Synthesis and Antimicrobial Screening of 2‐Aryl‐5‐((2‐arylthiazol‐4‐yl)methyl)‐1,3,4‐oxadiazole Derivatives

A new series of 2‐aryl‐5‐((2‐arylthiazol‐4‐yl)methyl)‐1,3,4‐oxadiazole derivatives was synthesized by condensation of 2‐(2‐substituted thiazol‐4‐yl)acetohydrazide with aryl aldehydes followed by oxidative cyclocondensation using iodobenzene diacetate. The structure of synthesized compounds was characterized by IR, NMR, and mass analysis. All the newly synthesized compounds were evaluated for their in vitro antimicrobial activity. Some of the compounds showed moderate antimicrobial activity.     

Design,Synthesis and Antimicrobial Evaluation of Novel Tricyclic Benzoxazine Fluoroquinolones under Conventional and Microwave Methods

In view of obtaining some potential antimicrobial compounds, we have described synthesis of novel fluoroquinolones bearing 2‐(piperidin‐4‐yl)‐1H‐benzo[d]imidazole and evaluated for their antimicrobial activity. Alternatively, synthesis of these products was also demonstrated using microwave irradiation technique. The antimicrobial activity of newly synthesized compounds was evaluated against number of microorganisms and the activity is compared with highly active levofloxacin.     

Utility of 6‐Amino‐2‐thiouracils as a Core of Biologically Potent Polynitrogen–Sulfur Fused Heterocycles

One pot three‐component reaction was assisted to form some new pyridopyrimidine derivatives to be investigated as antimicrobial and antitumor agents. The newly synthesized compounds showed high significant antimicrobial activity against the applied strains of both Gram‐positive and Gram‐negative bacteria and fungi. The cytotoxic activity of some compounds was evaluated as inhibitor of growth in both human liver carcinoma and breast cell lines. The results showed that some compounds exhibited very high cytotoxicity against human liver cell line and breast cancer cells.     

Synthesis of novel heterocycles with antimicrobial and surface activity

A new series of anionic surfactants with dual type of activity antimicrobial and surface activity have been synthesized by reaction of 4H‐3,1‐benzoxazinone 3 and quinazolinethione 10 with nitrogen nucleophiles and activated olefinic compounds. The compounds were evaluated for their surface activity as well as their antimicrobial and biodegradability properties.     

Synthesis,Characterization and Antimicrobial Activity of 1,2‐dihydroquinoxaline‐3‐yl‐3‐Substitutedphenyl‐1H‐pyrazole‐4‐Carbaldehyde

A series of 1,2‐dihydroquinoxaline‐3‐yl‐3‐substitutedphenyl‐1H‐pyrazole‐4‐carbaldehyde were synthesized and evaluated for their antimicrobial activity against two Gram‐positive and two Gram‐negative organisms and two fungal organisms. The study has shown that pyrazole‐4‐carbaldehyde‐incorporated quinoxaline was essential for activity. Among the compounds, 5a , 5c , 5d had shown significant activity against all selected strains when compared with control. These compounds may prove useful as antimicrobial agents.     

Synthesis and Antimicrobial Activity of 2-Methyl-5-nitroaniline Derivatives:A Structure-Activity Relationship Study

A series of 2‐methyl‐5‐nitroaniline derivatives, 5a – 5k and 6a – 6f , were synthesized in order to determine their in vitro antimicrobial activity. The chemical structures of the synthesized compounds were confirmed by elemental analyses, UV‐visible, FT‐IR, ¹H NMR and ¹³C NMR spectral studies. The structure‐activity relationships of the synthesized compounds were also discussed. Among the synthesized compounds, 5f , 5d , 6b and 6e showed good antimicrobial activity compared to standard drugs.     

Utility of Hantzsch Ester in Synthesis of Some 3,5‐Bis‐dihydropyridine Derivatives and Studying Their Biological Evaluation

The present work involves synthesis of new 3,5‐bis‐substituted dihydropyridine derivatives 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 starting from dihydropyridine‐3,5‐dicarboxylate ( 1 ) as starting material. Structures of new compounds were established by spectral and elemental analyses. Some of the new compounds were evaluated for anticancer and antimicrobial activity. Screening data of the tested compounds show promising anticancer and antimicrobial activity. The detail synthesis, spectroscopic data, and pharmacological activities are reported.     

Efficient Synthesis and Antimicrobial Evaluation of New Azolopyrimidines‐Bearing Pyrazole Moiety

Sodium salt of 3‐hydroxy‐1‐(1‐aryl‐5‐methylpyrazolyl)propenone derivatives was used as a precursor for synthesis of various fused azolopyrimidine ring systems as pyrazolopyrimidines, triazolopyrimidines, and pyrimidobenzimidazoles following many procedures. The identity of the prepared compounds was elucidated by their spectral data and elemental analyses. The in vitro antimicrobial activity of 13 new compounds was evaluated, and many derivatives showed good to moderate activity.     

