Novel one-pot multicomponent synthesis of (E)-2-(benzylideneamino)-5-mercapto-4H-1,2,4-triazol-3-yl)-2,3-dihydrophthalazine-1,4-dione derivatives

Abstract

An expeditious, one-pot multicomponent reaction has been developed for the synthesis of (E)-2-(benzylideneamino)-5-mercapto-4H-1,2,4-triazol-3-yl)-2,3-dihydrophthalazine-1,4-dione derivatives. Condensation of 4-amino-5-hydrazino-4H-1,2,4-triazole-3-thiol with phthalic anhydride and aromatic aldehyde afforded the (E)-2-(benzylideneamino)-5-mercapto-4H-1,2,4-triazol-3-yl)-2,3-dihydrophthalazine-1,4-diones in acetic acid medium with excellent yields. All the synthesized compounds were characterized by their analytical and spectral data.     

Synthesis,characterization, and investigations of antimicrobial activity of 6,6-dimethyl-3-aryl-3′,4′,6,7-tetrahydro-1′H,3H-spiro[benzofuran-2,2′-naphthalene]-1′,4(5H)-dione

Chalcone-like compounds 3a–l, 2-(benzylidene)-3,4-dihydronaphthalen-1(2H)-one, were synthesized from the addition of different benzaldehyde derivatives (2a–l) to 1,2,3,4-tetrahydro-1-napthalone (1) in basic medium. Mn(OAc)₃-mediated addition of dimedone (4) to chalcone-like compounds gave the spirobenzofuran derivatives (5a-l), 6,6-dimethyl-3-aryl-3′,4′,6,7-tetrahydro-1′H,3H-spiro[benzofuran-2,2′-naphthalene]-1′,4 (5H)-dione, in good yields. The structures of synthesized compounds 5a–l were elucidated on basis of spectral data (NMR, IR) and elemental analysis. In addition, their antibacterial activities were screened against some human pathogenic microorganisms.     

2-取代硫醚-5-(5,7-二甲基-1,2,4-三唑并[1,5-a]嘧啶基)-1,3,4-噁二唑/噻二唑类化合物的合成及生物活性

以5-氨基-1H-1,2,4-三唑-3-羧酸乙酯为起始原料, 设计合成了11个新型的2-取代硫醚-5-(5,7-二甲基-1,2,4-三唑并[1,5-a]嘧啶基)-1,3,4-噁二唑类化合物(5)和6个新型的2-取代硫醚-5-(5,7-二甲基-1,2,4-三唑并[1,5-a]嘧啶基)-1,3,4-噻二唑类化合物(8). 通过¹H NMR, MS和元素分析对所合成的化合物进行了结构表征. 初步的生物活性测试结果表明, 所合成的化合物均表现出不同程度的除草及杀菌活性, 其中化合物5k和8f的活性最好, 在50 mg/L浓度下对水稻纹枯病菌的抑制率达90%以上.     

Synthesis and Antibacterial Evaluation of Novel 3,6-Disubstituted Coumarin Derivatives

A novel series of 3,6-disubstituted coumarin derivatives were synthesized by the reaction of ethyl-2-(3-acetyl-2-oxo-2H-chromen-6-yl)-4-methylthiazole-5-carboxylate with thiosemicarbazide and various phenacyl bromides / 3-(2-bromoacetyl)-2H-chromen-2-ones / 2-(2-bromoacetyl)-3H-benzo[f]chromen-3-one in ethanol having catalytic amount of acetic acid under reflux conditions with good yields. All the synthesized compounds were fully characterized by spectral studies and evaluated for their in vitro antibacterial activity against Pseudomonas aeruginosa, Bacillus subtilis (Gram positive), Escherichia coli, and Azatobacter (Gram negative) bacterial strains. Activity results revealed that the compound 6h against Escherichia coli and compound 6i against Pseudomonas aeruginosa and Escherichia coli have shown maximum zones of inhibition. Remaining compounds showed moderate to good activity against all the tested bacterial strains compared with the standard drug cefotaxime.     

