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One of the most important methods of obtaining the 1,2,4-triazole system is based on recyclization reactions of 1,3,4-oxadiazoles under the action of amines and hydrazines [1,2]. These conversions are used for obtaining both monotriazoles and polytriazoles [2]. Recyclization in a series of individual aliphatic derivatives, particularly 2,5-dimethyl-1,3,4-oxadiazole, with amines (taking place at 110°C) has been known for a fairly long time [3]. Recyclization of aromatic derivatives, such as 2,5-diaryl-1,3,4-oxadiazoles, also gives triazoles, but are effected under more forcing conditions (150-200°C) [4]. However the latter process, according to our data, is accompanied by the formation of significant quantities of colored material which hinders the isolation of individual substances. In [5, 6] the recyclization is described of 2,5-dialkyl-1,3,4-oxadiazoles with hydrazines leading to derivatives of 4-amino-1,2,4-triazoles. It proceeds well with unsubstituted hydrazine even at room temperature, with monoalkylhydrazines with significantly more difficulty, on boiling in an excess of reactant, and leads to a low yield of 4-alkylamino-1,2,4-triazoles.Among the numerous variants of recyclization, the reaction of 5-unsubstituted oxadiazoles has not been studied, and might give 5-unsubstituted 1,2,4-triazoles, important precursors in the synthesis of stable carbenes of the 1,2,4-triazole series (their salts act as precursors). The reaction was not used for the synthesis of bistriazole systems, including those unsubstituted in positions 3 or 5.In connection with the development of the chemistry of stable carbenes it seemed of interest to synthesize 3-unsubstituted triazoles and the triazolium system. A method of obtaining triazolium salts is known, which consists of the conversion of amides with phosphorus oxychloride into the corresponding imidoyl chlorides, reaction of the latter with 1-substituted formhydrazides and cyclization of the condensation products __________________________________________________________________________________________ L.M. Litvinenko

Triazole derivatives R 0280 Recyclization of 1,3,4-Oxadiazoles and Bis-1,3,4-oxadiazoles into 1,2,4-Triazole Derivatives. Synthesis of 5-Unsubstituted 1,2,4-Triazoles. -(KOROTKIKH, N. I.; KISELEV, A. V.; KNISHEVITSKY, A. V.; RAENKO, G. F.; PEKHTEREVA, T. M.; SHVAIKA, O. P.; Chem. Heterocycl. Compd. (N. Y.) 41 (2005) 7, 866-871; Litvinenko Inst. Phys. Org. Coal Chem., Natl. Acad. Sci. Ukr., Donetsk 340114, Ukraine; Eng.) -A. Forchert 15-122

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