Synthesis and study of thermal stability of 3-nitro-1,2,4-triazole N-nitroxy-and N-azidomethyl derivatives

A method for the preparation of new 3-nitro-1,2,4-triazole derivatives has been suggested based on modification of the N-hydroxymethyl group by nitration and nucleophilic substitution reactions. Thermal stability of 3-nitro-1,2,4-triazole N-nitroxy- and N-azidomethyl derivatives, as well as of dinitrates, 5,5′-dinitro-2,2 ′-bisnitroxymethyl-2 H,2′H-3,3 ′-bi(1,2,4-triazole) and -(nitromethylene)bis(1,2,4-triazole), has been studied.     

Reactions of 1-glucosyl-5-nitro-1,2,4-triazole with nucleophiles

1-Glucosyl-5-nitro-1,2,4-triazole reacted with nucleophiles, such as water, aziridine, chloride ion and 4-dimethylaminopyridine to give the corresponding 5-substituted 1-glucosyl-1,2,4-triazole derivatives.     

Heterocyclic nitro compounds. 26. Reaction of 1-substituted 3,5-dinitro-1,2,4-triazoles with anions of heterocyclic NH acids

1-Substituted 3-nitro-5-(N-azolyl)-1,2,4-triazoles mixed with 1-substituted 3-nitro-1,2,4-triazol-5-ones are obtained in the reaction of 1-substituted 3,5-dinitro-1,2,4-triazoles with anions of heterocyclic NH acids (1,2,4-triazole, 1,2,3-triazole, pyrazole, benzotriazole, benzimidazole, and indazole derivatives). 1-Methyl-3-nitro-5-amino-1,2,4-triazole is formed instead of the expected 5-tetrazolyl derivative in the reaction of 1-methyl-3,5-dinitro-1,2,4-triazole with tetrazole in alkaline media. See [1] for communication 25. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 257–261, February, 1980.     

α-Oxides in reactions with N-H acids of the heterocyclic series

The reaction of epoxides with 3-nitro-5-bromo-1,2,4-triazole gave a series of 1-(β-hydroxyalkyl)-3-nitro-5-bromo-1,2,4-triazoles, which, under the influence of bases, undergo intramolecular cyclization with HBr elimination to give an ew heterocyclic system — 2-nitro-5,6-dihydrooxazolo[2,3-e]-1,2,4-triazole.     

Heterocyclic nitro compounds

Ketones of the 3-nitro-5-R-1,2,4-triazole series react with hydrazoic acid in concentrated sulfuric acid to give triazolyl-substituted acetamides. Acid hydrolysis of the latter leads to 1-aminoalkyl-3-nitro-5-R-1,2,4-triazoles. Intramolecular cyclization with the elimination of HNO₂ and the formation of 2-nitro-5,6-dihydro-1H-imidazo[2,3-b]-1,2,4-triazole was noted in the case of 1-(2-aminoethyl)-3,5-dinitro-1,2,4-triazole.See [1] for communication XX.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1271–1273, September, 1977.     

Notiz über die Reaktion von Methylhydrazin mit N-Cyano-azomethinen. Abhängigkeit des Reaktionsverlaufs von der Natur der Abgangsgruppe

The reaction of methylhydrazine with N-cyanoazomethines 1 containing a thioalkyl leaving group yields the 3-amino-1,2,4-triazole derivatives 2 , whereas the N-cyanoazomethines 1 containing an alkoxy leaving group give the isomeric 5-amino-1,2,4-triazoles 3. The yields are excellent and the position selectivity is high. The structures of the 1,2,4-triazole derivatives were determined with the aid of proton-coupled ¹³C-NMR. spectra.     

Radical-anions in the vicarious C-amination reactions of N-substituted nitrotriazoles

The vicarious nucleophilic substitution of hydrogen in symmetrical and vicinal nitrotriazoles by 1,1,1-trimethylhydrazinium iodide in t-BuOK/DMSO was studied by ESR. In the ESR monitoring of the reactions the primary radical-anions of 4-nitro-2-phenyl-1,2,3-triazole and 1-methyl-3-nitro-1,2,4-triazole were detected and characterized. It was shown by NMR that the amination of 4-nitro-2-phenyl-1,2,3-triazole takes place exclusively in the triazole ring with the formation of 5-amino-4-nitro-2-phenyl-1,2,3-triazole. 1-Methyl-3-nitro-1,2,4-triazole, like 3-nitro-1,2,4-triazole, does not form amination products. A possible mechanism for the vicarious C-amination of nitrotriazoles and the formation of the radical-anions of the substrates is discussed. Dedicated to Academician M. G. Voronkov on his 85th birthday. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1662–1670, November, 2006.     

