(3+2) Annulation of Amidinothioureas with Binucleophile: Synthesis and Antimicrobial Activity of 3‐Phenylamino‐5‐aryl/alkyl‐1,2,4‐oxadiazole Derivatives

Herein, we report an efficient method for preparation of 3‐phenylamino‐5‐aryl/alkyl‐1,2,4‐oxadiazole by (3+2) annulation of amidinothioureas with binucleophilic hydroxylamine hydrochloride in the presence of mercury (II) chloride. Desired 3‐phenylamino‐5‐aryl/alkyl‐1,2,4‐oxadiazole was prepared in good to moderate yields. On the basis of the literature precedence, the mechanism for the formation of 3‐phenylamino‐5‐aryl/alkyl‐1,2,4‐oxadiazole is proposed. The synthesized compounds were tested for their antimicrobial activity and showed promising inhibition of Gram‐positive bacteria (Staphylococcus aureus) and fungi (Candida albicans).     

Coordination Compounds of Palladium(II) and 4‐Amino‐1,2,4‐triazole

Mononuclear coordination compounds of the type [Pd(NH₂trz)₄]²⁺ with the counterions chloride, nitrate, trifluoromethanesulfonate, and methanesulfonate were synthesized and their structures identified with single‐crystal X‐ray diffraction. In case of the synthesis with methanesulfonate as the counterion the dominant product was of the generic formula [Pd₂(NH₂trz)₃](CH₃SO₃)₄, and the complex [Pd(NH₂trz)₄](CH₃SO₃)₂ only emerged as a byproduct. While the structure of the byproduct could be analyzed by single‐crystal X‐ray diffraction, suitable crystals of the main product [Pd₂(NH₂trz)₃](CH₃SO₃)₄ could not be obtained. However, stoichiometry implies a polynuclear nature with NH₂trz present in the rare μ₃‐η¹:η¹:η¹ coordination type, i.e. with NH₂trz molecules coordinating to three palladium atoms. Accordingly, identification of solids by single‐crystal analysis alone can be misleading in particular with NH₂trz as a ligand due to its versatile coordination behavior. Finally, analysis by differential scanning calorimetry (DSC) revealed that the complexes were thermally stable (the onset of decomposition well above 100 °C), with [Pd₂(NH₂trz)₃](CH₃SO₃)₄ being the most stable compound (onset of decomposition at 204 °C).     

Synthesis and Antimicrobial Evaluation of Novel Derivatives of Semicarbazide and 1,2,4‐triazole

Reaction of phenoxyacetic acid hydrazide with isocyanate was used to the synthesis of new semicarbazide derivatives. Cyclization of these compounds in a 2% aqueous solution of sodium hydroxide led to formation of 1,2,4‐triazole‐3‐one. The chemical structure of synthesized compounds was confirmed by elemental analysis and spectroscopic methods (¹H and ¹³C NMR). On the basis of the NMR, spectra were found that cyclic compounds 1,2,4‐triazole exist in the ‐one form. Moreover, all derivatives were examined for their in vitro activity against some species of bacteria. New compounds presented mild or moderate antimicrobial activity only against reference Gram‐positive bacteria. Two derivatives (one semicarbazide and one triazole) showed bactericidal or bacteriostatic activity.     

3-氨基-1H-1,2,4三唑类席夫碱的合成和生物活性

以醋酸为催化剂,用3-氨基-1H-1, 2, 4-三唑与取代苯甲醛反应合成了8个3-氨基-1H-1, 2, 4-三唑类席夫碱,化合物结构经1H NMR,IR和元素分析证实,并对其进行了生物活性测试,初步生物活性结果表明此类化合物具有良好的杀菌活性。     

3‐Amino‐1,2,4‐triazine

In the crystal structure of 3‐amino‐1,2,4‐triazine, C₃H₄N₄, the mol­ecules form hydrogen‐bonded chains that are almost parallel to the b axis (3.2°), and which are inclined to the a and c axes by ～21 and ～69°, respectively. The distortion of the 1,2,4‐triazine ring in the crystal is compared with gas‐phase ab initio molecular‐orbital calculations.     

Synthesis and Antimicrobial Activity of New 2,5‐Disubstituted 1,3,4‐Oxadiazoles and 1,2,4‐Triazoles and Their Sugar Derivatives

A series of new 2,5‐disubstituted‐1,3,4‐oxadiazole and 1,2,4‐triazole derivatives were synthesized by heterocyclization of acid hydrazide 1 and thiosemicarbazide derivative 2 . Furthermore, the acyclic C‐nucleoside analogs were prepared by cyclization of their corresponding sugar hydrazones by reaction with acetic anhydride. The antimicrobial activity of the prepared compounds was evaluated and some of the synthesized compounds revealed good activities against fungi.     

