- Transition-Metal-Controlled Inorganic Ligand-Supported Non-Precious Metal Catalysts for the Aerobic Oxidation of Amines to Imines
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Most state-of-art transition-metal catalysts usually require organic ligands, which are essential for controlling the reactivity and selectivity of reactions catalyzed by transition metals. However, organic ligands often suffer from severe problems including cost, toxicity, air/moisture sensitivity, and being commercially unavailable. Herein, we show a simple, mild, and efficient aerobic oxidation procedure of amines using inorganic ligand-supported non-precious metal catalysts 1, (NH4)n[MMo6O18(OH)6] (M=Cu2+; Fe3+; Co3+; Ni2+; Zn2+, n=3 or 4), synthesized by a simple one-step method in water at 100 °C, demonstrating that the catalytic activity and selectivity can be significantly improved by changing the central metal atom. In the presence of these catalysts, the catalytic oxidation of primary and secondary amines, as well as the coupling of alcohols and amines, can smoothly proceed to afford various imines with O2 (1 atm) as the sole oxidant. In particular, the catalysts 1 have transition-metal ion core, and the planar arrangement of the six MoVI centers at their highest oxidation states around the central heterometal can greatly enhance the Lewis acidity of catalytically active sites, and also enable the electrons in the center to delocalize onto the six edge-sharing MO6 units, in the same way as ligands in traditional organometallic complexes. The versatility of this methodology maybe opens a path to catalytic oxidation through inorganic ligand-coordinated metal catalysis.
- Yu, Han,Zhai, Yongyan,Dai, Guoyong,Ru, Shi,Han, Sheng,Wei, Yongge
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- Molecular Structural Design of Conjugated Microporous Poly(Benzooxadiazole) Networks for Enhanced Photocatalytic Activity with Visible Light
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A simple structural design principle and band position alignment of conjugated microporous polymers for enhanced photocatalytic efficiency is presented. The valence and conduction band positions of the polymer networks can be fine-tuned by altering the su
- Wang, Zi Jun,Ghasimi, Saman,Landfester, Katharina,Zhang, Kai A. I.
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- Nickel-decorated g-C3N4hollow spheres as an efficient photocatalyst for hydrogen evolution and oxidation of amines to imines
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Photocatalysts composed of earth-abundant elements are highly desired for photocatalytic hydrogen evolution as well as oxidation of amines to imines without the requirement of precious metals. Herein, non-precious Ni metal decorated g-C3N4 hollow spheres
- Zhang, Shishen,Qian, Xiaobing,Yan, Junqiu,Chen, Kelong,Huang, Jianhua
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- FeCl2-PPh3 as an efficient catalytic system for the acceptorless dehydrogenation of amines into imines
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In this work, a novel and simple catalytic system including FeCl2, PPh3 and potassium tert-butoxide has been employed for the synthesis of imines from amines. In order to prove the catalytic acceptorless dehydrogenation pathway for this transformation, the liberated H2 gas is detected by NMR spectroscopy. By utilizing this protocol, a variety of arylamines were used successfully for the preparation of corresponding imines in good to excellent yields (on a 1?mmol scale, 73–91% yield for homocoupling, 71 and 91% for heterocoupling).
- Nazarahari, Maryam,Azizian, Javad
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- Heterojunctions between amorphous and crystalline niobium oxide with enhanced photoactivity for selective aerobic oxidation of benzylamine to imine under visible light
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The formation of heterojunctions between two crystals with different band gap structures, acting as a tunnel for the unidirectional transfer of photogenerated charges, is an efficient strategy to enhance the photocatalytic performance of semiconductor pho
- Zhang, Yantao,Pei, Linjuan,Zheng, Zhanfeng,Yuan, Yong,Xie, Tengfeng,Yang, Juan,Chen, Shuai,Wang, Junwen,Waclawik, Eric R.,Zhu, Huaiyong
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- Unveiling the "three-Finger Pharmacophore" Required for p53-MDM2 Inhibition by Saturation-Transfer Difference (STD) NMR Initial Growth-Rates Approach
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Inhibitors of the p53-MDM2 protein-protein interaction are emerging as a new and validated approach to treating cancer. Herein, we describe the synthesis and inhibitory evaluation of a series of isoquinolin-1-one analogues, and highlight the utility of an initial growth-rates saturation-transfer difference (STD) NMR approach supported by protein-ligand docking to investigate p53-MDM2 inhibition. The approach is illustrated by the study of compound 1, providing key insights into the binding mode of this kind of MDM2 ligands and, more importantly, readily unveiling the previously proposed three-finger pharmacophore requirement for p53-MDM2 inhibition. Molecular modelling: Inhibitors of the p53-MDM2 protein-protein interaction are emerging as a new and validated approach to treating cancer. Herein, the synthesis and inhibitory evaluation of a series of isoquinolin-1-one analogues is described, and the utility of an initial growth-rates STD NMR approach supported by protein-ligand docking to investigate p53-MDM2 inhibition is highlighted (see figure).
- Angulo, Jesus,Goffin, Sarah A.,Gandhi, Daivik,Searcey, Mark,Howell, Lesley A.
