Reactions of 3-nitro-1,2,4-triazole derivatives with alkylating agents. 5. Selective synthesis of 1,4-dialkyl-and 1,4,5-trialkyl-3-nitro-1,2,4-triazolium salts from 1-alkyl-and 4,5-dialkyl-3-nitro-1,2,4-triazoles and dialkyl sulfates

Interaction of N₍₁₎-alkyl-substituted 3-nitro-5-R-1,2,4-triazoles with dialkyl sulphates proceeds selectively and results in the respective salts of 1,4-dialkyl-, 1,4,5-trialkyl-3-nitro-1,2,4-triazoliums. The reaction of N₍₄₎-alkyl-substituted 3-nitro-5-R-1,2,4-triazoles yields the mixtures of the salts of 1,4-dialkyl-, 1,4,5-trialkyl-3-nitro-1,2,4-triazoliums and 1,4-dialkyl-, 1,3,4-trialkyl-1,2,4-triazol-5-ones with predominance of quaternary salts. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 927–934, June, 2007.     

Acyl and Sulfonyl Derivatives of 3,5-Diamino-1-R-1,2,4-triazoles

3-Acylamino-5-amino-1-R-1,2,4-triazoles are formed regioselectively on acylating 3,5-diamino-1-R-1,2,4-triazoles with an equimolar amount of anhydrides, carboxylic acid chlorides, and sulfonyl chlorides. With an excess of anhydride and carboxylic acid chloride 3,5-diacylamino-1-R-1,2,4-triazoles are formed. 3-Acylamino-5-amino-1-R-1,2,4-triazoles do not interact with sulfonyl chlorides. The higher reactivity of the 3-amino group towards acylating agents is determined by electronic and not steric factors. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1342–1350, September, 2005.     

Alkylation of acyl and sulfonyl derivatives of 3,5-diamino-1-phenyl-1,2,4-triazole

Alkylation of 3-acylamino-, 5-amino-1-phenyl-3-tosylamino-1,2,4-triazoles and 3,5-diacetylamino-1-phenyl-1,2,4-triazole in the presence of an equimolar amount of sodium methylate in DMSO occurs regioselectively at the amide (sulfamide) group nitrogen atom. The benzylation of 3-acetylamino-5-amino-1-phenyl-1,2,4-triazole with excess base and benzyl chloride also alkylates the amino group at position 5. Alkylamino-1-R-1,2,4-triazoles can be conveniently prepared by alkylation of the corresponding acetylamino-1,2,4-triazoles in the presence of base and subsequent acid hydrolysis of the N-acetyl-N-alkyl derivatives. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 557–567, April, 2009.     

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.     

Reactions of 3-nitro-1,2,4-triazoles with alkylating agents. 3. Alkylation of a neutral heterocycle by diethyl sulfate

The reaction of 3-nitro-5-R-1,2,4-triazoles with diethyl sulfate gives 1-ethyl-3-R-5-nitro-, 4-ethyl-3-nitro-5-R-1,2,4-triazoles, 1,4-diethyl-, 1,4-diethyl-3-methyl-1,2,4-triazol-5-ones, and 1,4-diethyl-3-nitro-5-R-1,2,4-triazolium salts. When compared with the use of dimethyl sulfate as alkylating agent the ethylation products have a markedly increased fraction of triazolones (up to 30–37%) and a somewhat lowered yield of nitrotriazolium salts (up to 6–10%). The reaction time is increased by an order. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1378–1381, September, 2006.     

Synthesis of 3-carbamoyl-1,2,4-triazoles

3-Carbamoyl-1,2,4-triazoles were synthesized by the reaction of monothiooxamides with acid hydrazides Published inIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1487–1488, August, 2000.     

Syntheses and properties of related polyoxadiazoles and polytriazoles

New aromatic poly-1,2,4-triazoles and poly-1,3,4-oxadiazoles are studied as thermally stable membrane materials. Various groups were introduced onto the pendant phenyl groups of poly-1,2,4-triazoles. Glass transition temperature, degradation temperature, and cold crystallization behavior were studied as a function of these groups. Cold crystallization appeared to be highly sensitive to macromolecular regularity. The solubility of poly-1,3,4-oxadiazoles was highly improved upon incorporation of 5-t-butylisophthalic, 1,1,3-trimethyl-3-phenylindane, 4,4′-(2,2′-diphenyl) hexafluoro propane, and diphenyl ether groups into the polymeric main chain, whereas the high glass transition temperatures and degradation temperatures typical for aromatic poly-1,3,4-oxadiazoles were maintained. © 1994 John Wiley & Sons, Inc.     

On the lead tetraacetate oxidation of 4-amino-1,2,4-triazoles, 1-amino- and 2-amino-1,2,3-triazoles

Lead tetraacetate oxidation of 4-amino-1,2,4-triazoles, 1-amino- and 2-amino-1,2,3-triazoles affords mainly fragmentation to nitriles or acetylenes, even in the presence of intramolecularly attached double bonds.

