Benzimidazole, sugar derivatives

A number of purine 2 -amino-2 -deoxy-8-D-ribonuc1eosides have been prepared by microbial transglycosy1 ation between the purine base and 2 -amino-2 -deoxyuridine. The 3 -azido-3 -deoxy-6- and 3 -azido,2, 3 -dideoxy-a- and 3-D-ribofuranosides of benzimidazole were synthesized conventionally from 3-azido sugar derivatives. 

For a review of the substituted benzimidazoles derived from the sugar acids see N. K. Richtmyer, Advances in Carbohydrate Chemistry, 6, 175 (1951). 

Potential, chemotherapeutic activity of this class of compounds stimulated the synthesis313,337,352 of a series of benzimidazole-, pyrimidine-, and purine-substituted nucleosides of D-glucuronic acid derivatives, using, as the starting sugar-component, bromide 1 and methyl (2,3,4-tri-0-acetyl-D-glucopyranosylamine)uronate, respectively. 

When positive identifieation of a sugar is required, several criteria of identification must be applied. Chromatography employing two different solvent systems and the use of different spray reagents, which permit differentiation based on differences in color developed with particular sugars, can give important confirmatory evidence in identification. Finally, a specific colorimetric reaction or the isolation and characterization of the osazone or benzimidazole derivative should be used to substantiate the identification. 

From Nitro-sugars. - The 2-acetamido-2-deoxy-p-D-galactopyrano-sylamine 25 was obtained by addition of benzimidazole to a 2-nitro-galactal derivative (see Chapter 10). ... 

D-xylose, L-rhamnose and L-fucose have been shown to give mixtures of 2-(alditol-l-yl)-qulnoxallne derivatives, accompanied in the case of the latter two sugars by benzimidazole derivatives (40). The qulnoxaline derivative (41) has similarly been obtained by reaction of dehydro-D-arabino-ascorbie acid with o-phenylene-diamlne and subjected to further conversions. " ... 

Xylobenzimidazole forms the 2,5-anhydro derivative when heated with zinc chloride 40), The benzimidazoles are useful for the characterization of the sugars and of the aldonic, saccharic, saccharinic, and uronic acids 39 39a),... 

The benzimidazole derivatives prepared from the aldonic acids have been suggested for the identification of sugars and acids (SO), The benzimidazoles are made by oxidation of the sugars to the aldonic acids, and subsequent condensation of the aldonic acids with o-phenylenediamine. 

The separation of small quantities of the aldobenzimidazoles is facilitated by the formation of the insoluble copper salt from which the copper may be removed by exposure to hydrogen sulfide. The melting points and optical rotations of the benzimidazoles and of the corresponding hydrochlorides differ sufficiently for the different sugars so that the identification usually is assured. Fructose under the conditions outlined above is likely to be oxidized with the production of small quantities of D-arabobenzimidazole. Characteristic derivatives of hexuronic and saccharic acids also are obtained by condensation with o-phenylenediamine. 

Sugar degradation products were determined as benzimidazole derivatives after reaction with o-phenylenediamine. More than 120 amino-acid specific Maillard products have been isolated and identified from the reaction of L-proline, hydixn roline, < teine and methionine with monosaccharides at 150° for 1-1.5 h, in connection with studies of thermally generated aromas. Proline derived components were important constituents of bread, malt and beer, and cysteine and methionine derived components were predominant in roasted coffee and meat flavours. The effects of temperature, pH, and the relative concentration of rhamnose and proline on the quantity of specific volatiles produced in the Maillard reaction of these substrates have been studied, and the data have been analysed 1 computer methodology. The glucosylated cyclopentenone (44) was one of the products of decomposition of the Amadori product 1-deoxy-l-piperidino-maltulose in warm water. ... 

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