Experimental and theoretical studies on the reactions of 1-amino-5-benzoyl-4-phenyl-1<Emphasis Type="Italic">H</Emphasis>-pyrimidine-2-one/-thione compounds with ethyl acetoacetate

The reaction of 1-amino-5-(4-methylbenzoyl)-4-(4-methylphenyl)pyrimidin-2(1H)-one/-thione (1a,b) with ethyl acetoacetate (EA) afforded moderate to good yields (59–63%) of ethyl 2-methyl-4-(4-methylbenzoyl)-5-(4-methylphenyl)-7-oxo/-thioxo-3,3a-dihydropyrazolo[1,5-c]pyrimidine-3-carboxylate (2a,b). The newly synthesized compounds were characterized by elemental analyses, IR, ¹H and ¹³C NMR spectral data. All were compared with their previous analogues. The reaction mechanism of 1 with EA was studied by means of the B3LYP/6-31G(d,p) method. In addition, for reactants Fukui functions were performed using the data calculated with the Becke3–Lee–Yang–Parr (B3LYP) hybrid function.     

Facile synthesis of highly functionalized novel pyrazolopyridones using oxoketene dithioacetal and their anti-HIV activity

A series of novel 3-amino-4,5-dihydro-6-methyl-4-oxo-N-aryl-1H-pyrazolo[4,3-c]pyridine-7-carboxamide have been synthesized starting from various oxoketene dithioacetals. The cyclocondensation reaction of 2-(bis(methylthio)methylene)-3-oxo-N-arylbutanamide 2a–w with cyanoacetamide using NaOiPr as base under reflux condition afforded novel highly functionalized pyridone 3a–w derivatives. Further, [3?+?2] cyclocondensation reaction of pyridones with hydrazine in the presence of alcohol was yielded pyrazolopyridones (23 nos) 4a–w with excellent yields. All newly synthesized compounds were evaluated for in vitro anti-HIV activity using MTT method. Most of these compounds have showed moderate to potent activity against HIV-1 (III_B) and HIV-2 (ROD) strains with an IC₅₀ ranging from >18 IC₅₀[µg/ml] to <100 IC₅₀[µg/ml]. Among them, compounds 4j and 4v were identified as the most promising compound for both types of HIV strains. (IC₅₀?=?18?µg/ml). Three compounds 4l, 4m, and 4p have been found potent anti-HIV 1 and 2 activity against MT-4 cells.     

Synthesis of some novel 5-substituted benzamido-6-arylamino-pyrazolo[3,4-D]pyrimidin-4-one derivatives for herbicidal activity

Abstract

Sixteen novel 3-methylthio-5-substituted benzamido-6-arylamino-1-phenyl-1H-pyrazolo[3,4-d]pyrimidin-4 (5H)-one derivatives (4a–p) were successfully synthesized from iminophosphoranes, aryl isocyanate, and substituted benzoylhydrazine. The structures of the title compounds were elucidated by FT-IR, ¹H NMR, ¹³C NMR, and HRMS. Herbicidal activity of the compounds 4a–p against Brassica napus (rape), Echinochloa crusgalli (barnyard grass), Cucumis sativus (cucumber), and Triticum aestivum (wheat) were determined. The results showed that 5-(2-chlorobenzamido)-6-phenylamino-3-methylthio-1-phenyl-1H-pyrazolo[3,4-d]pyrimidin-4 (5H)-one (4c) displayed remarkable inhibition activity against the stalk and root of rape with 100% inhibition rate at the dosages of 10?mg/L and 100?mg/L, and 5-(4-nitrobenzamido)-6-phenylamino-3-methylthio-1-phenyl-1H-pyrazolo[3,4-d]pyrimidin-4 (5H) -one (4d) exhibited excellent activity against the stalk and root of barnyard grass with 100% inhibition rate at the same dosages.     