Reactions of 3-nitro-1,2,4-triazole derivatives with alkylating agents. 8*. Alkylation of 3-nitro-5-R-1,2,4-triazoles with derivatives of diethylene glycol in the presence of alkali

The interaction of 3-nitro-1,2,4-triazole and 5-methyl-3-nitro-1,2,4-triazole with bifunctional agents ‒ β,β′-dichloro- and β,β′-(dinitroxy)diethyl ethers ‒ in the presence of alkali proceeds with the formation of a mixture of products substituted at the N(1) and N(2) atoms of the heterocycle, consisting of three reaction products, the N(1),N′(1)-, N(1),N′(2)-, and N(2),N′(2) isomeric derivatives of nitrotriazoles. Replacement of the Cl leaving group in the alkylating agent by a NO₂ group does not lead to a substantial change in the degree of conversion and overall yield of alkylation products. The ratio of N(1),N′(1):N(1),N′(2):N(2),N′(2) isomeric reaction products from 3-nitro-1,2,4-triazole was (82.0-85.7): (7.7-9.9):(6.6-8.1), and from 5-methyl-3-nitro-1,2,4-triazole was (76.9-79.8):(10.1:11.4):(10.1-11.7) respectively.     

Reactions of 3-nitro-1,2,4-triazoles with alkylating agents. 6*. Alkylation of a neutral heterocycle by alcohols in acid media*

Reaction of 3-nitro-1,2,4-triazole and 5-methyl-3-nitro-1,2,4-triazole with secondary and tertiary alcohols in conc. H₂SO₄ takes place at the N(2) atom. Alkylation by 2-propanol occurs regioselectively to form the 1-isopropyl-3-nitro-and 1-isopropyl-3-methyl-5-nitro-1,2,4-triazoles. As a consequence of isomerization the alkylation using cyclohexyl or tert-butyl alcohols gives respectively a mixture of regioisomers substituted at atom N(1) (1-cyclohexyl-3-nitro-and 1-cyclohexyl-5-methyl-3-nitro-1,2,4-triazoles) and at atom N(2) (5-nitro-1-cyclohexyl-and 1-cyclohexyl-3-methyl-5-nitro-1,2,4-triazoles) and, in the second case, to 1-tert-butyl-3-nitro-1,2,4-triazole. * For Communication 5 see [1]. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1680–1687, November, 2008.     

Vibrational spectra and structure of 1,2,4-triazole derivatives

The frequencies and forms of the normal vibrations of 3-nitro-1,2,4-triazole, its 1-deuteroand 1-methyl derivatives, and 1-methyl-3-nitro-5-chloro(bromo)-1,2,4-triazole, which are classified as having C_S group symmetry, were calculated. The potential energy constants were refined by solution of the reciprocal spectral problem, and the frequencies in the experimental spectra were assigned to the principal types of vibrations.See [1] for communication I.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 707–712, May, 1973.     

Heterocyclic nitro compounds. 27. Methods for the synthesis of 3-nitro-5-R-1,2,4-triazoles

A method for the preparation of 3-nitro-5-R-1,2,4-triazoles by reaction of 1-(3'-oxobutyl)-3,5-dinitro-1,2,4-triazole with nucleophilic reagents with various structures with replacement of the nitro group in the 5 position of the triazole ring during subsequent elimination of the oxobutyl fragment in an alkaline medium is examined. A number of previously undescribed NH acids, viz., 1,2,4-triazole derivatives, including 3-nitro-5-azolyl-1,2,4-triazoles, were obtained, and the ionization constants were determined for some of them.See [1] for Communication 26.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp, 1553–1557, November, 1980.     

Synthesis of certain 1,2,4-triazole nucleoside derivatives

The syntheses of 3-amino-4-methyl-1-(β-D-ribofuranosyl)-1,2,4-triazolin-5-one ( 8a ) and its 2′-deoxy analog 8b as well as 5-amino-2-methyl-1-(β-D-ribofuranosyl)-1,2,4-triazolin-3-one ( 12 ) have been accomplished. Compounds 8a and 8b were synthesized via glycosylation of 3-bromo-5-nitro-1,2,4-triazole which was followed by replacement in three steps of the 3-bromo function to yield 3-nitro-1-(2,3,5-tri-O-acetyl-β-D-ribofuranosyl)-1,2,4-triazolin-5-one ( 4a ) and its 2′-deoxy analog 4b . Compounds 4a and 4b were methylated at N², hydrogenated and deblocked to give 3-amino-4-methyl-1-(β-D-ribofuranosyl)-1,2,4-triazolin-5-one ( 8a ) and the 2′-deoxy analog 8b . Compound 12 was synthesized by glycosylation of 3-amino-1-methyl-1,2,4-triazolin-5(2H)-one ( 10 ). The structures of 8b and 12 were confirmed by single crystal X-ray diffraction analysis.     

