3-0-Methyl-D-xylose

Methyl-D-xylose-(2 —> 1) 2,3,4-tri-O-methyl-D-glucosid-uronic acid Beech wood C a 70f... 

From 3-0-methyl-D-xylose are formed the two analogous five-carbon metasaccharinates. The main component of the reaction mixture is 3-deoxy-D- ljrxonate, although small amounts of 3-deoxy-D- xylonate are also found. Furthermore, 3-0-a-D-xylopyranosyl-L-arabinose is degraded, in lime water, to an acid salt and n-xylose. Alkaline degradation of 3-0-... 

A branching point also leads to the occurrence of a mono-O-methylated xylose residue in the 0-methylxylan. Although the absence of 2-0- or 3-0-methyl-D-xylose in the hydrolysate is good evidence for the absence of branching, the presence of small proportions of these sugars is of little structural significance, since a certain amount of de-O-methylation on methanolysis and hydrolysis of 0-methylated carbohydrates appears to be unavoidable. ... 

A survey of the composition of lipopolysaccharides and exopolysaccharides produced by Cystobacter, Archangium, Sorangium, and Stigmatella species has been reported. 3-0-Methyl-D-xylose was detected in several lipopolysaccharides. 

Equilibrated aqueous solutions of 3-0-methyl-D-xylose and -glucose have been shown to contain about 15% of furanoid forms, whereas none is found in those of the parent aldoses. ... 

Deoxy-l,2-0-isopropylidene-3-0-tosyl-D-xylose l,2-0-Isopropylidene-5-0-methyl-3-0-tosyl-D- KOH-aq. MeOH 263... 

Methyl-D-xylose-(3 —> 1) Pear, cell-wall xylan C a 68... 

Recently several new structural types of aglycons have been discovered in our laboratory [3-7]. Monosaccharide compositions of sea cucumber glycosides usually include D-xylose, D-quinovose, 3-0-methyl-D-glycose, D-3-O-methylxylose and D-glucose and rarely 6-O-acethyl-D-glucose [8,6]. 

Elimination of multiple peaks may also be achieved by conversion of a sugar into the dithioacetal or the nitrile. The suitability of the former type of derivative for g.l.c. appears to have been explored only in a model study on xylose methyl ethers. Lance and J. K. N. Jones also demonstrated that the acetylated nitriles derived from diese ethers give sharp, single peaks, and permit 2- and 3-0-methyl-i>-xylose to be distinguished from each other, a resolution not achieved by using alditol acetates. Nitriles have been used by Bouhours and Cheshire to demonstrate the occurrence of the same two xylose ethers in peat, and by Bacon and Cheshire to prove the natural existence of 3-O-methyl-D-galactose in leaves. 

The extracellular polysaccharide of Porphyridium cruentum contained D-xylose, D-glucose, D- and L-galactose, 3-O-methyl-D-xylose, 3 (or 4)-0-methyl-D-galactose, D-glucuronic acid, 2-0-methyl-D-glucuronic acid, and a 2-O-methyl hexose in the molar ratio 3 1 2.5 0.13 0.13 0.8 0.2 0.13, whereas that from P. aerugineum contained the first six sugar residues in the molar ratio 1.7 1.0 1.1 ... 

Small complex polysaccharide containing apiose, 2-0-methyl-L-fucose, 2-0-methyl-D-xylose, acetic acid, Penta-Ac, 3-deoxy-D-/yxo-heptulosaric acid and other sugars depending on source. Obt. by the action of liquefying enzymes on apple, tomato and carrot juice pectin. The main nondegraded soluble polysaccharide component of the juice. Also present in various other plant products, e.g. leaves of Panax ginseng (ginseng). 

The following 0-methylaldoses have been isolated from, or identified as constituents of, natural products 3-0-methylxylose (in the extracellular mucilage from the red alga Rhodella maculata), 3-0-methyl-L-xylose (together with L-xylose and L-rhamnose from the lipopolysaccharide of Pseudomonas maltophilia), 3-0-methy]-D-ribose (from the extracellular polysaccharide of a Cowpea strain of slow-growing Rhizobium, strain CB 756), 2-0-methyl- and 2,4-di-O-methyl-L-rhamnose (in the antibiotics steffimycin and steffimycin B produced by Strepto-myces steffisburgensis), and 3-0-methyl-galactose and -mannose (from the haemocyanin of snails). ... 

The sym-dimethyl ester derived from furan and dimethyl acetylenenedicarboxylate was efficiently hydrolysed by pig liver esterase to yield half esters with high optical purity. Precursors with the L-configuration were obtained by chemical transformation while chirality transfer through ester exchange led to precursors with the D-configuration both products were used to synthesize the enantiomeric riboses. 3-0-Methyl-L-xylose (5) (found in the lipopolysaccharides of Gram-negative bacteria) has been synthesized by the route shown in Scheme 3 ... 

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