合成路线1

The acetylation of N-acetyl-D-glucosamine (I) with Ac2O and pyridine gives the tetraacetoxy derivative (II), which is treated with dry HCl in acetic anhydride to yield 2-acetamido-3,4,6-tri-O-acetyl-1-chloro-2-deoxy-alpha-D-glucopyranose (III). The condensation of (III) with 7-benzyloxy-6-hydroxy-2H-1-benzopyran-2-one (IV) by means of NaOH and benzyl triethylammonium chloride in chloroform affords the acetylated glucoside (V), which is selectively deacetylated with NaOMe in hot methanol to provide the benzyl protected glucoside (VI). Finally, this compound is debenzylated by hydrogenation with H2 over Pd/C in dimethoxyethane/water to furnish the target glycoside. The intermediate 7-benzyloxy-6-hydroxy-2H-1-benzopyran-2-one (IV) is obtained as follows: The reaction of Esculein (VII) with benzyl chloride, K2CO3, KI and 18-C-6 in hot DMF gives 7-benzyloxy-6-(D-glucopyranosyloxy)-2H-1-benzopyran-2-one (VIII), which is finally deglycosylated by means of HCl in methanol to afford the target intermediate (IV).