Some Reactions of 5-(3 or 4-Pyridyl)-1,3,4-Oxadiazoles with Amines and Hydrazines

2-Amino-and 2-hydrazino-5-(3 or 4-pyridyl)-1, 3, 4-oxadiazoles [II_i-k] have been prepared by racting 2-chloro derivatives with the corresponding amines or hydrazines, the 2-hydrazino (II_i-k) compounds that obtained were heated with carbon disulphide and alcoholic potassium hydroxide where 5-(3 or 4-pyridyl)-1,3,4-oxadiazolo (2,3-C)-1,2,4-triazole 5-thione (III_a-c) were obtained, the given structures were biologically screened.     

Theoretical studies on the spectroscopic properties and the substituent effects of pyridyl triazole Os(II) complexes

To explore the spectroscopic properties of pyridyl triazole Os(II) complexes and how the substituent effects affect the spectroscopic properties of [Os(ptz)₂L₂] (L=PH₃; ptzH=(2-pyridyl)-1,2,4-triazole) (1), [Os(bptz)₂L₂] (bptzH=3-tert-butyl-5-(2-pyridyl)-1,2,4-triazole) (2), [Os(fptz)₂L₂] (fptzH=3-(trifluoreomethyl)-5-(2-pyridyl)-1,2,4-triazole) (3), and [Os(fbtz)₂L₂] (fbtzH=3-(trifluoreomethyl)-5-(4-tert-butyl- 2-pyridyl)-1,2, 4-triazole) (4), the density functional theory (DFT) method at the B3LYP level was used to optimize the geometrical structures in the ground and excited state. The absorption and emission properties of the dichloromethane solution were predicted at the time-dependent density functional theory (TD-DFT, B3LYP) level associated with the PCM solvent effect model, the transitions characters of them were assigned. Important correlations between substituent effects and emission spectra and the quantum yield have been obtained by comparing and analyzing the calculated results.     

Benzyne-mediated rearrangement of 3-(2-pyridyl)-1,2,4-triazines into 10-(1H-1,2,3-triazol-1-yl)pyrido[1,2-a]indoles

The reaction between 5-R-6-R¹-3-(2-pyridyl)-1,2,4-triazines and benzyne generated in situ in toluene under reflux results in the formation of 10-(1H-1,2,3-triazol-1-yl)pyrido[1,2-a]indoles 3 in up to 60% yields instead of the expected 3-R-4-R¹-1-(2-pyridyl)isoquinolines 2. The crystal structure of product 3c and the proposed mechanism for the formation of 3 are reported.     

3-(4-吡啶基)-4-(6-取代色酮-3-基-亚甲氨基)-5-芳氨基-1,2,4-三唑的合成

N-芳基-N'-[(4-吡啶基)羰基]氨基硫脲用85%的水合肼环化, 得到3-(4-吡啶基)-4-氨基-5-芳氨基-1,2,4-三唑(2a～2c). 然后再与3-甲酰基色酮(3a～3d)反应, 制备得到了一系列新化合物: 3-(4-吡啶基)-4-(6-取代色酮-3-基亚甲氨基)-5-芳氨基-1,2,4-三唑(4a～4c, 5a～5c, 6a～6c, 7a～7c). 化合物的结构经元素分析, IR, ¹H NMR和MS确证.     

Kinetic and mechanistic studies on the oxidation of hydroxylamine, semicarbazide, and thiosemicarbazide by iron(III) in the presence of triazines

In the presence of 3-(2-pyridyl)-5,6-bis(4-phenyl-sulphonicacid)-1,2,4-triazine disodium salt (PDTS), 3-(4-(4-phenylsulphonic-acid)-2-pyridyl)-5,6-bis(4-phenylsulphonic-acid)-1,2,4-triazine trisodium salt (PPDTS), or 2,4-bis(5,6-bis(4-phenylsulphonic-acid)-1,2,4-triazin-3-yl)pyridine tetra sodium salt (BDTPS), iron(III) oxidizes hydroxylamine to nitrogen gas, semicarbazide to CO₂ and NH₃ and thiosemicarbazide to a disulfide. The corresponding iron product is the 1:3 complex of iron(II) and PDTS, PPDTS, or BDTPS. The kinetics of these reactions was studied by monitoring the iron(II) product by conventional spectrophotometry. The reaction is first order in iron(III). Kinetic evidence was obtained for the formation of 1:1:2 ternary complexes of iron(III), substrate, and sulfonated triazine. Evidence for the ternary intermediate complexes was obtained by ion-exchange studies using ⁵⁹Fe-labeled iron(III) solutions. The dissociation of the ternary complex is identified as the rate-determining step.     

