506421-62-1Relevant articles and documents
Ruthenium-catalyzed acceptorless dehydrogenative coupling of o-aminobenzyl alcohols with ketones to quinolines in the presence of carbonate salt
Xu, Xiangchao,Ai, Yao,Wang, Rongzhou,Liu, Liping,Yang, Jiazhi,Li, Feng
, p. 340 - 349 (2021/02/27)
A ruthenium complex bearing a functional 2,2′-bibenzimidazole ligand [(p-cymene)Ru(BiBzImH2)Cl][Cl] was designed, synthesized and found to be a general and highly efficient catalyst for the synthesis of quinolines via acceptorless dehydrogenative coupling of o-aminobenzyl alcohols with ketones in the presence of carbonate salt. It was confirmed that NH units in the ligand are crucial for catalytic activity. The application of this catalytic system for the scale-gram synthesis of biologically active molecular was also undertaken. Notably, this research exhibits new potential of metal–ligand bifuctional catalysts for acceptorless dehydrogenative reactions.
Zinc Stabilized Azo-anion Radical in Dehydrogenative Synthesis of N-Heterocycles. An Exclusively Ligand Centered Redox Controlled Approach
Das, Siuli,Mondal, Rakesh,Chakraborty, Gargi,Guin, Amit Kumar,Das, Abhishek,Paul, Nanda D.
, p. 7498 - 7512 (2021/06/30)
Herein we report an exclusively ligand-centered redox controlled approach for the dehydrogenation of a variety of N-heterocycles using a Zn(II)-stabilized azo-anion radical complex as the catalyst. A simple, easy-to-prepare, and bench-stable Zn(II)-complex (1b) featuring the tridentate arylazo pincer, 2-((4-chlorophenyl)diazenyl)-1,10-phenanthroline, in the presence of zinc-dust, undergoes reduction to form the azo-anion radical species [1b]- which efficiently dehydrogenates various saturated N-heterocycles such as 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, and 1,2,3,4-tetrahydro-2-phenylquinazolines, among others, under air. The catalyst has further been found to be compatible with the cascade synthesis of these N-heterocycles via dehydrogenative coupling of alcohols with other suitable coupling partners under air. Mechanistic investigation reveals that the dehydrogenation reactions proceed via a one-electron hydrogen atom transfer (HAT) pathway where the zinc-stabilized azo-anion radical ligand abstracts the hydrogen atom from the organic substrate(s), and the whole catalytic cycle proceeds via the exclusive involvement of the ligand-centered redox events where the zinc acts only as the template.
Iron catalyzed metal-ligand cooperative approaches towards sustainable synthesis of quinolines and quinazolin-4(3H)-ones
Mondal, Rakesh,Chakraborty, Gargi,Guin, Amit Kumar,Pal, Subhasree,Paul, Nanda D.
, (2021/10/12)
Herein we report simple, efficient, and economically affordable metal-ligand cooperative strategies for synthesizing quinolines and quinazolin-4(3H)-ones via dehydrogenative functionalization of alcohols. Various polysubstituted quinolines and quinazolin-4(3H)-ones were prepared in good yields via dehydrogenative coupling of readily available alcohols with ketones and 2-aminobenzamides, respectively under air using a well-defined Fe(II)-catalyst, ([FeL1Cl2] (1)) bearing a redox-active azo-aromatic pincer 2-((4-chlorophenyl)diazenyl)-1,10-phenanthroline) (L1). Control experiments and mechanistic investigation disclose that the one-electron reduced mono-anionic species [1]? bearing an iron-stabilized azo-anion radical ligand catalyzes these reactions. Both iron and the redox-active arylazo ligand participate synergistically during the different steps of these catalytic reactions.
The preparation of a Co@C3N4catalyst and applications in the synthesis of quinolines from 2-aminobenzyl alcohols with ketones
Cao, Fei,Mao, Anruo,Yang, Bobin,Ge, Chenyang,Wang, Dawei
supporting information, p. 6768 - 6772 (2021/04/22)
An unsymmetrical diphenylphosphino-pyridinyl-triazole ligand was synthesized and characterized through IR, NMR and MS and the corresponding earth-abundant metal complex (cobalt) was prepared. Considering energy consumption and environmental friendliness, it is necessary to turn this diphenylphosphino-pyridinyl-triazole cobalt complex into a recyclable catalyst, which could easily be reused. Therefore, a heterogeneous catalyst was synthesized through Co-doping of C3N4, and the Co-nanoparticles on C3N4revealed high catalytic activity for the synthesis of quinolines with good recovery performance.
