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.

The synthesis of Gobichelin‐A, a naturally occurring mixed‐ligand siderophore isolated from Streptomyces sp. NRRL F‐4415, is described. The target molecule was planned to be synthesized by a convergent process involving the combination of two halves, Gob‐A 1st half and Gob‐A 2nd half, at the prefinal stage of the synthetic route. By adopting this method, fully protected Gobichelin‐A was synthesized in excellent yield.

Total synthesis of the marine natural product bengamide E and 5-epi-bengamide E has been accomplished with two routes (i) via a polyhydroxy acid precursor involving a total number of 16...