Glucosylamines, Amadori rearrangement amines

Although there is no positive evidence in support of it, a plausible alternative to the above reaction sequence is enolization of the aldose before condensation with the amine. In such a sequence, the Y-substituted glycosylamine would not be a precursor of the aminodeoxyketose. This postulate merits investigation because, in spite of attempts to isolate Y, Y-dibenzyl-D-glucosylamine, this compound could not be found in the reaction product of D-glucose with dibenzylamine only D-glucose or the Amadori rearrangement product was isolated. ... 

In contrast to the Amadori rearrangement products, the JV-aryl-n-glu-cosylamines are relatively stable in alkali. They do not readily liberate the amine, for their solutions give a constant optical rotation while remaining colorless in alkali over extended periods. - e, 7 However, the N-alkyl-n-glucosylamines are much more labile than the V-aryl derivatives in alkali 85, 86, 87... 

A most interesting application having commercial value is the formation of surface-active derivatives by the condensation of hydrophilic sugars with fatty amines. Only Amadori rearrangement gave hydrolysis-resistant compounds, displaying a considerable decrease in the surface tension of water, in contrast to the glucosylamine derivatives. 

This mechanism was developed mainly on the basis of experiments with A-aryl D-glycosylamines and, served a purpose to explain (a) the catalytic effect of carboxylic acids (b) the absence of die Amadori rearrangement in neutral medium" or for A-aryl D-glucosylamines derived from weakly basic amines such as dinitroaniline or indole "" (c) enoUzation, rattier ttian a 2,1-hydride shift, as ttie rate-determining step." ... 

The Amadori rearrangement also occurs for the glycosylamine derivatives of some secondary alkylamines and of primary and secondary aralkyl-amines it occurs in alcoholic solution in the presence of compounds such as ethyl malonate and acetylacetone which contain active hydrogen atoms 66), The direct reaction product from D-glucose and dibenzylamine was actually 1-dibenzylamino-l-deoxy-D-fructose (XI) 66) and not VjV-di-benzyl-D-glucosylamine (XII) as indicated earlier by Kuhn and Birkofer 76), This rearrangement was effected without benefit of acid catalysis 70) or by the use of ethyl malonate 66), The true V,i T-dibenzylglu-cosylamine (XII) could not be isolated. 

The imine (Formula 4.52) formed by the reaction of glucose with the amine is easily converted to the cyclic hemiaminal, a- and P-glucosylamine. However, N-glycosides of this type are relatively instable because they very easily mutarotate, i. e., they are easily hydrolyzed via the open-chain imine or are converted to the respective a- and P-anomer. However, the Amadori rearrangement leads to furanose, which as a hemiacetal, has a stability to mutarotation comparable with that of carbohydrates. 

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