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- Metal-free oxidation of benzyl amines to imines
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A convenient procedure for the oxidation of benzyl amines to the corresponding imines has been developed. Various imines were produced in good to excellent yields. Notably, no catalyst was needed, and H2O 2 was used as the oxidant an
- Wu, Xiao-Feng,Petrosyan, Andranik,Ghochikyan, Tariel V.,Saghyan, Ashot S.,Langer, Peter
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- ZnIn2S4: A photocatalyst for the selective aerobic oxidation of amines to imines under visible light
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Flowerlike nanospheres of ZnIn2S4 consisting of interweaving nanoflakes were prepared by a rapid microwave-assisted solvothermal method. The photocatalytic performance of ZnIn2S4 in the aerobic oxidation of amines to imines is for the first time revealed. As-prepared ZnIn2S4 showed high efficiency for the transformations of various amines into their corresponding imines under visible-light irradiation by using air as the oxidant. The photocatalytic performance of ZnIn2S4 in the selective oxidation of amines to their corresponding imines is much higher than that of graphitic C3N4 and CdS previously reported. A plausible mechanism involving the oxygenation of amines to form aldehydes, followed by the nucleophilic addition of the amines to afford the final imines is proposed. The use of a cheap, environmentally friendly inorganic semiconductor photocatalyst and solar energy makes this transformation green and sustainable.
- Ye, Lin,Li, Zhaohui
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- Calcined ZnCrCO3-HTlc for the oxidation of benzyl amines to Schiff bases
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Oxidation of benzylamines to Schiff bases has been carried out using a mixed oxide catalyst obtained by the calcination of ZnCrCO3-HTlc which is a member of the anionic clay family.
- Choudary,Narender,Bhuma
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- The Combination of Charge and Energy Transfer Processes in MOFs for Efficient Photocatalytic Oxidative Coupling of Amines
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Combining electron and energy transfer processes is very significant for efficient photocatalytic oxidation of organic molecules. The first synthesized MOF, Co2(L)(2,6-NDC)2·xguest (FJI-Y10, L = bis(N-pyridyl) tetrachloroperylene per
- Ju, Zhanfeng,Tan, Yan-Xi,Yuan, Daqiang,Zhang, Guoliang,Zhao, Feng-Juan
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- Designed Synthesis of a 2D Porphyrin-Based sp2 Carbon-Conjugated Covalent Organic Framework for Heterogeneous Photocatalysis
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The construction of stable covalent organic frameworks (COFs) for various applications is highly desirable. Herein, we report the synthesis of a novel two-dimensional (2D) porphyrin-based sp2 carbon-conjugated COF (Por-sp2c-COF), whi
- Chen, Rufan,Shi, Ji-Long,Ma, Yuan,Lin, Guiqing,Lang, Xianjun,Wang, Cheng
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- Synthesis of Imines by Selective Oxidation of Amines on alloy nanoparticles of palladium and gold under visible light irradiation at ambient temperatures
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Abstract: Imines are important intermediates in organic synthesis. To avoid derivatives, the research on direct oxidized amines as an alternative method is imminent. The gold (Au)–palladium (Pd) alloy nanoparticles (NPs) catalyst shows a favourable activi
- Eerdemutu,Ding, Lijun,Li, Chun,Zhao, Shuang,Sheng, Xianliang
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- Aerobic oxidation of amines to imines catalyzed by bulk gold powder and by alumina-supported gold
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Both bulk gold powder (~50 μm particle size) and alumina-supported gold (50-150 nm) are highly active catalysts for the aerobic oxidative dehydrogenation of amines (CH-NH) to imines (C{double bond, long}N) under the mild conditions of 1 atm O2 and 100 °C. Reactions using the 5% Au/Al2O3 catalyst make efficient use of the gold metal and offer a practical synthesis of imines from amines. These studies add to the growing list of reactions that are catalyzed by bulk gold metal.
- Zhu, Bolin,Lazar, Mihaela,Trewyn, Brian G.,Angelici, Robert J.
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- A New Cobalt(III)/[Mo6O19]2? Heterogeneous Catalyst for Promoting the Oxidative Coupling of Amines to Imines
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Abstract: Currently, the efficient preparation of imines is still a great challenge under mild conditions. In this article, by incorporating 2-acetylpyridine thiosemicarbazone (HL), Co(NO3)2·6H2O and Na2MoO
- Zhao, Meng,Li, Jie,Xing, Cuili,Han, Qiuxia,Ma, Lihua,Li, Mingxue
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- Cyclometalated Half-Sandwich Iridium(III) Complexes: Synthesis, Structure, and Diverse Catalytic Activity in Imine Synthesis Using Air as the Oxidant
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Four air-stable cyclometalated half-sandwich iridium complexes 1-4 with C,N-donor Schiff base ligands were prepared through C-H activation in moderate-to-good yields. These complexes have been well characterized, and their exact structure was elaborated on by single-crystal X-ray analysis. The iridium(III) complexes 1-4 showed good catalytic activity in the imine synthesis under open-flask conditions (air as the oxidant) from primary amine oxidative homocoupling, secondary amine dehydrogenation, and the cross-coupling reaction of amine and alcohol. Substituents bonded on the ligands of the iridium complexes displayed little effect on the catalytic efficiency. The stability and good catalytic efficiency of the iridium catalysts, mild reaction conditions, and substrate universality showed their potential application in industrial production.
- Li, Rong-Jian,Ling, Chun,Lv, Wen-Rui,Deng, Wei,Yao, Zi-Jian
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p. 5153 - 5162
(2021/05/04)
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- Base-Mediated Generation of Ketenimines from Ynamides: [3+2] Annulation with Azaallyl Anions
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Under basic conditions and heat, ynamides can serve as precursors to ketenimines, whose synthetic potential is often hampered by their difficulty of access. Herein, we report that they can undergo a [3+2] cycloaddition with 2-azaallyl anions, obtained from benzylimines under the same reaction conditions. This reaction between two highly reactive intermediates, both generated in situ from bench stable starting materials, gives access to various nitrogen-rich heterocycles. The reaction usually proceeds with excellent diastereoselectivity, in favor of the cis adduct. Deuteration experiments and DFT calculations helped rationalize the regio- and stereoselectivity of the process as well as the formation of side products. (Figure presented.).
