Condensation Of O-phenylenediamine Research Articles

Environmentally Benign Room-Temperature Synthesis of Quinoxalines using Silica-Supported PPA as a Recyclable Catalyst

We have reported highly proficient, environmental benign, SiO2@PPA catalyzed protocol for the synthesis of 2, 3-diphenyl quinoxalines via condensation of ophenylene diamine with α-diketones. Surface modified silica with polyphosphuric acid offered outstanding catalytic efficiency at room temperature and it sustained up to fifth cycle. The methodology boasts a hassle-free catalyst preparation process, operates under energy-conserving conditions, yields a commendable (93-84%) output of the targeted moieties and exhibits catalyst recyclability. These appealing features position it as a superior and eco-friendly alternative to traditional methods for synthesizing quinoxalines.

A new class of pyrrolo[2,3-b]quinoxalines: synthesis, anticancer and antimicrobial activities

Abstract A series of 3-chloro-1-aryl-4-dihydro-2H-pyrrolo[2,3-b]quinoxalin-2-ones and 3-chloro-1-aryl-6,7-dimethyl-1,4-dihydro-2H-pyrrolo[2,3-b]quinoxalin-2-ones was prepared by the condensation of o-phenylenediamine or 4,5-dimethyl-1,2-aminobenzene with N-aryl-3,4-dichloro-maleimides. All the prepared quinoxalines were tested for their antitumor activity against three human cancer cell lines (prostate cells PC3, colorectal cells Caco-2, and cervical cells HeLa), and a mammalian cell line (Vero cells). The compounds were also tested for their antibacterial properties against three different bacterial cells Escherichia coli, Bacillus spizizenii, and Pseudomonas aeruginosa. The compounds 3c, 3d, 3g, 3h, 3i and 4a, 4b, 4h showed anti-proliferative activity against the tested cell lines. Regarding their antibacterial activity, compounds 3a, 3g, 4a, and 4h showed inhibitory activity against E. coli, and B. spizizenii only.

Synthesis of 1H-benzimidazoles via the condensation of o-phenylenediamines with DMF promoted by organic acid under microwave irradiation

An effective, green and eco-friendly method was developed to synthesize 1H-benzimidazole under microwave irradiation. The reactions of substituted o-phenylenediamine with DMF were efficiently promoted by butanoic acid, and the desired product 1H-benzimidazole derivatives were obtained in good to excellent yields. Compared with the conventional heating method, microwave irradiation significantly reduced the reaction time and improved the yields of the target products.

Synthesis and Characterization of New benzimidazole-nitrone Derivatives, and Study of Their Effect as Anti-bacterial.

New benzimidazole derivatives (benzimidazole-nitrone) were synthesized from the condensation of o-phenylene diamine with p-amino benzaldehyde in the presence of (P-TsOH\EtOH). Then the benzimidazole compounds that containing an imine group were oxidized to obtain a nitrone group by used peracetic acid and identified by FT-IR, H1-NMR spectra, and elemental analysis. All compounds applied to the Escherichia coli and Staphylococcus aureus gave a different result. The compounds which have (OH, Br, Cl, OCH3) groups appeared activity as anti-bacterial while compound (2) when R=H don’t have activity for each type of bacteria that used

A Review on Modern Approaches to Benzimidazole Synthesis.

Cancer is the second most source of cessation of life globally, with 9.6 million expirations at each stage around the globe. The resistance to the current chemotherapies urges researchers to develop new drugs to be available in the market. Among the wide range of drugs synthesized, heterocyclic compounds play a major role due to the abundance of heterocyclic rings in biological substances. In medicinal chemistry, benzimidazole is an important pharmacophore and a privileged structure. This bicyclic compound is made up of the fusion of a six-membered benzene ring and a five-membered imidazole ring with two nitrogen atoms at 1,3-positions. The benzimidazole ring has a great deal of stability. Many strong acids and alkalis do not affect benzimidazoles. The benzene ring of benzimidazole cleaves only under extreme conditions. Except in certain circumstances, the benzimidazole ring is also quite resistant to reduction. It is the most popular nucleus to study because of its wide range of biological functions. The recently developed methods for preparing benzimidazoles, such as condensation of o-phenylene diamines (OPDs) with aldehydes and many others using a wide range of nano, metal-based catalysts under solventfree conditions, are discussed in detail in the current studies.

