Osotriazoles, from osazones

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... 

The first 1,2,4-triazoles were prepd in 1885 by J.A. Bladin (Ber 18), who did considerable work in the investigation of this class of compd H. vonPechmann published a paper in 1888 in which he described the prepn of some derivatives of 1,2,3-triazoles and proposed naming them Osotriazones because they were prepd from osazone . This name, was changed in 1891 by vonPechmann to osotriazole . A. Andreocci also investigated triazoles, and in 1889 and 1894 published papers in which he called some of them Pyrrodiazoles . All of these compds are now called triazoles ... 

The 1,2,3-triazole system can be formally derived from pyrrole or indole by replacing two carbons by two nitrogen atoms. The resulting parent compounds may be classified in terms of the constitutional formulae (l)-(3). In the literature this ring system is still named u-triazole , in order to distinguish it from s-triazole . While (1) and (2) can be considered to depict heteroaromatic systems, (3) is a non-aromatic compound and is rarely found in the literature. In the older literature the term osotriazole belongs to derivatives of (2), particularly if these are derived from osazones. 

Indirect evidence for the possible existence of cyclic forms of an osazone in solution appears from the different ways in which the osazones and their acetates react with nitrous acid, yielding the glycosulose in the first case and the osotriazole in the second. An explanation of this behavior was provided by the assumption that the osazones exist as equilibrium mixtures composed mainly of the acyclic form but also containing a small proportion of the cyclic forms (54). The glycosulose (55) was considered to be produced by the more rapid interaction of nitrous acid with the cyclic form, causing the equilibrium to shift in that direction imtil completion of the reaction, whereas the osotriazole (57) was thought to be produced by the interaction of nitrous acid with the acyclic form (56) of the acetate, which is incapable of cyclization. 

A compaxison of the yield of osotriazoles and time for their formation, from osazones having different substituents in the para position of the benzene ring, suggests (see Table I) that oso triazole formation is inhibited by electron-attracting groups and facilitated by electron-donating groups. ... 

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. 

The hydrazones and osazones rarely have sharp melting points, and disparities in reported values are often encountered. Moreover, optical rotations are frequently difficult to determine because of slow, complex mutarotations. Confirmation of the identity through a comparison of X-ray patterns or through other derivatives is desirable. The osotriazoles (Chapter VIII) prepared from the osazones by the reaction of copper sulfate generally have properties quite suitable for qualitative analyses. Isolation of the more-soluble osotriazoles is facilitated by adsorption on and elution from activated carbon (29a),... 

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