反应详情

1,2,3,4,6-penta-O-acetyl-β-D-glucopyranose (1) (50.0 g, 128 mmol) was dissolved in N,N-dimethylformamide (120 ml) at room temperature and cooled in an ice bath. To this solution was added ammonium acetate (20.0 g, 260 mmol), the ice bath was removed, and the mixture was stirred at room temperature for 21.5 hours. Since the remainder of the starting material was confirmed by thin layer chromatography (TLC), the reaction mixture was cooled in an ice bath, and ammonium acetate (5.0 g, 65 mmol) was added. Then, the ice bath was removed, the reaction mixture was stirred at room temperature for 3 hours, and the disappearance of the starting material was confirmed by TLC. The reaction container was cooled in an ice bath, water (600 ml) was added slowly, and the ice bath was removed. The mixture was extracted 5 times with diethyl ether (400 ml) at room temperature. The combined organic layer was washed with 15% brine (100 ml), dried over magnesium sulfate, and filtered, and the filtrate was concentrated under reduced pressure. The residue was purified by silica gel column chromatography (gradient; ethyl acetate:n-hexane=40:60→68:32) to give 2,3,4,6-tetra-O-acetyl-D-glucopyranose (2) (38.5 g, 111 mmol, yield 86%) as a colorless transparent oil. As a result of 1H-NMR analysis, it was a mixture of α form:β form at a ratio of about 3:2.

1. temperaturecooled in an ice bath
2. customthe ice bath was removed
3. temperaturethe reaction mixture was cooled in an ice bath
4. customThen, the ice bath was removed
5. stirringthe reaction mixture was stirred at room temperature for 3 hours
6. temperatureThe reaction container was cooled in an ice bath
7. additionwater (600 ml) was added slowly
8. customthe ice bath was removed
9. extractionThe mixture was extracted 5 times with diethyl ether (400 ml) at room temperature
10. washThe combined organic layer was washed with 15% brine (100 ml)
11. dry with materialdried over magnesium sulfate
12. filtrationfiltered
13. concentrationthe filtrate was concentrated under reduced pressure
14. customThe residue was purified by silica gel column chromatography (gradient; ethyl acetate:n-hexane=40:60→68:32)