- Correction to: Halogen-Bonding-Induced Hydrogen Transfer to C=N Bond with Hantzsch Ester (Org. Lett. (2014) 16:12 (3244-3247) DOI: 10.1021/ol501259q)
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The structure of C1 has been revised in the Graphical Abstract/Table of Contents graphic.(Figure presented)
- He, Wei,Ge, Yi-Cen,Tan, Choon-Hong
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Read Online
- Medium-Sized-Ring Analogues of Dibenzodiazepines by a Conformationally Induced Smiles Ring Expansion
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Analogues of dibenzodiazepines, in which the seven-membered nitrogen heterocycle is replaced by a 9–12-membered ring, were made by an unactivated Smiles rearrangement of five- to eight-membered heterocyclic anthranilamides. The conformational preference of the tertiary amide in the starting material leads to intramolecular migration of a range of aryl rings, even those lacking electron-withdrawing activating groups, and provides a method for n→n+4 ring expansion. The medium-ring products adopt a chiral ground state with an intramolecular, transannular hydrogen bond. The rate of interconversion of their enantiomeric conformers depends on solvent polarity. Ring size and adjacent steric hindrance modulate this hidden hydrophilicity, thus making this scaffold a good candidate for drug development.
- Costil, Romain,Lefebvre, Quentin,Clayden, Jonathan
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Read Online
- Study of Hydrodesulfurization by the Use of 35S-Labeled Dibenzothiophene. 2. Behavior of Sulfur in HDS, HDO, and HDN on Sulfided Mo/Al2O3 Catalyst
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To investigate the behavior of sulfur during the hydrodesulfurization (HDS), 35S-labeled dibenzothiophene (DBT) was reacted on sulfided Mo/Al2O3.It was found that 35S in DBT was accommodated on the catalyst and the concentration of 35S on the catalyst always reached a steady state under fixed reaction conditions. 35S accommodated on the catalyst cannot be removed without the incorporation of sulfur from HDS of sulfur compounds such as DBT, benzothiophene, thiophene, and thiophenol.The removal rate of 35S from the catelyst depended upon the rate of HDS of these compounds, that is, the amount of sulfur incorporated into the catalyst.It was suggested that H2S is formed from some portion of sulfur on the surface of the catalyst othe than from that in the sulfur compounds.When hydrodenitrogenation (HDN) and hydrodeoxygenation (HDO) reactions were carried out on the catalyst containing 35S, some portion of 35S could be replaced by oxygen atoms and released as H2S; in contrast to this, 35S was hardly replaced by N atoms.
- Kabe, Toshiaki,Quian, Weihua,Ishihara, Atsushi
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- Dehydrogenative and Redox-Neutral N-Heterocyclization of Aminoalcohols Catalyzed by Manganese Pincer Complexes
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A new manganese catalyzed heterocyclization of aminoalcohols has been accomplished. A wide range of heterocycles were synthesized, including 1,2,3,4-tetrahydroquinolines, dihydroquinolinones, and 2,3,4,5-tetrahydro-1H-benzo[b]azepines. The reaction is performed under mild reaction conditions using air and moisture stable manganese catalysts. The desired heterocycles were obtained in good to excellent yields.
- Brzozowska, Aleksandra,Rueping, Magnus,Sklyaruk, Jan,Zubar, Viktoriia
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- Chemoselective and Tandem Reduction of Arenes Using a Metal–Organic Framework-Supported Single-Site Cobalt Catalyst
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The development of heterogeneous, chemoselective, and tandem catalytic systems using abundant metals is vital for the sustainable synthesis of fine and commodity chemicals. We report a robust and recyclable single-site cobalt-hydride catalyst based on a porous aluminum metal–organic framework (DUT-5 MOF) for chemoselective hydrogenation of arenes. The DUT-5 node-supported cobalt(II) hydride (DUT-5-CoH) is a versatile solid catalyst for chemoselective hydrogenation of a range of nonpolar and polar arenes, including heteroarenes such as pyridines, quinolines, isoquinolines, indoles, and furans to afford cycloalkanes and saturated heterocycles in excellent yields. DUT-5-CoH exhibited excellent functional group tolerance and could be reusable at least five times without decreased activity. The same MOF-Co catalyst was also efficient for tandem hydrogenation–hydrodeoxygenation of aryl carbonyl compounds, including biomass-derived platform molecules such as furfural and hydroxymethylfurfural to cycloalkanes. In the case of hydrogenation of cumene, our spectroscopic, kinetic, and density functional theory (DFT) studies suggest the insertion of a trisubstituted alkene intermediate into the Co–H bond occurring in the turnover limiting step. Our work highlights the potential of MOF-supported single-site base–metal catalysts for sustainable and environment-friendly industrial production of chemicals and biofuels.
- Antil, Neha,Kumar, Ajay,Akhtar, Naved,Begum, Wahida,Chauhan, Manav,Newar, Rajashree,Rawat, Manhar Singh,Manna, Kuntal
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supporting information
p. 1031 - 1040
(2022/01/19)
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- Ru-decorated N-doped carbon nanoflakes for selective hydrogenation of levulinic acid to γ-valerolactone and quinoline to tetrahydroquinoline with HCOOH in water
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The effective dissociation of biomass-derived formic acid, as a sustainable hydrogen source, in water is explored for the hydrogenation of levulinic acid (LA) and quinoline. Ru decorated carbon nanoflakes prepared by carboreduction (in Ar/H2 atmosphere) of Ru containing N-doped carbon were used as catalysts. The successful formation of Ru-decorated N-doped carbons was confirmed by numerous spectroscopic tools. The catalyst exhibited outstanding activity and selectivity for the hydrogenation of LA and quinoline using formic acid as a hydrogen donor in water under mild conditions. The catalyst afforded 99.8% LA conversion and 100% selectivity for γ-valerolactone (GVL), whereas 99.8% quinoline conversion and 93% selectivity for 1,2,3,4-tetrahydroquinoline (THQ) were obtained. Recycling experiments suggested that the catalyst was stable even after the 5 cycles. Various controlled experiments and characterizations were conducted to demonstrate the structure-activity relations and suggest plausible reaction mechanisms for the hydrogenation of LA and quinoline. The exploration of formic acid as a sustainable H2 source and the development of metal decorated N-doped carbons for hydrogenation of LA and quinoline will be fascinating to catalysis researchers and industrialists.
- Chauhan, Arzoo,Kar, Ashish Kumar,Srivastava, Rajendra
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- Aromatic compound hydrogenation and hydrodeoxygenation method and application thereof
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The invention belongs to the technical field of medicines, and discloses an aromatic compound hydrogenation and hydrodeoxygenation method under mild conditions and application of the method in hydrogenation and hydrodeoxygenation reactions of the aromatic compounds and related mixtures. Specifically, the method comprises the following steps: contacting the aromatic compound or a mixture containing the aromatic compound with a catalyst and hydrogen with proper pressure in a solvent under a proper temperature condition, and reacting the hydrogen, the solvent and the aromatic compound under the action of the catalyst to obtain a corresponding hydrogenation product or/and a hydrodeoxygenation product without an oxygen-containing substituent group. The invention also discloses specific implementation conditions of the method and an aromatic compound structure type applicable to the method. The hydrogenation and hydrodeoxygenation reaction method used in the invention has the advantages of mild reaction conditions, high hydrodeoxygenation efficiency, wide substrate applicability, convenient post-treatment, and good laboratory and industrial application prospects.