α-Oxides in reactions with nh acids of the heterocyclic series

Alkylation of 3,5-dinitro-1,2,4-triazole with -epoxides in aprotic media gave a number of 1-(2-hydroxyalkyl)-3,5-dinitro-1,2,4-triazoles, which readily undergo intramolecular cyclization with elimination of HNO₂ to give 5,6-dihydrooxazolo[3,2-b]-1,2,4-triazole derivatives.See [1] for communication I.Translated from Khimiya Geterotsiklicheskih Soedinenii, No. 5, pp. 705–707, May, 1975.     

Reaction between 1-arenesulphonyl-3-nitro-1,2,4-triazoles and nucleoside base residues. Elucidation of the nature of side-reactions during oligonucleotide synthesis.

The protected guanosine and uridine derivatives (3a, 3b and 4) react with 1-(mesitylene-2-sulphonyl)-3-nitro-1,2,4-triazole (MSNT, 2a) to give 5a, 5b and 7, respectively: 9 is converted into 10 in the same way. The reactions proceed more rapidly in the presence of diphenyl phosphate.     

Electrode transformations of carbanions and heteroanions

Conclusions The electrolytic oxidation of the 3-nitro-1,2,4-triazole anion is realized through an intermediate radical, which splits out an H atom on reaction with the medium and reacts with benzene to give N-substituted phenyl-3-nitro-1,2,4-triazoles.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1643–1646, July, 1988.     

Thermal decomposition mechanisms of nitro-1,2,4-triazoles: A theoretical study

Possible decomposition mechanisms of C-nitro-and N-nitro-1,2,4-triazoles were simulated. We showed that in addition to the experimentally detected thermolysis products including N₂, N₂O, NO, CO₂, HCN, HNCO, 1,2,4-triazole, 3(5)-nitroso-1,2,4-triazole, and 1,2,4-triazolone, some other decompositon products (H₂O, CO, NO₂, cyanamide, cyanuric acid, and melamine) can be formed. Using the density functional approach (B3LYP/6-31G* approximation), we assessed the most favorable thermal decomposition pathways of nitrotriazoles and studied the relationships between the thermolysis pathways of these substances and their molecular and electronic structures. We found a correlation between the energy gap width (energy difference between the frontier molecular orbitals) and the stabilities of the C-nitro-1,2,4-triazole tautomers to thermal decomposition. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1338–1358, August, 2006.     

Heterocyclic nitro compounds

The reaction of 3(5)-nitro-1,2,4-triazole with hydrogen halides (HCl and HBr) leads to replacement of the nitro group by chlorine and bromine. In 1-methyl-3,5-dinitro-1,2,4-triazole the nitro group in the 5 position is replaced. Nucleophilic substitution of halogen in 1-methyl-3-nitro-5-halotriazoles leads to the formation of the corresponding 1-methyl-3-nitro-5-substituted 1,2,4-triazoles.See [1] for Communication VI.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1701–1703, December, 1970.     

Diphenylmethyl and tetrahydropyranyl protecting groups in the synthesis of 3-substituted 5-amino- and 5-hydrazino-1,2,4-triazoles

The use of hydrazine as reagent in nucleophilic substitution and reduction in the 1,2,4-triazole series in combination with introduction of labile protecting groups makes it possible to synthesize 5-hydrazino-3-nitro-1H-1,2,4-triazole and 3-chloro-5-hydrazino-1H-1,2,4-triazol-5-ylhydrazine which were difficultly accessible previously, as well as to extend the series of 3-substituted 5-amino-1H-1,2,4-triazoles. Original Russian Text V.V. Tolstyakov, I.V. Tselinskii, N.A. Dreving, 2007, published in Zhurnal Obshchei Khimii, 2007, Vol. 77, No. 12, pp. 2034-2040.     

EPR and polarography of nitroazoles. 6. 3-Nitro-1,2,4-triazoles

The electrochemical reduction of eight 3-nitro-1,2,4-triazole derivatives in acetonitrile was investigated by polarography and EPR spectroscopy.See [1] for communication 5.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 343–347, March, 1987.     

Synthesis of heterocyclic azoxy compounds from C-nitroheterocyclic compounds and metal derivatives oftert-butylamine

The reaction of 3-nitropyrazole and 3(5)-nitro-1,2,4-triazole with t-BuNHMgBr gives the corresponding asymmetrical diazene oxides. Furthermore, 3(5)-(1,1-dimethylethyl)azoxy-1,2,4-triazole was also synthesized by the reaction of 1-trimethylsilyl-3(5)-nitro-1,2,4-triazole with t-BuNHLi.N. D. Zelinskii Institute of Organic Chemistry, Russian Academy of Sciences, 117913 Moscow. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 7, pp. 1653–1654, July, 1992.