Methyl p-cellobioside

Lipkind et al. [85, 90] used their above mentioned procedure to calculate the conformations of methyl-P-cellobioside conformations with (p/ f of 30°/—40° (39%), 55°/20° (38%), -20°/-25° (10%), and 30°/175° (13%). They support their calculations with the 3Jch coupling constants across the glycosidic bond. Although these authors use a torsional potential around the glycosidic Cl-Ol bond, they assume that the exo anomeric effect does not exist. This was later criticized by Lemieux et al. [72] (cf. below). 

The following disaccharides and derivatives have been subjected to conformational analysis by n.m.r spectroscopy and/or computational methods cellobiose in aqueous solution, methyl P-xylobioside, methyl P-cellobioside, P-gentibiose, all possible monomethyl ethers of methyl p-lactoside, unsaturated, sulfated disaccharides, such as IS, obtained by cleavage of glycosaminoglycans with lyases, ° chondroitin sulfate-related ctmqmunds, such as 16, the uronic... 

Figure 7. (Upper) C-1 signal of methyl fi-cellobioside-da (in DgO solution). The multiplet to the left that overlaps it partially is the C-1 signal. Computer-simulated C-1 signal is shown on the right. (Lower left), C-4 signal of methyl p-cello-bioside-ds and (lower right), computer-simulated C-4 signal.

Aus Methyl-p-D-maltosid. W Aus Benzyl-p-D-maltosid. Aus Benzyl-3-D-cellobiosid. ... 

Cellulose I(S and cellulose II have monoclinic, two-chain unit cells. Cellulose IIIj has a monoclinic one-chain cell [227], and the one-chain unit cell of la is triclinic with no 2i symmetry. Still, all of the chain shapes are very similar to each other. It had been speculated that cellulose chain linkage geometries would alternate between the quite different linkages found in crystalline p-cellobiose and in methyl 3-cellobioside [196]. That idea is now obsolete. Such a departure from symmetry would be far greater than indicated by the above high-resolution studies. When molecules from the high-resolution structures for all of the polymorphs are superimposed, differences in their backbone structures are barely visible. 

This type of reaction has also been successful in more complicated instances. For example, methyl /3-cellobioside was converted to the 6,6 -ditrityl ether (XXXIII), the latter was acetylated (XXXIV), then detritylated (XXXV). The two primary hydroxyl groups were then esterified (XXXVI) with p-toluenesulfonyl chloride in pyridine and the ditosyl ester was converted to the diiodide (XXXVII) by treatment with... 

However, Head showed that glyoxal is produced by the treatment of both oxycellulose and periodate-oxidized methyl fl-cellobioside (121) with alkali. The other theory was that of Haskins and Hogshead, based on the p-alkoxycarbonyl elimination mechanism of Isbell for the formation of saccharinic acids on treatment of sugars with alkali. They suggested that fission of the C5—O bond would yield glyoxal and n-erythrose. Recent work has indicated that the degradation is, indeed, based on a jS-alkoxycarbonyl elimination, but the products are different from those postulated above. 

COf shows the expected selectivity for the anomeric hydrogens of methyl p-D-glucoside and cellobioside, reacting with the latter at a rate of 7 X 10 M s at 20 °C i.e. about five orders of magnitude slower than OH). However, when cellulose (as cotton linters ) was used as a substrate, hydrogen abstraction was indiscriminate, possibly because intrinsic chemical reactivities were counterbalanced by relative accessibility. ... 

By use of cellulase, P-D-lactosyl fluoride has been condensed with methyl-P-D-cellobioside and thereby a galactosyl glucotriose derivative was made. From this the galactose was enzymically cleaved and methyl P-cellotrioside resulted. Repetition of these two steps provided a route to methyl p-D-cellotetraoside. ... 

F. S. H. Head, Effect of daylight on the periodate oxidation of p-methyl glucoside, P-methyl cellobioside, and cellulose, J. Text. Inst, 44 (1953) T209-T223. 

C18H27NO10S 449.478 Improved functional affinity ligand for cellulases. Cryst. (EtOH aq.). Mp 258-260° (247-250°). Mg -50.9 (c, 0.5 in H2O). 4-Aminobenzyl glycoside p-Aminobenzyl 1 -thio-P-D-cellobioside. (4-Aminophe-nyl) methyl 4-O-P-D-glucopyranosyl-1-thio-P-D-glucopyranoside, 9CI [68636-49-7]... 

Methyl 4-0-(2,3,4,6-tetra-0-acetyl-p-D-glucopyranosyl)-2,3,6-tri-0-acetyl-a-D-mannopyranoside, G-432 Methyl 3-0 -(2,3,4,6-tetra-O -acetyl-a-D-mannopyranosyl)-a-D-mannopyranoside, M-93 Methyl 1-thio-p-D-cellobioside, T-60... 

Methyl 2,3,4-tri-Q-acetyl-)0-D-glucuronat-l-yl fluoride has been used to obtain the uronosides of p-nitrophenol, 4-methylumbelliferone and 4-trifluoromethylumbelliferone, and the 0-D-galactopyranoside of this last compound, which is a fluorigenic substrate for -galactosidase studies, has also been reported. a-L-Arabinofuranosides of a- and jc -pellatins and a -cellobioside of the latter have been made as have the a- and -naphthyl... 

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