Glycosylamines structure determination

Ellis and Honeyman80 have raised strong doubts as to the validity of the structural determinations that have been applied to glycosylamines these doubts are based on the fact that such compounds are readily isomerized, as evidenced by their mutarotation. The formation of a trityl ether cannot be considered valid evidence for the presence of a primary hydroxyl group in the compound tritylated, and periodate oxidation, which is often excessive, may lead to faulty conclusions. 

In the Maillard sequence, the initial reaction between a carbonyl group and a trivalent nitrogen atom is perhaps the most thoroughly investigated and best understood. As early as 1963, Reynolds (14) published a review with 140 references limited largely to the studies of reactions of aldoses with amines, the determination of the structures and properties of the first products of reaction (a glycosylamine), and the rearrangement of the latter to a more stable ketoseamine. 

Voto6ek and Wichterle " investigated the reaction of JV-substituted gly-cosylamines with hydrocyanic acid, but they did not start with the isolated glycosylamine. The sugar and amine were heated in alcohol, the hydrocyanic acid was added, and the mixture was allowed to cool. The structure of the crystalline nitrile isolated was not determined. Because the hydrogen cyanide could have added to the carbonyl group of the ketose after an Amadori rearrangement had occurred, the constitution of their products is open to question. 

Compounds having C=N— exhibit a band at 1660-1610 cm" that is useful in determining whether such compounds as IV-substituted glycosylamines are cyclic or acyclic (Ellis, 1966) (see Determination of Structure, in this chapter). Care must be taken to dry the compound completely, since moisture gives a band at 1650-16(X)cm". Also, if water of crystallization is present, a band appears at 1650-1640cm . For isothiocyanate —N=C=S and carbodiimides —N=C=N— there is a strong band at 21(X)cm . ... 

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