Ring structures bromine oxidation

This method was of value in that it gave an insight into the actual reaction of an aldose during bromine oxidation, and was also indicative of its ring structure. The method should be used with caution, however, especially in respect to the relative velocity of the anomeric forms of the various sugars. Formation of 5-lactones can be considered excellent... 

The ring structure of the ribose residue was ascertained" in the same general manner as for adenosine and guanosine. Triacetyl-dihydrouridine was prepared by the hydrogenation of triacetyl-uridine. On simultaneous deacetylation and methylation this was transformed to the fully methylated dihydro-uridine. By simultaneous hydrolysis and oxidation of this product, with hydrobromic acid and bromine, trimethyl -D-ribonolactone was formed, its identity being confirmed by oxidation to meso-dimethoxy-succinic acid. It follows that the ribose component has the furanose ring structure, and that uridine is 3 -D-ribofuranosyl-uracil. 

Saccharose consumes 3 moles (cf. Reaction 4.113) and maltose 4 moles of periodate. The final conclusion as to sugar linkage positions and ring structure is drawn from the periodate consumption, the amount of formic acid produced (in the case of saccharose, 1 mole maltose, 2 moles) and the other carbonyl fragments which are oxidized additionally by bromine to stable carboxylic acids and then released by hydrolysis. The glycol splitting reaction should be considered an optional or complementary method to the permethylation reaction applied in structural elucidation of carbohydrates. 

D-glucose and its lactone from 2,3,6-trimethyl-D-glucose provided conclusive proof that the ring system was not of the hexylene oxide type.142 188 The final evidence necessary to characterize the tetramethylglucose in question as a furanose derivative was provided by Haworth, Hirst and Miller,176 who demonstrated that oxidation of the tetramethylglucose with bromine water and of the resulting lactone with nitric acid yielded dimethoxysuccinic acid and oxalic acid, but not i-zyZo-trimethoxyglutaric acid, the absence of which ruled out a pyranose structure. 

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