合成路线1

The oxidative cleavage of 1,2,5,6-di-O-isopropylidene-D-galactofuranose (XLVII) with NaIO4 and H5IO6 gives aldehyde (XLVIII), which is reduced with NaBH4 in methanol to yield the 1,2-di-O-isopropylidene-L-arabinose (XLIX). Protection of the OH groups of compound (XLIX) with benzyl chloride and KOH in refluxing dioxane affords the dibenzyl ether (L), which is submitted to cleavage of the acetonide group by means of HCl in methanol to provide the methyl dibenzyl-L-arabinoside (LI). Reaction of the free OH group of (LI) with triflic anhydride and pyridine in dichloromethane gives the triflate (LII), which is reduced with Bu4NBH4 in refluxing benzene to yield methyl 3,5-di-O-benzyl-2-deoxy-L-riboside (LIII). Deben-zylation of (LIII) wit H2 over Pd/C affords methyl 2-deoxy-L-riboside (LIV), which is finally treated with Dowex [H+] in hot water to provide the telbivudine intermediate 2-deoxy-L-ribose (VI).