Chemical Synthesis of Glycosides

As the chemical synthesis of glycosides is cumbersome, biotechnological transglycosidation using glycosidases is attracting more and more attention [60]. 

Several mechanistic opportunities are available for designing the chemical synthesis of glycosides. The most important of these are enumerated here. Each one is then discussed in more detail. Practically all methods depend on creating some type of carbocationic centre at C-l, which can then react with a nucleophilic hydroxyl compound to give a glycoside. It is also possible to proceed through anionic intermediates. Probably, the majority of glycosylation reactions proceed via a preequilibrium to an ionic intermediate which then proceeds via a transition state to the product. These intermediates are considered next. 

The chemical synthesis of polysaccharides which involves the generation of many glycosidic bonds to form one molecule has been reviewed recently... 

From a strictly chemical point of view, the synthesis of glycosides still presents a formidable challenge to synthetic chemists in spite of major advances in the area [1], Unlike peptidic bonds, the formation of the glycosidic linkage is subject to various factors that include, among others, electronic, stereoelectronic, conformational, substituent, and reactivity effects generally associated with incipient oxocarbenium ions derived from carbohydrates. 

The third theme is concerned with the chemical synthesis of O- and Af-glycosy compounds, and of oligosaccharides, and is the subject of ten chapters. The most widely used methods for glycoside synthesis are discussed, together with the inclusion of concept tually new approaches to anmneric activation and glycoside synthesis. 

It may be concluded that polymerases possess a rather broad specificity towards the structure of the monosaccharide residues that participate in formation of a new glycosidic linkage. Chemical synthesis of polyprenyl... 

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