Monosaccharides glycosides

An exo-linker according to Fig. 10.1 must contain an enzyme labile group R, which is recognized and attacked by the biocatalyst Possible combinations could be phenylacetamide/penicillin amidase, ester/esterase, monosaccharide/glycosid-ase, phosphate/phosphatase, sulfate/sulfatase and peptides/peptidases [41]. The following systems have been worked out (Tab. 10.2). 

In most structural studies of the polysaccharides, oligosaccharides containing the nonulosonic acids were prepared in order to have better-resolved NMR spectra and for investigation by MS. In some examples, a monosaccharide or a monosaccharide glycoside were also prepared by chemical degradations. 

Tables I-III give some selected FAB data for anomeric pairs of monosaccharide glycosides in the positive ion mode. Differences occur in the mass spectral data recorded within a given anomeric pair and this is true for every pair studied.

From this preliminary review of monosaccharide glycosides, it is possible to see that the fragmentation pattern in FAB mass spectra is governed by at least three factors whose importance may vary (1) nature of the aglycone, (2) configuration of the anomeric carbon (3) remote stereochemical effects (i.e., the relative stereochemistry of the other carbohydrate carbons). 

Furthermore, only the positive-ion FAB mass spectra will be discussed this will be done on a group basis, rather that individually, as it was the case for the monosaccharide glycoside section just preceding. Data obtained from negative-ion spectra and recorded in various support matrices will only be used as complementary information. It is clear, however, that the latter will attract more attention in the future. 

The structures of methyl /S-lactoside and methyl /3 cellobioside have been correlated, " in the same way as for monosaccharide glycosides, by periodate oxidation followed by reduction. Both compounds gave the same... 

The use of trideuteriomethylsilyl derivatives has been investigated by Waller and coworkers it is claimed that a comparison of the mass spectra of the labelled and unlabelled derivatives avoids the necessity for high-resolution instrumentation. Sweeley and coworkers published a detailed paper on the mass spectra of monosaccharides, glycosides, and amino derivatives, and used the data to interpret peaks caused by minor compounds formed on silylation. Similar techniques may be used for the determination of imresolved components. ... 

Synthesis of Monosaccharide Glycosides - Three reviews have dealt with this important subject. ... 

Synthesis of Monosaccharide Glycosides.- Reviews on this topic have dealt with Issues Involved In the synthesis of 1,2-cls-related... 

Synthesis of Monosaccharide Glycosides.- A monograph on the stereo- and regio-control of synthesis in carbohydrate chemistry has covered several glycosidation procedures, while a second review... 

Synthesis of Monosaccharide Glycosides.- A very useful review has appeared on newer methods for glycoside formation, particularly those based on 0-alkylation and on the use of glycosyl trichloro-acetimidates, sulphonium salts and fluorides. A shorter paper has... 

Synthesis of Monosaccharide Glycosides.-Conversions of secondary alcohols 1 into their tetra-O benzoyl-P-D-glucopyranosides have the effects shown (on the 8-values) of the relevant protons, while the effects on these protons in the diastereoisomers produced from the enantiomers of 1 (R=H) are similar in magnitude but opposite in sign. The method, therefore, can be used for determining absolute configtirations of such alcohol centres. ... 

Synthesis of Monosaccharide Glycosides.-A further review on recent progress in methodological aspects of glycoside synthesis has appeared. ... 

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