Synthetic strategies and applications of positional thiol analogs of glycopyranose.

This review comprehensively summarizes synthetic approaches towards the site-selective conversion of hydroxyl groups into thio groups in glycopyranose derivatives. Thiosugars, which feature either thiol groups or an endocyclic sulfur atom, demonstrate potential biochemical and medical applications. Their unique properties set them apart from traditional O-glycosides. We first outline various strategies for synthesizing thiosugars, focusing on approaches for introducing sulfur atoms at different positions on the pyranose ring. Following this, we review the practical applications of these thiosugars in glycosylation, chemical functionalization, and biological evaluation. Furthermore, we highlight several recently established regioselective hydroxyl protection strategies, as these approaches enable efficient introduction of sulfur atoms at specific positions within the pyranose ring.