Synthesis and Antimicrobial Activity of Novel Thiazole Substituted Pyrazole Derivatives

A series of new 1‐[4‐(2,3,4‐substituted‐phenyl) thiazol‐2‐yl]‐3‐(2,3,4‐substituted‐phenyl)‐1H‐pyrazole‐4‐carbaldehyde ( 4a , 4b , 4c , 4d , 4e , 4f , 4g , 4h , 4i , 4j , 4k , 4l , 4m ), 4‐[4‐(4‐substituted‐phenyl) thiazol‐2‐yl]‐3‐(4‐substituted‐phenyl)‐1‐phenyl‐1H‐pyrazole ( 7a , 7b , 7c , 7d , 7e , 7f , 7g , 7h , 7i ), 4‐[4‐(4‐substituted phenyl)thiazol‐2‐yl]‐1‐phenyl‐1H‐pyrazol‐3‐amine ( 10a , 10b , 10c , 10d , 10e , 10f , 10g ) have been synthesized by using Vilsmeier Haack formylation and Hantzsch reaction in high yield. All the synthesized compounds were tested qualitative (Zone of inhibition) and quantitative antimicrobial activities (MIC). Most of the synthesized compounds showed potent antimicrobial activity against gram positive and gram negative bacteria as well as fungi species.     

An Efficient One‐Pot Synthesis of Highly Substituted Pyridone Derivatives and Their Antimicrobial and Antifungal Activity

A series of carboxamide and cyano functionalized pyridone derivatives 4a – q have been synthesized via one‐pot synthesis of various aldehydes 1a – q , acetoacetanilide 2 , and cyanoacetamide 3 . The reaction was simple and afforded pyridone derivatives in good yield, 89 to 93%. The novel pyridone derivatives were achieved by Hantzch one‐pot synthesis. Moreover, the synthesized compounds were screened against Gram‐positive and Gram‐negative bacteria and fungi for their activity. Among them, compound 4c shows highest inhibition at 4.25 mm against Staphylococcus aureus and 3.75 mm against Escherichia coli Gram‐positive and Gram‐negative bacteria, respectively.     

Synthesis and Antimicrobial Activity of Some Novel Quinoline,Chromene, Pyrazole Derivatives Bearing Triazolopyrimidine Moiety

7‐Amino‐3‐phenyl‐[1,2,4]triazolo [4,3‐a] pyrimidin‐5(1H )‐one ( 5 ) was utilized as key intermediate for the synthesis of some new, quinolines 9 , 10 , 11 , 12 , 13 , 14 and 18 , 19 , 20 , acrylonitrile 25 and 28 , coumarin 26 , and pyrazoles 31 , 32 , 33 , 34 incorporating triazolopyrimidines. The structures of the newly synthesized compounds were confirmed by elemental analysis, IR, ¹H NMR, and mass spectral data. Representative compounds of the synthesized products were tested and evaluated as antimicrobial. Compounds 25 , 28 , 31 , 32 , 33 , and 34 are the most promising.     

Synthesis and Antimicrobial Activity of Some Novel Hydrazide,Pyrazole, Triazine,Isoxazole, and Pyrimidine Derivatives

In continuation of our efforts to find a new class of antimicrobial agents, a series of pyrazole, 1,2,4‐triazine, isoxazole, pyrimidine, and other related products containing a hydrazide moiety were prepared via the reaction of 2‐cyano‐N‐((2‐methoxynaphthalen‐1‐yl)methylene) acetohydrazide ( 1 ) with appropriate chemical reagents. These compounds were evaluated for their antimicrobial activities, and also their minimum inhibitory concentration against most of test organisms was performed. Among the tested compounds 4 , 5 , 6 , and 16 displayed excellent antimicrobial activity. All the synthesized products were confirmed by elemental analysis, IR, ¹H‐NMR, ¹³C‐NMR, and mass spectral data.     

