Synthesis and Antimicrobial Activities of New Polyhalogenated Benzimidazoles

A series of new polyhalogenated benzimidazoles has been synthesized and their antibacterial and antiprotozoal activity was evaluated. Several of new substituted halogenobenzimidazoles and their 2′‐deoxynucleosides showed noteworthy antiprotozoal toxicity particularly against Giardia lamblia. The most potent agents against bacteria and fungi were 4,5,6,7‐tetrachlorobenzimidazoles with polyfluoroalkyl chain at position 2 of the heterocyclus.     

碘促进的苯并咪唑及其衍生物的合成

在碘的氧化作用下,由伯醇和邻苯二胺一步合成了苯并咪唑及其衍生物。考察了碘和碳酸钾用量及温度对反应产率的影响,反应较佳的条件为n(o-ClC6H4CH2OH)∶n(o-phenylenediamine)∶n(I2)∶n(K2CO3)=1.0∶1.1∶5.0∶5.0,反应温度70℃,反应时间5 h。用方法A在较佳的反应条件下2-(2-氯苯基)苯并咪唑的产率可达86%,用方法B其产率达69%。没有选择传统的醛或酸作为反应底物,而是选择了伯醇在碘的氧化作用下直接合成了目标产物,反应为合成苯并咪唑及其衍生物的一个新方法,探讨了可能的反应机理。     

Synthesis of Mono-and Di-fluorinated Benzimidazoles

Three efficient methods to synthesize mono‐ and di‐fluorinated benzimidazoles are reported. These methods provide 5‐amino‐6‐fluoro‐benzimidazoles ( 5 ), 5,7‐difluoro‐benzimidazoles ( 10 ), and 6‐fluoro‐benzimidazoles ( 13 ) starting from commercially available 1,5‐difluoro‐2,4‐dinitrobenzene (DFDNB), 2,3,4,5‐tetrafluoro‐6‐nitrobenzoic acid (TFNBA), and 2,4‐difluoro‐1‐nitrobenzene (DFNB), respectively.     

Synthesis and Antimicrobial Studies of Novel Billogical Heterocycles

The synthetic route of sildenafil promoted us to synthesize new object molecules. New analogues containing a 4-thiazolidinone ring bonded to the phenyl moiety at the 2-position, 7-(substituted anilino)-6-fluoro-2-(p-meth- oxy-m-{[2-(p-hydroxyphenyl)-4-oxo-1,3-thiazolidin-3-yl]aminocarbonyl}phenylsulfonamido)benzothiazoles (4a—4l) have been synthesized by cyclization with thioglycollic acid of Schiff bases 3a—3l from corresponding 7-(substituted anilino)-6-fluoro-2-(p-methoxy-m-hydrazinocarbonyl phenylsulfonamido)benzothiazoles (2a—2l). Compounds 2a—2l in turn were prepared by dehydroxyhalogenation followed by condensation with hydrazine hydrates of acids 1a—1l. Compounds 1a—1l in turn were prepared by chlorosulfonation of o-methoxy benzoic acid followed by condensation with 6-fluoro-7-(substituted anilino)-2-aminobenzothiazoles. Final compounds have been characterized by their elemental analysis, IR, NMR and mass spectra. All the synthesized compounds have been screened for their antimicrobial activities. Some of them showed good activities.     

Synthesis and Antimicrobial Studies of Some Quinolinylpyrimidine Derivatives

The quinolinylpyrimidine derivatives were prepared by the condensation of quinolinyl chalcones with urea (or thiourea) under basic conditions by using both conventional and microwave heating. Their IR, ¹H NMR, ¹³C NMR, mass spectra and CHN analyses confirmed the prepared compounds. The newly prepared quinolinylpyrimidine derivatives were screened for antimicrobial activities against the bacterial strains viz. S. aureus, Shigella, Salmonela, P. aeroginosa, B. Subtilus and E. coli and found considerably active against S. aureus, P. aeroginosa and E. coli.     

