Selective Synthesis of 2-Substituted and 1,2-Disubstituted Benzimidazoles Directly from Aromatic Diamines and Alcohols Catalyzed by Molecularly Defined Nonphosphine Manganese(I) Complex

Das, Kalicharan; Mondal, Avijit; Srimani, Dipankar

doi:10.1021/acs.joc.8b01316

Cited by 134 publications

(85 citation statements)

References 61 publications

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“…In the present work, dppb was efficiently obtained in reasonable yield by condensation of 4,5‐dimethyl‐1,2‐phenylenediamine with 2‐pyridinecarboxaldehyde in 1:2 molar ratio in a chloroform:methanol (1:1) solution. The reaction conditions described in this work for obtaining dppb were simpler than those previously mentioned, requiring no catalyst and no inert atmosphere. Furthermore, as indicated by GC–MS, 1 H and 13 C NMR, and elemental analyses, dppb was obtained with high purity.…”

Section: Resultssupporting

confidence: 76%

“…Geiger and DeStefano performed condensation of the substituted o ‐phenylenediamine with 2‐pyridinecarboxaldehyde under nitrogen atmosphere obtaining, after recrystallization, the compound dppb with low yield. Alternatively, Das et al . carried out a reaction of o ‐phenylenediamine derivative with the proper primary alcohol in the presence of a catalyst under argon atmosphere, obtaining the desired product with appreciable yield after purification.…”

Section: Resultsmentioning

confidence: 99%

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Dinuclear copper(II) complex with a benzimidazole derivative: Crystal structure, theoretical calculations, and cytotoxic activity

Cassemiro

Santos

Oliveira

et al. 2020

Applied Organom Chemis

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This work describes a facile synthesis of 5,6‐dimethyl‐2‐(pyridin‐2‐yl)‐1‐[(pyridin‐2‐yl)methyl]‐1H‐benzimidazole (dppb) and the preparation of a dinuclear copper(II) complex bearing this ligand in a ring‐like conformation of formula [Cu(dppb)(acn)ClO4]2(ClO4)2·4acn (1), where acn represents acetonitrile. The crystal structure of the complex was determined by single‐crystal X‐ray diffraction experiment, which showed that dppb acts as a bridge in 1 due to its bidentate–monodentate μ‐κ2NN′:κN″coordination mode, and the coordination sphere of each metal center is completed by one acn molecule and one perchlorate ion. The structure of dinuclear copper(II) complex is symmetric and the two square–pyramidal copper(II) centers are separated by 5.381(1) Å. The geometry optimization, electronic structure, and vibrational spectrum of the [Cu(dppb)(acn)ClO4]22+ cation were calculated using the density functional theory method. The geometrical parameters obtained theoretically were remarkably similar to those observed in the crystal structure of 1 and the calculated vibrational frequencies are in satisfactory coherence with experimental data. In solution, the prepared complex can bind to DNA (Kb = 1.43 × 105 M−1) and inhibit the growth of a human chronic myelogenous leukemia cell line (K562) in a concentration‐dependent manner; importantly, it is almost four times more active than the corresponding free benzimidazole.

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Section: Resultssupporting

confidence: 76%

Section: Resultsmentioning

confidence: 99%

Dinuclear copper(II) complex with a benzimidazole derivative: Crystal structure, theoretical calculations, and cytotoxic activity

Cassemiro

Santos

Oliveira

et al. 2020

Applied Organom Chemis

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“…Recently, Srimani et al. synthesized 2‐substituted benzimidazoles 36 via the ADC of aromatic diamines 27 and 1 catalyzed by the NNS‐manganese complex Mn‐4 (Scheme ) . Interestingly, 1,2‐disubstituted benzimidazoles 36’ were synthesized when two equivalent of KO t Bu was used whereas, in the presence of 0.27 equivalent of KOH, only 2‐substituted benzimidazoles 36 were obtained.…”

Section: C−c/c−x/x−x Multiple Bond Formationsmentioning

confidence: 99%

Manganese Catalyzed Acceptorless Dehydrogenative Coupling Reactions

Waiba

Maji

2020

ChemCatChem

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Acceptorless dehydrogenative coupling (ADC) has emerged as a powerful tool in the chemists’ arsenal for the construction of various carbon‐carbon and carbon‐heteroatom bonds. These protocols are highly atom economical and environmentally benign as they do not require pre‐functionalized starting material and produce only dihydrogen (and water) as the by‐product. This technique, coupled with Earths’ abundant and less toxic manganese catalysis, can prove to be a vital strategy for the generation of molecular complexity from simple starting materials. Manganese catalyzed DHC has been of growing interest, and various low‐ and high‐valent manganese catalysts have been developed. These catalysts were demonstrated to show excellent catalytic activity for the formation of carbon‐carbon, carbon‐heteroatom bonds, and cascade reactions. In this mini‐review, we would like to highlight the recent progress that has been made in manganese catalyzed ADC reactions.

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“…Recently Srimani et al. introduced a novel NNS pincer‐manganese complex 103 which effectively catalyses the dehydrogenative cross‐coupling of o ‐phenylenediamine (OPD) derivatives 140 with diversely substituted benzyl alcohols to afford 2‐substituted 141 and 1,2‐disubstituted benzimidazoles 142 (Scheme ) . This acceptor‐less dehydrogenative coupling strategy avoids the use of phosphine reagents and is more interesting due to the ability to realise a selective benzimidazole synthesis with the same catalytic system.…”

Section: Synthesis and Derivatisation Of Heterocyclic Compoundsmentioning

confidence: 99%

“… Proposed mechanism for the selective synthesis of benzimidazole derivatives using manganese catalysis (reproduced with permission from Ref …”

Section: Synthesis and Derivatisation Of Heterocyclic Compoundsmentioning

confidence: 99%

Manganese‐Catalysed Dehydrogenative Coupling – An Overview

et al. 2020

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Manganese‐catalysed reactions have attracted great attention recently due to the high relative abundance and cheap and eco‐friendly behaviour. Applications of manganese catalysis in cross‐dehydrogenative coupling are among the hottest areas since 90% of the contributions are very recent. Dehydrogenation of alcohols using Mn‐pincer systems is highly explored nowadays for cross‐coupling to synthesise a variety of products and Mn‐catalysed C−H activation, and radical reactions are applied in dehydrogenative couplings of various synthons. This review focuses on the synthesis of synthetically as well as biologically important motifs such as carbonyl compounds, olefins, nitrogen heterocycles, amines, imines, etc. using manganese‐catalysed dehydrogenative cross‐coupling reactions.

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Selective Synthesis of 2-Substituted and 1,2-Disubstituted Benzimidazoles Directly from Aromatic Diamines and Alcohols Catalyzed by Molecularly Defined Nonphosphine Manganese(I) Complex

Abstract: Herein, we present a selective synthesis of 2-substituted and 1,2-disubstituted benzimidazoles by acceptorless dehydrogenative coupling of aromatic diamine with primary alcohols. The reaction is catalyzed by a phosphine-free tridentate NNS ligand-derived manganese(I) complex.

Cited by 134 publications

References 61 publications

Dinuclear copper(II) complex with a benzimidazole derivative: Crystal structure, theoretical calculations, and cytotoxic activity

Dinuclear copper(II) complex with a benzimidazole derivative: Crystal structure, theoretical calculations, and cytotoxic activity

Manganese Catalyzed Acceptorless Dehydrogenative Coupling Reactions

Manganese‐Catalysed Dehydrogenative Coupling – An Overview

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