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Über die Bleitetraacetatoxidation von 4-Amino-1,2,4-triazolen, 1-Amino- und 2-Amino-1,2,3-triazolen (Kurze Mitteilung)

Zusammenfassung Bei der Oxidation von 4-Amino-1,2,4-triazolen, 1-Amino- und 2-Amino-1,2,3-triazolen mit Bleitetraacetat entstanden hauptsächlich Nitrile bzw. Acetylene durch Fragmentierung — trotz der Gegenwart von intramolekularen Doppelbindungen.

     

Conversion of 2-amino-5-R-phenyl-1,3,4-oxadiazoles into 3-R-phenyl-5-alkoxy-1,2,4-triazoles

2-Amino-5-R-phenyl-1,3,4-oxadiazoles have been shown to isomerize in alcoholic potassium hydroxide solution to 3-R-phenyl-5-alkoxy-1,2,4-triazoles. The dissociative ionization of 3-R-phenyl-5-alkoxy-1,2,4-triazoles and 3-R-phenyl-1,2,4-triazolin-5-ones has been examined. The mass spectra of the oxadiazoles have been compared with those of the triazoles.Translated from Khimiya Geterotslklicheskikh Soedinenii, No. 11, pp. 1553–1556, November, 1986.     

Heterocyclic synthesis using nitrile imines. 6. Synthesis of some new substituted 4,5-dihydro-1H-1,2,4-triazoles

A new series of substituted 1,2,4-triazoles was synthesized from the cycloaddition reaction of alkanal and cycloalkanal hydrazones containing electron-withdrawing groups (MeCO, PhCO, and MeOCO) with appropriate hydrazonoyl halides. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 392–398, March, 2007.     

Reaction of thiosemicarbazide with n-cyanoguanidine: synthesis of 3,5-diamino-1-thiocarbamoyl-and 3,5-diamino-1-thiazol-2-yl-1,2,4-triazoles

The reaction of thiosemicarbazide with N-cyanoguanidine in an acidic medium afforded 3,5-diamino-1-thiocarbamoyl-1,2,4-triazole, whose condensation with α-halo ketones gave 3,5-diamino-1-thiazol-2-yl-1,2,4-triazoles 7a–d. The latter were also prepared by the independent synthesis from 2-hydrazinothiazoles and N-cyanoguanidine. Acylation of compounds 7a,d under mild conditions and their condensation with aldehydes occur at the C(3′)NH₂group. The structure of aroyl derivative 11c was established by X-ray diffraction. Acylation of diaminothiazolyltriazole 7a in boiling Ac₂O afforded 3,5-diacetylamino-1-(4-phenylthiazol-2-yl)-1,2,4-triazole. Hydrogenation of arylidene derivatives 14b,c and aroyl derivative 11c gave the corresponding benzylaminotriazoles 15a,b. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 329–334, February, 2006.     

Synthesis and antimicrobial activity of pyrrolyl/pyrazolyl arylaminosulfonylmethyl 1,3,4-oxadiazoles, 1,3,4-thiadiazoles and 1,2,4-triazoles

A new class of pyrrolyl/pyrazolyl arylaminosulfonylmethyl 1,3,4-oxadiazoles, 1,3,4-thiadiazoles, and 1,2,4-triazoles were prepared and tested for antimicrobial activity. Amongst the tested compounds, 5c displayed high antimicrobial activity.     

均三唑并噻二唑衍生物的微波合成

在无溶剂无催化剂微波辐射下,羧酸与1,3-二氨基硫脲快速反应高产率得到了3-取代基-4-氨基-5-巯基-1,2,4-三唑,该化合物与苯甲酰氯在无溶剂无催化剂微波促进下可以方便地制备化合物3-取代基-6-苯基-1,2,4-三唑[3,4-b][1,3,4]噻二唑。该方法具有反应时间短、环境友好、易于纯化及高产率的优点。产物结构经IR和1HNMR谱进行了表征。     

From imidates to vinyl-1,2,4-triazoles: Synthesis,mechanistic aspects and first issues of their reactivity

The reaction of variously substituted acylimidates with hydrazine derivatives represents an efficient and easy to set synthetic entry towards 5-vinyl-1,2,4-triazole derivatives. The construction of the triazole ring allows the installation of variety of substituent combination at the N(1), C(3) and C(5) positions of the five-membered heterocycle in good to high yields. The method reveals selective towards 5-vinyl-1,2,4-triazoles avoiding the potential formation of seven- and five-membered side-products as supported by theoretical calculations and NMR experiments. First lines of Pd-catalyzed arylation of the vinyl fragment towards 5-styryl-1,2,4-triazoles and Cu-catalyzed arylation at the N(1) site are finally described.     

