C(O[C@@H:5]1[O:22][C@H:21]([CH2:23][O:24][C:25](=[O:27])[CH3:26])[C@@H:16]([O:17][C:18](=[O:20])[CH3:19])[C@H:11]([O:12][C:13](=[O:15])[CH3:14])[C@H:6]1[O:7][C:8](=[O:10])[CH3:9])(=O)C.C(OC(=O)C)(=O)C.[BrH:35].C(O)(=O)C>C1(C)C=CC=CC=1.[Cl-].[Na+].O>[C:8]([O:7][C@@H:6]1[C@@H:11]([O:12][C:13](=[O:15])[CH3:14])[C@H:16]([O:17][C:18](=[O:20])[CH3:19])[C@@H:21]([CH2:23][O:24][C:25](=[O:27])[CH3:26])[O:22][C@@H:5]1[Br:35])(=[O:10])[CH3:9]
1,2,3,4,6-Penta-O-acetyl-β-D-glucopyranose (100 g, 0.251 mol) is suspended in toluene (210 ml). Acetic anhydride (9.5 ml; 0.1 mol) is added followed by hydrobromic acid 30% in acetic acid (200 ml, 1 mol). The mixture is stirred at 18° C. for 30 min. A mixture of ice/water (300 ml) and brine (100 ml) is then added with stirring. The phases are separated and the aqueous phase is extracted with toluene (100 ml). The organic phases are combined and washed with aqueous sodium hydrogencarbonate (100 ml) and brine (100 ml). Drying and evaporation of the solvent under reduced pressure yields an oil which is crystallised by addition of methyl-t-butylether (150 ml) and methylcyclohexane (300 ml). The product is isolated by filtration, washed with methylcyclohexane and dried under vacuo at 45° C.
読み込み中…
