N-Glycosyl Amide

The use of N-glycosyl amides as glycosyl donors was reported by Pleuss and Kunz [240]. These amides were activated by Ph3P and CBr4 to produce bromo-N-imidates, which were spontaneously converted into the corresponding bromide concomitant with releasing nitrile, and then coupled with alcohols by activation with AgOTf (Scheme 5.86). 

Pleuss, N, Kunz, H, A-Glycosyl amides removal of the anomeric protecting group and conversion into glycosyl donors, Angew. Chem. Int. Ed., 42, 3174-3176, 2003. 

A generalised model for the glycan section (5) of the wild type consists of O-linked oligomeric chains and an N-linked chain. The O-linked chains, which comprise about 10% of Man residues, are joined to serine or threonine in the peptide. They can be selectively released by p-elimination with mild alkali [88] and consist of unbranched a-man oligomers (a = 1 to 5) linked (1-2) and (1-3), with (1-3) if present, on the terminal fourth and fifth units [97]. The N-linked chain divides into two sections, the inner core, which is joined by an N-glycosyl bond to the amide N of asparagine and the outer chain. The latter consists of an... 

In N-glycosylation, the addition of sugar chains can happen at the amide nitrogen on the side chain of the asparagine. 

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