Ethyl Acetate → 2-Bromoethyl 2,3,4,6-tetra-O-acetyl-beta-D-glucopyranoside

A solution of 9.46 g (24.3 mmol) of penta-O-acetyl-β-D-glucopyranose and 3.04 g (24.3 mmol) of ethylene bromohydrin in 100 mL of dichloromethane was put in a 200 mL round bottom flask in an argon atmosphere. Subsequently, 10 mL of boron trifluoride diethyl ether complex was slowly added dropwise to this solution with stirring. The resulting mixture was continuously stirred with ice cooling for another one hour and then stirred at room temperature overnight while protecting it from light. After the stirring, the color of the reaction solution turned orange. An adequate amount of ethyl acetate was added to the reaction solution, and the organic phase was washed with water, a saturated aqueous sodium hydrogen carbonate and a saturated saline successively. After the organic solution was dried over anhydrous sodium sulfate, the organic phase was filtered, and the solvent was evaporated under reduced pressure to give 2-bromoethyl 2,3,4,6-tetra-O-acetyl-β-D-glucopyranoside in the form of an oil (yield 11.0 g; 100%)