Reactions of 2-chloro-2-(4-pyridyl)propane with nucleophiles. Substitution on tertiary carbon

The reaction of 2-chloro-2-(4-pyridyl)propane ( 2 ) with lithium 2-propanenitronate affords the C-alkylation product 2-nitro-3-(4-pyridyl)-2,3-dimethylbutane ( 3 ), the Michael-adduct 2-nitro-2-methyl-4-(4-pyridyl)pentane ( 4 ), 4-isopropenylpyridine ( 5 ) and 2-(4-pyridyl)-2-propanol ( 6 ). Of these four products, only the formation of 3 is suppressed when the reaction is performed in the presence of radical inhibitors. The reaction of compound 2 with sodium azide gives the tertiary substitution product 2-azido-2-(4-pyridyl)propane ( 8 ). The reaction is not influenced by radical inhibitors. This is also the case in the reaction of 2 with sodium benzenethiolate, which affords 2-mercaptophenyl-2-(4-pyridyl)propane ( 9 ) and 1-mercaptophenyl-2-(4-pyridyl)propane ( 10 ). Compound 5 , the product of an E₂-type elimination is also formed in the azide and thiolate reactions. A Michael type addition of sodium benzenethiolate to 5 explains the formation of 10 . Similarly, generation of 5 in reactions of 2 with sodium methanethiolate and sodium cyanide accounts for the formation of 1-mercaptomethyl-2-(4-pyridyl)propane ( 11 ) and 3-(4-pridyl)butanenitrile ( 12 ), respectively.     

Syntheses,crystal structures and antibacterial activities of two new Mn(II) complexes based on triaryltriazoles

Two new Mn(II) complexes, trans-[Mn(L1-L2)₂(NCS)₂] (1–2) with triaryltriazole (1, L1 = 3-(p-bromophenyl)-4-phenyl-5-(2-pyridyl)-1,2,4-triazole; 2, L2 = 3,4-bis(p-methylphenyl)-5-(2-pyridyl)-1,2,4-triazole), have been synthesized and structurally characterized by elemental analysis, FT-IR, ESI-MS, and single-crystal X-ray crystallography. Crystallographic studies revealed that both 1 and 2 contain a distorted octahedral [MnN₆] core with two trans-disposed NCS^? ions. The L1 ligand, 1 and 2, together with four known homologous Mn(II) complexes, trans-[Mn(L3-L6)₂(NCS)₂] (3–6) (3, L3 = 3-(p-methoxyphenyl)-4-(p-chlorophenyl)-5-(2-pyridyl)-1,2,4-triazole; 4, L4 = 3-(p-methoxyphenyl)-4-(p-bromophenyl)-5-(2-pyridyl)-1,2,4-triazole; 5, L5 = 3-(p-chlorophenyl)-4-(p-methylphenyl)-5-(2-pyridyl)-1,2,4-triazole; 6, L6 = 3,5-bis(2-pyridyl)-4-(p-methylphenyl)-1,2,4-triazole), were tested in vitro for their antibacterial activities against two Gram-positive bacterial strains and two Gram-negative bacterial strains by the MTT method. The results indicate that 1 exhibited better activity than Penicillin and Kanamycin against Pseudomonas aeruginosa and also better than its free L1 ligand.     

Syntheses,crystal structures,and spectral properties of Mn(II) and Co(II) complexes with 3-(p-chlorophenyl)- 4-(p-methylphenyl)-5-(2-pyridyl)-1,2,4-triazole

Two new complexes, trans-[MnL₂(NCS)₂] (1) and trans-[CoL₂(H₂O)(EtOH)](ClO₄)₂?·?H₂O (2) with asymmetrical triaryltriazole ligands [L?=?3-(p-chlorophenyl)-4-(p-methylphenyl)-5-(2-pyridyl)-1,2,4-triazole], have been synthesized and characterized by elemental analysis, FT-IR, ESI-MS, and single-crystal X-ray diffraction. In the complexes each L adopts a chelating bidentate mode via the nitrogen of pyridyl and triazole. Both complexes have a similar distorted octahedral core with two NCS^? ions in the trans position in 1, while one H₂O and one EtOH are present in the axial sites in 2.     

