Bis-Thiourea Bearing Aryl and Amino Acids Side Chains and Their Antibacterial Activities

Abstract

A series of symmetrical 1,3-bis thiourea 1a–e and 1,4-bis thiourea derivatives 2a–e have been successfully synthesized from the reactions of amines with 3-acetylbenzoyl isothiocyanate and 4-acetylbenzoyl isothiocyanate, respectively. All the synthesized compounds were characterized by FT-IR spectroscopy and ¹H and ¹³C NMR spectroscopy. The compounds were screened for their antibacterial activity by turbidimetric method using gram-negative bacteria (E. coli ATCC 8739) using turbidimetric method. The newly synthesized bis-thiourea derivatives bearing aryl side chains showed good antibacterial activity against E. coli. The effect of the molecular structure of the synthesized compounds on the antibacterial activity is discussed.     

Synthesis,antimicrobial activity and QSAR studies of 2,5-disubstituted benzoxazoles

In this study, a new series of 2,5-disubstituted benzoxazoles was synthesized and their structures were elucidated by elemental analysis, MASS, ¹H-NMR, ¹³C-NMR and IR spectral data. Newly and previously synthesized 2,5-disubstituted benzoxazole derivatives were evaluated for antibacterial and antifungal activity against standard strains and their drug-resistant isolates. Microbiological results showed that the compounds presented a large spectrum of activity having MIC values of 250–7.8 µg mL^?1 against the tested microorganisms. Among the newly synthesized derivatives 3–22, compound 11 was the most active against Candida krusei out of all; however, it was one dilution less potent than standard drug fluconazole. In addition, all the new and previous compounds were more active than standard drugs ampicillin trihydrate and rifampicin against Pseudomonas aeruginosa and its gentamicin-resistant isolate. The 2D-QSAR (Quantitative Structure–Activity Relationship) analysis of a set of newly and previously synthesized benzoxazoles tested for growth inhibitory activity against methicillin-resistant Staphylococcus aureus (MRSA) was also performed by using multivariable regression analysis. The activity contributions for substituent effects of these compounds were determined from the correlation equation for predictions of the lead optimization.     

Synthesis,antitubercular evaluation and molecular docking studies of phthalimide bearing 1,2,3-triazoles

In a search for safer and potent antitubercular agents, here a library of newly substituted dioxoisoindolinylmethyl-triazolyl-N-phenylacetamide derivatives (5a–l) has been synthesized via click chemistry approach. All synthesized compounds were evaluated for their antitubercular activity against Mycobacterium tuberculosis H₃₇Rv (MTB). Among the screened compounds, 5d, 5e, 5h, and 5l showed good antitubercular activity. The compounds 5d and 5l have shown very effective antitubercular activity against Mycobacterium tuberculosis H₃₇Rv (MTB) with MIC 12.5?μg/mL. All the newly synthesized compounds were thoroughly characterized by ¹H NMR, ¹³C NMR, and HRMS spectral data. We further performed exploratory docking studies on the crystal structure of Mycobacterium tuberculosis enoyl reductase to demonstrate the mechanism of antitubercular activity.     

Design,synthesis and biological evaluation of novel N1,N8-bis(((4-((5-aryl-1,3,4-oxadiazol-2-yl)methoxy)phenyl)amino)oxy)-1-naphthamide derivatives

A new series of 1,8-bis(4-((5-phenyl-1,3,4-oxadiazol-2-yl) methoxy)-substituted aryl) naphthalene-1,8-dicarboxamide derivatives (6a–j) were synthesized in the presence of POCl₃ and obtained good yields. All the synthesized novel compounds were characterized by IR, ¹H NMR, ¹³C NMR, HRMS spectroscopic data and elemental analysis. All the synthesized compounds evaluated for their antibacterial and antifungal activities. The antibacterial activity screened against Gram-positive bacteria Staphylococcus aureus and Gram-negative bacteria Escherichia coli and used standard reference drug ciprofloxacin. The antifungal activity screened against two pathogenic fungal strains Aspergillus niger and Candida albicans used a reference standard drug Voriconazole. All these compounds (6a–j) demonstrate good antibacterial and antifungal activity. Among them, compounds 6h and 6c show highest antibacterial and antifungal activity.     

