1,2,4-Triazolo[1,5-a]benzimidazoles: Tautomerism and alkylation

The position of the tautomeric equilibrium in unsubstituted 1,2,4-triazolo[1,5-a] benzimidazole, as well as in its 2-methyl and 2-phenyl derivatives, was investigated by UV, IR, and PMR spectroscopy and by determination of the ionization constants. In all cases the amount of the 4H tautomer in the equilibrium mixture is two to three orders of magnitude greater than the amount of the 3H tautomer, while signs of the existence of the 1 H form are not observed. The synthesis of unsubstituted triazolo [1,5-a]-benzimidazole was accomplished for the first time. The alkylation of the indicated triazolo [1,5-a]benzimidazoles was studied and a relationship between the regiospecificity of this reaction and the position of the tautomeric equilibrium was established.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 209–220, February, 1989.     

1,2,4-Triazolo[1,5-a]pyrimidines from 3-formyl-2,5-dimethoxytetrahydrofurans

Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 1, pp. 229–230, January, 1993.     

1,2,4-三唑并[3,2-d][1,5]-苯并氧氮杂（艹/卓）化合物的合成

苯并二氢吡喃－４－酮的芳腙（１）衍生的偶氮基碳正离子（３）与腈发生１,３－偶极环加成反应,加成产物（４）通过「１,２」－迁移扩环重反应,形成新颖的三环系杂环化合物１,２,４－三唑并「３,２－ｄ」「１,５」－苯并氧氮杂Ｚｈｕｏ化合物５ａ－５ｋ。     

Coordination Compounds of Cobalt(II), Nickel(II), and Zinc(II) Valerates and Benzoates with Phenylacethydrazide

Complexes of cobalt(II), nickel(II), and zinc(II) valerates and benzoates with phenylacethydrazide were synthesized. These compounds were characterized by chemical analysis, IR spectroscopy, diffuse reflection spectroscopy, and thermogravimetry.     

Coordination Compounds of Cobalt(II), Nickel(II), and Zinc(II) Malonates and Phthalates with Benzohydrazide

Benzohydrazide complexes of cobalt(II), nickel(II), and zinc(II) malonates and phthalates were synthesized and characterized by chemical analysis, IR spectroscopy, diffuse reflectance spectroscopy, and thermogravimetry.     

Cobalt(II), Nickel(II), and Copper(II) Complexes with Diphenylthiocarbazide

New [ML(H₂O)₂] complexes (M = Co²⁺, Ni²⁺, or Cu²⁺; H₂L = diphenylthiocarbazide) were synthesized and studied using IR and diffuse reflection electronic spectroscopy, magnetic chemistry, conductometry, and DTA. The metals were shown to coordinate L^2–through nitrogen and sulfur atoms. The complex [CuL(H₂O)₂] is a dimer.     

An Improved Synthesis of 3-Substituted 1,2,4-Triazolo[4,3-a]pyridines and 1,2,4-Triazolo[4,3-b]pyridazines

The preliminary results of a simple and versatile one-pot procedure for the preparation of 3-substituted 1,2,4-triazolo[4,3-a] pyridines and 1,2,4-triazolo[4,3-b]pyridazines are described. Intramolecular cyclization of nitrile imine ylides are carried out by treatment of 2-pyridyl- and 3-pyridazinylhydrazones with chloramine T.     

新型1,2,4-三唑并[3,2-d][1,5]苯并氧氮杂(艹卓)-2-酮的合成

取代苯并二氢吡喃-4-酮(1)的芳腙在冰醋酸中与KNCO发生[3 2]环加成反应,加成产物经KMnO4氧化开环得偕偶氮异氰酸酯(3).3在HBF4的催化下发生环化-重排反应,合成得到一系列新型6-7-5三环系1,2,4-三唑并[3,2-d][1,5]苯并氧氮杂(艹卓)2-酮(5a～5g).由X单晶衍射测定了化合物5a的晶体结构.     