Design and synthesis of some new thiophene and 1,3,4-thiadiazole based heterocycles

Abstract

The reaction of 3-oxopropanenitriles with phenyl isothiocyanate in DMF containing KOH afforded the corresponding potassium salts. The latter salts were converted into ketene N,S-acetals upon acidification with hydrogen chloride. The reaction of the ketene N,S-acetals with 2-bromo-1-[5-methyl-1-(p-tolyl)-1H-1,2,3-triazol-4-yl]ethan-1-one or 3-(2-bromoacetyl)-2H-chromen-2-one gave novel thiophenes in good yields. Treatment of the ketene N,S-acetals with hydrazonyl halides afforded 1,3,4-thiadiazoles in good yields. The stereochemistry of the synthesized compounds was studied.     

Synthesis and characterization of novel benzoxazine-based arylidinyl succinimide derivatives

1,4-Benzoxazine skeleton holds substantial promise for further exploration owing to its immense pharmacological potential. In this pursuit, a series of 20 novel benzoxazine-based arylidinyl succinimide derivatives (23–42) were synthesized in moderate to good yields by the reaction of ethyl 2-(7-(2,5-dioxo-2,5-dihydro-1H-pyrrol-1-yl)-3-oxo-2H-benzo[b][1,4]oxazin-4(3H)-yl)acetate (22) with various aromatic aldehydes under Wittig reaction conditions in the presence of triphenylphosphine and ethanol. All these synthesized compounds were fully characterized from their spectral data (¹H, ¹³C, and ²D NMR, IR, UV, high-resolution mass spectroscopy (HRMS)) and further confirmed by X-ray crystallographic analysis of a representative compound (32). Antibacterial activity of obtained arylidinyl succinimide derivatives was evaluated against both Gram-positive and Gram-negative bacterial strains and were found to exhibit insignificant activity as compared to the reference.     

Silyl- and germylpropynals in the synthesis of azolyl-substituted 2-imidazoline 3-oxide 1-oxyls

Azolyl-substituted nitronylnitroxyls were synthesized using Me 3Si- and Et 3Ge-substituted propynals. When synthesizing 2-[3-(triethylgermyl)-l H-pyrazol-4-yl]-4,4,5,5-tetramethyl-4,5-dihydro-1 H-imidazole 3-oxide 1-oxyl ( 3b), the cycle was assembled by the reaction of CH2N2 with the corresponding triethylgermylethynyl-substituted nitronylnitroxyl. In the case of 2-[4-(trimethylsilyl)-l H-1,2,3-triazol-5yl]- (8a) and 2-[4-(triethylgermyl)-1 H-1,2,3-triazol-5-yl]-4,4,5,5-tetramethyl-4,5-dihydro-l H-imidazole 3-oxide l-oxyls (8b), the corresponding heterocyclic aldehydes were synthesized first and then were used for the preparation of compounds 8a and 8b. According to the X-ray diffraction study, the presence of the bulky substituent Me3Si or Et3Ge in the heterocycle causes its turn by 40.9(2)° in 8a and 33.6(6)° in 3b relative to the plane of the paramagnetic fragment ONCNO.     

Insecticidal Evaluation and [4+2] Aza‐Diels‐Alder Synthesis of 3,7‐Diaryl‐6,7‐dihydro‐5H‐6‐substituted Thiazolo[3,2‐a]pyrimidin‐5‐ones Under Coupled Ultrasonic Irradiation and PTC

A series of 3,7‐diaryl‐6,7‐dihydro‐5H‐6‐substituted‐thiazolo[3,2‐a]pyrimidin‐5‐ones ( 3a , 3b , 3c , 3d , 3e , 3f , 3g , 3h , 3i , 3j ) were synthesized by the [4+2] cycloaddition reaction of 2‐arylideneamino‐4‐arylthiazoles (2a–j) with in situ generated monosubstituted ketenes under PTC conditions coupled with ultrasonication in good to excellent yields. All the synthesized compounds were characterized on the basis of their spectral (IR, PMR, and Mass) and analytical data. The synthesized compounds were also screened for their insecticidal activity against Helicoverpa armigera and some of them showed promising activity.     

