and maintained at this temperature for 24 hours. Upon completion of the reaction, the reaction was cooled to room temperature, the reaction mixture was separated by centrifugation and concentrated under reduced pressure. To the concentrate was added 50 mL of dichloromethane and washed with 5 M aqueous hydrochloric acid. The aqueous phase was extracted with dichloromethane, the organic phases were combined, dried with anhydrous magnesium sulfate and concentrated under reduced pressure. The crude product was purified by column chromatography with the eluent being a solvent mixture of ether/hexane at 1:1 volume ratio. The target product 3-(2-(2-(2-(2-methoxyethoxy)ethoxy)ethoxy)thiophene was finally obtained as a yellow oil (10.35 g, 68% yield).1H-NMR (400 MHz, CDCl3) δ 7.18 (dd, J = 5.3, 3.1 Hz, 1H), 6.79 (dd, J = 5.3, 1.5 Hz, 1H), 6.28 (dd, J = 5.3, 1.5 Hz, 1H). 6.28 (dd, J = 3.1, 1.5 Hz, 1H), 4.17-4.10 (m, 2H), 3.89-3.83 (m, 2H), 3.77-3.72 (m, 2H), 3.72-3.64 (m, 4H), 3.57 (dd, J = 5.7, 3.6 Hz, 2H), 3.40 (s, 3H).