Organotin(IV) complexes with 2-hydroxynaphthaldehyde-N(4)-ethylthiosemicarbazone: Synthesis,characterization, and in vitro antibacterial activity

Four new organotin(IV) complexes with 2-hydroxynaphthaldehyde-N(4)-ethylthiosemicarbazone [(H₂DNET), (1)] of the type [MeSnCl(DNET] (2), [BuSnCl(DNET)] (3), [PhSnCl(DNET)] (4), and [Ph₂Sn(DNET] (5) have been synthesized by the direct reaction of H₂DNET (1) with organotin(IV) chloride(s) in the presence of potassium hydroxide in absolute methanol. All the compounds were characterized by elemental analyses, molar conductivity, UV-Vis, IR, ¹H, ¹³C, and ¹¹⁹Sn NMR spectral studies. The molecular structure of ligand (1) has been confirmed by X-ray single crystal diffraction. Spectroscopic data clearly suggested that Sn(IV) center is coordinated with the ONS tridentate ligand (H₂DNET) and exhibits a five-coordinate geometry in solution. Antibacterial studies were carried out in vitro against four bacterial strains. All organotin(IV) compounds (2–5) showed good activity against various bacteria but lower activity than the reference drug (Ciprofloxacin). The results demonstrate that organic groups attached to tin(IV) moiety have significant effect on their biological activities. Among them, diphenyltin(IV) derivative 5 exhibits significantly good activity than the other organotin(IV) derivatives (2–4).     

Studies on Antimicrobial Evaluation of Some 1-((1-(1H-Benzo[d]imidazol-2-yl)ethylidene)amino)-6-((arylidene)amino)-2-oxo-4-phenyl-1, 2-dihydropyridine-3,5-dicarbonitriles

A new series of 1-((1-(1H-benzo[d]imidazol-2-yl)ethylidene)amino)-6-((arylidene)amino)-2-oxo-4-phenyl-1,2-dihydropyridine-3,5-dicarbonitriles (4a–o) have been synthesized for the development of antimicrobial agents. Newly synthesized compounds were evaluated for their in vitro antibacterial activity against Gram-positive bacteria (Pseudomonas aeruginosa, Streptococcus pyogenes), Gram-negative bacteria (Escherichia coli, Staphylococcus aureus), and antifungal activity (Candida albicans, Aspergillus niger, Aspergillus clavatus). These compounds were characterized by infrared, ¹H NMR, ¹³C NMR, and mass spectra. The synthesized compounds 4b, 4e, 4 h, and 4k showed potent antimicrobial activity against tested microorganisms.     

Synthesis and nematicidal activities of 1,2,3-benzotriazin-4-one containing 4,5-dihydrothiazole-2-thiol derivatives against Meloidogyne incognita

Abstract

A series of novel 1,2,3-benzotriazin-4-one derivatives containing 4,5-dihydrothiazole-2-thiol were synthesized and characterized by ¹H NMR, ¹³C NMR, ¹⁹F NMR and HRMS. The bioassay results showed that compounds 3-(3-((4,5-dihydrothiazol-2-yl)thio)propyl)-7-methoxybenzo[d][1–3]triazin-4(3H)-one, 3-(3-((4,5-dihydrothiazol-2-yl)thio)propyl)-6-nitrobenzo[d][1–3]triazin-4(3H)-one, 7-chloro-3-(3-((4,5-dihydrothiazol-2-yl)thio)propyl)benzo[d][1–3]triazin-4(3H)-one exhibited good control efficacy against the cucumber root-knot nematode disease caused by Meloidogyne incognita at the concentration of 10.0?mg L^?1 in vivo. Compound 7-chloro-3-(3-((4,5-dihydrothiazol-2-yl)thio)propyl)benzo[d][1–3]triazin-4(3H)-one showed excellent nematicidal activity with inhibition 68.3% at a concentration of 1.0?mg L^?1. It suggested that the structure of 1,2,3-benzotriazin-4-one containing 4,5-dihydro-thiazole-2-thiol could be optimized further.     

