合成路线1

The reaction of 1,2:5,6-di-O-isopropylidene-alpha-D-glucofuranose (I) with methanesulfonyl chloride and pyridine gives the mesylate (II), which by treatment with sodium azide in DMF is converted into 3-azido-3-deoxy-1,2:5,6-di-O-isopropylidene-alpha-D-glucofuranose (III). Selective hydrolysis of (III) with 1N HCl in ethanol affords 3-azido-3-deoxy-1,2-O-isopropylidene-alpha-D-glucofuranose (IV) (1), which is oxidized with sodium metaperiodate to the aldehyde (V). The reduction of (V) with NaBH4 in EtOH gives 3-azido-3-deoxy-1,2-O-isopropylidene-alpha-D-xylofuranose (VI), which is treated with tosyl chloride and pyridine to yield the corresponding 5-O-tosylate (VII) (2). The reaction of (VII) with potassium thiobenzoate (VIII) in hot DMF gives 3-azido-5-S-benzoyl-3-deoxy-1,2-O-isopropylidene-5-thio-alpha-D-xylofuranose (IX), which is treated successively with NaOMe in methanol, to induce cyclization, with refluxing HCl in methanol, to eliminate the isopropylidene group, and finally with acetic anhydride to furnish 1,2,4-tri-O-acetyl-3-azido-3-deoxy-5-thio-D-xylopyranose (X). The condensation of (X) with 4-nitrothiophenol (XI) by means of trimethylsilyl triflate in dichloromethane yields the corresponding acylated dithiopyranoside, which is finally deacetylated with sodium methoxide in methanol.