An Efficient and Practical Process for the Synthesis of Benzimidazole and Benzothiazole Derivatives Catalyzed by Layered Zirconium Phosphate: Effect of Calcinations Temperature

Abstract—In this work, layered zirconium phosphates were synthesized via a reflux method and calcined at different temperatures (200, 400, and 600°C). The catalytic activity of the prepared solids was tested in the condensation of o-phenylenediamine and o-aminothiophenol with various aromatic aldehydes. The reaction conditions were optimized taking into account some parameters that control the reaction, namely the nature and volume of the solvent and the mass of the catalyst. The results showed that solid ZrP-200 (layered -zirconium phosphate calcined at 200°C) is the best performing catalyst for this reaction, because it has good catalytic activity and can be reused for at least five cycles with only a slight decrease in catalytic activity. In addition, a possible mechanism for the synthesis of benzimidazoles and benzothiazoles over ZrP-200 was proposed and discussed at the end of this study.

Synthesis of a dibenzimidazole compound and its corrosion inhibition behavior on AZ91D Mg alloy in 3.5 wt.% NaCl solution

In this work, a low-cost and easily purified small molecule dibenzimidazole compound (BBI) was synthesized by the condensation of o-phenylenediamine and malonic acid. BBI was a new corrosion inhibitor for magnesium alloys and its corrosion inhibition behavior on AZ91D magnesium alloy was studied by electrochemical measurements, surface analysis and theoretical calculations in 3.5 wt.% NaCl solution at 30 °C. The adsorption behavior and corrosion inhibition mechanism of BBI molecules were discussed. It was found that BBI exhibited excellent inhibition effect on the corrosion of magnesium alloy. When BBI concentration was 0.25 g/L, the optimal corrosion inhibition efficiency was 86.2%. The adsorption of BBI molecule obeyed Langmuir adsorption on the surface of magnesium alloy, and one side of BBI molecule was adsorbed on the surface of magnesium alloy in parallel through physical and chemical mixed adsorption.

Facile one pot synthesis of 2-substituted benzimidazole derivatives under mild conditions by using engineered MgO@DFNS as heterogeneous catalyst.

Benzimidazole derivatives are considered as important heterocyclic motifs that show a wide range of pharmaceutical applications. In view of their wide-ranging bioactivities, it is imperative to direct research on the sustainable catalytic synthesis of benzimidazole. Therefore, herein, we report a novel approach for the synthesis of benzimidazole and its derivatives with engineered MgO supported on dendritic fibrous nano silica (MgO@DFNS) as a sustainable heterogeneous catalyst. The catalyst MgO@DFNS was thoroughly characterized to understand its physio-chemical properties using XRD, FE-SEM, XPS, FT-IR, zeta potential, HR-TEM, TGA, TPR and TPD. The obtained results suggested that the catalyst MgO@DFNS prepared well and have the desired characteristics in it. After the successful characterisation of the prepared catalyst MgO@DFNS, it was applied in the synthesis of benzimidazole derivatives via condensation of o-phenylenediamine, and various aromatic and aliphatic aldehydes under ambient temperature. The catalyst produced a clean reaction profile with excellent yields in a shorter time under the umbrella of green chemistry. The effect of reaction parameters such as the effect of time, catalyst dosage, loading of MgO, effect of solvents and effect of different homo and heterogeneous catalyst were also tested. Furthermore, to understand the scope of the catalyst different substituted diamines and substituted aldehydes were reacted and obtained desired products in good to efficient yield. In addition, a recyclability study was also conducted and it was observed that the catalyst could be recycled for up to six cycles without noticeable changes in the morphology and activity. We believe that the present methodology gave several advantages such as an eco-friendly method, easy work-up, good selectivity, high yields and quick recovery of catalyst. MgO@DFNS is highly stable for several cycles without significant loss of its activity, which possibly demonstrates its applicability at the industrial scale.

