- Visible-Light-Mediated Oxidative Cyclization of 2-Aminobenzyl Alcohols and Secondary Alcohols Enabled by an Organic Photocatalyst
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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.
- Xu, Jing-Xiu,Pan, Nan-Lian,Chen, Jia-Xi,Zhao, Jin-Wu
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p. 10747 - 10754
(2021/08/16)
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- Method for synthesizing quinoline derivatives by copper catalysis
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The invention relates to a method for synthesizing quinoline derivatives by copper catalysis. The method comprises the following steps: mixing 2-aminobenzyl alcohol, acetophenone derivatives, an alkaline reagent, a copper catalyst and a nitrogen-containing ligand in an organic solvent, and reacting at room temperature for 6-12h; and after the reaction is finished, sequentially carrying out concentration and column chromatography separation on the obtained reaction solution to obtain the corresponding quinoline derivative. Compared with the prior art, the method has the advantages that 2-aminobenzyl alcohol and acetophenone derivatives which are cheap and easy to obtain are used as raw materials, cuprous iodide CuI or cuprous bromide CuBr with stable properties is used as a catalyst, the quinoline skeleton-containing derivatives are directly constructed, use of toxic reagents is avoided, and the method conforms to the development concept of green chemistry; and the method has the advantages of simple operation, mild reaction conditions, good substrate universality and the like, and has huge application potential in the aspect of drug intermediate synthesis.
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Paragraph 0050-0055
(2021/03/24)
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- Zinc Stabilized Azo-anion Radical in Dehydrogenative Synthesis of N-Heterocycles. An Exclusively Ligand Centered Redox Controlled Approach
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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.
- Das, Siuli,Mondal, Rakesh,Chakraborty, Gargi,Guin, Amit Kumar,Das, Abhishek,Paul, Nanda D.
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p. 7498 - 7512
(2021/06/30)
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- Continuous Flow Synthesis of Quinolines via a Scalable Tandem Photoisomerization-Cyclization Process
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A continuous photochemical process is presented that renders a series of quinoline products via an alkene isomerization and cyclocondensation cascade. It is demonstrated that a high-power LED lamp generates the desired targets with higher productivity and efficiency than a medium-pressure Hg-lamp. The scope of this tandem process is established and allows for the generation of various substituted quinolines in high yields and with throughputs of greater than one gram per hour. Finally, this effective flow process is coupled with a telescoped hydrogenation reaction to render a series of tetrahydroquinolines including the antimalarial natural product galipinine.
- Di Filippo, Mara,Baumann, Marcus
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p. 6199 - 6211
(2020/08/26)
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- Pd-Catalyzed Tandem Reaction of 2-Aminostyryl Nitriles with Arylboronic Acids: Synthesis of 2-Arylquinolines
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A novel palladium-catalyzed protocol for the synthesis of 2-arylquinolines via tandem reaction of 2-aminostyryl nitriles with arylboronic acids has been developed with good functional group tolerance. The presented approach offers a new synthetic pathway toward the core structures of 2-arylquinolines compared to classical condensation reaction of (E)-2-aminostyryl aryl ketones. Moreover, the present synthetic route could be readily scaled up to gram quantity without difficulty. Preliminary mechanistic experiments showed that this transformation involves a nucleophilic addition of aryl palladium species to the nitrile to generate an aryl ketone intermediate followed by an intramolecular cyclization and dehydration to quinoline ring.
- Xu, Tong,Shao, Yinlin,Dai, Ling,Yu, Shulin,Cheng, Tianxing,Chen, Jiuxi
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p. 13604 - 13614
(2019/10/16)
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- Synthesis of 2-Arylisoindoline Derivatives Catalyzed by Reusable 1,2,4-Triazole Iridium on Mesoporous Silica through a Cascade Borrowing Hydrogen Strategy
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Covalent attachment of a 1,2,4-triazole iridium complex to mesoporous MCM-41 generated a heterogeneous catalyst that was found to be effective in the synthesis of 2-aryl isoindolines, quinolines, cyclic amines, and symmetrical secondary amines through a cascade borrowing hydrogen strategy. Interestingly, the supported heterogeneous iridium catalyst prepared from the 1,2,4-triazole iridium complex and mesoporous MCM-41 exhibited high catalytic activity in the preparation of 2-aryl isoindoline derivatives and symmetrical secondary amines. The catalyst system is highly recyclable for at least five times. Besides the important effect of the triazole, iridium sites grafted on siliceous supports can act as multifunctional catalytic centers and thus greatly enhance the catalytic activity of the catalysts. Furthermore, mechanistic experiments revealed that the reaction is initiated by an initial alcohol dehydrogenation and promoted by an iridium hydride intermediate. Importantly, the direct detection of a diagnostic iridium hydride signal confirmed that the synthesis of 2-aryl isoindolines occurs by a borrowing hydrogen process. This work provides an efficient example of isoindolines synthesis through a borrowing hydrogen strategy.
