Synthesis and antimicrobial activity of 2,4-diaryl-2,3-dihydrobenzo[b][1,4]thiazepines

A new series of structurally diverse 2,3-dihydrobenzo[b][1,4]thiazepines (2,3-dihydro-1,5-benzothiazepines) with substituted phenyl groups at C(2) and C(4) have been synthesized by reaction of 3-(5-bromo-2-methoxyphenyl)-1-arylpropen-1-ones with 2-aminobenzenethiols. The structures of all the synthesized compounds were confirmed by their analytical and spectral data (IR, ¹H NMR, ¹³C NMR). All the synthesized compounds were evaluated for antibacterial and antifungal activity against a variety of bacterial and fungal strains and interesting results were obtained. Some of the compounds had antibacterial and antifungal activity comparable to that of ciprofloxacin and fluconazole.     

Synthesis and antibacterial activity of N-[2-(2-naphthyl)ethyl]piperazinyl quinolones

A series of N-[2-(2-naphthyl)ethyl]piperazinyl quinolones containing a carbonyl related functional groups (oxo- or oxyimino-) on the ethyl spacer was synthesized and evaluated for antibacterial activity. The synthesis of N-[2-(2-naphthyl)ethyl]piperazinyl quinolones was achieved through the versatile and efficient synthetic route that involved reaction of piperazinyl quinolones with appropriate α-bromoketone or α-bromooxime derivatives. The structures of new compounds were confirmed by elemental analysis, IR and NMR spectra. Antibacterial data indicated that some of the new N-[2-(2-naphthyl)ethyl]piperazinyl quinolones showed good antibacterial activity and modification of the position 8 and N-1 substituent on quinolone ring, and ethyl spacer functionality produced significant changes in activity against Gram-positive and Gram-negative bacteria.     

Engaging thieno[2,3-b]indole-2,3-dione for the efficient synthesis of spiro[indoline-3,4′-thiopyrano[2,3-b]indole] by reaction with N-substituted isatilidenes

A simple and efficient method, proceeding through a new mechanistic pathway, for the synthesis of spiro[indoline-3,4-thiopyrano[2.3-b]indole derivatives have been developed by exploiting the reaction of thieno[2,3-b]indole-2,3-dione with N-substituted isatilidenes. The compounds synthesized have been screened for antibacterial activity. The generality of the reaction and mechanistic rationale are presented.     

Synthesis and Antimicrobial Evaluation of New Monocyclic β‐Lactams

A simple, practical, and efficient approach to synthesize new series of 2‐(3‐(2,4‐dichlorophenoxy)‐2‐(4‐(dimethylamino)phenyl)‐4‐oxoazetidin‐1‐ylamino)‐N‐arylacetamide by Staudinger [2 + 2] cycloaddition reaction. The titled compounds were evaluated for their antibacterial and antifungal activity against eight microorganisms. All the newly synthesized compounds are characterized by IR, ¹H‐NMR, and mass spectroscopic data.     

Synthesis,Characterization, and Antimicrobial Studies of Some Quinolines Containing 1,3-Thiazines

6/8-Substituted-2-chloroquinoline-3-carboxylic acids, upon reaction with 3-(p-substituted aryl)-4H-5-mercapto-1,2,4-triazoles in the presence of sodium acetate and an acetic anhydride medium, afforded a novel series of 2-(p-substituted aryl)-s-triazolo[5,1-b]-6/8-substituted quinolino [1,3] thiazin-9(H)-ones. The structures of the new compounds were elucidated by IR, ¹H NMR, and mass spectral studies. All the newly synthesized compounds have been screened for their antibacterial and antifungal activities. Most of them showed significant activity comparable with that of the standards Furacin and Flucanazol.     

Novel 5H-[1,2,4]oxadiazolo[4,5-a]pyrimidin-5-one derivatives as antibacterial and anticancer agents: Synthesis and biological evaluation

A novel class of 5H-[1,2,4]oxadiazolo[4,5-a]pyrimidine derivatives was prepared, characterized, and tested for its antibacterial and anticancer potential against thirteen strains and five human cancer cell lines. The synthetic method was optimized, and a proposed reaction mechanism was also presented. The compounds containing the 5-bromo-pyrimidine moiety exhibited moderate antibacterial potencies against Gram-positive strains. Furthermore, the newly prepared compounds displayed selectively antiproliferative activity against human cancer cell lines. These current results will help us to further optimize and develop new drug candidates for clinical studies as novel antibacterial or anticancer agents.     

