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

Abstract

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.

A Short Route to the Synthesis of Digoxose Trisaccharide Glycal Donor via Mislow–Evans Rearrangement

“…Alongside, considerable efforts were done for the synthesis of the digoxose trisaccharide glycal unit using this protocol. Having obtained donor 12, PPh 3 •HBr mediated glycosylation of the C-4 secondary alcohol of acceptor 7 with donor 12 was performed following our previous method, 17 which afforded the disaccharide 13 with excellent β-selectivity and 90% yield (Scheme 3).…”