Kinetics of Dissociation of tris-{3-(2-pyridyl)-5,6-bis(2-furyl)-1,2,4-triazine}iron(II)

The kinetics of base hydrolysis of the low-spin iron(II)-diimine complex [Fe(fertri)₃]²⁺, where fertri=3-(2-pyridyl)-5,6-bis(2-furyl)-1,2,4-triazine, as a function of hydroxide concentration, solvent composition (water; aqueous MeOH), and pressure are reported. Rate constants are also reported for dissociation of the [Fe(fertri)₃]²⁺ cation in 50–64% MeOH, determined from replacement of the fertri ligands by 1,10-phenanthroline. The reactivity of this fertri complex is compared with reactivities of a selection of other iron(II)-diimine complexes and, where possible, their ligand-sulfonated derivatives. The activation volume for base hydrolysis of [Fe(fertri)₃]²⁺ is +10.7 cm³ mol⁻¹, in 40% MeOH.     

1D & 2D Supramolecular assemblies dominated by crystal structure of Pb(II) oxoanion ( and ) complexes with 3-(2-pyridyl)-5,6-diphenyl-1,2,4-triazine (PDPT)

The two lead(II) complexes, [Pb(PDPT)(NO₃)₂] _n and [Pb(PDPT)₂(ClO₄)₂EtOH]·CH₃OH, PDPT?=?3-(2-pyridyl)-5,6-diphenyl-1,2,4-triazine, have been synthesized and characterized. 1D & 2D supramolecular assemblies of these compounds in the solid state are discussed via covalent and noncovalent donor?···?acceptor interactions.     

Synthesis of pyridyloxadiazoles 1. Characterization and thermal rearrangement of an unexpected 1,2,4-oxadiazol-5(4H)one

The synthesis of pyridyloxadiazoles by the reaction of acid chlorides with 5-(2-pyrklyl)-tetrazole or 2-pyridineamidoxime was studied. Reaction of 2-pyridineamidoxime with N,N-dimethylcarbamyl chloride produced 3-(2-pyridyl)-4-N,N-dimethylaminocarbony 1-1,2,4-oxadi-azol-5(4H)one instead of the expected oxadiazole. The oxadiazolone underwent thermal rearrangement with expulsion of carbon dioxide to yield the desired 3-(2-pyridyl)-5-N,N-dimethylamino-1,2,4-oxadiazole.     

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...     

Palladium complex of 6-(2-hydroxy-5-methylphenyl)-3-(pyridin-2-yl)-1,2,4-triazin-5(2<Emphasis Type="Italic">H</Emphasis>)-one: Synthesis,structure, and catalytic activity

Palladium(II) complex with 6-(2-hydroxy-5-methylphenyl)-3-(pyridin-2-yl)-1,2,4-triazin-5(2H)-one was synthesized for the first time. The ligand was prepared from 3-(pyridin-2-yl)-1,2,4-triazin-5(2H)-one and 4-methylphenol via nucleophilic substitution of hydrogen (S_N^H reaction). The complex was readily soluble in basic medium, and it effectively catalyzed Mizoroki-Heck reaction.     

Spin crossover in iron(II) complexes of 3,5-di(2-pyridyl)-1,2,4-triazoles and 3,5-di(2-pyridyl)-1,2,4-triazolates

The iron coordination chemistry of 3,5-di(2-pyridyl)-1,2,4-triazoles and 3,5-di(2-pyridyl)-1,2,4-triazolates is reviewed. This includes both mononuclear and dinuclear complexes, and both iron(II) and iron(III) oxidation states. The main focus is on the synthesis, structure and magnetic properties of these complexes.     

Synthesis of the Ethyl Esters of 4-(3-Pyridyl)- and 4-(4-Pyridyl)-2-oxobutenoic Acids

We have developed a method for the synthesis of ethyl 4-(3-pyridyl)- and 4-(4-pyridyl)-2-oxobutenoates by condensation of 3-pyridinecarbaldehyde and 4-pyridinecarbaldehyde monohydrate respectively with ethyl pyruvate, esterifiction of the target acids, and hydrolysis of the corresponding ethyl ester ketals in the presence of FeCl₃·6H₂O.     