Synthesis and antibacterial activity of novel pyrano[2,3-d]pyrimidine-4-one–3-phenylisoxazole hybrids

A series of ethyl 2,7-dimethyl-4-oxo-5-phenyl-3-[(3-phenylisoxazol-5-yl)methyl]-3,5-dihydro-4H-pyrano[2,3-d]pyrimidine-6-carboxylates was synthesized and screened for antibacterial activity against Gram positive and Gram negative bacterial species. All new compounds were characterized by ¹H, ¹³C NMR, IR, and mass spectra. The results of the antibacterial study indicated that all compounds exhibited good to excellent antibacterial activity.

     

Base-mediated one-pot synthesis of 3,4,5,6-tetrahydro-4-substituted benzo[h]quinazoline-2(1H)-thione derivatives and evaluation of their antioxidant activity

One-pot three-component Beginelli-like reactions of a ketone 1, an aryl aldehyde 2, and thiourea 3 in the presence of sodium hydroxide are described. In this reaction, 3,4,5,6-tertrahydro-4-substituted quinazoline-2(1H)-thione derivatives 4a–h were obtained in good yields (73–85%). The compound 4a has been characterized by single crystal X-ray analysis. All the synthesized compounds 4a–h and 5a–b were screened for their in vitro antioxidant activity. Compounds 4c, 4e, and 4h have exhibited an excellent than the standard ascorbic acid. Compounds 4d, 4f, and 4g have also shown good activity. Remaining compounds show moderate antioxidant activity.     

A simple and efficient approach for the synthesis of a novel class aliphatic 1,3,4-thiadiazol-2(3H)-one derivatives via intramolecular nucleophilic substitution reaction

In this study, we synthesized a new series of substituted aliphatic 1,3,4-thiadiazol-2(3H)-one derivatives (6-24) in yields ranging from 42 to 70% with an interesting mechanism that involves internal nucleophilic substitution followed by an S_N2-type nucleophilic substitution. First, 1-(4-chlorophenyl)-2-((5-methyl-1,3,4-thiadiazol-2-yl)thio)ethanone (3) was synthesized from the reaction of 5-methyl-1,3,4-thiadiazole-2-thiol (1) with 2-bromo-1-(4-chlorophenyl)ethanone (2) in the presence of potassium hydroxide. Then, 1-(4-chlorophenyl)-2-((5-methyl-1,3,4-thiadiazol-2-yl)thio)ethanol (4) was synthesized by a reduction reaction of this compound using NaBH₄. Finally, 5-methyl-3-alkyl-1,3,4-thiadiazol-2(3H)-one derivatives (6-24), which are the target compounds, were synthesized from the reaction of this compound (4), which is a secondary alcohol with various alkyl halides (5a-n) in the presence of sodium hydride (NaH). This study presents an interesting reaction mechanism related to the synthesis of aliphatic 1,3,4-thiadiazol-2(3H)-one derivatives that is not recorded in the literature.     

Synthesis of Novel 3‐(3‐(5‐Methylisoxazol‐3‐yl)‐7H‐[1,2,4]Triazolo [3,4‐b][1,3,4]Thiadiazin‐6‐yl)‐2H‐Chromen‐2‐Ones

A novel series of coumarin substituted triazolo‐thiadiazine derivatives were designed and synthesized by using 5‐methyl isoxazole‐3‐carboxylic acid ( 1 ), thiocarbohydrazide ( 2 ), and various substituted 3‐(2‐bromo acetyl) coumarins ( 4a , 4b , 4c , 4e , 4d , 4f , 4g , 4h , 4i , 4j ). Fusion of 5‐methyl isoxazole‐3‐carboxylic acid with thiocarbohydrazide resulted in the formation of the intermediate 4‐amino‐5‐(5‐methylisoxazol‐3‐yl)‐4H‐1,2,4‐triazole‐3‐thiol ( 3 ). This intermediate on further reaction with substituted 3‐(2‐bromo acetyl) coumarins under simple reaction conditions formed the title products 3‐(3‐(5‐methylisoxazol‐3‐yl)‐7H‐[1,2,4]triazolo[3,4‐b][1,3,4]thiadiazin‐6‐yl‐2H‐chromen‐2‐ones ( 5a , 5b , 5c , 5d , 5e , 5f , 5g , 5h , 5i , 5j ) in good to excellent yields. All the synthesized compounds were well characterized by physical, analytical, and spectroscopic techniques.     