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Paragraph 0094-0095; 0114-0122
(2021/05/29)
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- Heterogeneous Hydrogenation of Quinoline Derivatives Effected by a Granular Cobalt Catalyst
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We communicate a convenient method for the pressure hydrogenation of quinolines in aqueous solution by using a particulate cobalt-based catalyst that is prepared in situ from simple Co(OAc)2 4H2O through reduction with abundant zinc powder. This catalytic protocol permits a brisk and atom-efficient access to a variety of 1,2,3,4-tetrahydroquinolines thereby relying solely on easy-to-handle reagents that are all readily obtained from commercial sources. Both the reaction setup assembly and the autoclave charging procedure are conducted on the bench outside an inert-gas-operated containment system, thus rendering the overall synthesis time-saving and operationally very simple.
- Timelthaler, Daniel,Topf, Christoph
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- CO2-tuned highly selective reduction of formamides to the corresponding methylamines
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We herein describe an efficient, CO2-tuned and highly selective C-O bond cleavage of N-methylated formanilides. With easy-to-handle and commercially available NaBH4 as the reductant, a variety of formanilides could be turned into the desired tertiary amines in moderate to excellent yields. The role of CO2 has been investigated in detail, and the mechanism is proposed on the basis of experiments.
- Chao, Jianbin,Guo, Zhiqiang,Pang, Tengfei,Wei, Xuehong,Xi, Chanjuan,Yan, Leilei
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supporting information
p. 7534 - 7538
(2021/10/12)
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- Zirconium-hydride-catalyzed site-selective hydroboration of amides for the synthesis of amines: Mechanism, scope, and application
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Developing mild and efficient catalytic methods for the selective synthesis of amines is a longstanding research objective. In this respect, catalytic deoxygenative amide reduction has proven to be promising but challenging, as this approach necessitates selective C–O bond cleavage. Herein, we report the selective hydroboration of primary, secondary, and tertiary amides at room temperature catalyzed by an earth-abundant-metal catalyst, Zr-H, for accessing diverse amines. Various readily reducible functional groups, such as esters, alkynes, and alkenes, were well tolerated. Furthermore, the methodology was extended to the synthesis of bio- and drug-derived amines. Detailed mechanistic studies revealed a reaction pathway entailing aldehyde and amido complex formation via an unusual C–N bond cleavage-reformation process, followed by C–O bond cleavage.
- Han, Bo,Jiao, Haijun,Wu, Lipeng,Zhang, Jiong
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p. 2059 - 2067
(2021/09/02)
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- Discovery of tetrahydroquinolines and benzomorpholines as novel potent RORγt agonists
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The retinoic acid receptor-related orphan receptor γt (RORγt) is an important nuclear receptor that regulates the differentiation of Th17 cells and production of interleukin 17(IL-17). RORγt agonists increase basal activity of RORγt and could provide a potential approach to cancer immunotherapy. Herein, hit compound 1 was identified as a weak RORγt agonist during in-house library screening. Changes in LHS core of 1 led to the identification of tetrahydroquinoline compound 6 as a partial RORγt agonist (max. act. = 39.3%). Detailed structure-activity relationship on substituent of the LHS core, amide linker and RHS arylsulfonyl moiety was explored and a novel series of tetrahydroquinolines and benzomorpholines was discovered as potent RORγt agonists. Tetrahydroquinoline compound 8g (EC50 = 8.9 ± 0.4 nM, max. act. = 104.5%) and benzomorpholine compound 9g (EC50 = 7.5 ± 0.6 nM, max. act. = 105.8%) were representative compounds with high RORγt agonistic activity in dual FRET assay, and they showed good activity in cell-based Gal4 reporter gene assay and Th17 cell differentiation assay (104.5% activation at 300 nM of 8g; 59.4% activation at 300 nM of 9g). The binding modes of 8g and 9g as well as the two RORγt inverse agonists accidentally discovered were also discussed.
- Xia, Yuehan,Yu, Mingcheng,Zhao, Yunpeng,Xia, Li,Huang, Yafei,Sun, Nannan,Song, Meiqi,Guo, Huimin,Zhang, Yunyi,Zhu, Di,Xie, Qiong,Wang, Yonghui
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- Palladium supported on magnesium hydroxyl fluoride: An effective acid catalyst for the hydrogenation of imines and N-heterocycles
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Palladium catalysts supported on acidic fluorinated magnesium hydroxide Pd/MgF2-x(OH)x were prepared through precipitation or impregnation methods. Applications to the hydrogenation of various aldimines and ketimines resulted in good catalytic activities at mild temperatures using one atmosphere of hydrogen. Quinolines, pyridines and other N-heterocycles were successfully hydrogenated at higher temperature and hydrogen pressure using low palladium loadings and without the use of any acid additive. Such reactivity trend confirmed the positive effect of the Br?nsted and Lewis acid sites from the fluorinated magnesium hydroxide support resulting in the effective pre-activation of N-heterocycle substrates and therefore in the good catalytic activity of the palladium nanoparticles during the hydrogenations. As demonstrated in the hydrogenation of imines, the catalyst was recycled up to 10 times without either loss of activity or palladium leaching. This journal is
- Agbossou-Niedercorn, Francine,Corre, Yann,Dongare, Mohan K.,Kemnitz, Erhard,Kokane, Reshma,Michon, Christophe,Umbarkar, Shubhangi B.
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supporting information
p. 19572 - 19583
(2021/11/04)
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- Pd/c catalyzed decarboxylation-transfer hydrogenation of quinoline carboxylic acids
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Pd/C catalyzed decarboxylation-transfer hydrogenation of quinoline carboxylic acids and transfer hydrogenation of quinolines had been developed for the synthesis of 1,2,3,4-tetrahydroquinolines. These two processes were implemented smoothly using Pd/C (0.9 mol%) as a catalyst with ammonium formate as a hydrogen source in ethanol at 80oC. The reaction system can also be applied to transfer hydrogenation of benzo[h]quinoline and 2,9-dimethyl-1,10-phenanthroline with good to excellent yields. And the gram scale and recycling of catalyst had been tested with good results. Furthermore, the mechanism of Pd/C catalyzed reduction of quino-line carboxylic acids and quinolines had been proposed.
- Zhou, Xiao-Yu,Chen, Xia
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p. 625 - 633
(2021/09/30)
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- Catalytic Hydrogenation of Substituted Quinolines on Co–Graphene Composites
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A set of 20 composites was prepared by pyrolysis of Co2+ complexes with 1,10-phenanthroline, melamine and 1,2-diaminobenzene. These composites were tested as the catalysts for the hydrogenation of quinolines. As shown by powder X-ray diffraction and TEM, the composited contained Co particles of several dozen nm sizes. The composition (elements content), Raman spectra X-ray photoelectron spectra parameters of the composites were analyzed. It was found that there was no distinct factor that controlled the yield of 1,2,3,4-tetrahydroquinolines in the investigated process. The yields of the respective products were in the range 90–100 %. The three most active composites were selected for scale-up and hydrogenation of a series of substituted quinolines. Up to 97 % yield of 1,2,3,4-tetrahydroquinoline was obtained on a 50 g scale. Five representative substituted quinolines were synthesized on a 10–20 grams scale using the Co-containing composites as the catalysts.
- Asaula, Vitalii M.,Buryanov, Volodymyr V.,Solod, Bohdan Y.,Tryus, Daryna M.,Pariiska, Olena O.,Kotenko, Igor E.,Volovenko, Yulian M.,Volochnyuk, Dmitriy M.,Ryabukhin, Sergey V.,Kolotilov, Sergey V.
