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.
An efficient method for the construction of sugar-derived chiral oxepanone−indole molecular hybrids is investigated. The reaction condition is optimized by monitoring the progress at various temperatures, with various solvents, and with different Lewis acid catalysts. Under optimized conditions, high stereoselectivity and efficiency are achieved in most of the formed cycloadducts. The accessibility of the strategy is evaluated by utilizing an array of carbohydrate-derived donor−acceptor cyclopropanes and variably substituted indole substrates. Additionally, quick access to the bridged indole−oxepanone framework is described by utilizing a diastereoselective (3+2) cycloaddition of aryl-substituted donor−acceptor cyclopropanes incorporated in a pyran ring.
The Mislow–Evans rearrangement
was used as a key
reaction
to construct digitoxose-derived glycals. The same rearrangement was
iteratively performed on di- and trisaccharides to form the digoxose
glycal donor component present in the cardenolides digitoxin, digoxin,
and gitoxin. The scalability of the trisaccharide synthesis was shown
by performing the reactions on a multigram scale. Glycosylation reactions
were also performed between the synthesized digoxin glycal donor and
aglycons digoxigenin and gitoxigenin to synthesize novel cardenolide
derivatives.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.