Two reaction routes for the preparation of aromatic polyoxadiazoles and polytriazoles: Syntheses and properties

Two reaction routes for the preparation of aromatic poly-1,3,4-oxadiazoles and poly-1,2,4-triazoles are studied and their influence on the physical properties, i.e., inherent viscosity, glass transition, degradation temperature, and film integrity of the final products are discussed. Aromatic poly-1,3,4-oxadiazoles are prepared by means of a polycondensation reaction of terephthaloyl chloride and isophthalic dihydrazide yielding a precursor polymer, poly(p, m-phenylene) hydrazide, which is converted into the corresponding poly-1,3,4-oxadiazole by means of a cyclodehydration reaction. Poly-1,3,4-oxadiazoles are also prepared by means of a polycondensation reaction between terephthalic and isophthalic acid and hydrazine yielding poly-1,3,4-oxadiazoles with higher inherent viscosities. Flexible poly-1,3,4-oxadiazole films are obtained only if the inherent viscosities of the polymers used are higher than 2.7 dL/g. The thermal stability is found to increase with increasing content of p-phenylene groups in the polymer backbone. Aromatic poly-1,2,4-triazoles are prepared using polyhydrazides with alternating para- and meta-phenylene groups and poly-1,3,4-oxadiazoles with a random incorporation of para- and meta-phenylene groups in the main chain as precursor polymers. The glass transition temperatures are found to increase with increasing content of p-phenylene groups in the main chain of these polymers. Cold crystallization is observed only for the alternating polymer. © 1994 John Wiley & Sons, Inc.     

Reaction Of 3-Nitro-1,2,4-triazolederivatives with Alkylating Agents. 1. Alkylation in the Presence of Alkali

Alkylation of 3-nitro-1,2,4-triazole and 5-methyl-3-nitro-1,2,4-triazole with dialkyl sulfates or alkyl halides in the presence of alkali proceeds with a low selectivity for the alkylating agent with the formation of two regioisomers at the N₍₁₎ and N₍₂₎ atoms of the heterocycle. Depending on the reaction conditions the proportion of the N₍₂₎ isomer was 14.6-33.8%. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 1020–1025, July, 2005.     

Synthesis and characterization of mono- and bicyclic heterocyclic derivatives containing 1,2,4-triazole, 1,3,4-thia-, and -oxadiazole rings

A series of new N- and S-substituted 1,3,4-oxadiazole derivatives were synthesized. 5-Pyridin-3-yl-3-[2-(5-thioxo-4,5-dihydro-l,3,4-thiadiazol-2-yl)ethyl]-1,3,4-oxadiazole-2(3H)-thione and 5-[(5-(pyridin-3-yl)-1,3,4-oxadiazol-2-ylthio)methyl]-N-phenyl-1,3,4-thiadiazol-2-amine were formed by cyclization of 3-(5-pyridin-3-yl-2-thioxo-1,3,4-oxadiazol-3(2H)-ylpropanimidohydrazide and 2-[(5-pyridin-3-yl-1,3,4-oxadiazol-2-yl)thio]thiosemicarbazide with CS₂ and H₂SO₄. On the other hand, a number of new bicyclic 1,2,4-triazolo[3,4-b][1,3,4]thiadiazole derivatives were synthesized. 6-Pyridin-3-ylbis[1,2,4]‐triazolo[3,4-b:4′,3′-d][1,3,4]thiadiazole-3(2H)-thione was synthesized by reaction of 6-(hydrazino)-3-pyridine-3-yl[1,2,4]triazolo[3,4-b][1,3,4]thiadiazole with CS₂/KOH/EtOH. The structures of the newly synthesized compounds were elucidated by the spectral and analytical data IR, Mass, and ¹H NMR spectra. Correspondence: Adel A.-H. Abdel-Rahman, Department of Chemistry, Faculty of Science, Menoufia University, Shebin El-Koam, Egypt; Wael A. El-Sayed, National Research Centre, Department of Photochemistry, Cairo, Egypt.     

Synthese de 5-Aryl-3-[(1-dialcoxyphosphonyl)methyl]-1,2,4-triazoles a Partir d'Imidates N-Chloroacyles

A variety of 5-aryl-3-[(1-dialcoxyphosphonyl)methyl]-1,2,4-triazoles 3 has been synthesized efficiently by treatment of trialkylphosphites with 5-aryl-3-chlorométhyl-1,2,4-triazoles 2 . Compound 2 has been prepared by action of N-chloroacylimidates 1 with hydrazines. The structure of triazoles 2 and 3 have been unequivocally confirmed by means of IR, 1 H, 13 C, 31 P NMR spectroscopy and mass spectra.     

Trimethylsilyl isothiocyanate (TMSNCS): an efficient reagent for the one-pot synthesis of mercapto-1,2,4-triazoles

A mild, convenient, and efficient one-pot synthesis of mercapto-1,2,4-triazoles is described. Various hydrazides efficiently reacted with trimethylsilyl isothiocyanate (TMSNCS) under basic condition to give mercapto-1,2,4-triazoles in high yields.     

Synthesis of Substituted 1,2,4-Triazoles and 1,3,4-Thiadiazoles

The cyclization of 4-substituted 1-arylacetyl- and 1-aryloxyacetylthiosemicarbazides and also the potassium salt of (4-bromophenoxy)acetodithiocarbazinic acid in the presence of base gives the novel 3-arylmethyl- and 3-aryloxymethyl-5-mercapto-1,2,4-triazoles and, in the presence of concentrated H₂SO₄, the novel 5-substituted 2-arylmethyl- and 2-aryloxymethyl-1,3,4-thiadiazoles.