Synthesis and characterization of N′-(11H-indeno[1,2-b]quinoxalin-11-ylidene)benzohydrazonamides as potential antimicrobial agents

Abstract

A series of new N′-(11H-indeno[1,2-b]quinoxalin-11-ylidene)benzohydrazonamides 3a–3j was synthesized in excellent yields from the reaction of N³-substituted benzohydrazonamides 1 and 2-(11H-indeno[1,2-b]quinoxalin-11-ylidene)malononitrile 2 in dichloromethane or with 11H-indeno[1,2-b]quinoxalin-11-one 4 in ethyl acetate at ambient temperature. The new compounds have been characterized and screened for biological activity. Some of them showed significant antibacterial and antifungal activities. In particular, compounds 3c and 3e showed interesting activities as antibacterial agents while compounds 3a 3c, 3e, 3g, and 3i showed high antifungal activities.     

Bis coumarinyl bis triazolothiadiazinyl ethane derivatives: Synthesis,antiviral activity evaluation,and molecular docking studies

A series of novel 3,3′-(3,3′-(dihydroxy/hydroxyethane-1,2-diyl)bis(7H-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazine-6,3-diyl))bis(2H-chromen-2-ones) were prepared by the condensation of thiocarbohydrazide with tartaric acid or malic acid followed by various 3-(2-bromoacetyl)-2H-chromen-2-ones in two steps with good yields. All the synthesized compounds were characterized by analytical and spectral (IR, ¹H NMR, ¹³C NMR, and mass) data. These synthesized bis(triazolothiadiazinyl coumarin) compounds were evaluated for broad spectrum of antiviral activity. Among all the tested compounds, compound 5f exhibited antiviral activity against H1N1 virus. The molecular docking studies of these compounds against H1N1 neuraminidase enzyme were performed. The binding affinity and binding values were compared with standard drugs.     

N-[5-(1-邻(对)氯苯氧乙基)-1,3,4-噻二唑-2-基]-N'-芳酰基硫脲的合成与生物活性

为了寻找高活性的杂环农药, 通过2-氨基-5-(1-邻氯苯氧乙基)-1,3,4-噻二唑和2-氨基-5-(1-对氯苯氧乙基)-1,3,4-噻二唑与芳酰基异硫氰酸酯反应, 合成了26种新的芳酰基硫脲. 采用核磁共振氢谱、红外光谱及元素分析确证了它们的结构. 初步的生物活性测定试验表明, 部分目标化合物表现出良好的植物生长调节活性, 其中3c, 3d, 3e, 4b和4c具有优良的生长素活性.     

Dicationic liquid mediated synthesis of tetrazoloquinolinyl methoxy phenyl 4-thiazolidinones and their antibacterial and antitubercular evaluation

In a search of new potentially active antitubercular agents here we have synthesized 3-substituted phenyl-2-(4-(tetrazolo[1,5-a]quinolin-4-ylmethoxy)phenyl)thiazolidin-4-ones (8a–l) and evaluated their antibacterial, particularly antitubercular activity. These have been conveniently synthesized by performing one–pot cyclocondensation of 4-(tetrazolo[1,5-a]quinolin-4-ylmethoxy)benzaldehyde, anilines and mercaptoacetic acid in dicationic ionic liquid, (3-methyl-1-[3-(methyl-1H-imidazolium-1-yl)propyl]-1H-imidazolium dibromide [C₃(MIM)₂–2Br]) and obtained excellent yields of (8a–l). 4-Thiazolidinones (8a–l) were thoroughly characterized by their spectral analyses. These compounds have been screened for their in vitro antitubercular activity against Mycobacterium tuberculosis H37Ra and Mycobacterium bovis (BCG). The compounds 8a, 8c, and 8e exhibited notable in vitro antitubercular activity compare to the reference, Rifampicin. Molecular docking study has also been performed to know the binding mode of these analogs in to the active site of DprE1 enzyme. The synthesized compounds were also evaluated for their in vitro antibacterial activity and amongst them compound 8k has shown moderate activity against both gram-negative and gram-positive bacterial strains.     

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).