Synthesis and Antimicrobial Activity of New Tetrazoles Incorporating Isoindole‐1,3‐dione Moiety and Their Sugar Derivatives

New tetrazole derivatives linked to isoindole‐1,3‐dione were prepared starting from the corresponding nitrile derivatives. The substituted hydrazides, their corresponding sugar hydrazones, and the derived acyclic C‐nucleoside analogs were also synthesized. The antimicrobial results indicated that most of the tested compounds exhibited moderate to high activity, whereas few compounds were found to exhibit little or no activity against the tested microorganisms.     

Synthesis and Antioxidant Activity of New Pyrazolo[1,5‐a]Pyrimidine Derivatives Incorporating a Thiazol‐2‐yldiazenyl Moiety

4‐(Thiazol‐2‐yldiazenyl)‐1H‐pyrazole‐3,5‐diamine ( 2 ) was prepared by the reaction of 2‐thiazolylazomalononitrile ( 1 ) with hydrazine hydrate in boiling ethanol and used as key intermediate for the synthesis of polyfunctionally substituted pyrazolo[1,5‐a]pyrimidines via its reactions with reagents having 1,3‐dielectrophilic centers. Structures of the newly synthesized compounds were established by elemental analysis and spectral data. Representative compounds of the synthesized products were tested and evaluated as antioxidant agents. The results revealed that compounds ( 3 ), ( 4 ), ( 5 ), and ( 9 ) displayed promising antioxidant activity compared to the activity of ascorbic acid.     

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 and Antimicrobial Activity of Some Novel Thiazoles, 1,3,4‐Thiadiazines, 1,3,4‐Thiadiazoles Incorporating Coumarin Moiety

Starting from 3‐acetyl‐2H‐chromen‐2‐one and hydrazinecarbothiohydrazide, new functionalized thiazoles, 1,3,4‐thiadiazines, and 1,3,4‐thiadiazoles were prepared. The structures of the compounds prepared were confirmed by both elemental and spectral analyses as well as by alternate synthesis. The antimicrobial activities of the compounds prepared were screened, and the results showed that most of such compounds exhibit considerable activities.     

Synthesis and Antimicrobial Activity of Novel Azolopyrimidines and Pyrido‐Triazolo‐Pyrimidinones Incorporating Pyrazole Moiety

A new series of azolopyrimidine derivatives incorporating pyrazole moiety were synthesized by reaction of 1‐(pyrazol‐3‐yl)‐2‐propenone with a number of heterocyclic amines in the presence of a catalytic amount of acetic acid. The mechanism of formation of the products was also discussed, and the structure assigned was elucidated based on both elemental and spectral analyses data. In addition, 7‐(pyrazolyl)‐2‐thioxo‐5‐phenyl‐1,3‐dihydropyrido[2,3‐d ]pyrimidin‐4‐one was used as starting material for preparation of a new series of pyridotriazolopyrimidines via its reaction with a variety of hydrazonoyl chlorides in dioxane using triethylamines as catalyst. The assigned structure for these products was also proved via elemental analysis and spectroscopic techniques (IR, ¹H NMR, and Mass). Moreover, the antimicrobial activity of some selected examples of the new products was evaluated, and the results obtained revealed high activity of compound 20a against the Gram positive bacteria Staphylococcus aureus and the Gram negative bacteria Klebsiella pneumonie . All the tested compounds have no antifungal activity.     

