合成路线1

The reaction of gamma-lactone (I) with N-(phenylsulfanyl)phthalimide (II) by means of LiHMDS in THF gives the 2,2-bis(phenylsulfanyl)lactone (III), which is reduced with DIBAL in THF to yield 5-O-(tert-butyldiphenylsilyl)-2,3-dideoxy-2,2-bis(phenylsulfanyl)-D-ribose (IV). The reaction of (IV) with acetic anhydride affords the acetylated ribose (V), which is condensed with bis(trimethylsilyl)thymine (VI) by means of TMS-OTf in acetonitrile to provide the glycosylated thymine (VII). The oxidation of (VII) with 1 mol of MCPBA in dichloromethane gives the sulfinyl compound (VIII), which is treated with tributylamine in refluxing xylene to yield the 2',3'-didehydro compound (IX). The oxidation of (IX) with MCPBA in dichloromethane gives the phenylsulfonyl derivative (X), which is desulfurized with sodium amalgam in methanol, yielding the silylated intermediate (XI). Finally, this compound is desilylated with TBAF in THF.