Osazones into Osotriazoles

An outstanding contribution to osazone chemistry was made by Hann and Hudson who examined the effect of boiling osazones with 

When a stream of air or oxygen is passed through an alkaline solution 

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The bishydrazones of the 1,2-diketones from inositols have also been converted into triazoles.222,223 The conversion of arylosazones into the corresponding osotriazoles requires the presence of an oxidant, and it is obvious that simple removal of aniline from the osazone, as suggested by the equation, is not involved. In addition to copper(II) sulfate, the reagent most commonly used, other oxidizing heavy-metal salts, such as ferric sulfate and chloride,224 and mercuric acetate,223 have been used, as well as halogens225 and nitro-sulfonates.226 The osazone acetates are converted into osotriazoles by nitrous acid,227 which decomposes the unacetylated osazones to the aldosuloses228 and the osazone formazans are cyclized with warm... 

In general, all osazones having at least one monosubstituted hydrazone residue, such as osazones of t3rpe A and B, respectively, can be converted into osotriazoles. If, however, the osazone has two disubstituted hydrazone residues (t3q>e C), hydrolysis takes place, and the osone hydrazone and, finally, the osone are obtained. 

CigH22N404 358.396 Formed from aldohexoses by treatment with phenylhydrazine. The reaction involves a formal oxidation step involving destruction of the chiral centre at C-2. The eight (enantiomeric pairs of) hexoses therefore form a total of four different osazones. In addition, the four keto-hexoses form the same osazones by formal oxidation at C-1. Key compds. for historical characterisation of the hexoses and their configurational interconversion (Fischer, 1889). Readily converted into osotriazoles which can be used for further characterisation. 

In 1944, Hann and Hudson found that, when refluxed with cupric sulfate, osazones are converted into colorless triazole derivatives which they designated osotriazoles. They determined the structure of the d-orahmo-hexulose derivative by means of the following reactions (1) it gave a tetraacetate and a tetrabenzoate which could be saponified to the parent osotriazole, indicating the presence of four free hydroxyl groups therein (2) on periodate oxidation, 3 moles of oxidant were consumed per mole of (71), giving 1 mole of formaldehyde, 2 moles of formic acid, and a known compound, 4-formyl-2-phenyl-l, 2,3-triazole (72). 

When an aqueous suspension of the osazone is treated with chlorine or bromine, the osazone is rapidly converted into the osotriazole, and, if C-4 of the benzene ring is free, the osotriazole formed is halogenated in that position. Iodine, on the other hand, reacts very slowly (3 to 21 days) to yield the osotriazole without halogenation. ... 

In the controversy on the mechanism of osazone formation, it was found that glucose-f-t is converted into the phenylosazone and the phenyl-osotriazole without loss of tritium." This finding was taken as evidence against formation, by the Amadori rearrangement, of an intermediate having two hydrogen atoms on C-1 as in Weygand s scheme" B. 

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