Reusable nano-catalyzed green protocols for the synthesis of quinoxalines: an overview.

Heterocyclic compounds are very widely distributed in nature and are essential for life activities. They play a vital role in the metabolism of all living cells, for example, vitamins and co-enzyme precursors thiamine, riboflavin etc. Quinoxalines are a class of N-heterocycles that are present in a variety of natural and synthetic compounds. The distinct pharmacological activities of quinoxalines have attracted medicinal chemists considerably over the past few decades. Quinoxaline-based compounds possess extensive potential applications as medicinal drugs, presently; more than fifteen drugs are available for the treatment of different diseases. Diverse synthetic protocols have been developed via a one-pot approach using efficient catalysts, reagents, and nano-composites/nanocatalysts etc. But the use of homogeneous and transition metal-based catalysts suffers some demerits such as low atom economy, recovery of catalysts, harsh reaction conditions, extended reaction period, expensive catalysts, the formation of by-products, and unsatisfactory yield of products as well as toxic solvents. These drawbacks have shifted the attention of chemists/researchers to develop green and efficient protocols for synthesizing quinoxaline derivatives. In this context, many efficient methods have been developed for the synthesis of quinoxalines using nanocatalysts or nanostructures. In this review, we have summarized the recent progress (till 2023) in the nano-catalyzed synthesis of quinoxalines using condensation of o-phenylenediamine with diketone/other reagents with plausible mechanistic details. With this review, we hope that some more efficient ways of synthesizing quinoxalines can be developed by synthetic chemists.

Elaboration of novel urea bearing schiff bases as potent in vitro anticancer candidates with low in vivo acute oral toxicity

A novel series of urea Schiff base derivatives were synthesized via the condensation of o-phenylenediamine, naphthyl isocyanate and appropriate aryl aldehyde. The results of the in vitro cytotoxic activities of compounds 5a–h against cancer cells lines PC3, SKOV-3 and HeLa, revealed that almost all compounds exhibited good to moderate activities Compound 5g owing bromine atom at p-position displayed higher activity compared to homolog 5b possessing chlorine atom due to adequate diameter of bromine which is more favourable than chlorine for the inhibition activity. In addition, compound 5h is the best candidate of this series exhibiting excellent activity for three cancer cells lines. Compound 5h demonstrated also an excellent activity with IC50 value of 0.6±0.3μg/mL for prostate cancer cell line PC3 and it is considered more effective than the standard drug doxorubicin Dox (IC50 = 2.6±0.03μg/mL). The most active compound 5h displayed the best activity against ovarian cancer cell line SKOV3 with IC50 = 1.8±0.2μg/mL. This results are higher than clinically used drug Dox (IC50. 2.2±0.02μg/mL). The results of screening activities cytotoxic effect toward cervix cancer cell line HeLa, affirm that compound 5h manifest an activity with IC50 value of 2.2±0.4μg/mL comparable to Dox (IC50. 1.9±0.04μg/mL). In the current study, in vivo acute oral toxicity assessment of urea Schiff base hybrid compounds 5a – h indicated that there was no mortality on treated female mice during 14 days assessment test compared with the vehicle-treated group confirming the safety with LD50 greater than 2000 mg/kg. In the actual study, the results affirmed that compounds 5a–h manifested in vivo no toxicity to saint cells, the compounds 5b, 5g and 5h presented higher anticancer activities against three cancer cells which authorizes promoters to use them as candidate anticancer agents.

