Amadori rearrangement hydrogenation

The usefulness of the Amadori rearrangement in chemical synthesis was demonstrated by Weygand who showed how n-arabinose, instead of the more expensive n-ribose, could be used in the preparation of riboflavin. Condensation of n-arabinose with 3,4-dimethylaniline in the presence of an acid catalyst gave the Amadori rearrangement product, 1-deoxy-l-(3,4-dimethylanilino)-D-er2/ liro-pentulose (not isolated), which could be catalytically hydrogenated in alkaline solution to produce the desired intermediate, l-deoxy-l-(3,4-dimethylanilino)-D-ribitol. Also, Amadori re-... 

Amadori rearrangement products can be hydrogenated readily in water or in aqueous alcohols in the presence of a platinum or Raney nickel catalyst. Sodium amalgam has also been used, but the alkali-lability of the l-amino-l-deoxy-2-ketoses makes this reagent less desirable. ... 

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. 

According to Weygand,51 the Amadori rearrangement is catalysed by hydrogen ions, but Hodge and Rist achieved this catalysis by means of sodium salts of CH-acidic compounds.52... 

In the controversy on the mechanism of osazone formation, it was found that glucose-f-t is converted into the phenylosazone and the phenyl-osotriazole without loss of tritium." This finding was taken as evidence against formation, by the Amadori rearrangement, of an intermediate having two hydrogen atoms on C-1 as in Weygand s scheme" B. 

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. 

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