Facile Microwave‐assisted Synthesis of 1,3,5‐Trisubstituted Pyrazoline Derivatives Incorporating Sulfonyl Moiety

We developed an environmentally benign, convenient microwave‐assisted process for the construction of 1,3,5‐trisubstitued pyrazolines ( 10a ～ 10f , 11a ～ 11f , 12a ～ 12f , 13a ～ 13f ). Chalcones, as the key intermedi‐ ates, were obtained by the condensation of each of appropriately substituted aromatic aldehydes ( 1 ～ 4 ) with 4‐substituted acetophenones ( 5a ～ 5f ) via a Claisen‐Schmidt reaction under the action of microwave irradiation. Cyclization of the chalcones ( 6a ～ 6f , 7a ～ 7f , 8a ～ 8f , 9a ～ 9f ) with p‐toluene sulfonhydrazide af‐ forded 1,3,5‐trisubstitued pyrazoline derivatives using microwave‐assisted process in 25 min and 140 watt power in glycol. The structures of targeted compounds were established by IR, ¹H NMR, MS and ele‐ mental analysis. The results indicate that microwave‐assisted synthetic process presents advantages in terms of enhancement in rate, decrease in reaction time, clean reaction and convenient operation.     

Synthesis and Antibacterial Activity of Novel 1H‐indol‐2‐ol Derivatives

A series of novel 1H‐indol‐2‐ol derivatives were synthesized and evaluated their antibacterial activities against rice bacterial leaf blight, tobacco bacterial wilt, and citrus canker caused by Xanthomonas oryzae pv. oryzae (Xoo), Ralstonia solanacearum, and Xanthomonas axonopodis pv. citri via the turbidimeter test in vitro. Antibacterial bioassay indicated that most compounds demonstrated good inhibitory effect against Xoo and Ralstonia solanacearum. Especially, compound 4k demonstrated the best inhibitory effect against Xoo with half‐maximal effective concentration (EC₅₀) value of 8.27 μg/mL, which was even better than those of commercial agents Bismerthiazol and Thiodiazole copper.     

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 of Some New Pyridine and Pyrimidine Derivatives Containing Benzothiazole Moiety

A variety of pyridine and pyrimidine rings incorporating benzothiazole moiety were synthesized by reaction of 1‐(2‐benzothiazolyl)‐1‐cyano‐3‐chloroacetone ( 1 ) with 2‐pyridone, 2‐thioxopyridine, thiouracil, and 2‐thioxopyrimidine derivatives to give compounds 7,9‐dimethylfuro[2,3‐b:4,5‐b′]dipyridin‐4‐ol 5 , 4, 6‐diphenylthieno[2,3‐b]pyridin‐2‐yl 9 , 2‐(benzo[d]thiazol‐2‐yl)‐2‐(7‐substituted‐5‐oxo‐5H‐thiazolo[3,2‐a]pyrimidin‐3‐yl)acetonitriles 12a and 12b , pyrimido[2,1‐b][1,3]thiazepine‐3‐carboxamide 15 , and benzo[4,5]thiazolo[3,2‐b]pyridazine‐3‐one 20 , respectively.     

Synthesis and Herbicidal Activity of Acylpyrazole Derivatives Containing 1,2,3‐Thiadiazole Moiety

A series of novel acylpyrazole derivatives containing 1,2,3‐thiadiazole ring 3a – 3m were synthesized by the condensations of 1‐phenyl‐3‐methyl‐4‐(substituted benzal or 4‐methyl‐1,2,3‐thiadiazole‐5‐carbonyl)‐5‐hydroxypyrazole 2 with 4‐methyl‐1,2,3‐thiadiazole‐5‐carbonyl chloride or substituted benzoyl chloride. Their structures were confirmed by IR, ¹H‐NMR, mass spectroscopy, and elemental analyses. The results of preliminary bioassays showed that some of the title compounds 3 exhibited moderate to good herbicidal activities against dicotyledonous plants (Brassica campestris L.) at the concentration of 100 mg/L. For example, compounds 3e , 3f , 3g , and 3k possessed 74.6%, 72.2%, 70.3%, and 84.5% inhibition against B. campestris L., respectively, whereas commercially available herbicide Sulcotrione showed only 35.0% inhibition at the same concentration. Moreover, these compounds displayed higher herbicidal activity against B. campestris L. than Echinochloa crus‐galli. However, these compounds showed weak activities at the concentration of 10 mg/L.     