- D'Hollander, Agathe C. A.,Romero, Eugénie,Vijayakumar, Kamsana,Le Houérou, Camille,Retailleau, Pascal,Dodd, Robert H.,Iorga, Bogdan I.,Cariou, Kevin
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supporting information
p. 2903 - 2908
(2021/04/21)
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- Photocatalytic carbon dioxide reduction coupled with benzylamine oxidation over Zn-Bi2WO6microflowers
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Using solar energy to realize CO2reduction and benzylamine oxidation is of great importance. Here, we design Zn-Bi2WO6microflowers catalyst, which can simultaneously reduce CO2to CO and oxidize benzylamine toN-benzylbenzaldimine with high activities and selectivities in a simple photocatalytic system.
- Tan, Dongxing,Cheng, Xiuyan,Zhang, Jianling,Sha, Yufei,Shen, Xiaojun,Su, Zhuizhui,Han, Buxing,Zheng, Lirong
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p. 2913 - 2917
(2021/05/07)
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- C70Fullerene Catalyzed Photoinduced Aerobic Oxidation of Benzylamines to Imines and Aldehydes
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C70 fullerene catalyzed photoinduced oxidation of benzylic amines at ambient conditions has been explored here. The developed strategy's main feature includes the additive/oxidant-free conversion of benzylic amine to corresponding imine and aldehydes. The reaction manifests broad substrate scope with excellent function group leniency and is applicable up to the gram scale. Further, symmetrical secondary amines can also be synthesized from benzylic amine in a one-pot two-step process. Various experiments and density functional theory studies revealed that the current reaction involves the generation of reactive oxygen species, single electron transfer reaction, and benzyl radical formation as key steps under photocatalytic conditions.
- Kumar, Inder,Kumar, Rakesh,Gupta, Shiv Shankar,Sharma, Upendra
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supporting information
p. 6449 - 6457
(2021/05/29)
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- Sulfur-stabilised copper nanoparticles for the aerobic oxidation of amines to imines under ambient conditions
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The stabilisation of metal nanoparticles and control of their oxidation state are crucial factors in nanocatalysis. Elemental sulfur has been found to be a cheap and effective stabilising agent for copper nanoparticles in the form of copper(i) oxide. The
- Martín-García, Iris,Díaz-Reyes, Gloria,Sloan, George,Moglie, Yanina,Alonso, Francisco
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supporting information
p. 11312 - 11322
(2021/05/19)
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- Type I ‘Lighted Metal-free’ Photosensitizing Assemblies of Phenazine for Aerobic Oxidative Transformations
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Highly photostable supramolecular photosensitizing ‘lighted metal-free’ assemblies of DPZ-Th have been developed which show strong absorption in the visible region and excellent electron transportation potential from donor to acceptor units. The as-prepar
- Kaur, Lovjot,Kaur, Harpreet,Kumar, Manoj,Bhalla, Vandana
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supporting information
p. 4179 - 4186
(2021/11/23)
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- One-Pot Direct Oxidation of Primary Amines to Carboxylic Acids through Tandem ortho-Naphthoquinone-Catalyzed and TBHP-Promoted Oxidation Sequence
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Biomimetic oxidation of primary amines to carboxylic acids has been developed where the copper-containing amine oxidase (CuAO)-like o-NQ-catalyzed aerobic oxidation was combined with the aldehyde dehydrogenase (ALDH)-like TBHP-mediated imine oxidation protocol. Notably, the current tandem oxidation strategy provides a new mechanistic insight into the imine intermediate and the seemingly simple TBHP-mediated oxidation pathways of imines. The developed metal-free amine oxidation protocol allows the use of molecular oxygen and TBHP, safe forms of oxidant that may appeal to the industrial application.
- Kim, Hun Young,Oh, Kyungsoo,Si, Tengda
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supporting information
p. 18150 - 18155
(2021/12/09)
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- Catalytic dehydrogenation of amines to imines and the in-situ reduction of sulfoxides into sulfides
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The catalytic acceptorless dehydrogenation of primary amines into imines and H2 represents one of the most important organic transformations, and the in-situ utilization of the generated H2 for chemical reduction reactions has never
- Li, Bo,Liu, Bing,Liu, Xixi,Wang, Wei,Wang, Yanxin,Xiang, Nian,Zhang, Zehui
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- Visible-light-responsive lanthanide coordination polymers for highly efficient photocatalytic aerobic oxidation of amines and thiols
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Development of visible-light-induced photocatalytic reactions using molecular oxygen as the terminal oxidant is intriguing in view of the current environmental and energy issues. We report herein the synthesis and characterization of a series of novel pho
- An, Shuyi,Che, Yan,Chen, Peng,Guo, Zhifen,Liu, Xin,Xing, Hongzhu
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p. 15767 - 15775
(2021/09/22)
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- Ball-Milling Induced Debonding of Surface Atoms from Metal Bulk for Construing High-Performance Dual-Site Single-Atom Catalysts
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One of the most pressing challenges in single-atom catalysis is the manipulation of the coordination environment of central metals to maximize the catalyst performance. Herein, we fabricated a high-performance catalyst (Co-SNC) by introducing S into the n
- Liu, Bo,Pan, Jing,Shi, Weidong,Song, Shuyan,Wang, Huilin,Wang, Xiao,Xu, Jing,Zhang, Hongjie,Zhang, Lingling,Zhao, Meng
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supporting information
p. 23154 - 23158
(2021/09/15)
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- Aprotic Amine-modified Manganese Dioxide Catalysts for Selectivity-tunable Oxidation of Amines
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Organic modifiers have shown promising potential for regulating the activity and selectivity of heterogeneous catalysts via tuning their surface properties. Despite the increasing application of organic modification technique in regulating the redox-acid
- Hao, Qianqian,Jia, Xiuquan,Ma, Jiping,Gao, Mingxia,Fan, Xiaomeng,Gao, Jin,Xu, Jie
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supporting information
p. 1388 - 1391
(2021/05/06)
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- Charge Transfer from Donor to Acceptor in Conjugated Microporous Polymer for Enhanced Photosensitization
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Photosensitization associated with light absorption and energy/electron-transfer represents the central processes for photosynthesis. However, it's still a challenge to develop a heavy-atom-free (HAF) strategy to improve the sensitizing ability of polymeric photosensitizers. Herein, we propose a new protocol to significantly improve the photosensitization by decorating mother conjugated microporous polymer (CMP-1) with polycyclic aromatic hydrocarbons (PAHs), resulting in a series of CMPs (CMP-2–4). Systematic study reveals that covalent modification with PAHs can transfer charge to Bodipy in CMP to further facilitate both intersystem crossing and electron-hole separation, which can dramatically boost energy-/electron-transfer reactions. Remarkably, CMP-2 as a representative CMP can efficiently drive the photosynthesis of methyl phenyl sulfoxide with 92 % yield, substantially higher than that of CMP-1 (32 %). Experiments and theory calculations demonstrate the structure-property-activity relationship of these CMPs, opening a new horizon for developing HAF heterogeneous photosensitizers with highly efficient sensitizing activity by rational structure regulation at a molecular level.
