Synthesis of D-glucose pentamethyl esters (D-Glu) and L-glucose pentamethyl esters (L-Glu)
The glucose (4.10 g, 22.51 mmol) was first dissolved in acetic acid (100 mL) and acetic anhydride (400 mL), then 1.5 mL of concentrated sulfuric acid was added to the reaction flask, and the reaction was carried out in ice bath for 2 hours. After the reaction was completed, 200 mL of DCM was added to dilute the mixture, and then the mixture was washed successively with ice water (3 × 300 mL), saturated Na2CO3 solution, and saturated brine until the aqueous solution was neutral. The organic phase was dried over anhydrous sodium sulfate, and then DCM was removed under reduced pressure to obtain D-Glu. L-Glu was also synthesized with the same procedure.27