Anhydro sugars in synthesis

The following scheme outlines some of the possibilities using glycals and anhydro sugars in oligosaccharide synthesis.182... 

The properties, synthesis, stability, and metabolism of l,4 3,6-dianhydro-D-glucitol dinitrate have been discussed. The i.r. and Raman spectra of powdered 1,5-anhydro-xylitol, -ribitol, and -L-arabinitol have been reported Raman spectra were also recorded for solutions of the anhydro-sugars in water and in [ HeJDMSO. ... 

This section presents selected examples of the use of zeolites and related porous materials for transformations of carbohydrates, that fall beyond the scope of the previous paragraphs. They include the use of zeolites in click chemistry and in a variety of reactions, including the synthesis of anhydro sugars, cyclization, elimination, and addition reactions to the carbonyl group. 

C-6,209,214 anhydro sugars,branched monosaccharides, fluori-nated amino sugars,difluorinated monosaccharides, and fluorinated monosaccharide phosphates,and phosphonates have been described. Further progress has been achieved in the synthesis and n.m.r.-spectral analysis of fluorinated avermectin Bu, tylono-lide, and neuraminic acid derivatives. " ... 

There are several instances where reactive intermediates present during the synthesis of septanosides have reacted intramolecularly to give ring-contracted or bicyclic products.91 Similar intramolecular reactions (such as the formation of 1,6-anhydro sugars) have precedents in the pyranose literature. Such cases of intramolecular reactivity described in the literature notably involve novel ethers or thioethers as the nucleophilic species in the ring contractions. 

Although 2,5-anhydro sugars had, for a long time, been poorly understood, they have now found useful application as intermediates in synthesis, and even as derivatives for the characterization of certain amino sugars. For example, a useful method for the analytical deter-... 

The synthesis of other anhydro sugar derivatives is usually accomplished by an internal displacement of a leaving group with inversion, as has already been emphasized for those anhydrides in which the anhydride bridge engages the anomeric position. Three such compounds that have been used in polymerizations deserve specific mention 5,6-anhydro-l,2-0-isopropylidene-a-D-glucofuranose,12 13 its 3-methyl ether,11 and 3,5-anhydro-l,2-0-isopropylidene-a-D-xylo-furanose,14 all of which were synthesized by p-toluenesulfonylation of the primary hydroxyl group of the parent, isopropylidene derivative, followed by treatment with base. 

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