Efficient synthesis of 5-thio-D-arabinopyranose and 5-thio-D-xylopyranose from the corresponding D-pentono-1,4-lactones.

5-Thio-D-arabinopyranose (5) and 5-thio-D-xylopyranose (10) were synthesized from the corresponding D-pentono-1,4-lactones. After regioselective bromination at C-5, transformation into 5-S-acetyl-5-thio derivatives, reduction into lactols and deprotection afforded the title compounds in 49 and 42% overall yield, respectively.