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p. 6616 - 6625
(2021/12/24)
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- Homogeneous pressure hydrogenation of quinolines effected by a bench-stable tungsten-based pre-catalyst
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We report on an operationally simple catalytic method for the tungsten-catalyzed hydrogenation of quinolines through the use of the easily handled and self-contained precursor [WCl(η5-Cp)(CO)3]. This half sandwich complex is indefinitely storable on the bench in simple screw-capped bottles or stoppered flasks and can, if required, be prepared on a multi-gram scale while the actual catalytic transformations were performed in the presence of a Lewis acid in order to achieve both decent substrate conversions and product yields. The described method represents a facile and atom-efficient access to a variety of 1,2,3,4-tetrahydroquinolines that circumvents the use of cost-intensive and oxygen-sensitive phosphine ligands as well as auxiliary hydride reagents.
- Heizinger, Christian,Topf, Christoph,Vielhaber, Thomas
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p. 451 - 461
(2021/11/11)
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- Organometallic Synthesis of Bimetallic Cobalt-Rhodium Nanoparticles in Supported Ionic Liquid Phases (CoxRh100?x@SILP) as Catalysts for the Selective Hydrogenation of Multifunctional Aromatic Substrates
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The synthesis, characterization, and catalytic properties of bimetallic cobalt-rhodium nanoparticles of defined Co:Rh ratios immobilized in an imidazolium-based supported ionic liquid phase (CoxRh100?x@SILP) are described. Following an organometallic approach, precise control of the Co:Rh ratios is accomplished. Electron microscopy and X-ray absorption spectroscopy confirm the formation of small, well-dispersed, and homogeneously alloyed zero-valent bimetallic nanoparticles in all investigated materials. Benzylideneacetone and various bicyclic heteroaromatics are used as chemical probes to investigate the hydrogenation performances of the CoxRh100?x@SILP materials. The Co:Rh ratio of the nanoparticles is found to have a critical influence on observed activity and selectivity, with clear synergistic effects arising from the combination of the noble metal and its 3d congener. In particular, the ability of CoxRh100?x@SILP catalysts to hydrogenate 6-membered aromatic rings is found to experience a remarkable sharp switch in a narrow composition range between Co25Rh75 (full ring hydrogenation) and Co30Rh70 (no ring hydrogenation).
- Rengshausen, Simon,Van Stappen, Casey,Levin, Natalia,Tricard, Simon,Luska, Kylie L.,DeBeer, Serena,Chaudret, Bruno,Bordet, Alexis,Leitner, Walter
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- Method for selective catalytic hydrogenation of aromatic heterocyclic compounds in non-hydrogen participation manner
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The invention discloses a method for selective catalytic hydrogenation of aromatic heterocyclic compounds in a non-hydrogen participation manner. The method comprises the following steps: by taking 1, 5-cyclooctadiene iridium chloride dimer as a catalyst and phenylsilane as a hydrogen source, carrying out stirring reaction under mild conditions without adding a ligand, namely catalytically hydrogenating the aromatic heterocyclic compounds to obtain hydrogenated products of the aromatic heterocyclic compounds. The method has the advantages of low cost, mild reaction conditions, high selectivity and the like, and special equipment such as a high-pressure kettle and the like and high-temperature conditions which are required when hydrogen is used are avoided.
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Paragraph 0025-0029
(2021/08/19)
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- Method for preparing tetrahydroquinoline compounds by catalytic hydrogenation of ruthenium catalyst
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The invention relates to a method for preparing tetrahydroquinoline compounds by catalytic hydrogenation of a ruthenium catalyst, which comprises the following steps: by using p-cymene ruthenium chloride dimer as a catalyst and hydrogen as a reducing agent, mixing the p-cymene ruthenium chloride dimer, phosphine ligand and quinoline compounds, and dissolving the mixture in an organic solvent to react, and carrying out post-treatment to obtain the tetrahydroquinoline derivative. Compared with the prior art, the method has the advantages of easily available raw materials, mild conditions, simpleoperation, atom economy, simple and green synthesis process, mild reaction conditions, excellent selectivity, high yield and good reaction universality, and has a wide application value in fine chemical intermediate synthesis.
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Paragraph 0026-0029
(2021/01/29)
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- Utilization of renewable formic acid from lignocellulosic biomass for the selective hydrogenation and/or N-methylation
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Lignocellulosic biomass is one of the most abundant renewable sources in nature. Herein, we have developed the utilization of renewable formic acid from lignocellulosic biomass as a hydrogen source and a carbon source for the selective hydrogenation and further N-methylation of various quinolines and the derivatives, various indoles under mild conditions in high efficiencies. N-methylation of various anilines is also developed. Mechanistic studies indicate that the hydrogenation occurs via a transfer hydrogenation pathway.
- Zhou, Chao-Zheng,Zhao, Yu-Rou,Tan, Fang-Fang,Guo, Yan-Jun,Li, Yang
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p. 4724 - 4728
(2021/09/06)
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- Reductive Alkylation of Quinolines to N-Alkyl Tetrahydroquinolines Catalyzed by Arylboronic Acid
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A boronic acid catalyzed one-pot tandem reduction of quinolines to tetrahydroquinolines followed by reductive alkylation by the aldehyde has been demonstrated. This step-economcial synthesis of N-alkyl tetrahydroquinolines has been achieved directly from readily available quinolines, aldehydes, and Hantzsch ester under mild reaction conditions. The mechanistic study demonstrates the unique behavior of organoboron catalysts as both Lewis acids and hydrogen-bond donors.
- Adhikari, Priyanka,Bhattacharyya, Dipanjan,Nandi, Sekhar,Kancharla, Pavan K.,Das, Animesh
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supporting information
p. 2437 - 2442
(2021/04/05)
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- Visible-Light-Induced Selective Photolysis of Phosphonium Iodide Salts for Monofluoromethylations
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The sigma (σ)-hole effect has emerged as a promising tool to construct novel architectures endowed with new properties. A simple yet effective strategy for the generation of monofluoromethyl radicals is a continuing challenge within the synthetic communit
- Chen, Xiang-Yu,Liu, Qiang,Lu, Yu,Sheng, He,Su, Xiao-Di,Wang, Zhi-Xiang,Zhang, Chao-Shen
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supporting information
p. 25477 - 25484
(2021/10/25)
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- Nanosized CdS as a Reusable Photocatalyst: The Study of Different Reaction Pathways between Tertiary Amines and Aryl Sulfonyl Chlorides through Visible-Light-Induced N-Dealkylation and C-H Activation Processes
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It has been found that the final products of the reaction of sulfonyl chlorides and tertiary amines in the presence of cadmium sulfide nanoparticles under visible light irradiation are highly dependent on the applied reaction conditions. Interestingly, with the change of a reaction condition, different pathways were conducted (visible-light-induced N-dealkylation or sp3 and sp2 C-H activation) that lead to different products such as secondary amines and various sulfonyl compounds. Remarkably, all of these reactions were performed under visible light irradiation and an air atmosphere without any additive or oxidant in benign solvents or under solvent-free conditions. During this study, the CdS nanoparticles as affordable, heterogeneous, and recyclable photocatalysts were designed, successfully synthesized, and fully characterized and applied for these protocols. During these studies, intermediates resulting from the oxidation of tertiary amines are trapped during the photoinduced electron transfer (PET) process. The reaction was carried out efficiently with a variety of substrates to give the corresponding products at relatively short times in good to excellent yields in parallel with the use of the visible light irradiation as a renewable energy source. Most of these processes are novel or are superior in terms of cost-effectiveness, safety, and simplicity to published reports.