- Guo, Guang-Chen,Guo, Song,Kong, Li-Hui,Lu, Tong-Bu,Peng, Yuan-Zhao,Zhang, Zhi-Ming
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supporting information
p. 22062 - 22069
(2021/08/30)
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- Covalent-organic frameworks with keto-enol tautomerism for efficient photocatalytic oxidative coupling of amines to imines under visible light
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Photocatalytic oxidation of organic molecules into highly value-added products is an innovative and challenging research which has gradually attracted remarkable attention of scientists. In this work, it is demonstrated that the COF-TpPa with keto-enol ta
- Wu, Zhenyu,Huang, Xiubing,Li, Xiangjun,Hai, Guangtong,Li, Baozhen,Wang, Ge
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p. 2169 - 2179
(2021/11/09)
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- Direct synthesis of amides and imines by dehydrogenative homo or cross-coupling of amines and alcohols catalyzed by Cu-MOF
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Oxidative dehydrogenative homo-coupling of amines to imines and cross-coupling of amines with alcohols to amides was achieved with high to moderate yields at room temperature in THF using Cu-MOF as an efficient and recyclable heterogeneous catalyst under mild conditions. Different primary benzyl amines and alcohols could be utilized for the synthesis of a wide variety of amides and imines. The Cu-MOF catalyst could be recycled and reused four times without loss of catalytic activity.
- Anbardan, Soheil Zamani,Bozcheloei, Abolfazl Hassani,Mokhtari, Javad,Yari, Ahmad
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p. 20788 - 20793
(2021/07/01)
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- Fe2Mn(μ3-O)(COO)6 Cluster Based Stable MOF for Oxidative Coupling of Amines via Heterometallic Synergy
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The direct catalytic oxidative coupling of amines is one of the attracting methods for the synthesis of a variety of pharmaceutical or industrial needed imines. Numerous earth-abundant manganese based salts, oxides, and complexes have been applied in this reaction. However, these compounds suffered from difficult separation, large catalyst loading, complicated reactivation or indeterminate activity. Considering the facts that metal-organic frameworks (MOFs) with crystalline structure, precise composition, and enormous surface area have superior performance in heterogeneous catalytic reactions, herein, we introduced Mn into [Fe3(μ3-O)(CH3COO)6], one of the precursors for the preparation of stable MOFs, and got [Fe2Mn(μ3-O)(CH3COO)6] cluster. After ligand replacement with biphenyl-3,4’,5-tricarboxylic acid (BPTC), heterometallic cluster-based [Fe2Mn(μ3-O)(BPTC)2(DMF)2(H2O)] (1) was obtained. As expected, 1 is stable and able to catalyze the homo- or cross-coupling of amines effectively and selectively with 0.9 mol% catalyst loading at room temperature. Control experiments indicated that the catalytic activity of 1 mainly stems from Mn sites and that Fe synergistically contributes to the stability. Additionally, 1 is recyclable and can be reused easily for at least 8 runs without obvious decrease in catalytic ability. To our knowledge, 1 should be the first heterometallic cluster-based MOF with defined structure suitable for the synthesis of diverse imines from oxidative coupling of amines under mild conditions, which may shed light on the easy preparation of effective heterogeneous catalysts for organic synthesis.
- Wang, Ying-Xia,Wang, Hui-Min,Meng, Pan,Song, Dong-Xia,Qi, Zhikai,Zhang, Xian-Ming
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p. 2983 - 2989
(2021/08/30)
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- 2D sp2 Carbon-Conjugated Porphyrin Covalent Organic Framework for Cooperative Photocatalysis with TEMPO
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2D covalent organic frameworks (COFs) are receiving ongoing attention in semiconductor photocatalysis. Herein, we present a photocatalytic selective chemical transformation by combining sp2 carbon-conjugated porphyrin-based covalent organic framework (Por-sp2c-COF) photocatalysis with TEMPO catalysis illuminated by 623 nm red light-emitting diodes (LEDs). Highly selective conversion of amines into imines was swiftly afforded in minutes. Specifically, the π-conjugation of porphyrin linker leads to extensive absorption of red light; the sp2 ?C=C? double bonds linkage ensures the stability of Por-sp2c-COF under high concentrations of amine. Most importantly, we found that crystalline framework of Por-sp2c-COF is pivotal for cooperative photocatalysis with (2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO). This work foreshadows that the outstanding hallmarks of COFs, particularly crystallinity, could be exploited to address energy and environmental challenges by cooperative photocatalysis.