Design,Synthesis, Safener Activity,and Molecular Docking of Novel N‐Substituted Thiazide/Thiazole Derivatives

A series of novel substituted thiazide/thiazole compounds were designed by splicing active groups and bioisosterism. The title compounds were synthesized via the cyclization, acylation, and carbamylation. All the compounds were characterized by IR, ¹H‐NMR, ¹³C‐NMR, and HRMS. The single crystal of compound 3f was determined by X‐ray crystallography. The biological activity tests indicated that all the compounds showed potential safener activity to the herbicide chlorsulfuron, in which compound 3e showed almost the same level as the commercialized safener AD‐67. The molecular docking results were in good agreement with the bioassay results, which demonstrated that compound 3e might compete with chlorsulfuron in the acetolactate synthase active site, causing the herbicide ineffective in maize.     

Synthesis,Reactions and Antimicrobial Activity of Some New Indolyl‐1,3,4‐Oxadiazole,Triazole and Pyrazole Derivatives

Indole‐3‐carboxylic acid hydrazide 3 was prepared and was treated with aromatic aldehydes in ethanol to give the corresponding hydrazone derivatives 4–7 in good yields. The indole carbohydrazide was incorporated into the 3‐indolyloxadiazoles 8–11 and 18 , 3‐indolyltriazoles 13–17 and 35 , 3‐indolylpyrazole derivatives 19–23 and carbamate derivatives 26–27 . Furthermore, interaction of the carboazide 24 with hydrazine hydrate in refluxing toluene afforded the corresponding semicarbazide derivative 30 . The thiadiazine derivative 34 was also prepared. Some of these compounds were screened in vitro for their antibacterial and antifungal activity.     

Ultrasound Assisted Synthesis of Some Novel Bis‐Pyridazine Derivatives

Bis‐enaminone 3 was coupled with aryldiazonium chlorides 4a , 4b to afford the bis‐arylhydrazonopropanals 6a , 6b . Compounds 6a , 6b could be utilized for the synthesis of a variety of bis‐(dimethyl 2,3‐dihydropyridazine‐3,4‐dicarboxylate), bis‐(pyridazin‐3(2H)‐one), bis‐(2,3‐dihydropyridazine‐4‐carbonitrile) and bis‐(3‐imino‐2,3‐dihydropyridazine) derivatives, under ultrasonic irradiation. A comparative study of aforementioned reactions was carried out under conventional method as well as under ultrasonic irradiation conditions.     

新型含噻唑和吡唑环的醛腙类化合物的合成

1-苯基-3-甲基-吡唑-4.-甲醛与氨基硫脲缩合制得醛缩氨基硫脲(Ⅱf～Ⅱh);Ⅱ与α-溴代芳基乙酮反应合成了15个新型的含噻唑和吡唑环的醛腙类化合物(2a～4e),其结构经1 H NMR,IR和元素分析表征.X-射线单晶衍射测试结果表明,2c属斜方晶系,空间群Pbca,晶胞参数a=18.607 9(3)A,b=15...     

取代苯基吡唑类化合物的合成及其除草活性

以1′-(4-氯-2-氟-5-甲基苯基)-4′,4′,4′-三氟-1,3-丁二酮为原料,合成了一系列具有取代苯基吡唑结构的新化合物.化合物结构经¹HNMR,IR,CIMS和元素分析确认.初步生物活性测试表明,所合成的化合物对阔叶杂草具有较高的活性.     

One Pot Regioselective Synthesis and Antimicrobial Studies of Some Novel Indazolyl–Thiazole Derivatives

2‐Benzylidene‐1‐tetralones, obtained via Claisen condensation of 1‐tetralones with aromatic aldehydes, in one pot condensation with thiosemicarbazide/semicarbazide and α‐haloketones in the presence of trifluoroethanol and conc. HCl gives rise to a series of new substituted‐3,3a,4,5‐tetrahydro‐2H‐benzo[g]indazol‐2yl‐thiazoles. The condensation was also carried out in two steps, and the intermediates 3‐substituted‐3,3a,4,5‐tetrahydro‐2H‐benzo[g]indazole‐2‐carbothioamides/carboxamides, obtained in the first step by the reaction of 2‐bezylidene‐1‐tetralones with thiosemicarbazide/semicarbazide, on reaction with α‐haloketones gives rise to indazolyl–thiazoles. A detailed X‐ray diffractometry of intermediate (3aR)‐3‐phenyl‐3,3a,4,5‐tetrahydro‐2H‐benzo[g]indazole‐2‐carbothioamide were carried out to establish its crystal structure. Further, density functional theory studies on (3aR)‐3‐phenyl‐3,3a,4,5‐tetrahydro‐2H‐benzo[g]indazole‐2‐carbothioamide and its regioisomer were carried out. There is good correlation between the theoretical and experimental spectral data. The antibacterial and antifungal activities of the selected compounds were examined, and some are found to exhibit excellent activities.     