Direct C-H Arylation and Alkylation of Electron-Deficient Heteroaromatic Compounds with Organozinc Reagents
Peng, Zhihua,Yu, Chuanman,Wang, Yilei,Wei, Dongyue,Jiang, Cuiyu
, p. 3678 - 3688 (2021/11/16)
A direct and convenient method for the C-H arylation and alkylation of electron-deficient N-heteroarenes with readily available organozinc reagents has been developed. This transformation could be readily performed in the absence of a transition-metal catalyst and external oxidants, affording a wide range of substituted heteroarenes with good functional group tolerance in good to excellent yields. The developed simple protocol is scalable to the gram level and suitable for late-stage modification of bioactive molecules and drugs.
NiH-Catalyzed Hydroamination/Cyclization Cascade: Rapid Access to Quinolines
Chen, Qian,Gao, Yang,Hu, Xiao-Qiang,Huo, Yanping,Li, Xianwei,Yang, Simin
, p. 7772 - 7779 (2021/06/30)
Despite the significant success of metal-H-catalyzed hydroamination methodologies, considerable limitations still exist in the selective hydroamination of alkynes, especially for terminal alkynes. Herein, we develop a highly efficient NiH catalytic system that activates readily available alkynes for a cascade hydroamination/cyclization reaction with anthranils. This mild, operationally simple protocol is amenable to a wide array of alkynes including terminal and internal, aryl and alkyl, electron-deficient and electron-rich ones, delivering structurally diverse quinolines in useful to excellent yields (>80 examples, up to 93% yield). The utility of this procedure is exhibited in the late-stage functionalization of several natural products and in the concise synthesis of an antitumor molecule graveolinine and a triplex DNA intercalator. Preliminary mechanistic experiments suggest an alkenylnickel-mediated alkyne hydroamination and an intramolecular cyclization/aromatization of putative enamine intermediates.
Visible-Light-Mediated Oxidative Cyclization of 2-Aminobenzyl Alcohols and Secondary Alcohols Enabled by an Organic Photocatalyst
Xu, Jing-Xiu,Pan, Nan-Lian,Chen, Jia-Xi,Zhao, Jin-Wu
, p. 10747 - 10754 (2021/08/16)
This paper describes a visible-light-mediated oxidative cyclization of 2-aminobenzyl alcohols and secondary alcohols to produce quinolines at room temperature. This photocatalytic method employed anthraquinone as an organic small-molecule catalyst and DMSO as an oxidant. According to this present procedure, a series of quinolines were prepared in satisfactory yields.
Bioinspired Radical-Mediated Transition-Metal-Free Synthesis of N-Heterocycles under Visible Light
K. Bains, Amreen,Ankit, Yadav,Adhikari, Debashis
, p. 324 - 329 (2020/11/30)
A redox-active iminoquinone motif connected with π-delocalized pyrene core has been reported that can perform efficient two-electron oxidation of a class of substrates. The design of the molecule was inspired by the organic redox cofactor topaquinone (TPQ), which executes amine oxidation in the enzyme, copper amine oxidase. Easy oxidation of both primary and secondary alcohols happened in the presence of catalytic KOtBu, which could reduce the ligand backbone to its iminosemiquinonate form under photoinduced conditions. Moreover, this easy oxidation of alcohols under aerobic condition could be elegantly extended to multi-component, one-pot coupling for the synthesis of quinoline and pyrimidine. This organocatalytic approach is very mild (70 °C, 8 h) compared to a multitude of transition-metal catalysts that have been used to prepare these heterocycles. A detailed mechanistic study proves the intermediacy of the iminosemiquinonate-type radical and a critical hydrogen atom transfer step to be involved in the dehydrogenation reaction.
Pr2O3 Supported Nano-layered Ruthenium Catalyzed Acceptorless Dehydrogenative Synthesis of 2-Substituted Quinolines and 1,8-Naphthyridines from 2-Aminoaryl Alcohols and Ketones
Chaudhari, Chandan,Sato, Katsutoshi,Ogura, Yuta,Miayahara, Shin-Ichiro,Nagaoka, Katsutoshi
, p. 2198 - 2202 (2020/03/24)
Pr2O3 supported Ru nanolayers and Ru nanoparticles catalysts were examined for the synthesis of quinolines. The Ru nanolayer was most active catalyst and showed a broad substrate scope. Structure-activity relationship demonstrated that the metallic state and morphology of Ru as well as the basic site of Pr2O3 were indispensable factors of this catalytic system.
PHOSPHINE FREE COBALT BASED CATALYST, PROCESS FOR PREPARATION AND USE THEREOF
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Paragraph 0068; 0142; 0154, (2020/12/29)
The present invention discloses a phosphine free cobalt based catalyst of formula (I) and a process for preparation thereof. The present invention further discloses a process for the synthesis of aromatic heterocyclic compounds of formula (II) and pyrazine derivative using the phosphine free cobalt based catalyst of formula (I).