Synthesis of Some New Biologically Active Sulfur Compounds Containing Pyrazolo[3,4-d] pyrimidine Moiety

A novel series of the pyrazolo[3,4-d]pyrimidines having biologically active sulfur moieties 3-20 were prepared via reaction of 4-mercapto-1-phenyl-1 H -pyrazolo[3,4-d]pyrimidine 3 with different reagents. Identification of the new compounds was established by elemental analyses, IR, 1 H-NMR, and mass spectral data. Some of the obtained compounds showed the interesting antimicrobial activity comparable to antibiotic chloramphenicol as standard antibacterial agent and Terbinafin as a standard antifungal agent.     

Synthesis of a 4H-anthra[1,2-b]pyran derivative and its antimicrobial activity

The five-step synthesis of the new 4H-anthra[1,2-b]pyran derivative 1 is reported. The key steps in this approach included a Marschalk alkylation of 1,4-dihydroxyanthraquinone followed by a Baker-Venkataraman reaction and then an acid-catalyzed cyclization of ring A to form the 4H-anthra[1,2-b]pyran system. Two compounds, the 4H-anthra[1,2-b]pyran 1 and the anthraquinone derivative 6 were evaluated for antimicrobial activity and showed moderate antialgal, antifungal, and antibacterial activities.     

Microwave-assisted synthesis and biological activity of new Schiff bases derived from dimers of 4-amino-3-[3-(1-benzyl)indole]-5-thiomethyl-1,2,4-triazole

An expeditious method with microwave irradiation has been developed for synthesis of novel Schiff bases from dimers of 4-amino-3-[3-(1-benzyl)indole]-5-thiomethyl-1,2,4-triazole. Its distinct advantages are short reaction times and good conversion. The structures of these new Schiff bases were established by ¹H NMR, IR, and mass spectroscopy, and elemental analysis. The antibacterial activity of ten novel Schiff bases against three bacterial strains was studied by the disk diffusion method. Preliminary results indicated that some of the compounds had strong antibacterial activity.     

Synthesis of Some New 4-{2-[(Aryl)amino]-1,3-thiazol4-yl}benzene-1,2-diols as Possible Antibacterial and Antifungal Agents

Some new 4-{2-[(aryl) amino]-1,3-thiazol-4-yl}benzene-1,2-diols are prepared and characterized by spectral analysis. The newly prepared compounds are studied for their antibacterial and antifungal activity. Interestingly, almost all the compounds are found to possess promising antibacterial and antifungal activity against all tested microorganisms.     

含脱羧脱氢松香基的1,2,4-三唑并[3,4-b]-1,3,4-噻二唑衍生物的合成、表征及抑菌活性

用POCl3为催化剂和脱水剂,3-取代-4-氨基-5-巯基-1,2,4-三唑4和10分别与脱氢松香酸1反应制得14种未见文献报道的3-取代-6-(4′-脱羧脱氢松香基)-1,2,4-三唑并[3,4-b-]-1,3,4-噻二唑衍生物]5a~5e和11a~11i;所有化合物的结构均经IR、¹H NMR、¹³C NMR 和MS测试技术分析确认。 抑菌活性测试表明,目标化合物对白色念珠菌(C.Albicans)、大肠杆菌(E.Coli)、藤黄微球菌(M.Luteus)和痢疾志贺杆菌(S.Dysenteriae)均有一定的抑制作用。     

Synthesis and antibacterial activity of novel 7-substituted-6-fluoro-1- fluoromethyl-4-oxo-4H-[1,3thiazeto[3,2-a]quinoline-3-carboxylic acid derivatives

A series of 7-substituted-6-fluoro-1-fluoromethyl-4-oxo-4H- [1,3]thiazeto[3,2-a]quinoline-3-carboxylic acid derivatives (2a-1) was prepared and evaluated for antibacterial activity. These compounds were obtained by deacylation of 4-benzoyloxy-2-(1-chloro-2-fluoroethyl)thio-6,7- difluoroquinoline-3-carboxylate (10) and subsequent intramolecular cyclization followed by substitution with cyclic amines and then hydrolysis. The intramolecular cyclization reaction of 18, one of the diastereomers (17, 18) revealed that the cyclization reaction proceeded through an inversion to afford (-)-11a in good chemical and optical yield. The enantiomers of 2a were prepared from the enantiomers of 11a, which were obtained by the optical resolution of the racemate using high-performance liquid chromatography (HPLC). Compounds 2a,b showed excellent in vitro and in vivo antibacterial activity against both gram-negative and gram-positive bacteria including quinolone and Methicillin-resistant Staphylococcus aureus.     

