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.     

One-Step Synthesis of 5-Methyl-1,2,4-triazines by the Transformation of Their 5-Phenacyl Derivatives

Russian Journal of Organic Chemistry - A convenient one-step synthesis of 5-methyl-1,2,4-triazines by the transformation of 5-phenacyl-1,2,4-triazines under alkaline conditions was developed. The...     

Reactions of 1,2,4-triazines with nitromethide ion. A convenient method of preparation of 1,2,4-triazin-5-ylcarbaldehyde oximes and their synthetic applications

An efficient procedure for the preparation of 1,2,4-triazin-5-ylcarbaldehyde oximes 2a-f from 1,2,4-triazines 1a-f and nitromethide ion is described. The oximes 2c-d were converted into corresponding 5-cyano-1,2,4-triazines 6c-d . The latter compounds react easily with various nucleophiles to afford 5-substituted 1,2,4-triazines 7a-i and with 1-pyrrolidino-1-cyclohexene to form cyano derivative of 5,6,7,8-tetrahydroisoquinoline 9 .     

Tandem oxidation processes for the regioselective preparation of 5-substituted and 6-substituted 1,2,4-triazines

α-Hydroxyketones undergo MnO₂-mediated oxidation, followed by in situ trapping with 2-pyridylamidrazone, to give 3-pyridyl-5-substituted 1,2,4-triazines in a one-pot procedure, which avoids the need to isolate the reactive α-ketoaldehyde intermediates. By modifying this procedure to allow condensation prior to oxidation, the corresponding 6-substituted 1,2,4-triazines were obtained. The preparation of a novel unsymmetrical 2,2′-bipyridine using one of the pyridyl 1,2,4-triazines prepared herein is also described.     

Rearrangement of 4-aryl-1,2,4-triazine into the 4-amino derivatives

The action of hydrazine on 3-methylmercapto-5-oxo-4-aryl-4,5-dihydro-1,2,4-triazines led to a novel rearrangement and gave 3-arylamino-4-amino-5-oxo-4,5-dihydro-1,2,4-triazines. The mechanism of this rearrangement was discussed.     

The mass spectra of 1,2,4-triazines and related compounds

The mass spectra of monocyclic 1,2,4-triazines and 1,2,4-triazines fused to a pyrazole ring through a bridgehead nitrogen have been investigated: fragmentation pathways were elucidated by the use of metastable ions and high resolution mass measurements. The spectra of the monocyclic 1,2,4-triazines indicate that loss of nitrogen from the molecular ions is a relatively unimportant feature. The decomposition modes of the bicyclic pyrazolo[3,2-c]-as-triazines are sensitive to the nature of the substituent in the triazine ring.     

Aminovinyl ketones and aminovinyl esters as CCN building blocks for the synthesis of 1H-pyrrolo[3,2-e]1,2,4-triazines

5,6-Unsubstituted-3-aryl-1,2,4-triazines were found to react with aminovinyl ketones and aminovinyl esters in acetic anhydride to form derivatives of 3a,4,7,7a-tetrahydro-1H-pyrrolo[3,2-e]1,2,4-triazines in good yields.     

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.     

Chloromethyl-, dichloromethyl-, and trichloromethyl-1,2,4-triazines and their 4-oxides: method for the synthesis and tele-substitution reactions with C-nucleophiles

A simple procedure was developed for the synthesis of 1,2,4-triazines and their 4-oxides containing the ClCH₂, Cl₂CH, or CCl₃ group at position 3 by cyclization of 2-aryl-2-hydrazono-1-oximinoethanes with the corresponding chloroacetonitriles. The reaction pathway depends on the number of halogen atoms in the acetonitrile used. The reactions with trichloroacetonitrile, monochloroacetonitrile, and dichloroacetonitrile afford 3-trichloromethyl-1,2,4-triazines, 3-chloromethyl-1,2,4-triazine 4-oxides, and a mixture of the corresponding dichloromethyltriazines and their 4-oxides, respectively. The reactions of 3-trichloromethyl-1,2,4-triazines with indoles and phenols are accompanied by tele-substitution with elimination of halogen from the trichloromethyl group to give 5-indolyl- (or 5-hydroxyphenyl)-3-dichloromethyl-1,2,4-triazines.     

Transformations of 1,2,4-Triazines in Reactions with Nucleophiles: V. SNH and ipso-Substitution in the Synthesis and Transformations of 5-Cyano-1,2,4-triazines

The scope of functionalization of 1,2,4-triazines can be considerably extended via successive nucleophilic substitution of hydrogen (S_N ^H) and ipso-substitution. A convenient procedure has been developed for direct cyanation of 1,2,4-triazine 4-oxides with acetone cyanohydrin in the presence of triethylamine. The cyano group in the resulting 5-cyano-1,2,4-triazines is readily replaced by reactions with various aliphatic alcohols and amines.     

Ring contraction of 1,2,4-triazine derivatives in the synthesis of imidazoles

The review systematizes the data on the reactions of 1,2,4-triazines proceeding with a triazine ring contraction to the imidazole one. Imidazole derivatives are obtained upon treatment of 1,2,4-triazines of different saturation degree with reducing agents, oxidants, acids, as well as with the agents initiating tandem reactions, the last step of which is a triazine ring contraction, for example, nitrosating and aminating agents, organometallic compounds and aromatic aldehydes.     

