Sugar ring structures

The two pyrimidine nucleosides of ribosenucleic acid are cytidine and uridine. Since cytidine is readily transformed to uridine by deamination, the two substances have the same sugar ring structure, point of union of sugar to base, and stereochemical configuration at carbon atom (1) of the sugar. 

To date, the sugar ring structure of only one desoxyribosyl nucleoside (namely, thymidine) is known. In 1935, Levene and Tipson - found that thymidine condenses with trityl chloride in the presence of dry pyridine to give a crystalline monotrityl-thymidine. From their previous proof of the structure of monotrityl-uridine as the 5-trityl ether, it seemed probable that the thymidine ether is 5-trityl-thymidine. This was confirmed by tosylation, to give tosyl-trityl-thymidine, followed by treatment with sodium iodide in acetone under standard conditions. 

See also Sugar Ring Structures, Derivatives of Monosaccharides, Oligosaccharides, Polysaccharides, Anomers, Ouabain, Amygdalin, Mutarotation... 

See also Sugar Ring Structures, Diastereomers, Mutarotation, De Novo Biosynthesis of Purine Nucleotides... 

See also Diastereomers, Sugar Ring Structures, Figure 9.14, Table 9.4... 

See also Sugar Ring Structures, Monosaccharide Nomenclature, Glycosides and Glycosidic Bonds, Biosynthesis of Amino Sugars (from Chapter 16)... 

Figure 1.26 Carbonyl groups and hydroxyls may react to form acetal or ketal products. Sugars naturally undergo these reactions to form ring structures in aqueous solution.

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