Intramolecular 1,3-dipolar cycloadditions of 5-azido-5-deoxyaldopentose ketene dithioacetal bis(sulfones) in the synthesis of imino sugar analogs

Article abstract of DOI:10.1016/0040-4039(96)00716-2

Oxidation of the dithioacetal groups in the O-acetylated 5-azido-5-deoxy dibenzyl dithioacetal 3 of D-xylose and that (7) of D-ribose leads to triazoline derivatives 4 and 8, the products of sequential oxidation to the bis(sulfones), loss of AcOH betwee C-1 and C-2 and, spontaneous intramolecular 1,3-dipolar cycloaddition of an azido ketene intermediate. A possible explanation of the observed diastereoselectivity is discussed.