Monosaccharides fluoride

Hydrogen fluoride Splits all O-glycosyl bonds to yield corresponding monosaccharide fluorides [256]... 

The monomer design of using j0-CF of two glucose unit structures was important. When j0-glucosyl fluoride of a monosaccharide structure was used, its polymerization by cellulase catalysis produced only cello-oligomers. This indicates that the monosaccharide fluoride is not appropriate enough as a starting monomer compared with j0-CF. The effectiveness of the disaccharide monomer structure j0-CF was considered as a possibile explanation of the cellulose biosynthesis mechanism [33-35]. 

Fischer projection, monosaccharides acyclic form, 56-57 cyclic forms, 59-60 modified, 60-61 Fluorine chemistry, 18-19 D-Fructofuranosides, degradation, 445 Fructofuranosyl cation, 217 Fructofuranosyl fluorides, 217 Fructose... 

It has also been observed281 that, for a number of fluorinated monosaccharides, geminal 19F- H coupling-constants for the pyranose series are larger when the fluorine substituent is axially rather than equatorially disposed. Exceptions to this generalization were subsequently found, as in the virtually identical value of/F 2, H-2 for peracetylated 2-deoxy-2-fluoro-a-D-gluco- and -manno-pyranosyl fluorides.71... 

The tables contain nearly all of the n.m.r. information currently available in the literature. Although there are more fluorinated monosaccharides known, for many of them no n.m.r. data have been reported so far. Throughout the Tables, S stands for solvent A for hexadeuterioacetone, B for hexadeuteriobenzene, C for deuteriochloro-form, D for deuterium oxide, F for liquid hydrogen fluoride, H for water, M for tetradeuteriomethanol, N for dichlorodideuteriomethane, and s for hexadeuteriodimethyl sulfoxide. 

When the 2-hydroxy group of a monosaccharide reacts with (diethylamino)sulfur tri-fluoride (DAST), quantitative and stereoselective rearrangements are observed (K..G Nico-laou, 1986). This reaction may simultaneously introduce fluorine to C-l and a new oxygen, sulfur, or nitrogen residue to C-2 with inversion of configuration. 

In most cases, the nonulosonic acids present in heteropolysaccharides could not be released as monosaccharides by direct acid hydrolysis because of their instability under the drastic conditions that were necessary to cleave the aldosidic linkage of the neighboring sugar residue. A combination of solvolysis with hydrogen fluoride and acid hydrolysis of the resulting... 

When the monosaccharide was not available directly after hydrolysis or solvolysis of the polysaccharide, a monomeric derivative for MS analysis could be obtained by a combination of chemical modifications and cleavages. Thus, in order to obtain an open-chain derivative of pseudaminic acid, OPS of S. boydii type 7 (Fig. 4, structure 12) was carboxyl-reduced, hydrolyzed under mild acid conditions, the products were carbonyl-reduced, solvolyzed with anhydrous hydrogen fluoride, and methylated.9,24... 

Glycosylfluorides. The anomeric hydroxyl or acetoxy group of monosaccharides is converted into a fluoro group by reaction with Olah s reagent in 70-90% yield. This reaction is useful for preparation of the thermodynamically more stable P-glycosyl fluoride (p/a >95 5). 

Most of the acetylated monosaccharides afford the more stable anomeric fluoride in this process. However, the action of a solution of hydrogen fluoride in acetic anhydride on 1,6-anhydro-j8-D-glucopyranose triacetate (1) gave tetra-O-acetyl-jS-D-glucopyranosyl fluoride (3). This result is prob-... 

The present article summarizes the data on application of hydrogen fluoride for structural analysis of polysaccharides, primarily those of bacterial origin. Some regularities in the stability of glycosidic linkages of different monosaccharides, and the mechanism of interaction between hydrogen fluoride and carbohydrates, are briefly discussed. The experimental technique for carrying out solvolysis is also described. 

The reactions of amylose, cellulose, inulin, starch, and xylans, and their constituent monosaccharides have been rather well studied. These polysaccharides dissolve in hydrogen fluoride at temperatures above — 20°, and undergo depolymerization to give the corresponding glycosyl fluorides fur-... 

Some glycosidic linkages have proved stable to hydrogen fluoride solvolysis. Attempts to isolate monosaccharides by solvolysis of the O-specific polysaccharide (13) of Shigella sonnet phase 1 with hydrogen fluoride and of the capsular polysaccharide (14) of Streptococcus pneumoniae type 1 failed. Prior acetylation of the free amino groups of the diamino sugar did not render the polymer susceptible to the solvolysis. 

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