3-杂环硫亚甲基头孢菌素衍生物的半合成及抗菌活性研究

通过取代噁二唑硫酮、噻二唑硫酮及三唑硫酮分别和头孢菌素母体7-ACA反应,制得14种7-氨基-3-杂环硫亚甲基头孢菌素新母体2a-2n,用1-芳基-5-甲基-1H-1,2,3-三唑-4-甲酰氯与头孢菌素新母体缩合,制得2种新的7β-(1-芳基-5-甲基-1H-1,2,3-三唑-4-甲酰胺基)-3-(2-取代1,3,4-bI二唑-5-硫亚甲基)头孢菌素4c,4d.新化合物结构经元素分析、IR、¹HNMR及FAB-MS确认.初步体外抗菌结果表明,新母体化合物2对革兰氏阳性菌有抑制活性且在相同浓度下比7-ACA强20倍,而头孢菌素4c,4d对革兰氏阳性和阴性菌都有显著抑制活性.     

Synthesis,spectral, DFT calculations and antibacterial studies of Fe(III) complexes of new fluorescent Schiff bases derived from imidazo[4',5':3,4]benzo[1,2‐c]isoxazole

New fluorescent heterocyclic ligands were synthesized by the reaction of 8‐(4‐chlorophenyl)‐3‐alkyl‐3H‐imidazo[4',5':3,4]benzo [1,2‐c]isoxazol‐5‐amine with p‐hydroxybenzaldehyde and p‐chlorobenzaldehyde in good yields. The coordination ability of the ligands with Fe³⁺ ion was examined in an aqueous metanolic solution. Schiff base ligands and their metal complexes were characterized by elemental analyses, IR, UV–vis, mass, and NMR spectra. The optical properties of the compounds were investigated and the results showed that the fluorescence of all compounds is intense and their obtained emission quantum yields are around 0.15 – 0.53. Optimized geometries and assignment of the IR bands and NMR chemical shifts of the new complexes were also computed by using density functional theory (DFT) methods. The DFT‐calculated vibrational wavenumbers and NMR chemical shifts are in good agreement with the experimental values, confirming suitability of the optimized geometries for Fe(III) complexes. Also, the 3D‐distribution map for HOMO and LUMO of the compounds were obtained. The new compounds showed potent antibacterial activity and their antibacterial activity (MIC) against Gram‐positive and Gram‐negative bacterial species were also determined. Results of antibacterial test revealed that coordination of ligands to Fe(III) leads to improvement in the antibacterial activity.     

Regioselective Synthesis and Antibacterial Activity Studies of 1,2,3‐Triazol‐4‐YL]‐4‐methyl‐2H‐chromen‐2‐ones

Synthesis, spectral analysis, and antibacterial activity of new coumarin derivatives are described in this paper. Twelve new coumarin derivatives were synthesized in moderate to good yields by the react with 4‐methyl‐6‐(prop‐2‐ynyloxy)‐2H‐chromen‐2‐one ( 3a – c ) and ethyl azide ( 4a – l ) and done by the click reaction to obtained 6‐[(l‐ethyl‐lH‐l,2,3‐triazol‐4‐yl)methoxy]‐4‐methyl‐2H‐chromen‐2‐ones ( 5a – l ). The structures of all the newly synthesized molecules were assigned by elemental analysis and spectral data. The synthesized compounds were screened for their antibacterial activities strains using Cup plate method.     

咪唑[1,5-a]吡啶鎓盐的合成、表征及生物活性测定

通过三组份串联反应合成一系列咪唑[1,5-a]吡啶鎓盐,利用1H NMR、13C NMR、MS以及X射线单晶衍射确定其结构,其中以二乙烯三胺与三乙烯四胺为原料获得预期外的结构。以青霉素作为对照,研究了化合物的抗菌性。结果表明,所合成的化合物对溶壁微球菌和乙型链球菌均有抗菌效果,化合物2的抗菌效果最好;含有杂原子O的化合物3对嗜麦芽单胞菌和肺炎克雷伯氏菌的抗菌能力优于青霉素;联苯桥联的刚性双齿咪唑[1,5-a]吡啶鎓(5)比乙基桥联的柔性双齿咪唑[1,5-a]吡啶鎓(4)的抗菌性更强;化合物6为单齿大π体系芳香环,其抗菌效果较好,而化合物7和8为双齿的大π体系芳香环,其抗菌效果较弱。     