Thio-I ehromannones 5,8-disubstituées et synthèses dans la série du thiéno[4,3,2-de] thiochromanne

With the aim of obtaining the thieno[4,3,2-de] thiochromane structure, various 5,8-disubstituted derivatives of [1]thiochromanone have been synthesized. The structures of the compounds thus obtained and of the intermediates used in their syntheses were confirmed by nmr spectroscopy or by chemical procedures.     

Synthesis,X‐ray Analysis,and Biological Activities of Novel Oxazolidinethiones

Oxazolidinethione compounds were synthesized starting from racemic and enantiopure β‐amino alcohols. The molecular structure of oxazolidinethione 6a was elucidated by single‐crystal x‐ray crystallography. Oxazolidinethione compounds screened for antimicrobial activity showed mild minimum inhibitory concentration values.     

Synthesis of Novel 1‐(5‐(Benzylsulfinyl)‐3‐methyl‐1,3,4‐thiadiazol‐2(3H)‐ylidene)‐thiourea/urea Derivatives and Evaluation of Their Antimicrobial Activities

A new series of 1‐(5‐(benzylsulfinyl)‐3‐methyl‐1,3,4‐thiadiazol‐2(3H)‐ylidene)‐thiourea/urea derivatives ( 1a – j ) were designed and synthesized. For the first time, (i) a new process was developed for N‐methylation of 1,3,4‐thiadiazole moiety using dimethyl carbonate an environmentally benign reagent in presence of N,N,N′,N′‐tetramethylethylenediamine and (ii) the sulfide was selectively oxidized to sulfoxide in higher yield by using chlorine (g) in aqueous acetic acid media under mild reaction condition. The synthesized compounds ( 1a – j ) were investigated for their antimicrobial activities. The tested compounds ( 1a – j ) were exhibited moderate to excellent antibacterial activities against both Gram‐positive and Gram‐negative bacterial strains. The same compounds exhibited good antifungal activities against selected fungal strains. Particularly, the compounds 1b , 1d , 1h , and 1i were proved to be promising leads exhibiting both antibacterial and antifungal activities compared with standard drugs, ciprofloxacin, and fluconazole. The presence of 1,3,4‐thiadiazole moiety has a significant role in the display of antimicrobial activity. In addition, the presence of both sulfinyl and thiourea or urea functionalities has enhanced the activity as per obtained antimicrobial activity data.     

Synthesis and Antimicrobial Activity of New 1,2,3‐Triazolopyrimidine Derivatives and Their Glycoside and Acyclic Nucleoside Analogs

New [1,2,4‐oxadiazolyl]methyl‐3H‐[1,2,3]triazolo[4,5‐d]pyrimidin derivatives were synthesized starting from N′‐Hydroxy‐1‐naphthimidamide. The N‐substituted acyclic nucleoside analogs as well as the substituted glycosides were also prepared by reaction with the corresponding reagents. The antimicrobial results indicated that most of the tested compounds exhibited moderate to high antimicrobial activity whereas few compounds were found to exhibit little or no activity against the tested microorganisms.     

Synthesis,Characterization, and Antimicrobial Properties of New 1,3,4‐Thiadiazoles Derived from Azo Dyes

Some new 1,3,4‐thiadiazoles derived from azo dyes were synthesized. Two different synthesis methods were used for these compounds: Esters pertaining to the azo dyes were converted into 1,3,4‐thiadiazoles, or benzothiazole ester derivatives were converted to 1,3,4‐thiadiazoles followed by the synthesis of azo dye derivatives. The desired products were successfully obtained using the latter method. The molecular structures of these compounds were characterized using spectroscopic methods such as FTIR, ¹H NMR, ¹³C NMR, and elemental analysis. Furthermore, antimicrobial activity was studied for the synthesized compounds. Compound 3e exhibited antimicrobial activity against three different microorganisms. Compounds 3a , 3b , and 3d had activity against two different microorganisms, while compound 3c showed activity against only one microorganism.     

Synthesis,antimicrobial, and antioxidant activities of new pyridyl‐ and thiazolyl‐bearing carbohydrazides

A series of novel substituted (E)‐N′‐benzylidene‐4‐methyl‐2‐(2‐propylpyridin‐4‐yl)thiazole‐5‐carbohydrazide derivatives ( 6a‐l ) have been synthesized by following the multistep synthetic route starting from prothionamide. The resulting compounds were characterized via ¹H, ¹³C NMR, and HRMS spectral data. The synthesized carbohydrazides were evaluated for their in vitro antimicrobial and antioxidant activities. Tested molecules have displayed moderate to good growth inhibition activity. Among the screened compounds, 6b , 6e , 6j, and 6k are found to be the more promising antimicrobial agents. A 2,2‐diphenyl‐1‐picrylhydrazyl assay was used to test the antioxidant activity of the carbohydrazides. The carbohydrazide derivatives 6b and 6i have shown better free‐radical scavenging ability than the other investigated compounds.     