Novel synthesis of substituted N-(3-aryl-1,8-naphthyridin-2-yl) and N,N′-bis(3-aryl-1,8-naphthyridin-2-yl)benzene-1,4-diamines and 2-(4-((3-aryl-1,8-naphthyridin-2-yl)amino)phenyl)isoindoline-1,3-diones and their biological evaluation

A straightforward and highly efficient series of new substituted 3-aryl-1,8-naphthyridine derivatives 3a–e, 4a–e, and 6a–e were synthesized. Condensation dissimilar quantities of 2-chloro-3-aryl-1,8-naphthyridine 1a–e with benzene-1,4-diamine 2 and sodium ethoxide refluxing in ethanol solvent yielded the compounds 3a–e and 4a–e. The 2-(4-((3-aryl-1,8-naphthyridin-2-yl)amino)phenyl)isoindoline-1,3-diones 6a–e were obtained by treatment of compounds 3a–e with phthalic anhydride 5 in refluxing N,N-dimethylformamide is described. All synthesized compounds evaluated for their antimicrobial activity. The structures of the compounds have been proven on the established of spectral (IR, ¹H NMR, and ¹³C NMR) data and elemental analyses. The reaction will be characterized by good efficacy, easy workup, simple purification of the products, and availability of catalyst.     

Synthesis,Structures, and Fungitoxicity of Novel Organophosphorus Compounds

Abstract

A series of biologically active organophosphorus compounds have been synthesized by the reactions of O,O-diethylchlorophosphate with Schiff bases derived from 5-(phenyl/substituted phenyl)-2-hydrazino-1,3,4-oxadiazole and salicylaldehyde/2-hydroxyacetophenone. The compounds have been characterized on the basis of analyses and spectral (IR, ¹H, ¹³C NMR) data. Fungicidal activities of these derivatives against Colletotrichum falcatum, Fusarium oxysporum, and Curvularia pallescence have been evaluated. All compounds showed moderate to significant antifungal activity.     

One-pot facile synthesis,crystal structure and antifungal activity of 1,2,3-triazoles bridged with amine-amide functionalities

A library of twenty five 1,2,3-triazoles bridged with amine-amide functionalities have been synthesized from reaction of N-substituted(prop-2-yn-1-yl)amines (2a–2e), 2-bromo-N-arylacetamides (4a–4e) and sodium azide through copper(I)-catalyzed alkyne-azide cycloaddition. The synthesized compounds were characterized by using FTIR, ¹H NMR, ¹³C NMR, and HRMS techniques. The structures of synthesized 5a (CCDC 1569245) and 5h (CCDC 1569249) were also confirmed by X-ray crystallography. Antifungal evaluation of newly synthesized triazoles was carried out against – Candida albicans and Aspergillus niger. Biological screening of synthesized 1,2,3-triazoles revealed moderate to good antifungal activity against tested strains.     

One-Pot,Multicomponent Condensation Reaction in Neutral Conditions: Synthesis,Characterization, and Biological Studies of Fused Thiazolo[2,3-b]quinazolinone Derivatives

A new series of 12-(2-chloro-6-quinoline-3-yl)-3,3,8-substituted-2,3,4,12-tetrahydro-benzo[4,5]thiazolo[2,3-b]quinazolin-1-ones 4 was synthesized in one pot by condensing various 2-chloro-3-formylquinolines 1, 2-amino-6-substituted-benzothiazoles 2, and 1,3-cyclohexanedione 3 in ethanol. All the compounds were characterized by IR, ¹H NMR, ¹³C NMR spectra and elemental analysis. All the synthesized compounds were screened for their antibacterial activity against Grampositive bacterial species Bacillus cereus and Bacillus substilus, Gram-negative bacterial species Escherichia coli, and their fungicidal activity against Aspergillus niger, Fuserium oxisporum, and Rhizopus species.     

新型2-(2'-取代亚肼基)-1,3-二硫杂环戊烷衍生物的合成和菌活性研究

通过结构改造并结合活性基团的拼接合成了11个未见文献报道的新型2-(2'-取代亚肼基)-1,3-二硫杂环戊烷类化合物, 所有的目标物的结构都经¹H NMR, MS, IR和元素分析证实, 选择了其中5个化合物对7种细菌进行了抑菌活性测试, 并与市售农药20%三环唑、70%威尔达甲托的抑菌活性进行对比, 发现它们比市售农药有更为广泛的杀菌谱, 对照农药只对金黄色葡萄球菌有良好的抑菌作用而这些化合物则对所选择的七个菌种均有良好的抑菌作用. 其中化合物2-(对氟苯氧乙酰亚肼基)-1,3-二硫杂环戊烷(4c)的杀菌谱很广, 它对金色葡萄球菌、大肠杆菌、白色念珠菌的抑杀活性都很好.     

