1. tetraethylene glycol monomethyl ether (2,5,8,11-tetraoxatridecan-13-ol, 5.0 g, 24.01 mmol) was dissolved in tetrahydrofuran (THF, 20.01 mL).
2. To the above solution, pyridine (5.83 mL, 72.0 mmol) and p-toluenesulfonyl chloride (4-methylbenzene-1-sulfonyl chloride, 5.49 g, 28.8 mmol) were added sequentially.
3. The reaction mixture was stirred at room temperature overnight.
4. Upon completion of the reaction, the reaction mixture was concentrated by rotary evaporator.
5. The concentrated residue was dissolved in dichloromethane. 6.
6. The organic phase was washed twice with saturated aqueous sodium bicarbonate. 7.
7. Combine the aqueous phases and back-extract with methylene chloride. 8.
8. All organic phases were combined and washed twice with 1N hydrochloric acid and once with saturated saline.
9. The organic phase was dried with anhydrous magnesium sulfate (MgSO?), filtered and concentrated to afford the target product 2,5,8,11-tetraoxatridecan-13-yl 4-methylbenzenesulfonate (4.12 g, 11.37 mmol, 47.3% yield), which could be used for the subsequent reaction without further purification.
