C−N Cross‐Coupling Reactions Under Mild Conditions Using Singlet Di‐Radical Nickel(II)‐Complexes as Catalyst: N‐Arylation and Quinazoline Synthesis DOI
Rina Sikari, Suman Sinha, Gargi Chakraborty

и другие.

Advanced Synthesis & Catalysis, Год журнала: 2019, Номер 361(18), С. 4342 - 4353

Опубликована: Июль 23, 2019

Abstract Herein we report a cost‐effective synthetic approach for C−N cross‐coupling reactions of broad array nitrogen nucleophiles and aryl halides under mild conditions. These are catalyzed by an inexpensive, air‐stable, earth‐abundant easy‐to‐prepare singlet di‐radical nickel(II)‐catalyst containing two antiferromagnetically coupled single‐electron oxidized diiminosemiquinonato type ligands. This protocol provides alternative method avoiding nickel(0)/nickel(II) or nickel(I)/nickel(III) redox processes via cooperative participation metal ligand‐centered events. Besides wide range N‐arylation reactions, judicious choice the synthesis variety polysubstituted quinazolines has been achieved in moderate to good yields relatively reaction Our catalyst found be almost equally effective quinazoline (i) 2‐bromobenzylamine with benzamide, (ii) 2‐bromobenzylbromide amidine. Control experiments DFT studies were performed improve understanding ligand (nickel)‐centered events during oxidative addition/reductive elimination catalytic cycle shed light on plausible mechanistic pathway reactions. magnified image

Язык: Английский

Synthetic and medicinal perspective of quinolines as antiviral agents DOI Open Access
Ramandeep Kaur, Kapil Kumar

European Journal of Medicinal Chemistry, Год журнала: 2021, Номер 215, С. 113220 - 113220

Опубликована: Янв. 24, 2021

Язык: Английский

Процитировано

149
Borrowing Hydrogen-Mediated N-Alkylation Reactions by a Well-Defined Homogeneous Nickel Catalyst DOI

Amreen K. Bains,

Abhishek Kundu, Sudha Yadav

и другие.

ACS Catalysis, Год журнала: 2019, Номер 9(10), С. 9051 - 9059

Опубликована: Авг. 19, 2019

We report herein a well-defined and bench-stable azo-phenolate ligand-coordinated nickel catalyst which can efficiently execute N-alkylation of variety anilines by alcohol. demonstrate that the redox-active azo ligand store hydrogen generated during alcohol oxidation redelivers same to an in-situ-generated imine bond result in amines. The reaction has wide scope, large array alcohols directly couple anilines. Mechanistic studies including deuterium labeling substrate establishes borrowing method from pinpoints crucial role moiety present on backbone. Isolation ketyl intermediate its trapped form with radical quencher higher kH/kD for step suggest altogether hydrogen-atom transfer (HAT) reduced backbone pave as opposed conventional metal–ligand bifunctional mechanism. This example clearly demonstrates inexpensive base metal accomplish important coupling help

Язык: Английский

Процитировано

127
Metal–Ligand Cooperative Approach To Achieve Dehydrogenative Functionalization of Alcohols to Quinolines and Quinazolin-4(3H)-ones under Mild Aerobic Conditions DOI
Siuli Das, Suman Sinha,

Deepannita Samanta

и другие.

The Journal of Organic Chemistry, Год журнала: 2019, Номер 84(16), С. 10160 - 10171

Опубликована: Июль 22, 2019

A simple metal–ligand cooperative approach for the dehydrogenative functionalization of alcohols to various substituted quinolines and quinazolin-4(3H)-ones under relatively mild reaction conditions (≤90 °C) is reported. Simple easy-to-prepare air-stable Cu(II) complexes featuring redox-active azo-aromatic scaffolds, 2-arylazo-(1,10-phenanthroline) (L1,2), are used as catalyst. wide variety were synthesized in moderate good isolated yields via coupling reactions inexpensive easily available starting materials aerobic conditions. few control experiments deuterium labeling studies carried out understand mechanism reactions, which indicate that both copper coordinated ligand participate a manner during catalytic cycle.

Язык: Английский

Процитировано

98
Manganese(I)-Catalyzed Sustainable Synthesis of Quinoxaline and Quinazoline Derivatives with the Liberation of Dihydrogen DOI
Akash Mondal, Manoj Kumar Sahoo, Murugan Subaramanian

и другие.

The Journal of Organic Chemistry, Год журнала: 2020, Номер 85(11), С. 7181 - 7191

Опубликована: Май 13, 2020

Direct synthesis of N-heterocycles via the acceptorless dehydrogenative coupling is very challenging and scarcely reported under 3d transition-metal catalysis. Here, we have developed an efficient Mn(I)-catalyzed sustainable various quinoxalines from 1,2-diaminobenzenes 1,2-diols reaction. Further, this strategy was successfully applied for unprecedented quinazolines by reaction 2-aminobenzyl alcohol with primary amides. The present protocol provides atom-economical route quinoxaline quinazoline derivatives employing earth-abundant manganese salt simple phosphine-free NNN-tridentate ligand.

Язык: Английский

Процитировано

83
Homogeneous Nickel-Catalyzed Sustainable Synthesis of Quinoline and Quinoxaline under Aerobic Conditions DOI

Amreen K. Bains,

Vikramjeet Singh, Debashis Adhikari

и другие.