Synthesis and Physicochemical Study of Iron(II), Cobalt(II), Nickel(II), and Copper(II) Complexes with 4-(2-Pyridyl)-1,2,4-Triazole

New complexes of iron(II), cobalt(II), and nickel(II) with 4-(2-pyridyl)-1,2,4-triazole (PyTrz), [Fe₃(PyTrz)₈(H₂O)₄]A₆ (A = NO₃ ^-, ClO₄ ^-, Br^-) and [M₃(PyTrz)₈(H₂O)₄](NO₃)₆ (M = Co, Ni), were synthesized and studied by X-ray diffraction, magnetochemical method, and electronic and IR spectroscopy. The complex [Fe₃(PyTrz)₈(H₂O)₄](NO₃)₆) was also studied by adiabatic calorimetry. The Fe(II), Co(II), and Ni(II) nitrate complexes were shown to be isostructural to the previously synthesized linear trinuclear [Cu₃(PyTrz)₈H₂O)₄](NO₃)₆ complex. In all compounds, antiferromagnetic exchange interactions between M²⁺ ions were detected. The complex [Fe₃(PyTrz)₈(H₂O)₄](NO₃)₆ undergoes the ¹ A ₁ ⁵ T ₂ spin transition.     

Synthesis,Structure, and Biological Activity of Coordination Compounds of Cobalt(II), Nickel(II), and Copper(II) with N-(Methoxyphenyl)-2-[(5-nitrofuryl)methylene]hydrazine Carbothioamides

Russian Journal of General Chemistry - 4-(2-Methoxyphenyl)-, 4-(3-methoxyphenyl)-, and 4-(4-memoxyphenyl)-2-[(5-mttofuryl)methylene]-hydrazine carboxamide (HL1–3) react with hydrates of...     

A new synthesis for 1,2,4-triazolo[1,5-a]-pyridines and 1,2,4-triazolo[1,5-a]isoquinolines

Summary Condensation of cyano acid hydrazide1 with cyclopentanone in refluxing ethanolic piperidine yields hydrazone2. With mixtures of aliphatic aldehydes and different active methylene reagents,2 reacts to 1,2,4-triazolo[1,5-a]pyridines (8a–f). Compound2 also reacts with arylidenes9a–g to give triazolopyridines10a–g. Reaction of2 with aromatic aldehydes affords compounds13a–c. Diazotation of2 with aryldiazonium chloride in ethanol at 0 °C leads to the azo adducts15a–d. The thieno-1,2,4-triazolopyridine16 is obtained by reaction of8a with elementary sulfur.16 undergoes cycloaddition with -nitrostyrene, maleic anhydride, N-arylmalemide, and acrylonitrile yielding the isoquinolines21–24. All new compounds have been characterized by their IR,¹H NMR, and mass spectra.

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Ein neuer Syntheseweg für 1,2,4-Triazolo[1,5-a]pyridine und 1,2,4-Triazolo[1,5-a]isochinoline

Zusammenfassung Kondensation des Cyanohydrazids1 mit Cyclopentanon in ethanolischem Piperidin bei Rückflußtemperatur ergibt das Hydrazon2. Mit Gemischen aus aliphatischen Aldehyden und verschiedenen Verbindungen mit aktiven Methylengruppen reagiert2 zu 1,2,4-Triazolo[1,5-a]pyridinen (8a–f). Verbindung2 reagiert außerdem mit den Arylidenen9a–g zu den Triazolopyridinen10a–g. Umsetzung von2 mit aromatischen Aldehyden führt zu den Verbindungen13a–c. Diazotierung von2 mit Aryldiazoniumchloriden in Ethanol bei 0°C ergibt die Azoaddukte15a–d. Das Thieno-1,2,4-triazolylpyridin16 erhält man durch Reaktion von8a mit elementarem Schwefel.16 geht it -Nitrostyrol, Maleinsäureanhydrid, N-Arylmaleimid und Acrylnitril eine Cycloaddition zu den Isochinolinen21–24 ein. Alle neuen Verbindungen wurden durch ihre IR-,¹H-NMR- und Massenspektren charakterisiert.