A synthesis and biological screening of newly substituted 9-methyl-6-aryl-[1,2,4]triazolo[4,3-a][1,8]naphthyridines using chloranil

An effective, mild, and convenient method for the synthesis of 10 new substituted 9-methyl-6-aryl-[1,2,4]triazolo[4,3-a][1,8]naphthyridines (5a–j) by the oxidation of the corresponding 2-(2-ethylidenehydrazinyl)-3-aryl-1,8-naphthyridines (4a–j) using chloranil under conventional method has been described. The structures of synthesized compounds (5a–j) were established on the basis of their elemental analysis and spectral (IR, Mass, ¹³C- and¹H-NMR) data. The new compounds were synthesized with the objective of studying their antibacterial activity. The reaction will be characterized by easy workup, good efficacy, simple purification of the products, and availability of catalyst.     

Synthesis and antimicrobial studies of new pyridine derivatives

2-(p-Acetylaminobenzenesulfonylamido)-substituted benzothiazoles were prepared from 2-amino-substituted benzothiazoles and p-acetamidobenzenesulfonyl chloride using a mixture of pyridine and Ac₂O, which formed an electrophilic N-acetyl- pyridinium complex facilitating condensation to give the desired products by removal of HCl. 2-[4-(Substituted benzothiazol-2-yl)aminosulfonylanilino]pyridine-3-carboxylic acids (synthesized from 2-chloropyridine-3-carboxylic acid and the corresponding substituted 2-(p-aminobenzenesulfonylamido)benzothiazole in 2-ethoxyethanol using Cu-powder and K₂CO₃) were then converted to acid chlorides, which on further reaction with piperazine and 4-methoxyphenylpiperazine yielded the corresponding 2-[4-(substituted benzothiazol-2-yl)amino-sulfonyl]anilino-3-(piperazinocarbonyl) pyridine and 2-[4-(substituted benzothiazol-2-yl)amino-sulfonyl]anilino-3-[(4-methoxyphenyl)piperazin-1-yl-carbonyl]pyridine. The structures of the new compounds have been established on the basis of their elemental analyses as well as IR, ¹H NMR, and mass-spectral data. All the compounds have been screened for antimicrobial activity and found to possess considerable antibacterial activity.     

Synthesis and antibacterial activity of some novel triazolothienopyrimidines

A novel series of some novel 5-substituted-1,2,4-triazolo[4,3-c]8,9,10-trihydrocyclopenta/8,9,10,11,12-pentahydrocyclohepta[b]thieno[3,2-e]pyrimidin-3-thiones has been synthesized. The intermediates 4-chloro-2-substituted-5,6,7-trihydrocyclopenta/5,6,7,8,9-pentahydrocyclohepta[b]thieno[2,3-d]pyrimidines were prepared by warming 2-substituted-5,6,7-trihydrocyclopenta/5,6,7,8,9-pentahydrocyclohepta[b]thieno[2,3-d]pyrimidin-4[3H]-ones with oxalyl chloride. Thieno[2,3-d]pyrimidin-4[3H]-ones were prepared by a novel, microwave assisted, solvent free, synthetic route under basic conditions hitherto unreported in the literature from ortho amino ester of thiophene. The chloro derivatives, without further purification, were hydrazinated to yield 2-substituted-4-hydrazino-5,6,7-trihydrocyclopenta/5,6,7,8,9-pentahydrocyclohepta[b]thieno[2,3-d]pyrimidines. These compounds were cyclized with carbon disulphide to give the title compounds in quantitative yields. The final compounds were screened for antibacterial activity by Kirby Bauer's method using ampicillin as the standard against various gram positive and gram negative bacteria. All the compounds showed antibacterial activity comparable with the standard.     

Synthesis and biological activity of new 1,3-dioxolanes as potential antibacterial and antifungal compounds

A series of new enantiomerically pure and racemic 1,3-dioxolanes 1-8 was synthesized in good yields and short reaction times by the reaction of salicylaldehyde with commercially available diols using a catalytic amount of Mont K10. Elemental analysis and spectroscopic characterization established the structure of all the newly synthesized compounds. These compounds were tested for their possible antibacterial and antifungal activity. Biological screening showed that all the tested compounds, except 1, show excellent antifungal activity against C. albicans, while most of the compounds have also shown significant antibacterial activity against S. aureus, S. epidermidis, E. faecalis and P. aeruginosa.