- Chen, Rufan,Hao, Huimin,Lang, Xianjun,Shi, Ji-Long,Wang, Cheng
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supporting information
p. 9088 - 9093
(2020/03/30)
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- The Hofmann reaction involving annulation of: O -(pyridin-2-yl)aryl amides selectively and rapidly leads to potential photocatalytically active 6 H -pyrido[1,2- c] quinazolin-6-one derivatives
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A highly efficient PIFA-mediated Hofmann reaction of o-(pyridin-2-yl)aryl amides has been developed to selectively and rapidly construct various potential photocatalytically active 6H-pyrido[1,2-c]quinazolin-6-one derivatives. The use of a nontoxic and ec
- Gao, Wenjing,Liu, Tongxin,Wan, Yameng,Wu, Hao,Zhang, Guisheng,Zhang, Zhiguo
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supporting information
p. 7955 - 7961
(2020/11/30)
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- G-C3N4/Uio-66-NH2 nanocomposites with enhanced visible light photocatalytic activity for hydrogen evolution and oxidation of amines to imines
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g-C3N4/Uio-66-NH2 (CNUIO) nanocomposites were prepared by growing an NH2-mediated zirconium-based metal-organic framework (Uio-66-NH2) in the presence of g-C3N4 nanotubes. CNUIO
- Zhang, Shishen,Chen, Kelong,Peng, Wen,Huang, Jianhua
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p. 3052 - 3061
(2020/03/03)
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- Mo/W/Ta ternary mixed polyoxometallate and application thereof in photocatalytic primary amine coupling reaction
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The invention discloses a Mo/W/Ta ternary mixed polyoxometallate and an application thereof in a photocatalytic coupling reaction, and belongs to the technical field of inorganic chemistry or photocatalysis. The molecular formula of the Mo/W/Ta ternary mi
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Paragraph 0035-0040
(2020/01/25)
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- Synthesis, characterization, catalytic and biological application of half-sandwich ruthenium complexes bearing hemilabile (κ2-: C, S)-thioether-functionalised NHC ligands
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A series of cationic Ru(ii)(η6-p-cymene) complexes with thioether-functionalised N-heterocyclic carbene ligands have been prepared and fully characterized. Steric and electronic influence of the R thioether substituent on the coordination of the sulfur atom was investigated. The molecular structure of three of them has been determined by means of X-ray diffractrometry and confirmed the bidentate (κ2-C,S) coordination mode of the ligand. Interestingly, only a single diastereomer, as an enantiomeric couple, was observed in the solid state for complexes 1c, 1i and 1j. DFT calculations established a low energy inversion barrier between the two diastereomers through a sulfur pyramidal inversion pathway with R donating group while a dissociative/associative mechanism is more likely with R substituents that contain electron withdrawing group, thus suggesting that the only species observed by the 1H-NMR correspond to an average resonance position of a fluxional mixtures of isomers. All these complexes were found to catalyse the oxydant-free double dehydrogenation of primary amine into nitrile. Ru complex bearing NHC-functionalised S-tBu group was further investigated in a wide range of amines and was found more selective for alkyl amine substrates than for benzylamine derivatives. Finally, preliminary results of the biological effects on various human cancer cells of four selected Ru complexes are reported.
- Achard, Thierry,Bellemin-Laponnaz, Stéphane,Chen, Weiguang,Egly, Julien,Maisse-Francois, Aline,Poblador-Bahamonde, Amalia I.
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supporting information
p. 3243 - 3252
(2020/03/19)
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- Confined pyrolysis of a dye pollutant for two-dimensional F,N,S tri-doped nanocarbon as a high performance oxidative coupling reaction catalyst
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Nanocarbon materials as metal-free catalysts for the oxidative coupling of primary amines to imines suffer from high catalyst loading, low reaction rate and high oxygen demand. Doping heteroatoms in nanocarbons is realized as an effective strategy to improve the catalytic activity, however, the doping of fluorine has been rarely studied. Here we synthesized a F,N,S tri-doped hierarchical nanocarbon (FNSHC) by pyrolyzing a fluorine-containing azo-sulphonate dye (acid red-337, a pollutant in wastewater) confined in a layered double hydroxide (LDH). The LDH-confined synthetic method is beneficial to the formation of a two-dimensional porous structure with a large specific surface area (~1432 m2 g-1) and high fluorine content, enabling remarkable catalytic performance (98% yield in 4 h at 2 wt% catalyst loading under open-air conditions) and high recyclability, outcompeting current metal-free carbocatalysts. The conversion of environmental pollutants into heteroatom-doped carbon materials provides a new green strategy for the design and synthesis of functional carbon catalysts.
- Chen, Sian,Hu, Yajing,Li, Fang-Fang,Liu, Sijie,Peng, Ping,Wang, Haining,Yu, Ao,Yu, Bingzhe
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p. 7839 - 7847
(2020/11/30)
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- Selective Acceptorless Dehydrogenation of Primary Amines to Imines by Core–Shell Cobalt Nanoparticles
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Core–shell nanocatalysts are attractive due to their versatility and stability. Here, we describe cobalt nanoparticles encapsulated within graphitic shells prepared via the pyrolysis of a cationic poly-ionic liquid (PIL) with a cobalt(II) chloride anion. The resulting material has a core–shell structure that displays excellent activity and selectivity in the self-dehydrogenation and hetero-dehydrogenation of primary amines to their corresponding imines. Furthermore, the catalyst exhibits excellent activity in the synthesis of secondary imines from substrates with various reducible functional groups (C=C, C≡C and C≡N) and amino acid derivatives.
- Cui, Xinjiang,Li, Wu,Junge, Kathrin,Fei, Zhaofu,Beller, Matthias,Dyson, Paul J.
