Unsubstituted Glycosylamines

The treatment of sugars in alcoholic solution (or suspension) with ammonia produces glycosylamines (glycosimines or glycose ammonias) by 

With ammonium chloride as a catalyst, Frush and Isbell (3) obtained two D-galactosylamines, one as a complex with one mole of ammonia these apparently represent a- and iS-pyranoid isomers. Diglycosylamines may also form in this type of preparation, since two isomeric di-D-glucosylamines were prepared under very similar conditions (4). 

An isomeric acetamide derivative has been prepared by the action of ammonia on aldehydo-ghxcose pentaacetate (6, 7) lead tetraacetate oxidation shows that it has a furanose structure. Evidently, the ammonia combines with the aldehyde group and an acetyl group migrates to the amino group from the 4-position. 

Diacetamide derivatives may result (6) from the action of ammonia on the acetylated nitriles (Wohl degradation), a process in which a carbon atom is lost. These substances probably have open-chain structures. 

Votocek and F. Valentin, Collection Czechoslov. Chem. Communs. 6, 77 (1934). 

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The unsubstituted amino group likewise shows a reactivity higher than that of the hydroxyl group this is shown by the ease with which aldoses form glycosylamines. The equilibrium 3 4 lies preponderantly in favor of 3. In the 4-amino sugar equilibrium, 9 10, the species 10 can be expected to be preponderant, especially in the pentose series. 

Benzoylation thus resembles acetylation in that the glycosylamine reacts in the pyranose form. However, only one anomer of each benzoate has been isolated. Again, this is an attractive method, alternative to the use of 0-benzoylaldosyl bromides, for preparing aldose benzoates with Cl unsubstituted. 

To form an anomeric N-acyl glycosylamine, the unsubstituted glyco-sylamine is usually used " but this form is quite labile and prone to potential anomerization and dimerization. Here the azide function was directly converted into its corresponding glycosyl amide without previous reduction to an amine. A modified Staudinger reaction was used with trimethylphosphine in the presence of different amino acids derivatives, for instance 26 activated with HOBt to give 27 (Scheme 5). 

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