- Firoozi, Somayeh,Hosseini-Sarvari, Mona
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p. 2117 - 2134
(2021/02/05)
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- Nano-Ni-MOFs: High Active Catalysts on the Cascade Hydrogenation of Quinolines
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Abstract: The reduction of nitrogen-containing heterocyclic compounds in aqueous medium under mild condition is quite challenging. In view of metal–organic frameworks (MOFs) possess adjustable pore size and modifiable organic linkers, MOFs could be used in heterogeneous catalysis. Herein, Three Nano-Ni-MOFs, MOF-74-Ni, MOF-69-Ni, and Ni–NH2 (constructed from similar ligands and Ni2+ ions) are introduced for hydrogenating of azacyclo-compounds. As expected, Ni–NH2 shows outstanding activity of hydrogenation of quinoline under mild conditions, due to the moderate pore size and the modified –NH2 function group, which makes the substrate anchored on the surface of the framework facilitate the following catalysis process. Theoretical calculations identified that the –NH2 group at the catalyst facilitates the H2 heterolytic dissociation for the hydrogenation reactions. Graphic Abstract: Compared to MOF-74-Ni and MOF-69-Ni, the catalyst of Ni–NH2 shows outstanding activity of hydrogenation of quinoline, due to the modified –NH2 function group which makes the substrate anchored on the surface of the framework facilitate the following catalysis process[Figure not available: see fulltext.]
- Yun, Ruirui,Ma, Zi-Wei,Hu, Yang,Zhan, Feiyang,Qiu, Chuang,Zheng, Baishu,Sheng, Tian
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p. 2445 - 2451
(2021/01/05)
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- Formic acid disproportionation into formaldehyde triggered by vanadium complexes with iridium catalysis under mild conditions inN-methylation
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Formaldehyde (CH2O) has been used as a key platform reagent in the chemical industry for many decades. Currently, the industrial production of CH2O mainly depends on fossil resources, involving a highly energetic three-step process (200-1100 °C). Herein, we describe renewable formic acid (HCO2H) disproportionation into CH2O triggered by vanadium complexes with iridium catalysis under mild conditions at 30-50 °C inN-methylation. The gram-scale application ofin situgenerated CH2O by HCO2H disproportionation is demonstrated.
- Guo, Yan-Jun,Li, Yang,Zhang, Ping,Zhao, Yu-Rou,Zhou, Chao-Zheng
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supporting information
p. 2918 - 2924
(2021/05/05)
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- Quasi-continuous synthesis of cobalt single atom catalysts for transfer hydrogenation of quinoline
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Improving the transfer hydrogenation of N-heteroarenes is of key importance for various industrial processes and remains a challenge so far. We reported here a microcapsule-pyrolysis strategy to quasi-continuous synthesis S, N co-doped carbon supported Co single atom catalysts (Co/SNC), which was used for transfer hydrogenation of quinoline with formic acid as the hydrogen donor. Given the unique geometric and electronic properties of the Co single atoms, the excellent catalytic activity, selectivity and stability were observed. Benefiting from the quasi-continuous synthesis method, the as-obtained catalysts provide a reference for the large-scale preparation of single atom catalysts without amplification effect. Highly catalytic performances and quasi-continuous preparation process, demonstrating a new and promising approach to rational design of atomically dispersed catalysts with maximum atomic efficiency in industrial.
- Cheng, Yujie,Gan, Tao,He, Qian,He, Xiaohui,Huang, Liyun,Ji, Hongbing,Sun, Qingdi,Zhang, Hao
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- Highly efficient one-pot multi-directional selective hydrogenation and N-alkylation catalyzed by Ru/LDH under mild conditions
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Atomic economy, non-toxicity, harmlessness and multidirectional selectivity advocated by green chemistry have increasingly become a hot and difficult research topic. Herein, we present a highly efficient, one-pot tandem and easy-to-operate method through which we could directly produce a broad range of multi-directional selective hydrogenated amines or N-alkyl aliphatic amines using aromatic nitro compounds as raw materials. Ru/LDH with characteristics of layered mesoporous structure, well dispersed small Ru nanoparticles and LDH stabilization to the Ru NPs was employed as the catalyst. It is remarkable that multi-directional superb chemoselectivity to aromatic amines, alicyclic amines as well as N-alkyl aliphatic amines could be achieved with excellent catalytic activity and recyclability by tuning reaction conditions over 5wt%Ru/LDH-2. Additionally, this catalytic system also exhibited attractive activity and multi-directional chemoselectivity in the hydrogenation of quinoline and its derivatives with solvents of different polarity. Chemoselectivity to 5,6,7,8-tetrahydroquinoline derivatives could reach as high as 95.6 %.
- Zhang, Sishi,Xu, Jie,Cheng, Hongmei,Zang, Cuicui,Sun, Bin,Jiang, Heyan,Bian, Fengxia
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supporting information
(2020/03/30)
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- Convenient synthesis of cobalt nanoparticles for the hydrogenation of quinolines in water
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Easily accessible cobalt nanoparticles are prepared by hydrolysis of NaBH4 in the presence of inexpensive Co(ii) salts. The resulting material is an efficient catalyst for the hydrogenation of quinoline derivatives in water. The activity and chemoselectivity of this catalyst are comparable to other cobalt-based heterogeneous catalysts.
- Beller, Matthias,Dorcet, Vincent,Fischmeister, Cedric,Hervochon, Julien,Junge, Kathrin
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p. 4820 - 4826
(2020/08/14)
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- Facile Synthesis of Size-Controlled Nitrogen-Doped Mesoporous Carbon Nanosphere Supported Ultrafine Ru Nanoparticles for Selective Hydrogenation of Quinolines
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Nitrogen-doped mesoporous carbon nanosphere (NMCS) with tunable sizes and uniform mesoporosity was synthesized by a facile soft-templating method. During the synthesis, F127 (PEO–PPO–PEO triblock copolymer) could be used not only as a soft template to generate the mesostructure but also as a size-control agent to tailor the size of NMCS in a relatively wide range of 100 to 700 nm. In addition, the synthesis process was simple and suitable for large-scale production. Moreover, the NMCS was used as support of ultrafine Ru nanoparticles (Ru/NMCS), which exhibited good catalytic performances for selective hydrogenation of quinolones. It is expected that the simple synthetic strategy for the NMCS can generate extensive interest in many catalysis and sorption applications.
- Huang, Minghua,Jiang, Haibin,Tian, Zhengbin,Wang, Guang-Hui
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p. 17000 - 17004
(2020/11/30)
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- Simple manganese carbonyl catalyzed hydrogenation of quinolines and imines
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Manganese-catalyzed hydrogenation of unsaturated molecules has made tremendous progresses recently benefiting from non-innocent pincer or bidentate ligands for manganese. Herein, we describe the hydrogenation of quinolines and imines catalyzed by simple manganese carbonyls, Mn2(CO)10 or MnBr(CO)5, thus eliminating the prerequisite pincer-type or bidentate ligands.
- Wang, Zelong,Chen, Lei,Mao, Guoliang,Wang, Congyang
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p. 1890 - 1894
(2020/03/04)
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- Phyllosilicate-derived Nickel-cobalt Bimetallic Nanoparticles for the Catalytic Hydrogenation of Imines, Oximes and N-heteroarenes
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The development of cost-effective, noble metal-free catalytic systems for the hydrogenation of unsaturated aliphatic, aromatic, and heterocyclic compounds is fundamental for future valorization of general feedstock. With this aim, we report here the preparation of highly dispersed bimetallic Ni/Co nanoparticles (NPs), by a one-pot deposition-precipitation of Ni and Co phases onto mesoporous SBA-15 silica. By adjusting the chemical composition in the starting mixture, three supported catalysts with different Ni to Co weight ratios were obtained, which were further subjected to treatments under reducing conditions at high temperatures. Characterization of the resulting solids evidenced a homogenous distribution of Ni and Co elements forming the NPs, the best results being obtained for Ni/Co-2 : 2 samples, for which 50 wt.percent Ni–50 wt.percent Co NPs are found located on the surface of the residual phyllosilicate. Ni/Co-2 : 2, presenting the best performances for the hydrogenation of 2-methyl-quinoline, was further evaluated in the catalytic hydrogenation of selected imines, oximes and N-heteroarenes. Due to the high dispersion of bimetallic Ni?Co NPs, excellent properties (activity and selectivity) in the conversion of the selected substrates are reported.
