N- glycosylamines

Two bases approaches are used in the synthesis of sugar carbamides direct interaction of carbohydrates with carbamides and their analogs in the conditions of acid catalysis (a) and interaction of acetylation N-glycosylisothiocyanates with amines (b) or interaction of acetylation N-glycosylamines with arylisothiocyanates (c) [3],... 

Although much work has been done in an attempt to elucidate the structure of iV-substituted glycosylamines, rigid proof of their structures has not yet been achieved.43 Spectroscopic evidence is inconclusive,69 whilst chemical methods are of limited value because equilibrium between open-chain, pyranose, and furanose forms is possible. However, all such derivatives as ethers and esters so far prepared directly from A-glycosylamines have been shown to be pyranoid, and periodate oxidation of some N-glycosylamines has confirmed this conclusion.70 71... 

A summary of the Maillard Reaction 1s given 1n Scheme 1 (4). The first step Involves the condensation between the carbonyl group of a reducing sugar, and the free amino group of an amino acid or peptide to produce a N-glycosylamine or fructosylamine. These... 

Another important reaction of N-glycosylamines is retroal-dolisation, which generates the highly reactive C2 intermediates... 

Such samples may also be treated with the enzyme PGNaseF (sometimes called N-glycanase) which will degrade the N-glycosylamine linkage between the saccharide chain and asparagine of the protein core (7). Alternatively this linkage may be cleaved by hydrazinolysis (8). 

The new selective amination protocol of unprotected sugar derivatives was also reported by Likhosherstov and coworkers who used the same reagent, but with the major advantage of an easy isolation of the reaction product. Most importantly, the N-glycosylamines formed by the reaction with ammonia are precipitated as carbamic acid salts and this prevents... 

Scheme 4 Imperiali s synthesis of N-glycosylamines via amination with ammonium carbamate,...

Scheme 7 Liu s stereoselective synthesis of N-glycosylamines from sugar enones.

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