358-23-6

540-51-2

103935-47-3

Pyridine (1.74 kg, 22.01 mol, 1.10 eq.) was dissolved in dichloromethane (20 L) under nitrogen protection and the solution was cooled to -20 °C. Subsequently, trifluoromethanesulfonic anhydride (5.87 kg, 20.81 mol, 1.04 eq.) was added slowly and dropwise. The reaction system was maintained at -20 °C with stirring for 0.5 hours. Then, 2-bromoethanol (2.50 kg, 20.01 mol, 1.0 eq.) was slowly added dropwise and the reaction temperature was ensured to be maintained below 0 °C and stirring was continued for 1.0 hour. The progress of the reaction was monitored by thin layer chromatography (TLC, unfolding agent ratio of petroleum ether: ethyl acetate = 5:1) to confirm the completion of the reaction. After completion of the reaction, the reaction mixture was filtered and the filtrate was concentrated. Petroleum ether (15 L) was added to the concentrate, the precipitated solid was filtered, and the filtrate was concentrated again to obtain the target product (4.80 kg, 93.33% yield) of trifluoromethanesulfonic acid (2-bromoethyl) ester as a dark yellow oil.