Arabinose phenylosazone

The benzaldehyde method has advantages, however, where high purity of the osone is desirable.98 When the reagent is employed, the purity of the osazone is of prime importance,90 and recrystallization from absolute ethanol may be usefully carried out for the xylose phenylosazones104 as well as for the arabinose phenylosazones.183... 

Arabinose phenylosazone Arabinose phenylosazone has proven to provide better resolution and sensitivity than DHB for neutral free glycans,39 also useful for the analysis of sialylated and sulfated glycans40,41 particularly in negative ion mode... 

The third process consists of converting methyl D-arabofuranosides (ct(3 mixture) into the 3,5-ditrityl ether (XXII) by treatment with trityl chloride in pyridine, from which by methylation and subsequent detri-tylation and hydrolysis, 2-methyl-D-arabinose was obtained.28 The product gave D-arabinose phenylosazone on treatment with phenyl-hydrazine acetate. 

Although Fischer described a lactose phenylosazone anhydride in 1887, little attention was paid to substances of this type until 1935 when Diels and Meyer reported the isolation of monoanhydrides of D-glucose phenylosazone, D-galactose phenylosazone, D-xylose phenylosazone, L-arabinose phenylosazone, lactose phenylosazone, and cellobiose phenylosazone, as well as a dianhydride of maltose phenylosazone, by boiling the corresponding osazones in alcoholic solution with a little sulfuric acid. Because of the apparent identity of the D-glucose phenylosazone anhydride with the 3,6-anhydro-D-glucose phenylosazone of Fischer and Zach, Diels and Meyer formulated these compounds as 3,6-anhydrides. 

It has been assumed in the preceding section that the phenylosazones of turanose, maltose, and D-glucosyl-D-arabinose have structures like that of D-glucose pjienylosazone. This normal osazone structure is now proved40 by the following data for the turanose and maltose osazones, and there can be little doubt that it also holds for the osazone of d-glucosyl-D-arabinose. Turanose phenylosazone has been converted by... 

Natural glucosamine gave glucose phenylosazone. D-Arabinose treated with hydrocyanic acid and ammonia formed a nitrile which could be... 

Exercise 20-7 D-Arabinose and D-ribose give the same phenylosazone. D-Ribose is reduced to the optically inactive 1,2,3,4,5-pentanepentol, ribitol. D-Arabinose can be degraded by the Ruff method, which involves the following reactions ... 

D-glucal, an acetyl group is removed from diacetyl-L-rhamnal by boiling its aqueous solution. The resulting monoacetyl-L-pseudorhamnal, however, is not as stable as diacetyl-D-pseudoglucal.7 Oxidation of diacetyl-L-rhamnal with ozone yielded 5-desoxy-L-arabinose, which was characterized as its phenylosazone and p-bromophenylosazone. 7 Deacetylation of diacetyl-L-rhamnal yields crystalline L-rhamnal (XLIV).7... 

Oxidation of digitoxal with ozone produces 5-desoxy-D-ribose, the phenylosazone and p-bromophenylosazone of which were proved identical with those of 5-desoxy-D-arabinose from n-epirhamnal.87 The addition of water to digitoxal regenerates the digitoxose. 

Repetition of this procedure on the galactosyl-arabinose gave O-jS-n-galacto-pyranosyl-D-erythrose (6) which did not give a phenylosazone. Hence, it was suggested that a 3-d-(1 4)-linkage is present in lactose (5). 

FIGURE 1.4 D-Glucose phenylosazone (4), L-arabinose (5), L-gluconic acid (6). 

Since phenylosazone formation also does not affect the stereochemistry about C3 and Ci of the pentose, the above structure also represents D-ribose whose structure differs only at the C-2 chiral center. Such compounds, differing in stereochemistry only about one carbon, are termed epimers. D-ribose is reduced to an optically inactive alditol, ribitol, and therefore we can determine the structure of D-ribose and its epimer, D-arabinose. 

S O-a B-Galdctopyranosyl-L-arabinose. Amorphous, [a] +152° (water) phenylosazone, m.p. 240°C. obtained by partial hydrolysis of Acacia cyanophylla gum 119). Hydrolysis of the methylated disaccharide gives 2,3,4,6-tetra-O-methyl-D-galactose and 2,4-di-O-methyl-L-arabinose. 

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