A convergent route for the synthesis of a new class of bicyclic nucleosides has been
developed. The synthetic route to the corresponding arabino-configured uracil and thymine bicyclic nucleosides proceeds in 24 and 27% overall
yields, respectively, starting from 1,2,5,6-di-O-isopropylidene-α-d-glucofuranose. This synthetic protocol includes some crucial steps such as Vorbrüggen
base coupling and chemo-enzymatic regioselective acetylation of the primary hydroxyl
group by using Lipozyme® TL IM where it was found that Lipozyme® TL IM could be recovered and reused for selective acetylation without losing its
selectivity.
Key words
chemo-enzymatic pathway - regioselective monoacetylation - Lipozyme
® TL IM - bicyclic nucleosides