反应详情

温度

0 °C

A mixture that consists of 54.1 g (100 mmol) of 2,3,4,6-tetra-O-benzyl-mannopyranose, 1.7 g (5 mmol) of tetrabutylammonium hydrogen sulfate and 24 g (600 mmol) of fine-powder sodium hydroxide in 350 ml of 1,2-dimethoxyethane is cooled to 0° C. At 0° C., 29.3 g (150 mmol) of bromoacetic acid ethyl ester is added in drops over 10 minutes while being stirred vigorously. It is stirred for one hour at 0° C. 250 ml of diethoxymethane is added, solid is filtered out, and the filtrate is evaporated to the dry state in a vacuum. The residue is taken up in 500 ml of ethanol/50 ml of water. 60 ml of 50% aqueous sodium hydroxide solution is added, and it is refluxed for four hours. It is cooled to 0° C., set at pH 8 with 10% aqueous hydrochloric acid, and then the solvent is distilled off (vacuum). The residue is taken up in 300 ml of water and 500 ml of ethyl acetate, and the pH of the aqueous phase is set at 2 while being stirred (10% aqueous hydrochloric acid). The organic phase is separated, and the aqueous phase is extracted once more with 200 ml of ethyl acetate. The combined organic phases are dried on magnesium sulfate, the solvent is distilled off in a vacuum, and the residue is chromatographed on silica gel (mobile solvent: dichloromethane/n=hexane/ethanol/acetic acid=20:5:3:0.5). The product-containing fractions are concentrated by evaporation, dissolved in 400 ml of ethyl acetate, and shaken out three times with 200 ml of water. Then, the organic phase is separated and evaporated to the dry state in a vacuum.

1. stirringIt is stirred for one hour at 0° C
2. filtrationsolid is filtered out
3. customthe filtrate is evaporated to the dry state in a vacuum
4. addition60 ml of 50% aqueous sodium hydroxide solution is added
5. temperatureit is refluxed for four hours
6. temperatureIt is cooled to 0° C.
7. distillationthe solvent is distilled off (vacuum)
8. stirringwhile being stirred (10% aqueous hydrochloric acid)
9. customThe organic phase is separated
10. extractionthe aqueous phase is extracted once more with 200 ml of ethyl acetate
11. customThe combined organic phases are dried on magnesium sulfate
12. distillationthe solvent is distilled off in a vacuum
13. customthe residue is chromatographed on silica gel (mobile solvent: dichloromethane/n=hexane/ethanol/acetic acid=20:5:3:0.5)
14. concentrationThe product-containing fractions are concentrated by evaporation
15. dissolutiondissolved in 400 ml of ethyl acetate
16. stirringshaken out three times with 200 ml of water
17. customThen, the organic phase is separated
18. customevaporated to the dry state in a vacuum