Preparation of new 1,2,4-triazines

Several 1,2,4-triazines were synthesized. ¹³C- and ¹⁵N-nmr spectroscopy was employed for structure determination.     

Ethylenimine derivatives of some 1,2,4-triazines

The first 3-ethylenimino-1,2,4-triazines ( 9 ) have been synthesized from the corresponding 3-(β-chloroethyl)amino-1,2,4-triazines ( 8 ). In addition some 2,3-dihydroimidazo[1,2-b]-1,2,4-triazines and imidazo[1,2-b]-1,2,4-triazines were obtained. The stability, properties and potential therapeutic value of these compounds are discussed.     

Synthesis of substituted 2,3,4,5-tetrahydro-1,2,4-triazines from nitroformaldehyde arylhydrazones

2,3,4,5-Tetrahydro-1,2,4-triazines were obtained by condensation of nitroformaldehyde arylhydrazones with aldehydes and ammonia or primary amines.     

From 3-chloromethyl-1,2,4-triazine 4-oxides to various substituted pyridines and 1,2,4-triazines

An efficient strategy for the synthesis of new pyridine and 1,2,4-triazine derivatives starting from available 6-aryl-3-chloromethyl-1,2,4-triazine 4-oxides was proposed. The deoxygenative nucleophilic hydrogen substitution in the triazine-oxide ring, nucleophilic substitution of the chlorine atom in the side chain, and transformations of the 1,2,4-triazine ring into the pyridine ring via the inverse-electron-demand Diels-Alder reactions, being used in different orders, are a rather flexible tool for the functionalization of the titled heterocycles. The cyanide anion, indoles, thiophenols, amines, and triphenylphosphine were used as nucleophiles. The direct introduction of indole residues into the 1,2,4-triazine ring followed by the substitution of the chlorine atom by a residue of the primary or secondary aliphatic amine was found to be the most convenient method for the library synthesis. Dedicated to Academician N. S. Zefirov on the occasion of his 70th birthday. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 2122–2131, September, 2005.     

From 1,2,4-triazines towards substituted pyridines and their cyclometallated Pt complexes

A new, efficient methodology for the synthesis of substituted thienylpyridines includes the synthesis of 3-thienyl-1,2,4-triazines using simple heterocyclisation followed by easy transformation of the triazine ring to a pyridine through an aza Diels-Alder approach. A variety of substituted pyridines can be easily achieved using cheap, commercially available reagents such as bromoacetylarenes, aroyl hydrazides, norbornadiene, and enamines in various combinations. New thienylpyridines form phosphorescent cyclometallated Pt complexes.     

Cascade reactions of substituted 1,2,4-triazines: rapid access to nitrogen-containing polycycles

A new and straightforward methodology for the construction of complex nitrogen-containing polycycles has been developed. This methodology exploits easily prepared 1,2,4-triazines as substrates for a pericyclic reaction cascade, forming the polycycles in good to excellent yield in a single operation.     

Nucleophilic substitution of 1,2,4-triazines

The reaction of 3-(methylthio)-5-carbethoxy-1,2,4-triazine (5) with ammonia was found to yield products from not only ammonia but also methanethiolate displacements. An account of the transformations and the products observed is given. The 3-position of 3,6-bis(methylthio)-5-carbamoyl-1,2,4-triazine (7) was shown to be more reactive than the 6-position toward nucleophilic substitution. Reduction at the 4,5 positions of triazine 5 occurred upon treatment with methanethiol under basic and neutral conditions.     

1,2,4-triazines. III. A convenient synthesis of 1,2,4-triazines and their covalent hydration

A general synthesis of 1,2,4-triazines, from 3-methylthiotriazines is described. It has been shown that 1,2,4-triazines undergo covalent hydration across the N₄-C₅ bond.     

Conversion of some substituted 1,2,4-triazole-3-thiones

An N-phenyl substituent and an N-allyl substituent in the 4 position of some substituted 1,2,4-triazole-3-thiones do not affect the course of cyanoethylation and alkylation reactions. Cyanoethylation leads to N-substituted derivatives, whereas alkylation gives S-substituted derivatives.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1425–1427, October, 1974.     

Acylation of some substituted 1,2,4-triazole-3-thiones

Acylation of some substituted 1,2,4-triazole-3-thiones in the presence of triethylamine gives N-substituted derivatives. S-Substituted derivatives, which are readily transacylated to the N-substituted derivatives on heating, are formed in the case of 4-phenyltriazolethiones in alkaline media. In the case of 4-allyltriazolethiones acylation in alkaline media gives only the N-substituted derivatives. Bromination of the acyl derivatives gives the disulfides.     

