Rings of sugars

Opening of the ring of sugar epoxides with tin nucleophiles... 

Methyl groups ortho to the triazole ring or to a nitro group on the benzene ring of sugar arylosotriazoles are very resistant to oxidation. ... 

The stmcture of monosaccharides is often written in the acycHc form although only very minor amounts of it ever occur in that form. Because the interconversions are rapid, the carbonyl groups of sugars can and do react both as if they are free and as if they are in a hemiacetal ring form. 

The next major bonded phase project was the development of the GBR resin, which stands for modified glucose bonded on both the backbone and the ring of basic PDVB gels. The manufacture of this product was ultimately achieved, as outlined later. The gel is first brominated, which places bromine atoms on both tertiary hydrogens of the PDVB. The brominated gel is then reacted with chlorosulfonic acid, and a specially treated reduced D-glucosamine is coupled to the gel. This process has the potential to covalently bond up to three sugar residues to each available divinylbenzene residue in the PDVB polymer. The exact reaction conditions used are proprietary however, the surface of the finished product is believed to look similar to Figs. 13.11 and 13.12. 

FIGURE 1.9 (a) Amino acids build proteins by connecting the n-carboxyl C atom of one amino acid to the n-amino N atom of the next amino acid in line, (b) Polysaccharides are built by combining the C-1 of one sugar to the C-4 O of the next sugar in the polymer, (c) Nucleic acids are polymers of nucleotides linked by bonds between the 3 -OH of the ribose ring of one nucleotide to the 5 -P04 of its neighboring nucleotide. All three of these polymerization processes involve bond formations accompanied by the elimination of water (dehydration synthesis reactions). 

Synthesis of Ring-Deoxy Sugars (Pseudo-Hexoses)... 

Peaks at m/e 113 and 85 have been found in the mass spectra (12) of other O-isopropylidene ketals of sugars, as well as in Figure 7. Since these shift to m/e 119 and to m/e 88 and 91 in the mass spectrum of 10a as they did for the d6-analogs in Reference 12, the structures, 17, 18, and 19 from Reference 12 are shown as possible explanations. The peak at m/e 85 (91) could alternatively be from m/e 113 (119) by loss of carbon monoxide (28 mass units) from the six-membered-ring of structure 17b. 

Cyclic hemiacetals or hemiketals of sugars with a five-membered (tetrahydrofuran) ring are called furanoses, those with a six-membered (tetrahydropyran) ring pyran-oses. For sugars with other ring sizes see 2-Carb-5. 

Note 1. The term glycal is a non-preferred, trivial name for cyclic enol ether derivatives of sugars having a double bond between carbon atoms 1 and 2 of the ring. It should not be used or modified as a class name for monosaccharide derivatives having a double bond in any other position. 

Fig. 3-2 Chemical diagram of ATP (adenosine triphosphate). The three functional groups are the base adenosine (upper right), a five-carbon ribose sugar (middle), and three molecules of phosphate (left). Lines at bottom of sugar ring indicate hydroxyl groups.

A nucleic acid polymer contains nucleotide chains in which the phosphate group of one nucleotide links to the sugar ring of a second. The resulting backbone is an alternating sequence of sugars and phosphates, as shown in... 

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