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supporting information
p. 7501 - 7507
(2020/03/16)
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- Air-Stable Half-Sandwich Iridium Complexes as Aerobic Oxidation Catalysts for Imine Synthesis
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Several N,O-coordinate half-sandwich iridium complexes, 1-5, containing constrained bulky β-enaminoketonato ligands were prepared and clearly characterized. Single-crystal X-ray diffraction characterization of these complexes indicates that the iridium center adopts a distorted octahedral geometry. Complexes 1-5 showed good catalytic efficiency in the oxidative homocoupling of primary amines, dehydrogenation of secondary amines, and the oxidative cross-coupling of amines and alcohols, which furnished various types of imines in good yields and high selectivities using O2 as an oxidant under mild conditions. No distinctive substituent effects of the iridium catalysts were observed in these reactions. The diverse catalytic activity, broad substrate scope, mild reaction conditions, and high yields of the products made this catalytic system attractive in industrial processes.
- Deng, Wei,Fan, Xiao-Nan,Ou, Hui-Dan,Yao, Zi-Jian
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supporting information
(2020/04/02)
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- Bis-Anthracene Fused Porphyrin as an Efficient Photocatalyst: Facile Synthesis and Visible-Light-Driven Oxidative Coupling of Amines
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Development of high-performance photocatalysts for the conversion of amines is of great importance, but has remained a challenging task. Here, a bis-anthracene fused porphyrin (AFP) was synthesized in a high yield by a facile synthetic protocol, which involves a Suzuki coupling for the conjugation of two anthracene groups with a porphyrin ring, followed by oxidative cyclodehydrogenation. When serving as a photocatalyst, AFP exhibits an outstanding photocatalytic performance for the visible-light-induced aerobic oxidation of amines to imines at ambient conditions. Density functional theory calculations revealed that the low energy band gap, caused by the large planar and π-extended porphyrin structure of AFP, contributed to its high photocatalytic performance.
- Droste, J?rn,Hansen, Michael Ryan,Klabunde, Sina,Mai, Yiyong,Yin, Yucheng,Yu, Chunyang,Zhang, Pengfei
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supporting information
p. 16497 - 16503
(2020/12/01)
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- NHC-assisted Ni(II)-catalyzed acceptorless dehydronation of amines and secondary alcohols
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A novel catalytic system including NiCl2-NHC ligand precursor has been developed for the preparation of imines from amines and ketones from alcohols. Owing to the acceptorless dehydrogenation pathway for this reaction, the hydrogen gas is liberated as a by-product. The active catalyst is generated in situ by the reaction of nickel (II) chloride, bis (imidazolium) chlorides and potassium tert-butoxide. The products were obtained in good to excellent yields and a wide variety of amines and ketones were applied successfully in this protocol.
- Takallou, Ahmad,Habibi, Azizollah,Halimehjan, Azim Ziyaei,Balalaie, Saeed
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- A Cu-BTC metal-organic framework (MOF) as an efficient heterogeneous catalyst for the aerobic oxidative synthesis of imines from primary amines under solvent free conditions
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A Cu-BTC (MOF-199) [copper(ii)-benzene-1,3,5-tricarboxylate] catalyst has been synthesized and evaluated for imine synthesis from amine compounds under neat conditions. The performance of the Cu-BTC MOF was significantly higher than that of the CuO supported on Al2O3, TiO2 and SiO2 catalysts. The role of surface Lewis acid sites on the catalyst in the formation of imine products was illustrated by the pyridine-IR studies. The recovered Cu-BTC catalyst demonstrated consistent activity for five cycles under similar experimental conditions. The physicochemical properties of the catalysts were analyzed by XRD, BET-SA, FT-IR, UV-DRS, SEM, TEM, XPS and pyridine adsorbed DRIFT spectroscopy.
- Venu, Boosa,Shirisha, Varimalla,Vishali, Bilakanti,Naresh, Gutta,Kishore, Ramineni,Sreedhar, Inkollu,Venugopal, Akula
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supporting information
p. 5972 - 5979
(2020/04/27)
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- Conjugated HCl-doped polyaniline for photocatalytic oxidative coupling of amines under visible light
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HCl-Doped polyaniline (PANI-ES) and PANIs of different oxidation states were prepared by a typical oxidative polymerization and subsequent redox reaction, respectively. The photocatalytic performance of PANIs towards selective benzylamine oxidation reacti
- Kong, Peng,Liu, Pei,Ge, Zhenyu,Tan, Hao,Pei, Linjuan,Wang, Jie,Zhu, Pengqi,Gu, Xianmo,Zheng, Zhanfeng,Li, Zhong
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p. 753 - 761
(2019/02/14)
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- Photoorganocatalytic Aerobic Oxidative Amine Dehydrogenation/Super Acid-Mediated Pictet-Spengler Cyclization: Synthesis of cis-1,3-Diaryl Tetrahydroisoquinolines
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Aerobic oxidative dehydrogenation reactions of benzylamines to imines were studied and the efficiencies of various ground- and excited state quinone organocatalysts were compared. Long wave-absorbing anthraquinones readily catalyze the aerobic photodehydr
- Unkel, Lisa-Natascha,Malcherek, Simon,Schendera, Eva,Hoffmann, Frank,Rehbein, Julia,Brasholz, Malte
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supporting information
p. 2870 - 2876
(2019/05/01)
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- Nitrogen-Doped Carbon-Supported Nickel Nanoparticles: A Robust Catalyst to Bridge the Hydrogenation of Nitriles and the Reductive Amination of Carbonyl Compounds for the Synthesis of Primary Amines
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An efficient method was developed for the synthesis of primary amines either from the hydrogenation of nitriles or reductive amination of carbonyl compounds. The reactions were catalyzed by nitrogen-doped mesoporous carbon (MC)-supported nickel nanoparticles (abbreviated as MC/Ni). The MC/Ni catalyst demonstrated high catalytic activity for the hydrogenation of nitriles into primary amines in high yields (81.9–99 %) under mild reaction conditions (80 °C and 2.5 bar H2). The MC/Ni catalyst also promoted the reductive amination of carbonyl compounds for the synthesis of primary amines at 80 °C and 1 bar H2. The hydrogenation of nitriles and the reductive amination proceeded through the same intermediates for the generation of the primary amines. To the best of our knowledge, no other heterogeneous non-noble metal catalysts have been reported for the synthesis of primary amines under mild conditions, both from the hydrogenation of nitriles and reductive amination.