由邻硝基苯胺一锅法合成苯并咪唑化合物

以邻硝基苯胺为原料, 在SnCl2•2H2O/KI/HCl体系中, 100 ℃条件下, 一锅法合成12种苯并咪唑化合物. 该方法以水为溶剂, 条件温和, 操作简单, 催化剂易得, 产率较高, 为该类化合物的合成提供了一种新的便利方法.     

Synthesis of Benzimidazoles in Dry Medium

A new route to obtain 2-alkylbenzimidazoles and benzimidazol-2-one or thione is reported, using a natural clay and infrared irradiation in solvent free conditions. This method is a good option to obtain the title compounds in a simple and an inexpensive way.     

Efficient and Inexpensive Synthesis of Benzimidazoles and Quinoxalines

o-Phenylenediamines were reacted with carbonyl compounds, β-ketoesters, and 1,2-diketones in presence of ammonium salts to give benzimidazoles and quinoxalines in very good yields. Ammonium salts are commercial and environmentally benign catalysts.     

苯并咪唑类化合物的合成研究进展

苯并咪唑类化合物应用广泛. 按不同的合成原料和合成方法进行分类, 综述了近年来苯并咪唑类化合物合成研究的新进展.     

Triphenylphosphine Mediated Simple Synthesis of Vinyl-Substituted Benzimidazoles

N -isopropenylbenzimidazolone undergoes a smooth reaction with triphenylphosphine and dialkyl acetylenedicarboxylates to produce highly functionalized salt-free phosphorus ylides in good yields. These stabilized phosphorus ylides exist as a mixture of two geometrical isomers as a result of restricted rotation around the carbon-carbon partial double bond resulting from conjugation of the ylide moiety with the adjacent carbonyl group. These ylides are converted to dialkyl 2-(1-isopropenyl-1H-benzimidazol-2-yl)-but-2-enedioates in boiling toluene.     

合成苯并咪唑类化合物的工艺改进

邻苯二胺磷酸盐与脂肪酸在无溶剂的条件下回流反应合成了苯并咪唑类化合物,其结构经IR确证。正交试验确定最佳反应条件为:邻苯二胺50 mmol,n(邻苯二胺):n(甲酸)=1.0:1.5,磷酸4 g,回流反应7 h。在最佳反应条件下做放大实验,产率89.3%。     

Synthesis and Structural Studies of 4-Thioxopyrimidines with Antimicrobial Activities

Summary. This work describes a two-step, one-pot synthetic method for the formal aza-[3 + 3] cycloaddition between N-alkyl substituted enaminones and benzoyl isothiocyanate, which afforded 4-thioxopyrimidines in reasonable yields. Reaction of acyclic enaminone with a sterically hindered group attached to the nitrogen atom afforded pyridine-2-thione, yet in low yield. The antibacterial, antifungal, and trypanocidal activities of the thioxopyrimidines were evaluated and five compounds exhibited moderate activity against Candida albicans, Micrococcus luteus, and Trypanosoma cruzi. The solid state structures of a thioxopyrimidine, an organic disulfide, and a 1,2,4-triazole were determined by X-ray diffraction analysis.     

Advances in the Synthesis of Ring-Fused Benzimidazoles and Imidazobenzimidazoles

This review article provides a perspective on the synthesis of alicyclic and heterocyclic ring-fused benzimidazoles, imidazo[4,5-f]benzimidazoles, and imidazo[5,4-f]benzimidazoles. These heterocycles have a plethora of biological activities with the iminoquinone and quinone derivatives displaying potent bioreductive antitumor activity. Synthesis is categorized according to the cyclization reaction and mechanisms are detailed. Nitrobenzene reduction, cyclization of aryl amidines, lactams and isothiocyanates are described. Protocols include condensation, cross-dehydrogenative coupling with transition metal catalysis, annulation onto benzimidazole, often using CuI-catalysis, and radical cyclization with homolytic aromatic substitution. Many oxidative transformations are under metal-free conditions, including using thermal, photochemical, and electrochemical methods. Syntheses of diazole analogues of mitomycin C derivatives are described. Traditional oxidations of o-(cycloamino)anilines using peroxides in acid via the t-amino effect remain popular.     