- Ciotonea, Carmen,Hammi, Nisrine,Dhainaut, Jérémy,Marinova, Maya,Ungureanu, Adrian,El Kadib, Abdelkrim,Michon, Christophe,Royer, Sébastien
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p. 4652 - 4663
(2020/08/19)
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- Fast and Efficient Nickel(II)-catalysed Transfer Hydrogenation of Quinolines with Ammonia Borane
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Herein we report the first Ni(II)-catalysed transfer hydrogenation of quinolines using ammonia borane (AB) as hydrogen (H2) source. An in situ generated Ni(II)-bis(pyrazolyl)pyridine pre-catalyst could hydrogenate quinoline and its derivatives in excellent yields of up to 90% at 25 °C in 30 minutes. Spectroscopic studies revealed that a Ni(II)-hydride is responsible for the transfer hydrogenation of quinoline to 1,2,3,4-tetrahydroquinoline via a 1,4-dihydroquinoline intermediate. (Figure presented.).
- Vermaak, Vincent,Vosloo, Hermanus C. M.,Swarts, Andrew J.
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p. 5788 - 5793
(2020/12/01)
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- Co Nanoparticles Encapsulated in Nitrogen Doped Carbon Tubes for Efficient Hydrogenation of Quinoline under Mild Conditions
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The hydrogenation of nitrogen-containing heterocyclic precursors in aqueous medium is quite challenging, especially at low temperature and without imposing molecular hydrogen pressure. In the light of the edges of metal nanoparticles (NPs) possess high selective activity, but most of the exposed metal surface does not. Hence, to influence the activity of the entire NPs surface, the use of zeolitic imidazolate frameworks (ZIFs) to obtain the metal NPs encapsulated in the carbon tubes which has been applied frequently. Herein, we design and synthesize a series of metal catalysts encapsulated in N-doped carbon nanotubes (NCT), which disperse on the hollow N-doped carbon framework (HNC), via pyrolysis ZIF-67, ZIF-67@ZIF-8, and ZIF-8@ZIF-67 step by step. The catalyst of Co@NCT/HNC shows outstanding activity of hydrogenation of quinoline under mild conditions, due to the synergistic effects between Co NPs, NCT and HNC, such as the NCT make the hydrogen reach the surface of the reactant rapidly, and the encapsulated structure can enormously prevent the metal aggregating.
- Yun, Ruirui,Hong, Lirui,Ma, Wanjiao,Zhang, Ruiyu,Zhan, Feiyang,Duan, Jingui,Zheng, Baishu,Wang, Suna
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p. 129 - 134
(2019/11/16)
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- Boric acid catalyzed chemoselective reduction of quinolines
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Boric acid promoted transfer hydrogenation of substituted quinolines to synthetically versatile 1,2,3,4-tetrahydroquinolines (1,2,3,4-THQs) was described under mild reaction conditions using a Hantzsch ester as a mild organic hydrogen source. This methodology is practical and efficient, where isolated yields are excellent and reducible functional groups are well tolerated in the N-heteroarene moiety. The reaction parameters and tentative mechanistic pathways are demonstrated by various control experiments and NMR studies. The present work can also be scaled up to obtain gram quantities and the utility of the developed process is illustrated by the transformation of 1,2,3,4-THQs into a series of biologically important molecules including the antiarrhythmic drug nicainoprol.
- Adhikari, Priyanka,Bhattacharyya, Dipanjan,Das, Animesh,Konwar, Monuranjan,Nandi, Sekhar,Sarmah, Bikash Kumar
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supporting information
p. 1214 - 1220
(2020/02/22)
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- Hydrogenation reaction method
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The invention relates to a hydrogenation reaction method, and belongs to the technical field of organic synthesis. The hydrogenation reaction method provided by the invention comprises the following steps: carrying out a hydrogen transfer reaction on a hydrogen acceptor compound, pinacol borane and a catalyst in a solvent in the presence of proton hydrogen, so that the hydrogen acceptor compound is subjected to a hydrogenation reaction; the catalyst is one or more than two of a palladium catalyst, an iridium catalyst and a rhodium catalyst; the hydrogen acceptor compound comprises one or morethan two functional groups of carbon-carbon double bonds, carbon-carbon triple bonds, carbon-oxygen double bonds, carbon-nitrogen double bonds, nitrogen-nitrogen double bonds, nitryl, carbon-nitrogentriple bonds and epoxy. The method is mild in reaction condition, easy to operate, high in yield, short in reaction time, wide in substrate application range, suitable for carbon-carbon double bonds,carbon-carbon triple bonds, carbon-oxygen double bonds, carbon-nitrogen double bonds, nitrogen-nitrogen double bonds, nitryl, carbon-nitrogen triple bonds and epoxy functional groups, good in selectivity and high in reaction specificity.
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Paragraph 0034; 0217-0220
(2020/05/14)
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- Generalized Chemoselective Transfer Hydrogenation/Hydrodeuteration
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A generalized, simple and efficient transfer hydrogenation of unsaturated bonds has been developed using HBPin and various proton reagents as hydrogen sources. The substrates, including alkenes, alkynes, aromatic heterocycles, aldehydes, ketones, imines, azo, nitro, epoxy and nitrile compounds, are all applied to this catalytic system. Various groups, which cannot survive under the Pd/C/H2 combination, are tolerated. The activity of the reactants was studied and the trends are as follows: styrene'diphenylmethanimine'benzaldehyde'azobenzene'nitrobenzene'quinoline'acetophenone'benzonitrile. Substrates bearing two or more different unsaturated bonds were also investigated and transfer hydrogenation occurred with excellent chemoselectivity. Nano-palladium catalyst in situ generated from Pd(OAc)2 and HBPin extremely improved the TH efficiency. Furthermore, chemoselective anti-Markovnikov hydrodeuteration of terminal aromatic olefins was achieved using D2O and HBPin via in situ HD generation and discrimination. (Figure presented.).
