Methyl glycosides, periodic acid oxidation

The use of periodic acid oxidation in structure determination can be illustrated by a case in which a previously unknown methyl glycoside was obtained by the reaction of D-arabinose with methanol and hydrogen chloride. The size of the ring was identified as five-membered because only one mole of periodic acid was consumed per mole of glycoside and no formic acid was produced. Were the ring six-membered, two moles of periodic acid would be required per mole of glycoside and one mole of formic acid would be produced. 

Formation of the methyl glycoside (using CH3OH and FIC1), followed by periodic acid oxidation, gives a mixture of products that includes (-t-)-glyceraldehyde. 

The a-methyl glycosides of the pyranose forms of all four D-aldopentoses give the same product on periodic acid oxidation. What is this product ... 

The evidence given above and explained in more detail later (p. 212) confirmed in most instances the structures obtained by the earlier methyla-tion-oxidation studies. The periodic acid oxidation method is used widely because of its simplicity. As a result of the application of the methylation-oxidation technique and of the periodic acid method, it is knowm that the most common ring present in the glycosides is of the six-membered type connecting carbon atoms 1 and 5. However, rings formed between the 1-... 

The structure of the uronic acid was established as follows (a) periodate oxidation, followed by bromine oxidation, gave 2-hydroxy-3-methoxy-L-erj/f/tro-succinic acid 1413 (b) reduction of the methyl glycoside methyl ester with lithium aluminum hydride, followed by hydrolysis, gave 4-0-methyl-D-glucose.13... 

The incorporation of [2-14C]pyruvate and [l-14C]acetate into sugars 17 and 18 was investigated.27 Oxidation of the methyl glycosides of sugar 17 with periodate yielded acetaldehyde from the 1-hydroxyethyl branch. The acetaldehyde (2,4-dinitrophenyl)hydrazone was further oxidized by Kuhn-Roth oxidation to acetic acid, which was degraded by the Schmidt reaction to methylamine and carbon dioxide. Periodate oxidation of the methyl glycosides of sugar 18 produced acetic acid from the C-acetyl branch. The acetic acid was isolated, and purified as 1-acetamidonaphthalene. 

After the discovery by Malaprade 92) that polyhydroxy compounds were oxidized by periodate ion, Fleury and co-wOrkers 93) pointed out that the reaction is selective for hydroxyl groups on adjacent carbon atoms and results in chain scission. Hudson and co-workers 9Jf) developed periodate oxidation into an extremely convenient method for structural studies in carbohydrates 95). Because of the masking effect of the aglycon on the reducing carbon, the methyl glycosides are particularly suitable materials for this type of analysis. The method involves the determination of the molar ratios of oxidant consumed and of formic acid and formaldehyde produced. D-Mannitol, for example, consumes five moles of oxidant and produces four moles of formic acid and two moles of formaldehyde. 

The periodate oxidation of 9-O-acetyl and 4,9-di-O-acetyI derivatives of the methyl ester of 7V-acetyl-)8-D-neuraminic acid methyl glycoside has been studied the 9-O-acetyl group was found to hinder the oxidation, thus accounting for the low molar absorbancy coefficient of such derivatives in the periodate-thiobarbituric acid assay. The reactivity of a seven-carbon analogue of AT-acetylneuraminic acid, namely 5-acetamido-3,5-dideoxy-L-ara //io-heptulosonic acid, in the thiobarbituric acid and resorcinol assays has also been evaluated and the formation of the various chromophores discussed. ... 

A new colorimetric method for the measurement of free and glycosidically bound sialic acid was introduced by Durand et al. (1974) and Massamiri et al. (1978, 1979), based on the reaction of methyl-3-benzothiazolinone-2-hydrazone (MBTH) with the formaldehyde liberated on periodate oxidation of the sialic acid side chain. The molar extinction coefficient for Neu5Ac is 67,000 at 625 nm, and the method is thus similar in sensitivity to the periodic acid/thiobarbituric acid methods. 

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