O-glycoside

Methanolysis of quaternary ammonium and triphenylphosphonium salts derived from 2,3,4-tri-0-benzyl-6-0-(N-phenylcarbamoyl)-D-glucopyranosyl bro- 

Reagents i, I+(collidine)gC104 -ROH ii, AgBF -DMSO-EtjN iii, (PhaP)2RhCOCl iv, OsO -py V, BzCl-py vi, CrOj-py vii, NaBH viii, ACjO-py 

Brigl s anhydride and the addition of nitrosyl chloride to an unsaturated sugar, and 2-acetamido-2-deoxy-6-0-a-D-glucopyranosyl-a-D-galactopyranose and its 4-aminophenyl glycoside.  

Other disaccharides synthesized during the past year include a-o-glucopyrano-syl a-L-sorbopyranoside (by an enzymic method), gentiobiose, 6-0-j3-D- 

An efficient synthesis of carbohydrate 1,2-orthoesters relies on treatment of reactive, acylated aldopentofuranosyl halides with iV,iV-dimethylformamide 

A book (Jmo pp.) has been published by Russian authors entitled Chemistry of the 0-Glycosidic Bond / and a symposium sponsored by the American Chemical Society on the anomeric effect yielded several relevant reports, including one on the influence of reactant structure and solvent on glycosidation reactions/ A further review has appeared on the Koenigs-Knorr reaction applied to the synthesis of both pyranosides and non-pyranoid glycosides, and a more specific one on glycosidation processes applied to drugs/ 

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Glycosides are a large and very important class of carbohydrate derivatives character ized by the replacement of the anomeric hydroxyl group by some other substituent Gly cosides are termed O glycosides N glycosides S glycosides and so on according to the atom attached to the anomeric carbon... 

Linamann (an O glycoside obtained from manioc a type of yam widely distnbuted in southeast Asia)... 

Sfrucfurally O glycosides are mixed acefals fhaf involve fhe anomeric posifion of furanose and pyranose forms of carbohydrates Recall fhe sequence of mfermediafes m acefal formalion (Secfion 17 8)... 

Glycoside (Section 25.13) A carbohydrate derivative in which the hydroxyl group at the anomeric position has been replaced by some other group. An O-glycoside is an ether of a carbohydrate in which the anomeric position bears an alkoxy group. 

The glycosidic bond to an anomeric carbon can be either a or (3. Maltose, the disaccharide obtained by enzyme-catalyzed hydrolysis of starch, consists of two cv-D-glucopyranose units joined by a 1->4-o-glycoside bond. Cellobiose, the disaccharide obtained by partial hydrolysis of cellulose, consists of two /3-o-glucopyranose units joined by a 1—>4-/3-glycoside bond. 

A. F. Bochkov and G. E. Zaikov, Chemistry of the O-Glycosidic Bond Formation and Cleavage, Pergamon Press, Oxford, 1979. 

Glycosides are formed by condensation between the hydroxyl group of the anomeric carbon of a monosaccharide, or monosaccharide residue, and a second compound that may—or may not (in the case of an aglycone)—be another monosaccharide. If the second group is a hydroxyl, the O-glycosidic bond is an acetal link because it results from a reaction between a hemiacetal group (formed from an aldehyde and an —OH group) and an-... 

Based on the nature of the linkage between their polypeptide chains and their oligosaccharide chains, glycoproteins can be divided into three major classes (Figure 47-1) (1) those containing an O-glycosidic linkage (ie,... 

GLYCOPROTEINS CONTAIN SEVERAL TYPES OF O-GLYCOSIDIC LINKAGES... 

Tkn O-glycosidic bond between xylose (Xyl) and Ser, a bond that is unique to proteoglycans. This linkage is formed by transfer of a Xyl residue to Ser from UDP-xylose. Two residues of Gal are then added to the... 

Proteoglycans linked to chondroitin sulfate by the Xyl-Ser O-glycosidic bond are prominent components of cartilage (see below). The repeating disaccharide is similar to that found in hyaluronic acid, containing... 

Cloran, F., Carmichael, I., Serianni, A. S., 1999b, Density Functional Calculations on Disaccharide Mimics Studies of Molecular Geometries and Trans-O-glycosidic 3Jcoch and 3Jcocc Spin Couplings , J. Am. Chem. Soc., 121, 9843. 

Similarly, ketose sugars participate in polysaccharide formation by reaction of their ano-meric carbon with a hydroxyl of another monosaccharide to create a ketal linkage. The acetal and ketal bonds within polysaccharides are termed o-glycosidic linkages. 

Polysaccharide solubility in aqueous solutions usually is dependent on polymer size and its allied three-dimensional structure. Even water-insoluble carbohydrates may be solubilized by controlled hydrolysis of o-glycosidic linkages to create smaller polysaccharide molecules. Thus, cellulose may be solubilized by heating in an alkaline solution until the polymers are broken up sufficiently to reduce their average molecular weight. Many such soluble forms of common polysaccharides are available commercially. 

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