- Wang, Yong,Cao, Xinyi,Zhao, Leyao,Pi, Chao,Ji, Jingfei,Cui, Xiuling,Wu, Yangjie
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supporting information
p. 4119 - 4129
(2020/08/10)
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- A proton-responsive annulated mesoionic carbene (MIC) scaffold on IR complex for proton/hydride shuttle: An experimental and computational investigation on reductive amination of aldehyde
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A Cp*Ir(III) complex (1) bearing a proton-responsive hydroxy unit on an annulated imidazo[1,2-a][1,8]naphthyridine based mesoionic carbene scaffold was synthesized by two different synthetic routes. The molecular structure of 1 revealed an anionic lactam form of the ligand. The acid?base equilibrium between the lactam-lactim tautomers on the ligand scaffold was examined by 1H NMR and UV?vis spectra. The pKa of the appendage ?OH group in the lactim form of 1 was estimated to assess the proton transfer property of the catalyst. The catalytic efficacy of 1 for reductive amination of aldehyde was evaluated by utilizing three different hydrogen sources: molecular H2iPrOH/KOtBu combination, and HCOOH/Et3N (5:2) azeotropic mixture. The HCOOH/Et3N (5:2) azeotropic mixture rotocol was found to be the best amon the three different h dro enation methods. Catalyst 1 hydrogenates imines chemoselectively over carbonyls under the reaction conditions. A range of aldehydes was reductively aminated to the corresponding secondary amines using the HCOOH/Et3N (5:2) azeotropic mixture. Further, catalyst 1 showed high efficiency for the reduction of a wide variety of N-heterocyclic imine derivatives. The lactam-lactim tautomerization of the ligand system is proposed for direct hydrogenation, whereas only the lactam form operates in the strongly basic medium (iPrOH/KOtBu). Under HCOOH/Et3N (5:2) conditions, the lactam scaffold is not protonated; rather, an outer-sphere hydride transfer from formate to the Ir is proposed, which is supported by 1H NMR and DFT calculations. Finally, ligand-promoted hydride transfer from metal-hydride to the protonated imine affords the corresponding amine. A close agreement between the experimentally estimated and computed thermodynamic/kinetic parameters gives credence to the metal-ligand cooperative mechanism for the imine hydrogenation reaction using the HCOOH/Et3N (5:2) azeotropic mixture.
- Bera, Jitendra K.,Daw, Prosenjit,Din Reshi, Noor U.,Ehmann, Kira R.,H?lscher, Markus,Leitner, Walter,Pandey, Pragati
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p. 3849 - 3863
(2020/11/23)
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- One-pot dual catalysis for the hydrogenation of heteroarenes and arenes
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A simple dinuclear monohydrido bridged ruthenium complex [{(η6-p-cymene)RuCl}2(μ-H-μ-Cl)] acts as an efficient and selective catalyst for the hydrogenation of various heteroarenes and arenes. The nature of the catalytically active species was investigated using a combination of techniques including in situ reaction monitoring, kinetic studies, quantitative poisoning experiments and electron microscopy, evidencing a dual reactivity. The results suggest that the hydrogenation of heteroarenes proceeds via molecular catalysis. In particular, monitoring the reaction progress by NMR spectroscopy indicates that [{(η6-p-cymene)RuCl}2(μ-H-μ-Cl)] is transformed into monomeric ruthenium intermediates, which upon subsequent activation of dihydrogen and hydride transfer accomplish the hydrogenation of heteroarenes under homogeneous conditions. In contrast, carbocyclic aryl motifs are hydrogenated via a heterogeneous pathway, by in situ generated ruthenium nanoparticles. Remarkably, these hydrogenation reactions can be performed using molecular hydrogen under solvent-free conditions or with 1,4-dioxane, and thus give access to a broad range of saturated heterocycles and carbocycles while generating no waste.
- Chatterjee, Basujit,Kalsi, Deepti,Kaithal, Akash,Bordet, Alexis,Leitner, Walter,Gunanathan, Chidambaram
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p. 5163 - 5170
(2020/09/07)
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- Visible light-mediated Smiles rearrangements and annulations of non-activated aromatics
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We report the first examples of radical cation Smiles rearrangements. A series of aryloxy alkylamines underwent spontaneous reaction, with the amino group displacing theipso-alkoxy group through substitution, at ambient temperature and under photoactivation by visible light in the presence of an acridinium catalyst (5 mol%). The study was extended to 3-(2-methoxyphenyl)propan-1-amine derivatives, which lack an appropriateipsoleaving group. Here, efficient cyclisations resulted in displacement of the methoxy group and formation of tetrahydroquinolines.
- Lawson, Connor A.,Dominey, Andrew P.,Williams, Glynn D.,Murphy, John A.
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p. 11445 - 11448
(2020/10/12)
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- Dual-Active-Sites Design of Co@C Catalysts for Ultrahigh Selective Hydrogenation of N-Heteroarenes
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The dual-active-sites Co@C catalyst provides a general powerful strategy to break the limitation of scaling relation on traditional metal surfaces and thus affords unprecedentedly selective hydrogenation of various N-heteroarenes as well as high activity and stability. A porous carbon shell not only allows H2 diffusion to Co sites for activation but also blocks accessibility of N-heteroarenes, and the hydrogenation of N-heteroarenes is achieved on carbon by the spilled hydrogen from Co sites. In addition, the presence of surface/subsurface carbon at the Co sites shows high anti-sulfur poisoning and anti-oxidant capability. Ideal heterogeneous metal hydrogenation catalysts are featured by simultaneously high activity, selectivity, and stability. Herein, we report a general yet powerful strategy to design and fabricate dual-active-sites Co@C core-shell nanoparticle for boosting selective hydrogenation of various N-heteroarenes. It can break the limitation of scaling relation on traditional metal surfaces, and thus afford unprecedentedly high selectivity, activity, and stability. Combining kinetics analysis and DFT calculations with multiple techniques directly unveil that the critical porous carbon shell with a pore size of 0.53 nm not only allows H2 diffusion to Co sites for activation and blocks accessibility of N-heteroarenes but also catalyzes hydrogenation of N-heteroarenes via hydrogen spillover from Co sites. In addition, the presence of surface/subsurface carbon at the Co sites shows high anti-sulfur poisoning and anti-oxidant capability. This work is valuable for guiding the design and manipulation of cost-effective and robust hydrogenation catalysts. Our research can provide an environmentally friendly approach to afford unprecedentedly selective N-heteroarenes hydrogenation, which will greatly reduce the resource and energy consumption and decrease the amount of waste discharge and water pollution. Therefore, these results could help in achieving the “Clean water and sanitation” goal in the 10 UN Sustainable Development Goals. Meanwhile, the products of N-heteroarenes hydrogenation are the core structural motifs in both fine and bulk chemicals, which will make our life more beautiful. Thus, our research also benefits the “Good health and well-being” goal.
- Zhang, Sai,Gan, Jie,Xia, Zhaoming,Chen, Xiao,Zou, Yong,Duan, Xuezhi,Qu, Yongquan
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supporting information
p. 2994 - 3006
(2020/09/04)
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- Catalytically Active Co?Nx Species Stabilized on Nitrogen-doped Porous Carbon for Efficient Hydrogenation and Dehydrogenation of N-heteroarenes
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The development of bifunctional, highly active and stable non-noble-metal catalysts is important for synthetic chemistry. In this study, a highly dispersed Co catalyst stabilized on the mesoporous N-doped carbon layers was prepared by adsorption and pyrolysis of cobalt complex on dendritic fibrous silica nanospheres (KCC-1@Co?N?C?T). The characterizations of HAADF-STEM, XRD and XPS together with the KSCN poisoning tests determine the absence of Co0 or CoOx nanoparticles and suggest that the Co?Nx species are the active sites. The formation of Co?Nx species results from the properties of N-rich cobalt-phenanthroline complex and dendritic fibrous silica supports, increasing the original spatial distance between Co atoms and thus preventing them from aggregation. The KCC-1@Co?N?C-800 catalyst showed excellent activity and selectivity for the oxidative dehydrogenation (ODH) of saturated N-heterocycles and base-free catalytic transfer hydrogenation (CTH) of unsaturated N-heterocycles.
