Synthesis of Hexenuloses and a Library of Disaccharides Possessing 3-oxo-glycal Unit

An expeditious method for the synthesis of monosaccharides and disaccharides possessing 3-oxo-glycal units is revealed. Several monosaccharides and disaccharide-derived glycals are converted to the corresponding hexenuloses in three steps involving halo-alkoxylation, dehydrohalogenation, and ketalyzation reactions. A number of 3-oxo-glycals are synthesized to show the methodology's importance and generality. Further, the protocol is successfully applied to synthesize a rare-sugar disaccharide donor unit present as part of the trisaccharide moiety in the reported natural product, versipelostatin.