Zinc(II) and cadmium(II) chloride complexes with 4,4′‐bi‐1,2,4‐triazole

New coordination compounds with the 4,4′‐bi‐1,2,4‐triazole ligand (btr), namely tetraaqua‐2κ⁴O‐di‐μ₂‐4,4′‐bi‐1,2,4‐triazole‐1:2κ²N¹:N^1′;2:3κ²N¹:N^1′‐hexachlorido‐1κ³Cl,3κ³Cl‐trizinc(II), [Zn₃Cl₆(C₄H₄N₆)₂(H₂O)₄], (I), and poly[cadmium(II)‐μ₂‐4,4′‐bi‐1,2,4‐triazole‐κ²N¹:N²‐di‐μ₂‐chlorido], [CdCl₂(C₄H₄N₆)]_n, (II), reveal an unprecedented molecular zwitterionic structure for (I) and a polymeric two‐dimensional layer structure for (II). Differences between these products, which involve the formation of either charge‐separated chlorometallate/aquametal fragments or complementary organic and inorganic bridges, are attributable to the hardness–softness characters of the metal cations. In (I), two N¹,N^1′‐bidentate btr molecules connect one [Zn(H₂O)₄]²⁺ cation and two [ZnCl₃]⁻ anions into a linear trizinc motif (the Zn atom of the cation occupies a centre of inversion in an N₂O₄ coordination octahedron, whereas the Zn atom of the anion possesses a distorted tetrahedral Cl₃N environment). In (II), the distorted vertex‐sharing CdCl₄N₂ octahedra are linked into binuclear [Cd₂(μ₂‐Cl)(μ₂‐btr)₂]³⁺ fragments by unprecedented N¹:N²‐bidentate btr double bridges and bridging chloride ligands, while the additional chloride anions are also bridging, providing further propagation of the fragments into a two‐dimensional network [Cd—Cl = 2.5869 (2)–2.6248 (7) Å].     

Copper(II) and cadmium(II) isothiocyanate coordination polymers with 4,4′‐bi‐1,2,4‐triazole

The coordination polymers catena‐poly[[[(4,4′‐bi‐1,2,4‐triazole‐κN¹)bis(thiocyanato‐κN)copper(II)]‐μ‐4,4′‐bi‐1,2,4‐triazole‐κ²N¹:N^1′] dihydrate], {[Cu(NCS)₂(C₄H₄N₆)₂]·2H₂O}_n, (I), and poly[tetrakis(μ‐4,4′‐bi‐1,2,4‐triazole‐κ²N¹:N^1′)bis(μ‐thiocyanato‐κ²N:S)tetrakis(thiocyanato‐κN)tricadmium(II)], [Cd₃(NCS)₆(C₄H₄N₆)₄]_n, (II), exhibit chain and two‐dimensional layer structures, respectively. The differentiation of the Lewis acidic nature of Cu^II and Cd^II has an influence on the coordination modes of the triazole and thiocyanate ligands, leading to topologically different polymeric motifs. In (I), copper ions are linked by bitriazole N:N′‐bridges into zigzag chains and the tetragonal–pyramidal CuN₅ environment is composed of two thiocyanate N atoms and three triazole N atoms [basal Cu—N = 1.9530 (18)–2.0390 (14) Å and apical Cu—N = 2.2637 (15) Å]. The structure of (II) contains two types of crystallographically unique Cd^II atoms. One type lies on an inversion center in a distorted CdN₆ octahedral environment, with bitriazole ligands in the equatorial plane and terminal isothiocyanate N atoms in the axial positions. The other type lies on a general position and forms centrosymmetric binuclear [Cd₂(μ‐NCS‐κ²N:S)₂(NCS)₂] units (tetragonal–pyramidal CdN₄S coordination). N:N′‐Bridging bitriazole ligands link the Cd centers into a flat (4,4)‐network.     

Synthesis and Antimicrobial Activity of New Derivatives of 1,3,4‐Thiadiazoles and 1,2,4‐Triazoles with 5‐Nitroindazole as Support

The synthesis of new derivatives of 1,3,4‐thiadiazoles and 1,2,4‐triazoles was achieved using the 1,4‐disubstituted thiosemicarbazides as intermediaries.     

Synthesis and Antimicrobial Activity of 1,3,4‐Oxadiazole‐2(3H)‐thione and Azidomethanone Derivatives Based on Quinoline‐4‐carbohydrazide Derivatives

A new series compounds of quinoline derivatives were synthesized by reaction of 3‐(carboxymethyl)‐2‐arylquinoline‐4‐carboxylic acids 1a , 1b , 1c with different nucleophiles. The structures of the new compounds were elucidated on the basis of FTIR, ¹H‐NMR, ¹³C‐NMR spectral data, GC/MS, and chemical analysis. Investigation of antimicrobial activity of all new compounds was evaluated using a broth dilution technique in terms of minimal inhibitory concentration count against four pathogenic bacteria and two pathogenic fungi. Most of the new compounds were significantly active against bacteria and fungi.     

Synthesis and Antimicrobial Activity of N‐Aryl‐4‐(cyano/alkoxycarbonyl)‐5‐(pyridin‐3‐yl)‐1H/3H‐1,2,3‐triazole Derivatives

A convenient synthesis of a new series of N‐aryl‐5‐(pyridin‐3‐yl)‐1H/3H‐1,2,3‐triazole‐4‐carbonitriles and alkyl N‐aryl‐5‐(pyridin‐3‐yl)‐1H/3H‐1,2,3‐triazole‐4‐carboxylic acid esters is reported. The newly synthesized 5‐(pyridin‐3‐yl)‐1,2,3‐triazole derivatives are evaluated for their antibacterial and antifungal activity. Some of these triazole derivatives have exhibited moderate antimicrobial activity.     