- Xu, Dan,Zhao, Hong,Dong, Zhengping,Ma, Jiantai
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p. 4406 - 4415
(2020/07/06)
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- PtRuNi/C novel nanostructures of platinum-ruthenium island-on-Ni/Ni(OH)2 nanoparticles for the selective hydrogenation of quinoline
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Ni/C was successfully synthesized via hydrazine hydrate reduction at room temperature (RT). Pt/C, Ru/C and PtRu/C were prepared via an impregnation method. PtNi/C, RuNi/C and PtRuNi/C were synthesized via a chemical replacement method. The characterization results revealed that PtRuNi nanoparticles (NPs) were highly and uniformly dispersed on carbon black in PtRuNi/C. PtRuNi/C showed a novel nanostructure in which PtRu islands (PtRu nanoclusters or PtRu binary atoms) covered Ni/Ni(OH)2 NPs. PtRuNi/C trimetallic nanomaterial exhibited an optimum catalytic performance (turnover frequency (TOF) = 211.4 h?1 and selectivity for the production of 1,2,3,4-tetrahydroquinoline (py-THQ) > 99%) in the selective hydrogenation of quinoline at 60 °C under 5.0 MPa H2. The catalytic properties of PtRuNi/C were significantly improved as compared to bimetallic (PtNi/C, RuNi/C and PtRu/C) and monometallic (Ni/C, Pt/C and Ru/C) nanomaterials due to its unique nanostructure, with an observed nano-synergy effect among Pt-, Ru- and Ni-related species.
- Chen, Bing Hui,Liao, Jianhua,Pei, An,Ruan, Luna,Wang, Jiexiang,Yang, Kai,Zhang, Huan,Zhu, Lihua
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- Au Nanoparticles Confined in SBA-15 as a Highly Efficient and Stable Catalyst for Hydrogenation of Quinoline to 1,2,3,4-Tetrahydroquinoline
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Abstract: Au nanoparticles confined within the mesopores of the modified SBA-15 were obtained through adsorption-reduction method and firstly employed as chemoselective catalyst for quinoline hydrogenation. The effects of Au loadings, calcination temperature as well as structure of support on catalytic performances of Au catalysts were explored. The as-obtained 1.2percentAu@SBA-15-500 catalyst exhibited high activity, excellent selectivity towards 1,2,3,4-tetrahydroquinoline and extraordinary sintering-resistant property as high as 800?°C, which is sharp contrast to the 1.3percentAu/SiO2-500 catalyst. It also showed good recyclability and versatility for quinoline derivatives. The observed properties were assigned to small-sized Au nanoparticles and mesopores of SBA-15. Our work provides a facile and promising approach to construct metal nanocatalysts with high catalytic performance by the use of mesoporous materials. Graphic Abstract: [Figure not available: see fulltext.].
- Zhao, Jianbo,Yuan, Haifeng,Qin, Xiaomei,Tian, Kuan,Liu, Yingfan,Wei, Chengzhen,Zhang, Zhiqiang,Zhou, Liming,Fang, Shaoming
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p. 2841 - 2849
(2020/03/30)
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- Catalytic Reductions Without External Hydrogen Gas: Broad Scope Hydrogenations with Tetrahydroxydiboron and a Tertiary Amine
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Facile reduction of aryl halides with a combination of 5% Pd/C, B2(OH)4, and 4-methylmorpholine is reported. Aryl bromides, iodides, and chlorides were efficiently reduced. Aryl dihalides containing two different halogen atoms underwent selective reduction: I over Br and Cl, and Br over Cl. Beyond these, aryl triflates were efficiently reduced. This combination was broadly general, effectuating reductions of benzylic halides and ethers, alkenes, alkynes, aldehydes, and azides, as well as for N-Cbz deprotection. A cyano group was unaffected, but a nitro group and a ketone underwent reduction to a low extent. When B2(OD)4 was used for aryl halide reduction, a significant amount of deuteriation occurred. However, H atom incorporation competed and increased in slower reactions. 4-Methylmorpholine was identified as a possible source of H atoms in this, but a combination of only 4-methylmorpholine and Pd/C did not result in reduction. Hydrogen gas has been observed to form with this reagent combination. Experiments aimed at understanding the chemistry led to the proposal of a plausible mechanism and to the identification of N,N-bis(methyl-d3)pyridin-4-amine (DMAP-d6) and B2(OD)4 as an effective combination for full aromatic deuteriation. (Figure presented.).
- Korvinson, Kirill A.,Akula, Hari K.,Malinchak, Casina T.,Sebastian, Dellamol,Wei, Wei,Khandaker, Tashrique A.,Andrzejewska, Magdalena R.,Zajc, Barbara,Lakshman, Mahesh K.
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p. 166 - 176
(2020/01/02)
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- A NaH-promoted N-detosylation reaction of diverse p-toluenesulfonamides
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A NaH-mediated detosylation reaction of various Ts-protected indoles, azaheterocycles, anilines and dibenzylamine was reported. The method features cheap reagent, convenient operations, mild reaction conditions and broad substrate scope. Moreover, this study revealed that the loading of NaH in tosylation reactions of nitrogen-containing compounds with NaH as a base in DMA or DMF should be controlled due to the possibility of adverse detosylation.
- Sun, Wanwan,Chen, Xiaobei,Hu, Ying,Geng, Huihui,Jiang, Yuanrui,Zhou, Yuxin,Zhu, Wenjing,Hu, Min,Hu, Haohua,Wang, Xingyi,Wang, Xinli,Zhang, Shilei,Hu, Yanwei
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supporting information
(2020/10/05)
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- Sodium Triethylborohydride-Catalyzed Controlled Reduction of Unactivated Amides to Secondary or Tertiary Amines
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The first transition-metal-free catalytic protocol for controlled reduction of amide functions using cheap and bench-stable hydrosilanes as reducing agents has been established. By altering the hydrosilane and solvent, the new method enables the selective cleavage of unactivated C-O bonds in amides and allows the C-N bonds to selectively break via the deacylated cleavage. Overall, this novel process may offer a versatile alternative to current methodologies employing stoichiometric metal systems for the controlled reduction of carboxamides.
- Yao, Wubing,He, Lili,Han, Deman,Zhong, Aiguo
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p. 14627 - 14635
(2019/12/02)
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- Hydrogenation of N-Heteroarenes Using Rhodium Precatalysts: Reductive Elimination Leads to Formation of Multimetallic Clusters
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A rhodium-catalyzed method for the hydrogenation of N-heteroarenes is described. A diverse array of unsubstituted N-heteroarenes including pyridine, pyrrole, and pyrazine, traditionally challenging substrates for hydrogenation, were successfully hydrogenated using the organometallic precatalysts, [(η5-C5Me5)Rh(N-C)H] (N-C = 2-phenylpyridinyl (ppy) or benzo[h]quinolinyl (bq)). In addition, the hydrogenation of polyaromatic N-heteroarenes exhibited uncommon chemoselectivity. Studies into catalyst activation revealed that photochemical or thermal activation of [(η5-C5Me5)Rh(bq)H] induced C(sp2)-H reductive elimination and generated the bimetallic complex, [(η5-C5Me5)Rh(μ2,η2-bq)Rh(η5-C5Me5)H]. In the presence of H2, both of the [(η5-C5Me5)Rh(N-C)H] precursors and [(η5-C5Me5)Rh(μ2,η2-bq)Rh(η5-C5Me5)H] converted to a pentametallic rhodium hydride cluster, [(η5-C5Me5)4Rh5H7], the structure of which was established by NMR spectroscopy, X-ray diffraction, and neutron diffraction. Kinetic studies on pyridine hydrogenation were conducted with each of the isolated rhodium complexes to identify catalytically relevant species. The data are most consistent with hydrogenation catalysis prompted by an unobserved multimetallic cluster with formation of [(η5-C5Me5)4Rh5H7] serving as a deactivation pathway.