An Efficient Synthesis of Novel 2‐(5‐indolyl)‐1H‐benzimidazole Derivatives and Evaluation of Their Antimicrobial Activities

In this paper, we report the synthesis of novel 2‐(5‐indolyl)‐1H‐benzimidazole derivatives. The methodology involves the Sonogashira reaction of 4‐(1H‐benzimidazol‐2‐yl)‐2‐bromo‐N,N‐dimethylaniline ( 3 ) with variety of terminal alkynes to get corresponding novel 4‐(1H‐benzimidazol‐2‐yl)‐2‐alkynyl‐N,N‐dimethylaniline derivatives ( 4 ). These compounds on iodocyclization afforded novel iodoindolylbenzimidazole derivatives ( 5 ). The resulting compounds were functionalized further via palladium‐mediated carbon–carbon bond formation for generating novel structurally diversified heterocyclic compounds. All these newly synthesized compounds were evaluated for antimicrobial activity.     

New 1,3,4‐Thiadiazole Derivatives: Synthesis,Characterization, and Antimicrobial Activity

In the present study, 2,5‐bis(mercapto‐acetichydrazide)‐1,3,4‐thiadiazole ( 1 ) was utilized by different reagents, namely, ethoxymethylene malononitrile, ethoxymethylene ethyl cyanoacetate, triethyl orthoformate, phenyl isothiocyanate, carbon disulfide, isatin, acetophenone, cyclohexanone, different aldehydes, and different anhydrides, to yield a new series of 2,5‐disubstituted‐1,3,4‐thiadiazoles 2 – 18 . The chemical structure of these products was characterized by the spectral data IR, ¹H‐NMR, ¹³C‐NMR, MS, and elemental analysis. All the synthesized compounds were screened for their antibacterial activity.     

An Efficient Synthesis of 3‐(1H‐Tetrazol‐5‐yl)coumarins (=3‐(1H‐Tetrazol‐5‐yl)‐2H‐1‐benzopyran‐2‐ones) via Domino Knoevenagel Condensation,Pinner Reaction,and 1,3‐Dipolar Cycloaddition in Water

A novel straightforward synthesis of 3‐(1H‐tetrazol‐5‐yl)coumarins (=3‐(1H‐tetrazol‐5‐yl)‐2H‐1‐benzopyran‐2‐ones) 6 via domino Knoevenagel condensation, Pinner reaction, and 1,3‐dipolar cycloaddition of substituted salicylaldehydes (=2‐hydroxybenzaldehydes), malononitrile (propanedinitrile), and sodium azide in H₂O is reported (Scheme 1 and Table 2). This general protocol provides a wide variety of 3‐(1H‐tetrazol‐5‐yl)coumarins in good yields under mild reaction conditions.     

Synthesis and Antifungal Activity of Novel 1,2,4‐Triazole Derivatives Containing 1,2,3‐Thiadiazole Moiety

Starting from carbonic acid diethyl ester, a series of 1,2,4‐triazole derivatives containing 1,2,3‐thiadiazole were synthesized. Reactions were performed by microwave irradiation or ultrasonic irradiation as well as by conventional heating. The structure of title compounds was characterized by ¹H‐NMR, MS, and elemental analyses. The fungicidal activities of these compounds were tested in vivo. Most of title compounds exhibited good antifungal activity against Pseudoperonospora cubensis. Some of title compounds displayed moderate antifungal activities against Fusarium oxysporum, Pseudoperonospora cubensis, Sphaerotheca fuligenea, Corynespora cassiicola, and Xanthomonas axonopodis.     