Synthesis of Benzimidazole and Benzothiazole Derivatives using Reusable Waste Stem of Trigonella Foenum-graecum Assisted Zinc Sulphide Nanoparticles: A Green and Efficient Solid Acid Catalyst

In this study, the simple and rapid methods for the preparation of benzimidazole and benzothiazole by the condensation of o-phenylenediamine with the aromatic aldehyde in presence of the zinc sulphide nanoparticles derived from the waste stem of the Trigonella foenum-graecum. The catalyst was prepared by using the waste stem of the Trigonella foenum-graecum. Most of the reaction carried under the mild condition with very high excellent yield. The method is used for the aromatic, unsaturated and heteroaromatic aldehyde. The main advantage of this method is that it takes very short reaction time, solvent free reaction condition, reusable catalyst, milder reaction, easy workup and waste stem of the plant was used.

Antibacterial Potential of 2-(-(2-Hydroxyphenyl)-methylidene)-amino)nicotinic Acid: Experimental, DFT Studies, and Molecular Docking Approach.

The problems associated with antibacterial drug discovery have kept the model of antibacterial drug to an extraordinary low level. Humans carry millions of bacteria; some species of bacteria can cause infectious disease, while some are pathogenic. Infectious bacteria which can reproduce quickly in the body can cause diseases such as tuberculosis, cholera, pneumonia, and typhoid, thus arises an urgent need to develop new drugs. Herein, 2-{[(2-hydroxyphenyl)methylidene]amino}nicotinic acid was synthesized from the condensation of o-phenylenediamine and 5-nitrosalicaldehyde followed by detailed characterization by ultraviolet-visible spectroscopy, vibrational studies FT-IR, nuclear magnetic resonance (1H-NMR, 13C-NMR), and gas chromatography coupled with mass spectroscopy (GC-MS). The complex synthesized was screened against selected microbes in order to establish their potential antimicrobial activity using selected known drugs as reference. From the results obtained, the Schiff base exhibited antimicrobial activity against all the tested microorganisms except Candida albicans isolate, which exhibited zero diameter zone of inhibition. The theoretical investigations of the synthesized compounds were computed using density functional theory (DFT) at the B3LYP/6-311 + + G(d, p) level of theory and in silico molecular docking simulation. By comparing binding affinity of the studied compound and the standard drug (ampicillin), the studied compound docked against bacterial protein showed a high binding affinity for E. coli 6.6kcal/mol and makes it effective as an antibacterial agent for E. coli.

Synthesis and Characterization of New benzimidazole-nitrone Derivatives and Study of Their Effect as Anti-fungal

New benzimidazole derivatives (benzimidazole-nitrone) were synthesized from the condensation of o-phenylene diamine with p-amino benzaldehyde in the presence of (P-TSOH\EtOH) then the benzimidazole compounds that containing an imine group were oxidized to obtain a nitrone group by used peracetic acid and identified by FT-IR, H1-NMR spectra, and elemental analysis. all compounds applied to the candida and aspergillus fungi gave a different result. The compounds have Ph, OH and N(CH3)2 groups as substituted in synthesized benzimidazole derivatives were showed reactivity as anti-fungal.

Synthesis and Pharmacological Evaluation of Novel Benzimidazole Derivatives as Antiulcer and H+ K+ ATPase Inhibitor