Synthesis and Evaluation of Antimicrobial Activity of Some New Hetaryl‐Azoles Derivatives Obtained from 2‐Aryl‐4‐methylthiazol‐5‐carbohydrazides and Isonicotinic Acid Hydrazide

A series of new 1,3,4‐oxadiazole/thiadiazole and 1,2,4‐triazole derivatives have been synthesized starting from 2‐aryl‐4‐methylthiazol‐5‐carbohydrazides and isonicotinic acid hydrazide. All the newly synthesized compounds were characterized by IR, ¹H NMR, ¹³C NMR, and mass spectrometry. The synthesized compounds were screened for their antibacterial and antifungal activity, assessed as growth inhibition diameter. Some of them showed good antibacterial activity against gram positive Staphylococcus aureus, while the antibacterial activity against Listeria monocytogenes, Escherichia coli, and Salmonella typhymurium and antifungal activity against Candida albicans was modest. None of the tested compounds showed inhibitory activity against gram positive bacteria Enterococcus faecalis and Bacillus cereus and against gram negative bacteria Pseudomonas aeruginosa.     

Ecofriendly Solventless Synthesis and Reduction Reaction of Some Triazole Compounds and Evaluation of Their Antimicrobial Activity

A number of triazole-3-one compounds have been synthesized, and reduction of the carbonyl group in the molecule has been carried out to give a corresponding hydroxyl group that possesses asymmetric carbon atom in good yields and short reaction times. It is ecofriendly because it is produced by straightforward microwave irradiation in the absence of solvent. All newly synthesized compounds were also screened for their antimicrobial activities. The antimicrobial activity study revealed that 2d, 2i, 3c, and 3g–j showed good activity against a variety of microorganisms.

Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communications® to view the free supplemental file.     

A Convenient One-Pot Synthesis of Some New 3-(2-Phenyl-6-(2-thienyl)-4-pyridyl)hydroquinolin-2-ones Under Microwave Irradiation and Their Antimicrobial Activities

A series of 3-(2-phenyl-6-(2-thienyl)-4-pyridyl)hydroquinolin-2-ones 4a–o were synthesized in high yields by a one–pot cyclocondensation reaction under Kröhnke's reaction conditions using 2-chloro-3-formyl quinoline 1a–c, 2-acetyl thiophene 2, and various N-phenacylpyridinium bromides 3a–e in a mixture of ammonium acetate and acetic acid by microwave irradiation. All the compounds have been characterized by elemental analysis, FT-IR, ¹H NMR, and ¹³C NMR spectral analysis. These compounds have been screened for their antimicrobial activities.

Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.     

Design,synthesis and herbicidal activity of novel cyclic phosphonates with diaryl ethers containing pyrimidine

Abstract

Thirteen novel cyclic phosphates were rationally designed and synthesized by introducing diary ethers containing pyrimidine. All the target compounds were characterized by ¹H, ¹³C, ³¹P NMR and HRMS. The test of herbicidal activity indicated that most of the compounds showed good herbicidal activities against Amaranthus retroflexus. The compounds IA-2 (1-(5,5-dimethyl-2-oxido-1,3,2-dioxaphosphinan-2-yl)propyl-2-((4,6-dimethoxypyrimidin-2-yl)oxy)benzoate) and IA-3 ((5,5-dimethyl-2-oxido-1,3,2-dioxaphosphinan-2-yl)(phenyl)methyl-2-((4,6-dimethoxypyrimidin-2-yl)oxy)benzoate) exhibited remarkable post-emergency herbicidal activity against the tested monocotyledonous weed at the dosage of 112.5?g ai/ha.     