Ultrasound‐assisted Synthesis of Novel Pyrazole and Pyrimidine Derivatives as Antimicrobial Agents

Herein, we report a convenient and facile methodology for the synthesis of new series of pyrazole and pyrimidine derivatives 2a – f and 3a – f under ultrasound irradiation. Pyrazole and pyrimidine derivatives have been synthesized in better yields and shorter reaction times compared with the conventional method. The chemical structures of all the synthesized compounds were elucidated by their IR, ¹H NMR, ¹³C NMR, MS, and elemental analysis. Further, the target compounds were screened for their antimicrobial activity against four bacteria (Staphylococcus aureus, Bacillus subtilis, Escherichia coli, Pseudomonas aeruginosa) and two fungi (Candida albicans, Aspergillus niger). In particular, compounds 2a , 2d , 2e , 3a , 3e , and 3f exhibited potent antimicrobial activity.     

Synthesis,Antimicrobial Activity and Molecular Docking Study of Thiazole Derivatives

The reaction of 4‐thiochromane thiocarbohydrazone with a series of hydrazonoyl halides in dioxane in the presence of triethylamine afforded novel thiochromane derivatives incorporating 1,3‐thiazole moiety. The structure of the latter compounds was established by elemental analysis and spectral technique and by their chemical transformation. Moreover, the antimicrobial activity of the newly synthesized compounds was screened and the results showed that some compounds have higher activity than the applied fungicide and bactericide. The antimicrobial activity of the most active compounds was interpreted by molecular docking study.     

Synthesis of Some Pyrazole,Thiazole, Pyridine,and 1,3,4‐Thiadiazole Derivatives Incorporating 2‐Thiazolyl Moiety

Reaction of N‐(5‐acetyl‐4‐methylthiazol‐2‐yl)‐2‐cyanoacetamide 2 with hydrazonoyl chlorides ( 3a,b ) yielded the corresponding aminopyrazole derivatives ( 5a,b ), respectively. Reaction of 2 with α,β‐benzylidenemalononitrile derivatives 8a,b and 13a,b afforded the corresponding pyridine derivatives 12a,b and 17a,b , respectively. Treatment of 2 with phenylisothiocyanate in dimethylformamide/KOH followed by the addition of ethyl chloroacetate and the appropriate hydrazonoyl chlorides 3a,b and 27 gave the corresponding 1,3‐thiazole 21 and 1,2,4‐thiadiazole derivatives 24a,b and 30 , respectively. The newly synthesized compounds were confirmed from their elemental analyses and spectral data.     

Synthesis of Some New Triphenylphosphanylidenes,Alkylphosphonates, and Heterocycles of Pyrazole Derivatives and Their Antimicrobial Activity

Abstract

The reaction of 5(4H)-pyrazolone with phosphorus ylides afforded new triphenylphosphanylidene alkanone derivatives. Moreover, its benzylidene derivative reacted with Wittig–Horner reagents to give the corresponding dialkoxyphosphoryl, alkyl phosphonate, and heterocyclic products. Treatment of pyrazole-4-carbaldehyde with Wittig–Horner reagents and trialkyl phosphites gave the respective alkyl phosphonate adducts. Mechanisms accounting for the formation of the new products are discussed. The biological activity of some of the newly synthesized compounds was also examined.     

Synthesis and Insecticidal Activity of Novel Thiazole Acrylonitrile Derivatives

A series of novel thiazole acrylonitrile derivatives was designed and synthesized utilizing NC‐510 as a precursor. Their structures were characterized by NMR spectrometry, MS, and elemental analysis. The results of bioassay indicated that some of these title compounds exhibited 100% mortality at 50 mg/L against Aphis fabae . In particular, the compound 11c displayed the best activity: Its LC₅₀ value achieved 1.45 mg/L, and its insecticidal potency is comparable with that of NC‐510.     