- Yao, Wei,Ge, Chenyang,Zhang, Yilin,Xia, Xiao-Feng,Wang, Long,Wang, Dawei
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supporting information
p. 16099 - 16105
(2019/11/26)
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- Dehydrogenative Synthesis of Quinolines, 2-Aminoquinolines, and Quinazolines Using Singlet Diradical Ni(II)-Catalysts
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Simple, straightforward, and atom economic methods for the synthesis of quinolines, 2-aminoquinolines, and quinazolines via biomimetic dehydrogenative condensation/coupling reactions, catalyzed by well-defined inexpensive and easy to prepare singlet diradical Ni(II)-catalysts featuring two antiferromagnetically coupled singlet diradical diamine type ligands are described. Various polysubstituted quinolines, 2-aminoquinolines, and quinazolines were synthesized in moderate to good yields from different low-cost and readily accessible starting materials. Several control experiments were carried out to get insight into the reaction mechanism which shows that the nickel and the coordinated diamine ligands participate in a synergistic way during the dehydrogenation of alcohols.
- Chakraborty, Gargi,Sikari, Rina,Das, Siuli,Mondal, Rakesh,Sinha, Suman,Banerjee, Seemika,Paul, Nanda D.
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p. 2626 - 2641
(2019/02/26)
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- Metal-Ligand Cooperative Approach to Achieve Dehydrogenative Functionalization of Alcohols to Quinolines and Quinazolin-4(3 H)-ones under Mild Aerobic Conditions
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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 and 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. A wide variety of substituted quinolines and quinazolin-4(3H)-ones were synthesized in moderate to good isolated yields via dehydrogenative coupling reactions of various inexpensive and easily available starting materials under aerobic conditions. A few control experiments and deuterium labeling studies were carried out to understand the mechanism of the dehydrogenative coupling reactions, which indicate that both copper and the coordinated azo-aromatic ligand participate in a cooperative manner during the catalytic cycle.
- Das, Siuli,Sinha, Suman,Samanta, Deepannita,Mondal, Rakesh,Chakraborty, Gargi,Branda?, Paula,Paul, Nanda D.
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p. 10160 - 10171
(2019/08/20)
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- π-Allylpalladium Species in Micelles of FI-750-M for Sustainable and General Suzuki-Miyaura Couplings of Unactivated Quinoline Systems in Water
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General, clean, and sustainable Suzuki-Miyaura cross-couplings of 2-and 4-quinoline and isoquinoline systems have been demonstrated with use of π-allyl Pd catalyst in the nanomicelles of environmentally benign, proline-derived surfactant FI-750-M. Optimiz
- Handa, Sachin,Ibrahim, Faisal,Ansari, Tharique N.,Gallou, Fabrice
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p. 4229 - 4233
(2018/09/21)
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- A nickel catalyzed acceptorless dehydrogenative approach to quinolines
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A general, efficient and environmentally benign, one-step synthesis of substituted quinoline derivatives was achieved by acceptorless dehydrogenative coupling of o-aminobenzylalcohols with ketones and secondary alcohols catalyzed by a cheap, earth abundant and easy to prepare nickel catalyst [Ni(MeTAA)], featuring a tetraaza macrocyclic ligand (tetramethyltetraaza[14]annulene (MeTAA)). A wide variety of substituted quinolines were synthesized in high yields starting from readily available o-aminobenzylalcohols and ketones or secondary alcohols. A few controlled reactions were carried out to establish the acceptorless dehydrogenative nature of the reactions.
- Parua, Seuli,Sikari, Rina,Sinha, Suman,Das, Siuli,Chakraborty, Gargi,Paul, Nanda D.
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p. 274 - 284
(2018/01/12)
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- Synthesis and structure of arene ruthenium(II) complexes: One-pot catalytic approach to synthesis of bioactive quinolines under mild conditions
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Efficient catalytic one-step synthesis of substituted quinoline derivatives using newly synthesized Ru(II) half-sandwich complexes of the type [Ru(η6-p-cymene)Cl(L)] (L = pyrrole-2-aldehydehydrazones) under mild conditions is described. The synthesized complexes exhibit excellent catalytic activity towards the coupling of 2-amino alcohol with functionalized ketones and secondary alcohols in the optimal conditions and afforded the corresponding quinoline derivatives. The synthetic pathway proceeds with high atom efficiency via a sequence of acceptorless dehydrogenation and condensation steps. The maximum isolated yield of the product obtained was up to 97% using 0.3?mol% of catalyst loading for 5?h. These findings significantly advance the scope of the synthesis of bioactive heterocyclic compounds from readily available starting materials.
- Subramanian, Muthumari,Sundar, Saranya,Rengan, Ramesh
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- Indium-mediated reductive cyclization of 2-nitrochalcones to quinolines
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The reductive cyclization of 2-nitrochalcones using indium in an aqueous alcohol solution containing ammonium chloride produced the corresponding quinolines in reasonable yields.{A figure is presented}.
- Han, Rongbi,Chen, Shen,Lee, Sun Jung,Qi, Fang,Wu, Xue,Kim, Byeong Hyo
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p. 1675 - 1684
(2007/10/03)
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