Methyl ethers periodate oxidation

Methyl ethers of polyhydric compounds may also be obtained by the periodate oxidation of methylated glycoses followed by boro-hydride reduction this matter will be discussed in Part II of this article. 

The branched nature of polyglucoses prepared from free, unsubstituted sugars has been indicated qualitatively by the pronounced solubility of the methylated derivatives in petroleum ether,25 and by the necessity for four successive sequences of periodate oxidation and borohydride reduction in order that complete oxidation of all of the sugar residues may be achieved.182 A decrease in the intrinsic viscosity has also been used as an indication of an increase in branching.178 Quantitative data are not, however, derivable from such observations. 

Bobbitt, J. M., Periodate Oxidation of Carbohydrates, 11, 1-41 Boeseken, J., The Use of Boric Add for the Determination of the Configuration of Carbohydrates, 4, 189-210 Bonner, T. G., Applications of Trifluoro-acetic Anhydride in Carbohydrate Chemistry, 16, 59-84 Bonneb, William A., Friedel-Crafts and Grignard Processes in the Carbohydrate Series, 6, 251-289 Bourne, E. J., and Peat, Stanley, The Methyl Ethers of D-Glucose, 6, 145-190... 

D-xylose on hydrolysis with dilute nitric acid. Percival and Chanda7 isolated a xylan from the same plant. They found that the methylated xylan produced on hydrolysis 2-methyl-D-xylose, 2,3-dimethyl-D-xylose, 2,4-dimethyl-D-xylose and 2,3,4-trimethyl-D-xylose. From this and from the results of periodate oxidation, Percival and Chanda considered that the polysaccharide contains 1 — 3 and 1 —> 4 linkages with a non-reducing endgroup (yielding the 2,3,4-trimethyl-D-xylose) for every 20-21 D-xylose units. They considered that this xylan was not a mixture of 1 —> 3 and 1 —> 4 linked polysaccharides because careful fractionation of its diacetate and dimethyl ether failed to establish any polymer heterogeneity. Barry, Dillon, Hawkins and O Colla74 confirmed the conclusion of Percival and Chanda. 

When primary alkyl phenyl tellurium or secondary alkyl phenyl tellurium compounds in methanol were treated with an excess of 3-chloroperoxybenzoic acid at 20, the phenyltelluro group was eliminated and replaced by a methoxy group. This reaction, which converts alkyl halides used in the synthesis of alkyl phenyl telluriums to alkyl methyl ethers, produced the ethers in yields as high as 90%3-4 Olefins are by-products in these reactions4 With ethanol as the solvent, ethyl ethers were formed. Other oxidizing agents (hydrogen peroxide, ozone, (ert.-butyl hydroperoxide, sodium periodate) did not produce alkyl methyl ethers. 

Finally, Hirst s later contributions to monosaccharide chemistry must not be overlooked. With E. G. V. and Elizabeth Percival, four different trimethyl, 3,4- and 4,5-dimethyl, and the 4-methyl ethers of D-fructose were synthesized from isopropylidene derivatives having well established structures. Certain methyl ethers of D-mannuronic acid and D-glucuronic acid were also prepared, and their periodate oxidation was compared with that of related ethers of D-galacturonic acid. With Elizabeth Percival, he also contributed articles on the methyl ethers of mono- and di-saccharides, and on glycofuranosides from cyclic carbonates, to Methods in Carbohydrate Chemistry, Vol. 2 (1963). 

The other compound, called Zl, which was much more acid-labile, was hydrolyzed to equimolar amounts of pyruvate and shikimate, and was tentatively assigned the structure of shikimate 3- or 5-enolpyruvate ether. In a more recent study, it was found that the barium salt of Zl does not absorb in the carbonyl region of the infrared absorption spectrum (no ester structure), and that it has a strong band at 8.2iu characteristic of a vinyl ether. It is oxidized very rapidly by periodate, giving rise to an unstable compound with maximum absorption at 235 m i ( = 4000). A similar unstable chromophore, most likely having the structure XVII, was produced by periodate oxidation of shikimate 3-phosphate but not of shikimate 5-phosphate. (3-Methyl-crotonaldehyde shows Xm 235, t = 6700. ) These observations suggest that Zl is shikimate 3-enolpyruvate ether (XVIII). 

Although known for almost forty years, and in spite of a total synthesis of its racemate, the stereochemistry of doisynolic acid has remained in doubt. This problem has now been settled by a stepwise chemical conversion (Scheme 23) of 14)5-oestrone methyl ether (339), prepared from natural oestrone (114a), into c/s-doisynolic acid methyl ether (342). Osmium tetroxide oxidation of the enol acetate corresponding to (339) provided 16a-hydroxy-14)S-oestrone methyl ether. Subsequent periodic acid oxidation afforded the lactol (340), which upon treatment with diazomethane gave the aldehydo-ester (341). Electrochemical reduction of the aldehyde (341) afforded a methyl ester which by alkaline hydrolysis provided (-f )-ds-doisynolic acid 3-methyl ether (342), thus defining its complete stereochemistry. ... 

During the elucidation of the structure of mannosidostreptomycin by methylation. Fried and Stavely isolated two derivatives of a dimethyl ether of iV-methyl-L-glucosamine. In order to compare their physical constants with those of a known compound in the n-series. Fried and Walz prepared derivatives of 2-deoxy-3,6-di-0-methyl-2-methylamino-n-glucose. The addition of methylamine and hydrogen cyanide to 2,5-di-0-methyl-D-arabinose (prepared by the periodate oxidation of 3,6-di-O-methyl-D-glucose) was followed by hydrolysis, and jdelded a mixture of a dextro- and a levo-rotatory acid. The dextrorotatory product was con-... 

The micromethod of Perlin has been employed in the determination of the formic acid produced by the periodate oxidation of the methyl ethers of 2-amino-2-deoxy-D-glucose and 2-amino-2-deoxy-D-galactose. With most derivatives, especially those possessing a methoxyl group at C4, the amount of formic acid liberated does not reach the theoretical value. It is evident that most derivatives react in the cyclic form, and that the formate ester formed at the hydroxyl group of C5 by splitting of the C1-C2 linkage is stable, or only very slowly hydrolyzed, at the pH used, namely, 5.7. 

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