Synthesis and reactions of some substituted 1, 3, 5-triazines

The reactions of 2-substituted 4, 6-dihydroxytriazines with PCl₅ and SOCl₂ are investigated. It is shown that conversion of 2-(aryl- and substituted styryl)-4, 6-dihydroxy-1, 3, 5-triazine to the corresponding 4, 6-dichloro compounds is accompanied by ring opening and, in the case of styryl derivatives, by chlorination of the ethylene group. Analysis of the IR spectra of 4, 6-dihydroxytriazines establishes that under ordinary conditions they are 4, 6-dihydroxytetrahydrotriazines. Shift of the lactim-lactam equilibrium towards the oxo form is considered to be the reason why these compounds react with difficulty with SOCl₂. A mechanism for the reaction of triazine hydroxy derivatives with PCl₅ is put forward. New substituted triazines and intermediates are synthesized.     

New possibilities of 1,2,4-triazines functionalization: first examples of synthesis and structure of boron-containing 1,2,4-triazines

By oxidation of 3-thioderivatives of 1,2,4-triazine 1a,b 3-alkylsulfonic derivatives 2a,b were obtained. Interaction of the sulfonic derivative 2a with indole leads to 3-oxo-5-indolyl-5-phenyl-as-triazine 4. The sulfone 2a reacts with 1-ethyl-2,6-dimethylquinolinium iodide to give 3-(1-ethyl-6-methyl-1,2-dihydroquinoline-2-methylene)-5-phenyl-1,2,4-triazine 5. The 3-morpholino- 3 and 3-thioderivatives 6, 7a,b of as-triazine were obtained by interaction of the sulfone 2 with morpholine and organic boron-containing thiols. The crystal structure of boron-containing derivative of as-triazine 7b was investigated by X-ray analysis.     

Synthesis of fluoro-containing substituted 1,3,5-triazines

Conclusions By the method of acylation-cyclodehydration of imidoylamidines we have prepared 1,3,5-triazines with three different substituents, among them reactive unsaturated and nitrile groups.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 4, pp. 928–933, April, 1989.     

Transformations of some substituted 5-benzyl-1,2,4-triazoline-3-thiones

The acylation of some substituted 5-benzyl-1,2,4-triazoline-3-thiones both in the presence of triethylamine and in alkaline media gives N-substituted derivatives. N-Substituted derivatives were obtained by cyanoethylation, whereas S-substituted derivatives were obtained by alkylation. Bromination of the acyl derivatives gives disulfides.     

Mass spectra of some perfluoroalkyl and perfluoroalkylether substituted 1,2,4-oxadiazoles

Electron impact fragmentation patterns were obtained for 1,4-bis[(5-perfluoro-n-heptyl)-1,2,4-oxadiazolyl]-benzene, its perfluoroalkylether substituted analogue, 3,5-bis(perfluoroalkyl)-, 3,5-bis(perfluoroalkylether)- and 3-perfluoroalkylether-5-perfluoroalkyl-1,2,4-oxadiazoles. In the compounds containing the phenylene group the molecular ion constituted the base peak; the main process was the breakdown of the oxadiazole ring with concurrent liberation of the perfluoroalkyl or perfluoroalkylether nitrile molecule; cleavage of the fluorinated chain α to the oxadiazole ring was found to take place to a considerable degree. In the perfluorinated 1,2,4-oxadiazoles cleavage β to the oxadiazole ring occurred preferentially; fragmentation of the ring itself took place to a limited degree only. The 3-perfluoroalkylether-5-perfluoroalkyl-1,2,4-oxadiazole appeared to undergo the primary β-cleavage exclusively at the perfluoroalkylether sidechain.     

Biologically active azolo-1,2,4-triazines and azolopyrimidines

The review presents current data on the methods of synthesis and biological activity of purine-isosteric azolo-annulated 1,2,4-triazines and pyrimidines with a bridgehead nitrogen atom, which are among the most promising classes of biologically active compounds.     

Synthesis of some substituted 1,2,4-triazole and 1,3,4-thiadiazole derivatives

New S-substituted 1,2,4-triazole and 1,3,4-thiadiazole derivatives have been prepared. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1712–1715, November, 2008.     

One-Pot Preparation Method of 5-Alkyl-3-(benzo)pyridyl-1,2,4-triazines

Russian Journal of Organic Chemistry - Convenient one-pot method was developed for the preparation of 5-alkyl-3-(2-pyridyl)-, 5-alkyl-3-(4-pyridyl)- or 5-alkyl-3-(quinolin-2-yl)-1,2,4-triazines in...