     

Characterization of copper(II) coordination compounds of 5,7-dimethyl[1,2,4]triazolo[1,5-a]pyrimidine: the crystal structure of diaquatetrakis(5,7-dimethyl[1,2,4]triazolo[1,5-a]pyrimidine-N3)-copper(II) hexafluorophosphate

Copper(II) coordination compounds of several CuA₂ salts (A = PF₆, BF₄, ClO₄, CF₃SO₃ or NO₃) with 5,7-dimethyl[1,2,4]triazolo[1,5-a]pyrimidine (dmtp) as a ligand have been studied. The crystal structure of [Cu(dmtp)₄(H₂O)₂](PF₆)₂ is described. This compound is monoclinic, space group P2₁/c, a = 11.826(2) Å, b = 9.463(2) Å, c = 17.673(3) Å, β = 97.50(1)°, Z = 2, d_calc. = 1.66 Mg m⁻³, and has been refined to a final discrepancy factor (R) of 0.0382 based on 2316 reflections. The structure consists of PF⁻₆ anions and centrosymmetric mononuclear [Cu(dmtp)₄(H₂O)₂]²⁺ cations, Cu₂₊ being coordinated by four equatorial N(3)-bonded dmtp molecules with CuN = 2.019 and 2.050 Å, and by two axial water molecules with CuO = 2.650 Å. The water molecules form intramolecular hydrogen bonds with the dmtp N(4) atoms.     

2-aryl(hetaryl)-4H-[1,2,4]triazolo[1,5-a]benzimidazoles

2-(4-Methylphenyl)-4H-[1,2,4]triazolo[1,5-a]benzimidazole and its previously unknown 2-(2-furyl)- and 2-(2-thienyl)-substituted analogs were synthesized by cyclization of benzimidazole-1,2-diamine with the corresponding carboxylic acid chlorides. The IR, ¹H, ¹³C, and ¹⁵N NMR, and mass spectra of the cyclization products in combination with the results of quantum-chemical calculations of NMR chemical shifts showed radical differences of [1,2,4]triazolo[1,5-a]benzimidazoles having no substituent on N⁴ from the recently reported low-melting products of oxidation of 2-amino-1-arylmethylideneaminobenzimidazoles with (diacetoxy-λ³-iodanyl)benzene, which, as we believe, were erroneously assigned analogous structure.     

Cobalt(II) complexes of 5,7-dimethyl[1,2,4]-triazolo-[1,5-a]-pyrimidine. Spectroscopic characterization,XRD study and antimicrobial activity

Summary Several cobalt(II) complexes of 5,7-dimethyl-[1,2,4]-tria-zolo-[1,5-a]-pyrimidine (DMTP) have been prepared and characterized by thermal and spectroscopic techniques. The crystal structure of [Co(DMTP)₂(H₂O)₄]Br₂·2H₂O has been determined by XRD; the metal ion is octahedrally coordinated by two DMTP ligands through the usual N(3) site and four water molecules. Metal binding to N(3) for DMTP is consistent with the electronic properties calculated with the MOPAC programme. All the complexes were screened for their activity against several types of bacteria, showing a broad-spectrum antimicrobial activity.     

含1,2,4-三唑-5-硫酮席夫碱的新型1,2,4-三唑并[1,5-a]嘧啶衍生物的合成及生物活性研究

以2-苄硫基-5-甲基-7-羟基-1,2,4-三唑并[1,5-a]嘧啶为原料,经醚化、肼解、成盐、关环和席夫碱反应合成了20个新型的含1,2,4-三唑-5-硫酮席夫碱的1,2,4-三唑并[1,5-a]嘧啶类化合物,通过IR,1H NMR,MS和元素分析对所合成的化合物进行了结构表征.初步生物活性测试结果表明,部分化合物表现出一定的抑菌或较好的抗烟草花叶病毒(TMV)活性.在500μg/mL浓度下,化合物6b,6f和6p对TMV的抑制率分别为41%,43%和40%.     

Synthesis and crystal structure of piperidinium 2-aryl[1,2,4]triazolo[1,5-a]pyridinides and their neutralization to 2-aryl[1,2,4]triazolo[1,5-a]pyridines

A one step synthesis of novel piperidinium 2-aryl[1,2,4]triazolo[1,5-a]pyridinides 6 from 2′-benzoyl-2-cyanoacetohydrazide (2) and α-substituted cinnamonitriles 3 is described. The reaction takes place by 6-exodig cyclization followed by an 5-exo-trig process to afford salts 6 . The X-ray diffraction of compound 6a reveal that the cation is strongly linked to the anion by hydrogen bonds and a characteristic partial stacking motive. 2-Aryl[1,2,4]triazolo[1,5-a]pyridines were obtained from salts 6 by treatment with hydrochloric acid.