Nucleophilic substitution of hydrogen in the reaction of 1,2,4-triazin-4-oxides with cyanamide

It was shown that cyanamide can successfully be used in reactions of nucleophilic substitution of hydrogen with 1,2,4-triazin-4-oxides in the presence of a base to give 5-cyanoimino-1,2,4-triazines. It was found by¹³C NMR spectroscopy that these compounds and their alkylation products at the cyclic nitrogen atom exist in the form of 5-cyanoimino-2,5-dihydro-1,2,4-triazines. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1128–1130, June, 2000.     

Ring-chain tautomerism of substituted hydrazones. 22. Synthesis,structure, and oxidation of alkylidene derivatives of 2-aminoethylhydrazines

Alkylidene derivatives of 2-aminoethylhydrazines exist in solutions either as 2-aminoethylhydrazones or as the ring-chain tautomeric mixtures of the hydrazone—perhydro-1,2,4-triazine depending on the structure. The oxidation of perhydro-1,2,4-triazines leads to the formation of 2,3,4,5-tetrahydro-1,2,4-triazines.For Communication 21, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1392–1396, October, 1991.     

Synthesis of Substituted 1,2,4-Triazines Based on 1,2-Bis(2,5-dimethyl-3-thienyl)ethanedione

A novel, convenient method has been developed for the synthesis of 1,2-bis(2,5-dimethyl-3-thienyl)ethanedione, from which were prepared 5,6-bis(2,5-dimethyl-3-thienyl)-1,2,4-triazines (analogs of the photochromic 1,2-diarylethenes). The principial possibility of using 1,2,4-triazines obtained as photochromic agents was investigated.     

Reactions of the derivatives of 5,6-diaryl-2,5-dihydro-1,2,4-triazines with dimethyl acetylenedicarboxylate—structural reassignments of the products and further observations

The structures of the dihydro derivatives of 5,6-diaryl-1,2,4-triazines and of the products from the title reactions have been reassigned as 5,6-diaryl-2,5-dihydro-1,2,4-triazines ($\text{5}$a-g) and 2,6-diaryl-4-methyl-5-substituted-1,8-bis-methoxycarbonyl-3,4,7-triaza-bicyclo[3.3.0]octa-2,7-dienes ($\text{7}$a-g), respectively.     

Reaction of 4-aryl-1,2,4-triazines with hydrazine

The action of hydrazine on 3,5-dioxo-4-aryl-2,3,4,5-tetrahydro-1,2,4-triazines gave 4-amino-3,5-dixo-2,3,4,5-tetrahydro-1,2,4-triazines. The intermediates of this reaction were isolated and shown to be α-ketoacidhydra-zide 4-arylsemicarbazones and not the α-ketoanilidecarbohydrazones. The realtive rates of cyclization of the latter isomeric derivatives provide a support for a proposed intermediates which were not isolated in the reaction of 3-mercapto and 3-methylmercapto-4-aryl-5-oxo-4,5-dihydro-1,2,4-triazines with hydrazine.     

Reaction of N,N-dimethylcarbamoyl bromide with 1,2,4-triazines

The acylation of substituted 1,2,4-triazines with N,N-dimethylcarbamoyl bromide was studied. 4,5-Dihydro-4-(N,N-dimethylcarbamoyl)-3-thioxo(oxo)-5-oxo-6-R-1,2,4-triazines were synthesized. The spectral characteristics of the synthesized compounds are discussed.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 969–971, July, 1989.     

Palladium-catalyzed cross-coupling of 5-acyl and 5-formyl-1,2,4-triazines and their derivatives with heteroaromatic tin compounds

The synthesis of novel mono- and di(substituted)-1,2,4-triazine derivatives containing thiophene and furan rings are described. Heteroaromatic rings were provided using palladium-catalyzed cross-coupling reaction between 3-alkylsulfanyl-5-acyl-1,2,4-triazines or 5-cyano-3-alkylsulfanyl-1,2,4-triazines and heteroaromatic tin compounds. New compounds bearing masked acyl groups were also obtained. These reactions were optimized to determine the scope and limitations of this methodology and were used for preparation of oligothiophenes bearing terminal heterocyclic ring.     

Synthesis of thieno[2,3-e]-1,2,4-triazines

3-Methylmercapto-5-oxo-6-vinyl- and 2-methyl-3-mercapto-5-oxo-6-vinyl-2,5-dihydro-1,2,4-triazines were readily converted into the corresponding thieno[2,3-e]-1,2,4-triazine in one step by the action of phosphorus pentasulfide in pyridine. 4-Methyl-3-mercapto-5-oxo-4,5-dihydro-1,2,4-triazine is only converted into the 5-thioxo analog and no thiophene ring product was obtained under the same conditions. Thieno[2,3-e]-1,2,4-triazines were also more efficiently obtained by the action of phosphorus petnasulfide in pyridine on the appropriate 6-acylmethyl-3-mercapto-5-oxo-2,5-dihydro-1,2,4-triazine.     

3-氨基-5-取代苯氨基-6-苯基-1,2,4-三嗪的合成

3-氨基-1,2,4-三嗪化合物具有广泛的生理活性,如:治疗支气管扩张、抑制乳酸菌和症原虫繁殖杀菌等,因此,研究这类化合物合成方法应运而生。本文以苯甲酰基硫代甲酰胺为原料,进一步合成了氨基-5-取代苯氨基-6-苯基-1,2,4-三嗪。