Highly Efficient One‐Pot Three‐Component Synthesis and Antimicrobial Activity of 2‐Amino‐4H‐chromene Derivatives

A remarkably efficient three‐component reaction to synthesize 2‐amino‐4H‐chromenes derivatives from malononitrile, various aromatic aldehydes, and orcinol was described at room temperature in CH₂Cl₂ in the presence of catalytic amount of triethylamine. In a facile one‐pot procedure, excellent yields of products were achieved in less than 1 h. Some of the synthesized 2‐amino‐4H‐chromenes derivatives demonstrated potent antibacterial activities against Gram‐positive bacteria including Staphylococcus aureus and Bacillus anthracis, indicated by disk method, minimum inhibitory concentration, and minimum bactericidal concentration approaches. However, none of the tested compounds expressed any antibacterial activities against Enterococcus faecalis and Gram‐negative bacteria.     

Synthesis and Acaricidal Activity of Some New 1,2,4‐Triazine Derivatives

A new series of 1,2,4‐triazine derivatives were designed, synthesized, and identified on the basis of IR, ¹H‐NMR, ¹³C‐NMR, and EI‐MS spectral data. The potent acaricidal activity of 1,2,4‐triazine derivatives against eggs and adult female of Tetranychus urticae (Koch) was assessed compared with pyridaben under laboratory conditions. Structure acaricidal activity relationships of the promising 1,2,4‐triazine derivatives were analyzed for eggs and adult female; the nature and position of the substituents were important in demonstration of the activities.     

Synthesis of New Triazole and Oxadiazole Derivatives of Quinazolin‐4(3H)‐one and Their Antimicrobial Activity

A series of new triazole derivatives of quinazolin‐4(3H)‐one and new oxadiazole derivatives of quinazolin‐4(3H)‐one were synthesized. The newly synthesized compounds were characterized by IR, ¹H NMR, ¹³C NMR and mass spectral data. All the newly synthesized compounds were screened for antibacterial activity against Staphylococcus aureus, Bacillus subtilis (gram‐positive bacteria), Escherichia coli, Pseudomonas aeruginosa (gram‐negative bacteria), and antifungal activity was carried out against Candida albicans and Aspergillus niger.     

Synthesis and Antimicrobial Activity of Novel Hydrazone and 1,2,4-Triazole-3-thione Derivatives

Russian Journal of General Chemistry - Novel hydrazone and 1,2,4-triazole-3-thione derivatives were obtained via the reaction of...     

Synthesis and Biological Activity of Novel Furan/Thiophene and Piperazine‐Containing (Bis)1,2,4‐triazole Mannich Bases

Series of novel furan/thiophene and piperazine‐containing 1,2,4‐triazole Mannich bases and bis(1,2,4‐triazole) Mannich bases have been conveniently synthesized via Mannich reaction with triazole Schiff bases, various piperazine derivatives, and formaldehyde as intermediates in good yields. Their structures were characterized by melting points, ¹H NMR, ¹³C NMR, IR and elemental analysis. The preliminary bioassay showed that most compounds exhibited significant in vitro and in vivo fungicidal activity against several test plant fungi. Among 32 new compounds, the trifluoromethyl‐containing compounds showed superior activity than the methyl‐containing ones. Several compounds, such as F8 , F9 , F10 , G5 , H7 , H8 , I3 and I4 , were comparable with some commercial fungicides against different fungi during the present study and could be further structurally optimized. Meanwhile, several compounds showed good herbicidal activity against Brassica campestris at 100 µg/mL and KARI inhibitory activity at 200 µg/mL. However, compounds exhibited poor insecticidal activity against oriental armyworm at 200 µg/mL in the preliminary studies. The research results will provide useful information for the design and discovery of new agrochemicals with novel heterocyclic structures.     

Synthesis and Fungicidal Activity of (E)‐α‐(Methoxyimino)benzeneacetate Derivatives Containing 1,2,4‐Triazole Schiff Base Side Chain

To find new strobilurin analogs with high activity against resistant pathogens, twelve (E)‐α‐(methoxyimino)benzeneacetate derivatives containing 1,2,4‐triazole Schiff base side chain 3a , 3b , 3c , 3d , 3e , 3f , 3g , 3h , 3i , 3j , 3k , 3l were designed and synthesized. Their structures were confirmed by IR, ¹H‐NMR, EIMS, and elemental analyses. Bioassays indicated that most of the target compounds showed moderate to good fungicidal activities against Physalospora piricola Nose and Alternaria solani. For example, compounds 3d , 3e , and 3f possessed 99.5%, 100%, and 95.6% inhibition against Physalospora piricola Nose, whereas compounds 3d , 3f , and 3g exhibited 92%, 91%, and 92% inhibition against Alternaria solani at the concentration of 50 mg/L, respectively.