1,2-Di-O-acetyl-5-O-benzoyl-3-deoxy-l-erythro-pentofuranose, a convenient precursor for the stereospecific synthesis of nucleoside analogues with the unnatural β-l-configuration

The title compound 1,2-di-O-acetyl-5-O-benzoyl-3-deoxy-l-erythro-pentofuranose (5), a useful precursor for the stereospecific synthesis of β-l-nucleoside analogues as potential antiviral agents, has been synthesised by a multi-step reaction sequence from l-xylose with a 38% overall yield. The preparation involved conversion of l-xylose to 1,2-O-isopropylidene-α-l-xylofuranose which, upon selective 5-O-benzoylation and subsequent radical deoxygenation, provided the protected 3-deoxy sugar derivative. Finally, cleavage of the acetonide group gave the resulting 5-O-benzoyl-3-deoxy-l-erythro-pentose which was acetylated to afford crystalline α,β-5.