Synthesis and Antimicrobial Activity of New Substituted 5‐(Pyridine‐3‐yl)‐1,3,4‐Thiadiazoles and Their Sugar Derivatives

New substituted 5‐(pyridine‐3‐yl)‐1,3,4‐thiadiazoles, their sugar hydrazones and acyclic C‐nucleoside analogs as well as the corresponding thioglycoside derivatives were synthesized. The synthesized compounds were tested for their antimicrobial activity against Escherichia coli, Bacillus subtilis, Staph aureus, Aspergillus niger, and Candida albicans The obtained results indicated that most of tested compounds exhibited moderate to high antimicrobial activity while few compounds were found to exhibit little or no activity against the tested microorganisms.     

Synthesis and Herbicidal Activity of 1,2,4‐Triazole Derivatives Containing a Pyrazole Moiety

A series of triazole derivatives containing a pyrazole moiety were synthesized and characterized by ¹H NMR, ¹³C NMR, and HRMS. The herbicidal activities of these compounds were tested against lettuce and bentgrass. Most of the tested compounds were moderately herbicidal activity against lettuce and bentgrass. Among them, compounds 6f and 6g had the highest herbicidal activity (80% inhibitory) against lettuce and bentgrass.     

Facile Synthesis and Antimicrobial Activity of 5‐Amino‐3‐methyl‐1‐phenyl‐1H‐thieno[3,2‐c]pyrazole‐6‐carbonitrile and Their Derivatives

5‐Amino‐thieno[3,2‐c]pyrazole derivative 2 was prepared by Gewald reaction in a one‐pot procedure. The amino group of compound 2 like primary aromatic amine formed the diazonium salt when treated with NaNO₂/HCl, followed by coupling with different nucleophiles to yield the azo coupling products 3a – d . The reactivity of 5‐amino‐thienopyrazole 2 has been investigated towards different electrophilic reagents such as aromatic aldehydes, alkyl halide, acid chloride, acid anhydride, phenyl isothiocyanate, carbon disulfide, ethyl glycinate, and thioacetamide, which afforded the reaction products 4 – 14 , respectively.     

Synthesis and Antimicrobial Activity of 2‐(Pyridine‐3‐yl)‐4H‐chromen‐4‐one Derivatives

An efficiently synthesis of chromones via cyclodehydration of corresponding 1‐(2‐hydroxyphenyl)‐3‐(pyridine‐3‐yl)propane‐1,3‐dione is described under ultrasound irradiation. A series of novel 2‐(pyridine‐3‐yl)‐4H‐chromen‐4‐one derivatives was confirmed on the basis of ¹H‐NMR, mass, IR spectral data, and elemental analysis. The synthesized compounds were evaluated for their antibacterial and antifungal activities. Most of the compounds were found to be comparable potent than the reference standard drugs. Utilization of ultrasound irradiation, simple reaction conditions, isolation, and purification makes this manipulation very interesting from an economic and environmental perspective.     

Synthesis and Biological Activity of 3‐Methyl‐1H‐pyrazole‐4‐carboxylic Ester Derivatives

In search of novel pyrazole derivatives with bioactivity, a series of 3‐methyl‐1H‐pyrazole‐4‐caboxylic: ester derivatives were synthesized via α‐oxoketene dithioacetals as starting material. The structures of all compounds prepared were confirmed by ^lH NMR, IR, MS and elemental analyses. Preliminary bioassays indicated that some compounds showed fungicidal activity against wheat rust, phoma asparagi and antiviral activity against TMV.     

Synthesis of 4,5,6,7‐Tetrabromo‐1H‐benzimidazole Derivatives

A convenient and simple method for the preparation of polybrominated benzimidazole derivatives has been described. Reaction of 4,5,6,7‐tetrabromo‐1‐(3‐chloropropyl)‐1H‐benzimidazole, obtained by alkylation of 4,5,6,7‐tetrabromo‐1H‐benzimidazole (TBBi) with 1‐bromo‐3‐chloropropane in the presence of KOH, with morpholine, aniline, benzylamine, N‐methyl piperazine, and 2‐arylpyrrolidines afforded new TBBi derivatives.