Arabinose oxime

L-arabinose, AE7T arabinose oxime, AE90 arabinose semicarbazone, AI24... 

The structures of D-arabinose and D-glucose oximes have been determined by means of various physical techniques. o-Arabinose oxime was shown to exist in the anti(Z) acyclic form in the solid state and to isomerize to a 4 1 mixture of the syn E) and antiiZ) forms in aqueous solution o-glucose oxime exists in the cyclic /S-pyranose form in the solid state and isomerizes to a mixture of the J3-pyranose (23%), a-pyranose (7%), anti(Z) (13.5%), and syn(E) (56.5%) forms in aqueous solution. 

A mechanism for the mutarotation of -D-arabinose oxime has been proposed, and involves cyclic N-arabinosyl hydroxylamlne inter-mediates. Separable mixtures of N-glycosylated L-a-amino-... 

C5HuN05 L-Arabinose st/n-oxime (SARBOX)243 P21212I Z = 4 D = 1.61 R = 0.04 for 1,387 intensities. The acyclic molecule has the planar, zigzag conformation. The terminal OH and N-OH groups are oriented—syn and ap, respectively. Despite the difference in crystal symmetry, the hydrogen bonding is remarkably similar to that of the anti compound (see preceding abstract), with the same spiral of O-H N bonds. 

Tetrabenzoyl-L-rhamnononitrile was prepared by Restelli de Labriola and Deulofeu in 91 % yield from the oxime with pyridine and benzoyl chloride, and was degraded to 5-desoxy-L-arabinose dibenzamide in very small yield (13%) by treatment with ammonia in ethanol. 

Melibiose. An octaacetylmeUbiononitrile of 64% purity was prepared by Zempl n in about 50% yield, from pure melibiose oxime. It was degraded in a 68-78% yield to 5-(a-D-galactopyranosyl)-D-arabinose, obtained only in solution. 

Regioselective oxidation by brominolysis of dioxastannolane obtained from methyl / -L-ara-binopyranoside made it possible to accomplish (after subsequent oximation and reduction) a facile synthesis of 4-amino-4-deoxy-L-arabinose, an amino-sugar found in lipopolysaccharides of some Salmonella R. mutant strains <83CPB3778>. 

The well-known Ruff degradation of aldonic acids to aldoses with one less carbon was first applied with bromine as the oxidant. Calcium D-gluconate was treated with an excess of bromine at 20° for ten hours the acidity of the solution was kept low with lead carbonate. The filtrate was processed and D-arabinose was obtained in small yield as the oxime. However, Ruff found that the effect of hydrogen peroxide was much better and abandoned the use of bromine. Fenton noted the same effect in the oxidation of tartaric acid to dihydroxymaleic acid the action of oxygen was more effective than that of the halogens. It was assumed that a keto aldonic acid was the intermediate in the degradation of the aldonic acid to the new aldose, and the apparent stability of the keto acids to further oxidation by bromine may be the reason for the low yields with this oxidant. 

D-Galactopyranosyl-D-arabinose was prepared from lactose oxime by dehydration with acetic anhydride and degradation of the resultant nitrile with sodium methoxide in chloroform. This galactosylarabinose has also been prepared by the oxidation of calcium lactobionate with hydrogen peroxide and a ferric salt (the Ruff degradation ). Under... 

Hydrogenation of aldose oximes (aldoses D-arabinose, D-mannose and D-galactose) at 50 °C over 5 % Pt/C catalyst, under 100 bar hydrogen, resulted in quantitative conversion of the oximes to a mixture of mono- and dialditylamines from which the latter were isolated in fairly good yield (26-80%) [44]. 

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