Solid Phase Luminescence and Thermal Transformations of Palladium(II) Complexes with 3-(2-Pyridyl)-1,2,4-Triazoles

Theoretical and Experimental Chemistry - The thermal behavior and luminescent properties of palladium(II) Pd(LR)2 complexes with 3-(2-pyridyl)-5-R-1,2,4-triazoles (LR , where R = H, Ph, Me) in...     

1-( p -Fluorophenyl)-2-(2′-pyridyl)ethanol and 1-( p -fluorophenyl)-2-(2′-pyridyl)ethene obtained from the condensation reaction of 2-picoline and p -fluorophenylaldehyde under catalyst-and solvent-free conditions

The novel intermediate 1-(p-fluorophenyl)-2-(2′-pyridyl)ethanol or 2-[2′-(1-hydroxy-1-(p-fluorophenyl)ethyl]pyridine and the corresponding novel dehydration compound 1-(p-fluorophenyl)-2-(2′-pyridyl)ethene or 2-[p-fluorophenylvinyl]pyridine were obtained from the condensation reaction of p-fluorophenylaldehyde and 2-picoline under catalyst-and solvent-free conditions. The intermediate 1-(p-fluorophenyl)-2-(2′-pyridyl)ethanol was obtained at 42 h reaction time and temperature of 120°C, respectively. ¹H-NMR, IR spectroscopic data of the 1-(p-fluorophenyl)-2-(2-pyridyl)ethanol clearly showed the presence of the-CH₂-CHOH-group. The compound was obtained as a white powder with m.p. 121–122°C and a yield of 8%. For 1-(p-fluorophenyl)-2-(2-pyridyl)ethene, the reaction conditions were similar, but the reaction temperature was increased to yield the double bond in the 1-(p-fluorophenyl)-2-(2′-pyridyl)ethene. At the reaction temperature of 140°C, the compound was a slightly brown powder with a m.p. of 78°C and yield of 18%. ¹H-NMR, IR spectroscopic data for the 1-(p-fluorophenyl)-2-(2′-pyridyl)ethene showed the presence of a double bond in trans configuration (-CH=CH-), characteristic of a styrylpyridine.     

3-(3-吡啶基)-4-氨基-5-芳胺基-1,2,4-三唑的合成与表征

以烟酸与芳胺为基本原料，经多步反应，制得1－烟酰基－4－芳基氨基硫脲；后者在水合肼存在下关环，合成了一系列新化合物3－（3－吡啶基）－4－氨基－5－芳胺基－1，2，4－三唑。化合物结构经元素分析、IR，^1H NMR,^13C NMR确证。     

Cobalt(II) coordination polymers built on isomeric dipyridyl triazole ligands with pyromellitic acid: Synthesis, characterization and their effects on the thermal decomposition of ammonium perchlorate

Three new cobalt(Ⅱ) coordination compounds,[Co(3,3’-Hbpt)2(H2pm)(H2O)2]·2H2O(1),[Co(4,4’-Hbpt)(pm)0.5(H2O)]·3H2O (2) and [Co(3,4’-Hbpt)(pm) 0.5 (H2O)3]·2H2O(3)(3,3’-Hbpt=3,5-bis(3-pyridyl)-1H-1,2,4-triazole;4,4’-bpt=3,5-bis(4-pyridyl)1H-1,2,4-triazole,3,4’-Hbpt=3-(3-pyridyl)-5-(4’-pyridyl)-1H-1,2,4-triazole and H4pm=pyromellitic acid) have been synthesized by hydrothermal reactions.Single-crystal X-ray diffraction reveals that compound 1 has a one-dimensional (1D) chain network,2 exhibits a four-connected three-dimensional (3D) structure with 1D open channels encapsulated by water molecules,while 3 displays a regular two-dimensional (2D) architecture connected through 1D metal helical chains.In addition,the efficacy of compounds 1-3 as additives to promote the thermal decomposition of ammonium perchlorate (AP) is explored by differential scanning calorimetry (DSC).