Recent Advances in the Synthesis of Isoquinoline-Fused Benzimidazoles

This review includes recent developments in the synthesis of benzo[4,5]imidazo[2,1-a]isoquinolines with particular attention given to categorizing protocols based on the structural features of the ring architecture and crystallographically characterized reaction products.     

Efficient One-Pot Synthesis of Benzimidazoles Under Solvent-Free Conditions

A green, efficient method for the synthesis of various 2-aryl-benzimidazoles in the presence of hypervalent iodine as the oxidant at room temperature under solvent-free conditions is reported. The salient features of this method include mild conditions, short reaction times (3–5 min), excellent yields, and simple procedure.     

Synthesis and Antimicrobial Studies of Novel Imidazole Containing Bisazetidinones and Bisthiazolidinone Derivatives

A simple, practical, and efficient approach to new series of imidazole containing bisazetidinones ( 7a , 7b , 7c , 7d , 7e , 7f , 7g , 7h , 7i , 7j and 9a , 9b , 9c , 9d , 9e , 9f , 9g , 9h , 9i , 9j ) was prepared by Staudinger [2 + 2] cycloaddition reaction, and bisthiazolidinones ( 8a , 8b , 8c , 8d , 8e , 8f , 8g , 8h , 8i , 8j and 10a , 10b , 10c , 10d , 10e , 10f , 10g , 10h , 10i , 10j ) were obtained by cyclization of bisimines with thioglycolic acid. The bisimines ( 5a , 5b , 5c , 5d , 5e , 5f , 5g , 5h , 5i , 5j and 6a , 6b , 6c , 6d , 6e , 6f , 6g , 6h , 6i , 6j ) were synthesized by the condensation of 3‐(1‐(3‐aminobenzyl)‐4, 5‐dihydro‐1H‐imidazol‐2‐yl) aniline ( 3 , 4 ) with a series of different substituted aromatic aldehydes. All the newly synthesized target compounds were evaluated for their in vitro antimicrobial activity against two Gram‐positive bacteria and two Gram‐negative bacteria. Additionally, these synthesized compounds were tested for their antifungal activities. Few compounds showed very good antibacterial and antifungal activity.     

Reusable Nano-Zirconia-Catalyzed Synthesis of Benzimidazoles and Their Antibacterial and Antifungal Activities

In this article, a zirconia-based nano-catalyst (Nano-ZrO₂), with intermolecular C-N bond formation for the synthesis of various benzimidazole-fused heterocycles in a concise method is reported. The robustness of this reaction is demonstrated by the synthesis of a series of benzimidazole drugs in a one-pot method. All synthesized materials were characterized using ¹HNMR, ¹³CNMR, and LC-MS spectroscopy as well as microanalysis data. Furthermore, the synthesis of nano-ZrO₂ was processed using a standard hydrothermal technique in pure form. The crystal structure of nano-ZrO₂ and phase purity were studied, and the crystallite size was calculated from XRD analysis using the Debye–Scherrer equation. Furthermore, the antimicrobial activity of the synthesized benzimidazole drugs was evaluated in terms of Gram-positive, Gram-negative, and antifungal activity, and the results were satisfactory.     

苯并咪唑及其衍生物合成与应用研究进展

苯并咪唑及其衍生物具有良好的生物活性, 而且是一种重要的药物中间体. 由于它们具有良好的生物活性和反应活性, 一直都是研究的热点. 从该类化合物的合成与应用两个方面综述了近年来该领域的重要研究成果.     

两步法无催化剂高效合成2-取代苯并咪唑

芳香醛与NaHSO3加成得到羟基磺酸盐,加入邻苯二胺或取代邻苯二胺在乙醇中回流反应,空气氧化直接得到2-取代苯并咪唑. 在合成的15个化合物中,产率均超过80%. 其中化合物2-(4-氯苯基)-6-甲氧基-1H-苯并咪唑尚未见报道. 所有产物结构经元素分析、IR、1H NMR分析技术得到确证. 合成方法无需任何催化剂,操作简单,条件温和,环境友好.