1,2-di-O-acetyl-5-O-benzoyl-3-deoxy-L-erythro-pentofuran ose, a convenient precursor for the stereospecific synthesis of nucleoside analogues with the unnatural beta-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 beta-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-alpha-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 alpha,beta-5.