Aims: To Synthesis the novel substituted benzimidazole derivatives and screened Pharmacologically as antiulcer and H+ K+ ATPase inhibitor.
 Study Design: Study design as series of substituted benzimidazole derivatives prepared by three different reaction scheme and further evaluated pharmacologically in desired activity.
 Place and Duration of Study: In Patal Dhamal Wadwani College of Pharmacy Yavatmal, Maharashtra, India, between July 2014 to August 2017.
 Methodology: A series of new 2-[(substituted-pyrimidin-4-yl) sulfinyl]-1H-benzimidazole (54a-54i) were synthesized by the condensation of O-phenylenediamine, KOH and CS2 resulting potassium 1-H-benzimidazole 2-thiolate further treated with glacial acetic acid gives 1H-benzimidazole 2- thiol (2-mercaptobenzimidazole). 4-Chloro 2 Methyl, 6-Alkylpyrimidine- 4-ol prepared by ethanimidamide and alkyl acetoacetate gives 2-Methyl, 6-Alkylpyrimidine-4-ol by chlorination using thionyl chloride 4-Chloro 2 Methyl, 6-Alkylpyrimidine- 4-ol was obtained. further reacted with sodium oxide followed by m-chloroperbenzoic finally gives 2-[(substituted-pyrimidin-4-yl) sulfinyl]-1H-benzimidazole. Structural characterization of these synthesized compounds was confirmed by FT-IR, 1HNMR, and Mass spectral data. Later synthesized derivatives evaluated for their antiulcer and H+ K+ ATPase inhibitory activity by aspirin induced method and assays of H+/K+-ATPase activity respectively.
 Results: Compound 54c (74.03%), 54f (72.87%) and 54i (75.15%) shows highly significant antiulcer activity compared to standard drug and compound 54c (88.88 %), 54d (91.03 %), 54f (86.48%) and 54g (84.21%) shows highly significant antisecretory activity when compare to standard drug.
 Conclusion: Our research work provokes further to work for development of different derivatives of 2-(pyrimidinyl-sulfinyl) benzimidazole which have lesser side effect and better action than few of marketed drugs.

UV-visible light-induced photochemical synthesis of benzimidazoles by coomassie brilliant blue coated on W-ZnO@NH2 nanoparticles.

Heterogeneous photocatalysts proffer a promising method to actualize eco-friendly and green organic transformations. Herein, a new photochemical-based methodology is disclosed in the preparation of a wide range of benzimidazoles through condensation of o-phenylenediamine with benzyl alcohols in the air under the illumination of an HP mercury lamp in the absence of any oxidizing species catalyzed by a new photocatalyst W–ZnO@NH2–CBB. In this photocatalyst, coomassie brilliant blue (CBB) is heterogenized onto W–ZnO@NH2 to improve the surface characteristics at the molecular level and enhance the photocatalytic activity of both W–ZnO@NH2 and CBB fragments. This unprecedented heterogeneous nanocatalyst is also identified by means of XRD, FT-IR, EDS, TGA-DTG, and SEM. The impact of some influencing parameters on the synthesis route and effects on the catalytic efficacy of W–ZnO@NH2–CBB are also assessed. The appropriate products are attained for both the electron-withdrawing and electron-donating substituents in the utilized aromatic alcohols. Furthermore, preparation of benzimidazoles is demonstrated to occur mainly via a radical mechanism, which shows that reactive species such as ·O2−, OH˙ and h+ would be involved in the photocatalytic process. Stability and reusability studies also warrant good reproducibility of the nanophotocatalyst for at least five runs. Eventually, a hot filtration test proved that the nanohybrid photocatalyst is stable in the reaction medium. Using an inexpensive catalyst, UV-vis light energy and air, as a low cost and plentiful oxidant, puts this methodology in the green chemistry domain and energy-saving organic synthesis strategies. Finally, the anticancer activity of W–ZnO nanoparticles is investigated on MCF7 breast cancer cells by MTT assay. This experiment reveals that the mentioned nanoparticles have significant cytotoxicity towards the selected cell line.

NaOH/PEG-400: An eloquent system for the synthesis of new thienyl benzo[b]1,4-diazepines

A simple and eloquent procedure for the synthesis of a new series of thienyl benzo[b]1,4-diazepines is reported. They were synthesized by the condensation of o-phenylenediamine (o-PDA) with distinct hetero chalcones using NaOH in polyethylene glycol (PEG-400) as green and alternative reaction solvent. The significances of this present method are shorter reaction time, easy work-up, high yields, and mild reaction conditions. Furthermore, this method is environment friendly and without use of an expensive catalyst. The all newly synthesized compounds are characterized by the spectroscopic methods.