- Zhang, Yangmin,Yang, Hanmin,Chi, Quan,Zhang, Zehui
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p. 1246 - 1255
(2019/03/07)
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- Easy Ruthenium-Catalysed Oxidation of Primary Amines to Nitriles under Oxidant-Free Conditions
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A dehydrogenation of primary amine to give the corresponding nitrile under oxidant- and base-free conditions catalysed by simple [Ru(p-cym)Cl2]2 with no extra ligand is reported. The system is highly selective for alkyl amines, whereas benzylamine derivatives gave the nitrile product together with the imine in a ratio ranging from 14:1 to 4:1 depending on the substrate. Preliminary mechanistic investigations have been performed to identify the key factors that govern the selectivity.
- Achard, Thierry,Egly, Julien,Sigrist, Michel,Maisse-Fran?ois, Aline,Bellemin-Laponnaz, Stéphane
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supporting information
p. 13271 - 13274
(2019/10/21)
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- Metal-free nitrogen -doped carbon nanosheets: A catalyst for the direct synthesis of imines under mild conditions
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Herein, a highly stable, porous, multifunctional and metal-free catalyst was developed, which exhibited significant catalytic performance in the oxidation of amines and transfer hydrogenation of nitriles under mild conditions; this could be attributed to the presence of numerous active sites and their outstanding BET surface area. The obtained results showed that most of the yields of imines exceeded 90%, and the cycling performance of the catalyst could be at least seven runs without any decay in the reaction activity, which could be comparable to those of metal catalysts. Subsequently, a kinetic study has demonstrated that the apparent activation energy for the direct synthesis of imines from amines is 67.39 kJ mol-1, which has been performed to testify that the catalytic performances are rational. Via catalyst characterizations and experimental data, graphitic-N has been proven to be the active site of the catalyst. Hence, this study is beneficial to comprehend the mechanism of action of a metal-free N-doped carbon catalyst in the formation of imines.
- Wang, Kaizhi,Jiang, Pengbo,Yang, Ming,Ma, Ping,Qin, Jiaheng,Huang, Xiaokang,Ma, Lei,Li, Rong
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p. 2448 - 2461
(2019/05/17)
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- Functions of hydroxyapatite in fabricating N-doped carbon for excellent catalysts and supercapacitors
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Functions of hydroxyapatite (HAP) in fabricating nitrogen-containing carbon materials with 1,10-phenanthroline as a precursor were demonstrated. HAP can efficiently prevent 1,10-phenanthroline from subliming and promote it to graphitized carbon during the
- Chu, Minzhe,Zhai, Yingying,Shang, Ningzhao,Zhang, Xiaoyu,Wang, Chun,Zhang, Yunrui,Wang, Haijun,Gao, Yongjun
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p. 4952 - 4960
(2019/10/05)
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- An Efficient Mesoporous Cu-Organic Nanorod for Friedl?nder Synthesis of Quinoline and Click Reactions
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Within the green chemistry context, heterogeneous catalysis for the synthesis of N-heterocycles from renewable resources using non-precious metals has garnered great interest in terms of economic and environmental perspectives. Herein, we present a triazine functional hierarchical mesoporous organic polymer (HMOP) with nanorod morphology together with large BET surface area ~1218 m2 g?1, huge pore volumeγτ“;6 mL g?1 and dual micro/mesopore architectures. Subsequent Cu-coordination with nitrogen atoms of the HMOP provides a robust catalyst (Cu-HMOP) to accomplish multi-step cascade reactions for preparation of N-heterocycles by different routes. For instance, the Cu-HMOP efficiently catalyzes one-pot sequential multi-step oxidative dehydrogenative coupling of 2-aminobenzyl alcohol with diverse aromatic ketones to afford corresponding quinolines in excellent isolated yields (up to 97 %). Secondly, the present catalyst exhibits good aerobic oxidative dehydrogenation activity of amines to imines. Thirdly, for “click” reaction involving azides-alkynes, the Cu-HMOP produced quantitative yield for 1,4-disubstituted 1,2,3-triazole derivatives at room temperature using water as solvent. Verification of active metal leaching by a hot filtration test as well as reusability of the retrieved Cu-HMOP catalysts shows a consistent activity in the multi-component quinoline synthesis as model reaction.
- Elavarasan, Samaraj,Bhaumik, Asim,Sasidharan, Manickam
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p. 4340 - 4350
(2019/08/12)
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- Method for electrochemically synthesizing Schiff base
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The invention relates to a method for electrochemically synthesizing Schiff base, and belongs to the field of organic synthesis. The method uses a benzylamine compound as a substrate, the substrate and an electrolyte are added to an organic solvent, an el
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Paragraph 0028-0031; 0034; 0036
(2019/11/17)
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- Silver doped reduced graphene oxide as a promising plasmonic photocatalyst for oxidative coupling of benzylamines under visible light irradiation
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Visible light assisted photocatalytic transformations have been considered as an efficient and sustainable approach for the production of high-value chemicals. The present paper describes the synthesis of plasmonic silver nanoparticle incorporated reduced
- Kumar, Anurag,Sadanandhan, Aathira M.,Jain, Suman L.
