Cobalt-Catalyzed Sustainable Synthesis of Benzimidazoles by Redox-Economical Coupling of <i>o</i>-Nitroanilines and Alcohols

Das, Sanju; Mallick, Samrat; Sarkar, Suman De

doi:10.1021/acs.joc.9b02090

Cited by 71 publications

(38 citation statements)

References 61 publications

(40 reference statements)

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“…Several groups, namely Huang and co-workers, 74 Nguyen, Al-Mourabit and co-worker, 75 Han and co-workers, 76 De Sarkar and co-workers, 77 and Hong and co-workers, 78 developed methods for the synthesis of 2-(het)arylbenzimidazoles from 2-nitroanilines 41 and aryl-56 and hetarylmethanols 57 using catalysts such as dppf , 74 Na 75 Pd(dppf)Cl 2 , 76 Co(acac) 2 , 77 tricarbonyl(η 4 -cyclopentadienone)iron(0) complex 78 (Table 5). It is assumed that these tandem reactions proceed through alcohol oxidation, reduction of the nitro group, condensation, and dehydrogenation.…”

Section: Review Synthesismentioning

confidence: 99%

Recent Developments Towards Synthesis of (Het)arylbenzimidazoles

Мамедов¹,

Zhukova²

2021

Synthesis

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Benzimidazole is an important heterocycle that is widely researched and utilized by the pharmaceutical industry and is one of the five most commonly used five-membered aromatic heterocyclic compounds approved by the US Food and Drug Administration. In view of their wide-ranging bioactivities, systems containing benzimidazole as one of the moieties occupy a special place among other benzimidazole derivatives. Since 2010, many improved synthetic strategies have been developed for the construction of hetaryl- and arylbenzimidazole molecular scaffolds under environmentally benign conditions. This review emphasizes the recent trends and modifications frequently used in the synthesis of derivatives of benzimidazole such as the Phillips–Ladenburg and Weidenhagen reactions, as well as entirely new methods of synthesis, involving oxidative cyclization, cross-coupling, ring distortion strategy, and rearrangements carried out under environmentally benign conditions.1 Introduction2 From 1,2-Diaminobenzenes with Various One-Carbon Unit Suppliers2.1 Phillips–Ladenburg Reaction2.1.1 With (Het)arenecarboxylic Acids2.2.2 With (Het)arenecarboxylic Acid Derivatives2.2 Weidenhagen Reaction2.2.1 With (Het)arenecarbaldehydes or (Het)aryl Methyl Ketones2.2.2 With Primary Alcohols2.2.3 With Primary Alkylamines2.2.4 With 2-Methylazaarenes2.2.5 With Other One-Carbon Fragment Suppliers3 From 2-Haloacetanilides and Amines4 From Amidines5 From Tetrahydroquinazolines6 Mamedov Rearrangement7 Conclusions and Outlook

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Section: Review Synthesismentioning

confidence: 99%

Recent Developments Towards Synthesis of (Het)arylbenzimidazoles

Мамедов¹,

Zhukova²

2021

Synthesis

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“…On the basis of these preliminary studies and previous reports, [23,24,25,26] a plausible pathway for the cobalt mediated formation of 2 a is proposed in Scheme 4. Firstly, a free radical NO 2* was generated from Co(NO 3 ) 2 under thermal conditions [22] which reacts with 1 to produce intermediate (A).…”

Section: Communications Ascwiley-vchdementioning

confidence: 56%

From Phenylhydrazone to 1H‐1,2,4‐Triazoles via Nitrification, Reduction and Cyclization

et al. 2020

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Herein we report an annulation of phenylhydrazone via a tandem nitrification, reduction, cyclization protocol employing cobalt nitrate and 1,2-dichloroethane to produce substituted 1H-1,2,4triazoles. Notably, 1,2-dichloroethane serves both the solvent and a hydrogen source for transfer hydrogenation. This methodology works under mild conditions, providing a direct approach for the synthesis of 1H-1,2,4-triazoles.

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“…Based on the above-described results as well as the related processes, [36] a possible reaction mechanism is shown in Scheme 5. The overall mechanism can be divided into threeparts: (1) vicinal diols dehydrogenation to methylglyoxal; (2) reduction of o-nitroamine to o-phenylenediamine; (3) at last, the desired product 3 a was obtained by imidization and cyclization reaction (Scheme 5).…”

Section: Scheme 3 Synthesis Of Imine and Benzoimidazolementioning

confidence: 98%

Hydrogen Auto‐transfer Synthesis of Quinoxalines from o‐Nitroanilines and Biomass‐based Diols Catalyzed by MOF‐derived N,P Co‐doped Cobalt Catalysts

Sun

et al. 2020

ChemCatChem

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A Co‐based heterogeneous catalyst supported on N,P co‐doped porous carbon (Co@NCP) is prepared via a facile in‐situ doping‐carbonization method. The Co@NCP composite features a large surface area, high pore volume, high‐density and strong basic sites. Furthermore, doping of P atoms can regulate the electronic density of Co. Therefore, Co@NCP exhibits good performance for the synthesis of quinoxalines from o‐nitroanilines and biomass‐derived diols under alkali‐free conditions.

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Cobalt-Catalyzed Sustainable Synthesis of Benzimidazoles by Redox-Economical Coupling of o-Nitroanilines and Alcohols

Cited by 71 publications

References 61 publications

Recent Developments Towards Synthesis of (Het)arylbenzimidazoles

Recent Developments Towards Synthesis of (Het)arylbenzimidazoles

From Phenylhydrazone to 1H‐1,2,4‐Triazoles via Nitrification, Reduction and Cyclization

Hydrogen Auto‐transfer Synthesis of Quinoxalines from o‐Nitroanilines and Biomass‐based Diols Catalyzed by MOF‐derived N,P Co‐doped Cobalt Catalysts

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