Additive Free Greener Synthesis of 1,2-Disubstituted Benzimidazoles Using Aqueous Extract of Acacia concinna Pods as an Efficient Surfactant Type Catalyst

An efficient environmentally benign method for the synthesis of 1,2-disubstituted benzimidazole derivatives via one-pot multicomponent has been reported using aqueous extract of Acacia concinna pods as a naturally occurring surfactant type catalyst. The present surfactant medium was found superior and additive free for the condensation of o-phenylene diamine and two equivalent of aldehyde to yield 1,2-disubstituted benzimidazole derivatives in excellent yields under mild conditions. A simple, economically viable and biocompatible catalytic system suggested the possible utility of the present protocol for the large scale construction of benzimidazole derivatives.

Kaolin-SO3H nanoparticles: A new efficient and reusable catalyst for synthesis of 2-substituted benzimidazoles at room temperature

Kaolinite clay found its application in medicine, in toothpaste, in cosmetic and as a food additive. Recently, a specially formulated spray is used in fruit and vegetable production to repel the insects and prevent sunburn. Kaolin-SO3H nanoparticles were prepared via reaction of kaolin and chlorosulfonic acid and characterized by FT-IR, XRD, FESEM, TEM, XRF, EDS, BET and TGA. 2-Substituted benzimidazoles have been used as selective neuro-peptides YY, receptor antagonists, antitumor, antivirus, antimicrobial, antioxidant, antiparasitic, antihelmintics, antiproliferative, anti-HIV, anticonvulsant, anti-inflammatory, antihypertensive, antineoplastic, analgesicand antitrichinellosis, topoisomerase IV inhibitors, potent inhibitors of TiE-2 and VEGFER-2 tyrosine kinase receptor, and 5-HT3 antagonists. 2-Substituted benzimidazoles are prepared via condensation of o-phenylenediamines and aldehydes. In this article, we have used Kaolin-SO3H nanoparticles for the synthesis of 2-substituted benzimidazoles under mild reaction conditions. The structure of products were identified by FT-IR, 1H-NMR and 13C-NMR. This method has the advantages of high yields, short reaction times and easy work-up.

Synthesis, Characterization and Biological Evaluation of Novel 1, 4-Benzodiazepine Derivatives as Potent Anti-Tubercular Agents

Background: Benzodiazepines are interesting compounds due to their therapeutic properties. TB chemotherapy is highly regulated and Its research research is often considered non-remunerative. Hence, there remains a pressing requisite to discover novel, potent and safe anti-TB agents. Objective: One of the biggest problem of Tuberculosis is the lack of effective treatments. Bedaquiline (2013) and Delaminid (2014) are the only two agents approved for treating tuberculosis after Rifampicin (1963). This clearly shows the need for new lead molecules to fight against tuberculosis. Methodology: In the present work, a series of eighteen derivatives of 1, 4-Benzodiazepines were synthesized by condensation of o-phenylenediamines with 1, 3-diketone (Dimedone). Further these synthesized derivatives were analyzed by IR, NMR and MASS spectral studies and are screened for anti-tubercular and antimicrobial activity. Results: Among these, potent activity were observed for compounds 9, 10 (MIC 1.6 μg/mL) followed by 11(3.12 μg/mL), 04 (6.25 μg/mL) against M. tuberculosis H37Rv. We report here the synthesis, screening data and SAR studies of Benzodiazepines and its derivatives as Antitubercular agents. Conclusion: In conclusion, we synthesized eighteen 1, 4-Benzodiazepines derivatives with selective anti-tubercular activity. Key words: Benzodiazepines, M. tuberculosis H37Rv, Antitubercular.

Preparation of a Polymer via Condensation of o-Phenylenediamine with p-Xylylene Dibromide and Its Properties

Condensation of para-dibromoxylene and ortho-phenylenediamine in glass ampule at 150°С in an alkaline aqueous solution has yielded polymer with completely substituted N–H hydrogen atoms, capable of formation of polymeric cation-radicals. Complexes of this polymer and N,N,N',N'-tetrabenzyl-o-phenylenediamine with Co(II), Ni(II), Cu(II), and Ag(I) have been obtained, and their structure has been studied.