Glycosylation oligosaccharides

Among all the synthetic methods developed for glycosidic bond formation, the trichloroacetimidate method developed by Richard Schmidt and coworkers [18] is probably the most popular and widely used for the synthesis of complex oligosaccharides. Glycosyl trichloroacetimidates can be readily prepared by a base-catalyzed addition of the anomeric hydroxy group to trichloroacetonitrile. The stereochemistry can be influenced by the addition of different bases the use of K2C03 favors formation... 

The number of potential glycosylation sites in the different NAs varies from 3 to 7, and NA contains mannose-rich as well as complex oligosaccharides. Glycosylation at a specific site has been correlated with the unique growth properties and virulence of the WSN strain of influenza virus (Schulman and Palese,1977 Li et al., 1993). In contrast to HA, influenza NA does not undergo any proteolytic processing. 

There are two established methods in use for citing locants either in parentheses between the glycosyl and glycose terms, or in front of the glycosyl prefix, as in the names of glycosides. The former (preferred) method is derived from that used to designate residues in oligosaccharides (see 2-Carb-37 and -38). 

Cyclic oligosaccharides composed of a single type of residue can be named by giving the systematic name of the glycosyl residue, preceded by the linkage type in parentheses, preceded in turn by cyclo- with a multiplicative suffix (i.e. cyclohexakis- etc.)... 

Of the many methods described for glycoside synthesis, those predominantly used in current oligosaccharide synthesis, in which the glycosyl donor has O- or N- functionality at C-2 (that is, excluding 2-deoxyglycosides), are the following ... 

The synthesis is an excellent example of the use of thioglycosides as glycosyl donors in the block synthesis of complex oligosaccharides as well as the use of partial glycosylation of diols to achieve short paths to the target. 

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