Pyridinium Ylide Assisted Highly Stereoselective One‐Pot Synthesis of trans‐2‐(4‐Chlorobenzoyl)‐3‐aryl‐spiro[cyclopropane‐1,2′‐inden]‐1′,3′‐diones and Their Antimicrobial and Nematicidal Activities

A series of highly stereoselective polysubstituted cyclopropane derivatives were synthesized via one‐pot two‐step tandem reaction starting from pyridine, 4‐chloro phenacyl bromide, 1,3‐indandione and aromatic aldehydes in acetonitrile using triethylamine as catalyst. Pyridinium ylide generated from 4‐chloro phenacyl bromide undergo cyclopropanation with 2‐arylidene‐2H‐indene‐1,3‐dione in situ afford the title compounds. Structures of all the compounds were confirmed by their analytical and spectral studies. Single crystal X‐ray analysis was also performed on compound 4c in order to determine the crystal structure. All the compounds were screened for antimicrobial and nematicidal activities. Significant antimicrobial activity was shown by the compounds derived from 2‐hydroxybenzaldehyde ( 4i ) and 4‐(dimethylamino)benzaldehyde ( 4m ) against all the tested bacterial and fungal strains. Compound 4i has shown good activity (48% mortality) against Meloidogyne incognita after 48 h of exposure at 250 µg/mL concentration.     

Synthesis of Heterocycles Having Double Characters: As Antimicrobial and Surface Active Agents

A new series of anionic surfactants having double function as antimicrobial and surface active agents have been synthesized by reaction of 4(H)‐3,1‐benzoxazinone 3 and quinazolinethione 10 with nitrogen nucleophiles and activated olefinic compounds. The compounds were evaluated for their surface activity as well as the antimicrobial and biodegradability properties.     

Synthesis,characterization and biological activity of bis(3‐Aryl‐1‐hexahydropyrimidinyl)methanes. Novel heterocyclic polyamine derivatives

A method is described for the synthesis of bis(3‐aryl‐1‐hexahydropyrimidinyl)methanes 1, by condensation of N‐aryl‐1,3‐propanediarnines 2 with formaldehyde. The reaction mechanism involves N‐arylhexahydropyrimidines 3 as intermediates. Such compounds can also be prepared efficiently by a methylene exchange reaction between bis‐hexahydropyrimidines 1 and the corresponding diamines 2. The antimicrobial activity of compounds 1 was evaluated by the disk diffusion method and some of them showed moderate to good growth inhibition activity.     

Synthesis and in vitro Study of Novel Methylenebis(phenyl- 1,5-benzothiazepine)s and Methylenebis(benzofuryl-1,5- benzothiazepine)s as Antimicrobial Agents

A series of methylenebis(phenyl-1,5-benzothiazepine)s 4 and methylenebis(benzofuryl-1,5-benzothiazepine)s 5 were prepared by the reaction of methylene-bis-chalcones 3 with 2-aminothiophenol for 4 and followed by the condensation with chloroacetone for 5. The structures of the synthesized compounds have been confirmed by their IR, 1H NMR, 13C NMR, MS and elemental analyses. All the synthesized compounds were tested for their antimicrobial activity against Gram-positive, Gram-negative bacteria and fungi. To elucidate the essential structural requirements for the antimicrobial activity, the preliminary structure-activity relationship has been described. Among the compounds tested, the dimeric compounds 4f, 4g, 5f and 5g were found to be most active against Bacillus subtilis, Bacillus sphaericus, Staphylococcus aureus, Klebsiella aerogenes and Chromobacterium violaceum. Similarly these dimeric compounds showed potent antifungal activity against Candida albicans, Aspergillus fumigatus, Trichophyton rubrum, and Trichophyton mentagrophytes. It is interesting to note that the dimeric compounds with substituents of heterocyclic ring at the 4th position of benzothiazepine system displayed notable antibacterial activity equal to that of streptomycin and penicillin. Further, the activity of all the dimeric compounds was compared with that of their monomeric compounds, and it is interesting to note that almost all the dimeric compounds showed enhanced activity than their monomeric compounds.     

Synthesis of 1,4-Benzothiazine Compounds Containing Isatin Hydrazone Moiety as Antimicrobial Agent

A series of novel 3‐methyl‐N"‐(2‐oxoindolin‐3‐ylidene)‐4H‐benzo[b][1,4]thiazine‐2‐carbohyrazides have been synthesized and studied on their in vitro antimicrobial activity potency to establish structure‐activity relationship. Several compounds demonstrated promising antifungal and antibacterial activity; however, other tested compounds exhibited moderate to poor antimicrobial activity with respect to the reference drug against the test strains.     

Synthesis and Pharmacological Evaluation of Some New Chromeno[3,4‐c]pyrrole‐3,4‐dione‐based N‐Heterocycles as Antimicrobial Agents

The reaction of 2‐oxo‐2H‐chromene‐3‐carboxamide ( 1 ) with carbon disulfide afforded 1‐mercaptopyrrolo[3,4‐c ]chromene‐3,4‐dione ( 3 ). The latter compound was utilized as versatile building block for new azole systems via incorporating in a series of manipulations including cyclocondensation reactions. The structure of the newly synthesized compounds has been confirmed by IR, ¹H NMR, ¹³C NMR, mass spectral, and elemental analysis. Furthermore, some selected compounds were screened in vitro for their antimicrobial activities. The results declared that most of the synthesized compounds have high antimicrobial activity.