- Kim, Sangmin,Loose, Florian,Bezdek, Máté J.,Wang, Xiaoping,Chirik, Paul J.
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p. 17900 - 17908
(2019/11/19)
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- Formal Deoxygenative Hydrogenation of Lactams Using PNHP-Pincer Ruthenium Complexes under Nonacidic Conditions
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A formal deoxygenative hydrogenation of amides to amines with RuCl2(NHC)(PNHP) (NHC = 1,3-dimethylimizadol-2-ylidene, PNHP = bis(2-diphenylphosphinoethyl)amine) is described. Various secondary amides, especially NH-lactams, are reduced with H2 (3.0-5.0 MPa) to amines at a temperature range of 120-150 °C with 1.0-2.0 mol % of PNHP-Ru catalysts in the presence of Cs2CO3. This process consists of (1) deaminative hydrogenation of secondary amides to generate primary amines and alcohols, (2) dehydrogenative coupling of the transient amines with alcohols to generate imines, and (3) hydrogenation of imines to give the formally deoxygenated secondary amine products.
- Ogata, Osamu,Nara, Hideki,Matsumura, Kazuhiko,Kayaki, Yoshihito
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supporting information
p. 9954 - 9959
(2019/12/24)
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- Chemoselective reduction of quinoline over Rh-C60 nanocatalysts
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The design and engineering of heterogeneous nanocatalysts that are both highly active and selective for hydrogenation reactions constitute a crucial challenge. In that context, herein a series of Rh-C60 nanocatalysts have been synthesized via the decomposition of an organometallic rhodium complex in the presence of fullerene C60 under a H2 atmosphere. Rhodium atomically dispersed or rhodium nanoparticles on Rh-C60 spherical fulleride particles were produced by tuning the Rh/C60 molar ratio. Significant charge transfer between rhodium and C60 was evidenced through Raman and X-ray photoelectron spectroscopy, which indicates electron-deficient Rh species. The resulting heterostructured nanomaterials were applied successfully in the catalytic hydrogenation of quinoline, exhibiting excellent activity and producing selectively the partially hydrogenated product, 1,2,3,4-tetrahydroquinoline. Density functional theory (DFT) calculations show that the hydride coverage of the Rh NPs plays a key role in the adsorption modes of quinoline and 1,2,3,4-tetrahydroquinoline on the surface of the NPs, and that these adsorption modes are modulated by the presence of fullerene C60, thus affecting the activity and selectivity obtained with this rhodium based catalyst.
- Luo, Zhishan,Min, Yuanyuan,Nechiyil, Divya,Bacsa, Wolfgang,Tison, Yann,Martinez, Hervé,Lecante, Pierre,Gerber, Iann C.,Serp, Philippe,Axet, M. Rosa
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p. 6884 - 6898
(2019/12/26)
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- B(C6F5)3-Catalyzed Deoxygenative Reduction of Amides to Amines with Ammonia Borane
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The first B(C6F5)3-catalyzed deoxygenative reduction of amides into the corresponding amines with readily accessible and stable ammonia borane (AB) as a reducing agent under mild reaction conditions is reported. This metal-free protocol provides facile access to a wide range of structurally diverse amine products in good to excellent yields, and various functional groups including those that are reduction-sensitive were well tolerated. This new method is also applicable to chiral amide substrates without erosion of the enantiomeric purity. The role of BF3 ? OEt2 co-catalyst in this reaction is to activate the amide carbonyl group via the in situ formation of an amide-boron adduct. (Figure presented.).
- Pan, Yixiao,Luo, Zhenli,Han, Jiahong,Xu, Xin,Chen, Changjun,Zhao, Haoqiang,Xu, Lijin,Fan, Qinghua,Xiao, Jianliang
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supporting information
p. 2301 - 2308
(2019/01/30)
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- Ru-Catalyzed Deoxygenative Transfer Hydrogenation of Amides to Amines with Formic Acid/Triethylamine
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A ruthenium(II)-catalyzed deoxygenative transfer hydrogenation of amides to amines using HCO2H/NEt3 as the reducing agent is reported for the first time. The catalyst system consisting of [Ru(2-methylallyl)2(COD)], 1,1,1-tris(diphenylphosphinomethyl) ethane (triphos) and Bis(trifluoromethane sulfonimide) (HNTf2) performed well for deoxygenative reduction of various secondary and tertiary amides into the corresponding amines in high yields with excellent selectivities, and exhibits high tolerance toward functional groups including those that are reduction-sensitive. The choice of hydrogen source and acid co-catalyst is critical for catalysis. Mechanistic studies suggest that the reductive amination of the in situ generated alcohol and amine via borrowing hydrogen is the dominant pathway. (Figure presented.).
- Pan, Yixiao,Luo, Zhenli,Xu, Xin,Zhao, Haoqiang,Han, Jiahong,Xu, Lijin,Fan, Qinghua,Xiao, Jianliang
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supporting information
p. 3800 - 3806
(2019/07/12)
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- Ru subnanoparticles on N-doped carbon layer coated SBA-15 as efficient Catalysts for arene hydrogenation
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The N-doped carbon layer coated SBA-15 support has been accomplished via a pyrolysis process. The ultra-low loading Ru nanoparticles (ca. 0.1 wt.%) was incorporated into the support by impregnation and the sequential reduction. The images of HAADF-STEM revealed that the Ru particles with sub-1-nm size (0.2-0.7 nm) were uniformly dispersed on the support. The ultrafine Ru particles displayed the excellent activity for the hydrogenation of olefins, arenes, phenol derivatives and heteroarenes in aqueous phase. The aliphatic or alicyclic compounds were produced selectively without the hydrogenolysis of C–O and C–N bonds. The high turnover frequency (TOF) values can reach up to 10,000 h?1. Notably, the activity of these catalysts improved dramatically with decreasing the sizes of Ru particles. Meanwhile, the N-doped carbon layer coating endowed the high stability of the Ru catalysts and prevented the leaching of the Ru species owning to the strong interaction between doped-N atoms and the ultrafine Ru particles. Overall, this work provides a highly attractive strategy to construct the supported sub-1-nm Ru particles utilized for the aqueous hydrogenation.
- Qian, Wei,Lin, Lina,Qiao, Yunxiang,Zhao,Xu, Zichen,Gong, Honghui,Li,Chen,Huang, Rong,Hou, Zhenshan
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- Cobalt-Catalyzed Hydrogenations via Olefin Cobaltate and Hydride Intermediates
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Redox noninnocent ligands are a promising tool to moderate electron transfer processes within base-metal catalysts. This report introduces bis(imino)acenaphthene (BIAN) cobaltate complexes as hydrogenation catalysts. Sterically hindered trisubstituted alkenes, imines, and quinolines underwent clean hydrogenation under mild conditions (2-10 bar, 20-80 °C) by use of the stable catalyst precursor [(DippBIAN)CoBr2] and the cocatalyst LiEt3BH. Mechanistic studies support a homogeneous catalysis pathway involving alkene and hydrido cobaltates as active catalyst species. Furthermore, considerable reaction acceleration by alkali cations and Lewis acids was observed. The dinuclear hydridocobaltate anion with bridging hydride ligands was isolated and fully characterized.
- Sandl, Sebastian,Maier, Thomas M.,Van Leest, Nicolaas P.,Kr?ncke, Susanne,Chakraborty, Uttam,Demeshko, Serhiy,Koszinowski, Konrad,De Bruin, Bas,Meyer, Franc,Bodensteiner, Michael,Herrmann, Carmen,Wolf, Robert,Von Jacobi Wangelin, Axel
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p. 7596 - 7606
(2019/08/20)
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