The Journal of Organic Chemistry, Год журнала: 2020, Номер 85(23), С. 14971 - 14979

Опубликована: Ноя. 11, 2020

Dehydrogenative coupling-based reactions have emerged as an efficient route toward the synthesis of a plethora heterocyclic rings. Herein, we report efficacious, nickel-catalyzed two important heterocycles such quinoline and quinoxaline. The catalyst is molecularly defined, phosphine-free, can operate at mild reaction temperature 80 °C. Both be easily assembled via double dehydrogenative coupling, starting from 2-aminobenzyl alcohol/1-phenylethanol diamine/diol, respectively, in shorter span time. This environmentally benign synthetic protocol employing inexpensive rival many other transition-metal systems that been developed for fabrication putative heterocycles. Mechanistically, dehydrogenation secondary alcohol follows clean pseudo-first-order kinetics exhibits sizable kinetic isotope effect. Intriguingly, this provides example storing trapped hydrogen ligand backbone, avoiding metal-hydride formation. Easy regeneration oxidized form under aerobic/O2 oxidation makes eco-friendly easy to handle.

Язык: Английский

Процитировано

79
Tandem transformations and multicomponent reactions utilizing alcohols following dehydrogenation strategy DOI
Bhaskar Paul, Milan Maji, Kaushik Chakrabarti

и другие.

Organic & Biomolecular Chemistry, Год журнала: 2020, Номер 18(12), С. 2193 - 2214

Опубликована: Янв. 1, 2020

In this review, the progress of tandem transformation nitro, nitrile and azide functionalities is summarised to develop new C–C C–N bonds as well multi-component reactions using alcohols.

Язык: Английский

Процитировано

72
Zinc Stabilized Azo-anion Radical in Dehydrogenative Synthesis of N-Heterocycles. An Exclusively Ligand Centered Redox Controlled Approach DOI
Siuli Das, Rakesh Mondal, Gargi Chakraborty

и другие.

ACS Catalysis, Год журнала: 2021, Номер 11(12), С. 7498 - 7512

Опубликована: Июнь 9, 2021

Herein we report an exclusively ligand-centered redox controlled approach for the dehydrogenation of a variety N-heterocycles using Zn(II)-stabilized azo-anion radical complex as catalyst. A simple, easy-to-prepare, and bench-stable Zn(II)-complex (1b) featuring tridentate arylazo pincer, 2-((4-chlorophenyl)diazenyl)-1,10-phenanthroline, in presence zinc-dust, undergoes reduction to form species [1b]− which efficiently dehydrogenates various saturated such 1,2,3,4-tetrahydro-2-methylquinoline, 1,2,3,4-tetrahydro-isoquinoline, indoline, 2-phenyl-2,3-dihydro-1H-benzoimidazole, 2,3-dihydro-2-phenylquinazolin-4(1H)-one, 1,2,3,4-tetrahydro-2-phenylquinazolines, among others, under air. The catalyst has further been found be compatible with cascade synthesis these via dehydrogenative coupling alcohols other suitable partners Mechanistic investigation reveals that reactions proceed one-electron hydrogen atom transfer (HAT) pathway where zinc-stabilized ligand abstracts from organic substrate(s), whole catalytic cycle proceeds exclusive involvement events zinc acts only template.

Язык: Английский

Процитировано

63
Recent advances in nickel-catalyzed C–C and C–N bond formation via HA and ADC reactions DOI
Murugan Subaramanian, Ganesan Sivakumar, Ekambaram Balaraman

и другие.

Organic & Biomolecular Chemistry, Год журнала: 2021, Номер 19(19), С. 4213 - 4227

Опубликована: Янв. 1, 2021

In this review article, recent advances in nickel-catalyzed hydrogen auto-transfer (HA) and acceptorless dehydrogenative coupling (ADC) reactions for the construction of C–C C–N bonds have been discussed.

Язык: Английский

Процитировано

61
Well-Defined Phosphine-Free Manganese(II)-Complex-Catalyzed Synthesis of Quinolines, Pyrroles, and Pyridines DOI
Ankur Maji, Shivangi Gupta, Milan Maji

и другие.

The Journal of Organic Chemistry, Год журнала: 2022, Номер 87(13), С. 8351 - 8367

Опубликована: Июнь 21, 2022

Herein, we report a simple, phosphine-free, and inexpensive catalytic system based on manganese(II) complex for synthesizing different important N-heterocycles such as quinolines, pyrroles, pyridines from amino alcohols ketones. Several control experiments, kinetic studies, DFT calculations were carried out to support the plausible reaction mechanism. We also detected two potential intermediates in cycle using ESI-MS analysis. Based these metal-ligand cooperative mechanism was proposed.

Язык: Английский

Процитировано

42
Achieving Nickel Catalyzed C–S Cross-Coupling under Mild Conditions Using Metal–Ligand Cooperativity DOI
Rina Sikari, Suman Sinha, Siuli Das

и другие.

The Journal of Organic Chemistry, Год журнала: 2019, Номер 84(7), С. 4072 - 4085

Опубликована: Март 11, 2019

A simple and efficient approach of C-S cross-coupling a wide variety (hetero)aryl thiols halides under mild conditions, mostly at room temperature, catalyzed by well-defined singlet diradical Ni(II) catalysts bearing redox noninnocent ligands is reported. Taking advantage ligand centered events, the high-energetic Ni(0)/Ni(II) or Ni(I)/Ni(III) steps were avoided in catalytic cycle. The cooperative participation both nickel coordinated during oxidative addition/reductive elimination allowed us to perform reactions conditions.

Язык: Английский

Процитировано

72