N-Heterocyclic carbene-Pd(II)-PPh3 complexes as a new highly efficient catalyst system for the Sonogashira cross-coupling reaction: Synthesis,characterization and biological activities

A novel series of N-heterocyclic carbene-phosphine palladium(II) complexes has been synthesized and fully characterized by IR, ¹H NMR, ¹³C NMR, and ³¹P NMR spectroscopies, and elemental analysis. The new N-heterocyclic carbene (NHC)-phosphine palladium(II) complexes 3a–h have been easily prepared by the reaction of the corresponding PEPPSI (pyridine-enhanced precatalyst preparation stabilization and initiation) complexes 2a–h and triphenylphosphine in dichloromethane in high yields. These complexes were applied as catalyst precursors which efficiently catalyzed Sonogashira reactions between aryl bromides and phenylacetylene to afford the corresponding products in good yields. The bulky NHC-Pd-PPh₃ complexes 3 were tested against Gram-positive and Gram-negative bacteria to study their biological activity. All the complexes exhibit antibacterial against these organisms. Investigation of the anti-acetylcholinesterase activity of the studied complexes showed that compounds 3a and 3b exhibited moderate activity at 100 μg mL^?1 and product 3b is the most active.     

New Hydrazides and Thiosemicarbazides Derived from Ethylenedioxythiophene as Potential Anticonvulsants

A series of ethyl 7-({2-[(substituted)carbonyl]hydrazino}carbonyl)-2,3-dihydrothieno [3,4-b][1,4]dioxine-5-carboxylates (5–13) and ethyl 7-{[({2-[(substituted)carbonyl]hydra-zino}carbonothioyl)amino]carbonyl}-2,3-dihydrothieno[3,4-b][1,4]dioxine-5-carboxy-lates (15–20) were synthesized in good yield by condensing ethyl-7-(chlorocarbonyl)-2,3-dihydrothieno[3,4-b][1,4]dioxine-5-carboxylate (4) with suitable hydrazides. The newly synthesized compounds were characterized using FTIR, ¹H NMR, ¹³C NMR, mass spectroscopy, and elemental analyses. The anticonvulsant activity of all the title compounds was investigated against maximal electroshock-induced seizures (MES) and pentylenetetrazole (PTZ)-induced convulsion models. None of the compounds showed toxicity at the maximum dose of 2000 mg/kg. Almost all the compounds showed protection in flexion and extension stage against induced convulsion. Among them, naphthyloxy-substituted derivatives exhibited very good response against induced seizures.

Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.     

Synthesis and Antimicrobial Studies of Organophosphates Derived From 2-(2″-Hydroxynaphthyl)Benzoxazole

Abstract

A series of biologically active phenoxy derivatives of 2-substituted benzoxazole organophosphates have been synthesized by the reaction of O-(naphthyl benzoxazolyl-2-) phosphorodichloridate/phosphorodichloridothioate with phenol/4-chlorophenol/4-nitroph- enol in 1:1 and 1:2 molar ratios. These compounds have been characterized on the basis of elemental analysis, IR, ¹H NMR, ³¹P NMR, and mass spectral studies. The antibacterial activity of these 2-substituted benzoxazole phenoxy derivatives has been evaluated against pathogenic bacteria Staphylococcus aureus (+ve) and Escherichia coli (?ve). The antifungal activity of these 2-substituted benzoxazole phenoxy derivatives has been evaluated against pathogenic fungi Aspergillus niger and Fusarium oxysporium. All compounds were found to have significant antibacterial and antifungal activity.     

酰基硫脲衍生物的合成、结构表征及生物活性研究

在超声波辐射下, 以PEG-400为固-液相转移催化剂, 用芳胺与双酰基异硫氰酸酯反应, 合成出了15种新的结构不对称的双酰基硫脲类化合物(6和6')和9种新的分子中含酰胺基团的单酰基硫脲类化合物(7和7'). 利用元素分析, IR, ¹H NMR, ¹³C NMR, APT, 1D NOE及2D NMR技术确定了所合成化合物6和6'及7和7'的结构, 并对它们NMR谱中低场C, H进行了归属. 杀菌、杀虫和除草活性筛选测定实验结果表明, 所测试化合物对瓜炭疽病菌均具有抑制作用, 其中6e抑制率最高, 达到62.4%; 目标化合物7a对黄瓜白粉病菌有一定的抑制作用. 单胺氧化酶活性测定实验表明：大部分目标化合物对单胺氧化酶具有一定的抑制活性, 其中浓度在1×10^－3 mol•L^－1时目标化合物6'c和6'd的抑制活性较强, 明显高于其它化合物. 目标化合物没有抗惊厥活性.