Synthesis,Characterization, and Antibacterial Activity of Some Novel Substituted Imidazole Derivatives via One‐pot Three‐Component

A simple and highly efficient one‐pot, three‐component synthesis of novel substituted imidazole derivatives has been reported by the reaction of 3‐(2‐bromoacetyl)‐2H‐chromen‐2‐one, ammonium thiocyanate, and phenacyl aniline in the presence of acetic acid as a solvent under reflux condition with good yields. The structures of newly synthesized compounds were characterized by their analytical and spectral data. One of these compounds 4a showed good antibacterial activity against Escherichia coli gram‐negative strains.     

Synthesis,Antimicrobial Activity and Molecular Docking Studies of 1,3‐Thiazole Derivatives Incorporating Adamantanyl Moiety

Synthesis, characterization and investigation of antimicrobial activity of 11 novel adamantanyl‐thiazoles are presented. Their structures were determined using ¹H and ¹³C NMR, EI(+)‐MS, HRMS, and elemental analyses. Among the derivatives, compound 3c showed very strong activity, especially against Candida albicans ATCC 10231 and Candida parapsilosis ATCC 22019 with minimal inhibitory concentration (MIC) values ranging from 1.95 to 7.81 µg/ml. Compounds 3a and 3b showed good antifungal activity. Among the examined compounds, the widest spectrum of antibacterial activity possessed 3f that showed good activity, especially against Staphylococcus epidermidis ATCC 12228, Micrococcus luteus ATCC 10240, Bacillus subtilis ATCC 6633 with MIC values ranging from 31.25 to 62.5 µg/ml. Molecular docking studies of all compounds on the active sites of microbial enzymes indicated possible targets sterol 14α‐demethylase, secreted aspartic proteinase (SAP), N‐myristoyltransferase (NMT), and topoisomerase II. Thiazoles 3a , 3b , 3c , 3d , 3e , 3f , 3g , 3h , 3i , 3j , 3k showed more favorable affinity to SAP and NMT than the native ligand.     

Synthesis,Structural Characterization,and Biological Evaluation of Novel Substituted 1,3‐Thiazole Derivatives Containing Schiff Bases

In this study, thiazole derivatives containing Schiff bases ( 7a , 7b , 7c , 7d , 7e , 7f , 8a , 8b , 8c , 8d , 8e , 8f , 9a , 9b , 9c , 9d , 9e , 9f ) were synthesized in moderate to high yields (49–94%) using the Hantzsch reaction with thiosemicarbazone derivatives ( 5a , 5b , 5c ) and 2‐bromo‐1‐phenylethanone derivatives ( 6a , 6b , 6c , 6d , 6e , 6f ). The structures of synthesized compounds were elucidated by IR, ¹H NMR, ¹³C NMR, elemental analyses, mass spectroscopy and X‐ray diffraction analysis techniques. Moreover, the synthesized compounds were tested for their in vitro antifungal activity and most of them exhibited moderate to good activity against Fusariumoxysporumf.sp. lycopersici.      

Synthesis and Bioactivity of Novel Bis‐heterocyclic Compounds Containing Pyrazole and Oxadiazoline

Nucleophilic addition of the starting material 3‐aryl‐1‐phenyl‐4‐formylpyrazoles ( 1～3 ) and 4‐substituted aryloxyacetyl hydrazine ( 4a～4e ) afford hydrazone compounds containg pyrazolyl ( 5a～5e, 6a～6e, 7a～7e ) in the ethanol. These adducts were refluxed in Ac₂O and furnished a series of novel bis‐hetero‐cyclic compounds. ( 8a～8e, 9a～9e, 10a～10e ) via cyclic reaction. The structures of all newly synthesized compounds were established by IR, ¹H NMR, MS and elemental analysis. New compounds conducted preliminary tests of antibacterial activities about Fusarium oxyaporium, Verticillium dahliae, Rhizoctonia solani, Pychium aphanidermatum, Alternaria solani, Sclerotinia sclerotiorum. The results showed that the inhibiting rate of the bis‐heterocyclic compounds ( 8a～8e, 9a～9e, 10a～10e ) was higher than the pyrazolyl hydrazones ( 5a～5e, 6a～6e, 7a～7e ) obviously.