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p. 9116 - 9122
(2019/06/18)
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- Selectivity-tunable amine aerobic oxidation catalysed by metal-free N,O-doped carbons
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Herein, we present a series of N,O-doped mesoporous carbons obtained at different pyrolysis temperatures as the first metal-free catalysts which successfully switch between imine and nitrile products for amine oxidation. Systematic characterization studies and control experiments revealed that the C-O group on the surface could function as a catalytically active site for nitrile synthesis and the N-doping environment was essential.
- Li, Yingguang,Shang, Sensen,Wang, Lianyue,Lv, Ying,Niu, Jingyang,Gao, Shuang
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supporting information
p. 12251 - 12254
(2019/10/21)
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- Cobalt-Catalyzed Dehydrogenative Coupling of Amines into Imines
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Primary amines have been subjected to an acceptorless dehydrogenative homo- and heterocoupling into imines with a cobalt catalyst. The catalytically active species are composed of cobalt nanoparticles, which are generated in situ by heating Co2(CO)8 in the presence of trioctylphosphine oxide as a surfactant. The nanoparticles have been characterized by transmission electron microscopy where the image showed spherical and small particles with a narrow size distribution. The catalyst can be recovered and used again with essentially no effect on the yield. The catalyst can also be used for the dehydrogenative coupling of alcohols and amines into imines.
- Bottaro, Fabrizio,Takallou, Ahmad,Chehaiber, Ahmad,Madsen, Robert
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supporting information
p. 7164 - 7168
(2019/11/16)
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- Aerobic Oxidative Homo- and Cross-Coupling of Amines Catalyzed by Phenazine Radical Cations
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Phenazine radical cations (PhRCs) were used for the first time as efficient metal-free catalysts for the oxidative homo- and cross-coupling of a variety of different amines. A series of functional PhRCs were prepared, characterized with X-ray diffraction, and their radical character was investigated with DFT calculations. They were tested as catalysts under neat conditions with low oxygen pressure to prepare homo- and cross-coupled aliphatic and aromatic imines in high yields. Although all synthesized phenazines were catalytically active, the highest reaction rates and the best selectivity were achieved using the 5,10-dihydro-5,10-dimethylphenazine radical cation. By means of fluorescence, UV-vis and EPR spectroscopy, a mechanism of the oxidative amine coupling, catalyzed by PhRCs, is proposed.
- Bri?ar, Rok,Unglaube, Felix,Hollmann, Dirk,Jiao, Haijun,Mejía, Esteban
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p. 13481 - 13490
(2018/11/02)
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- Carbazole-triazine based donor-acceptor porous organic frameworks for efficient visible-light photocatalytic aerobic oxidation reactions
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We report the synthesis of a series of carbazole-triazine based donor-acceptor (D-A) POFs and their photocatalytic activities for aerobic oxidation reactions. The simultaneous introduction of a carbazole-based electron donor and a triazine-based electron acceptor in D-A POFs stabilizes the charge transfer state and enables an efficient triplet-triplet energy transfer to generate 1O2. Meanwhile, systematic variation of the D-A distance results in the tunable photoredox properties and consequently the efficiency for generation of reactive oxygen species (ROSs). Upon visible light excitation, all three D-A POFs exhibit excellent capability to promote three aerobic oxidations: sulfide oxidation, oxidative amine coupling, and Mannich reactions. This systematic study validates the design principle of D-A POFs as high-performance photo-oxidation catalysts with wide substrate scope and excellent stability and recyclability.
- Luo, Jian,Lu, Jingzhi,Zhang, Jian
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supporting information
p. 15154 - 15161
(2018/08/17)
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- Method for preparing imine compounds
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The invention discloses a method for preparing an imine compounds. According to the method, under the absence of an oxidizing agent, a copper catalyst is utilized to for catalyzingse an amine compounds to prepare imine in a coupling manner. According to t
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Paragraph 0033; 0034; 0035
(2019/01/08)
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- Method for synthesizing imide type compound by carrying out visible light catalytic oxidation on amine type compound
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The invention discloses a method for synthesizing an imide type compound by carrying out visible light catalytic oxidation on an amine type compound. The method takes tetrahydroxymethyl tetra(1,4-dithiin)tetraaza-cobalt porphyrin as a catalyst and molecul
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Paragraph 0034-0040; 0065-0071
(2019/08/30)
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- Method for synthesizing imine compounds
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The invention relates to a method for synthesizing imine compounds. According to the method, the imine compounds are synthesized from aromatic aldehyde as a substrate, ammonia or ammonium salt as a nitrogen source and formic acid or formate as a reducing agent. The substrate aldehyde, ammonia or ammonium salt and formic acid or formate are dissolved in a solvent respectively, and a reaction is performed for 5-120 min at 80-120 DEG C; after the reaction, the low-boiling-point solvent is removed through reduced-pressure distillation, water is added to a solution, and organic matter is extractedwith ethyl acetate, organic phases obtained after the extraction are combined, an extraction agent is removed through distillation, an obtained crude product is separated with silica gel column chromatography, and the imine compounds are obtained through purification. The synthesis method probably has great application in the aspect of imine synthesis.
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Paragraph 0031-0032
(2018/06/26)
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- Photocatalytic Hydrogen Production Coupled with Selective Benzylamine Oxidation over MOF Composites
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Photocatalytic water splitting requires separation of the mixed H2 and O2 products and is often hampered by the sluggish O2-producing half reaction. An approach is now reported to address these issues by coupling the H2-producing half reaction with value-added benzylamine oxidation reaction using metal–organic framework (MOF) composites. Upon MOF photoexcitation, the electrons rapidly reduce the protons to generate H2 and the holes promote considerable benzylamine oxidation to N-benzylbenzaldimine with high selectivity. Further experimental characterizations and theoretical calculation reveal that the highly conjugated s-triazine strut in the MOF structure is crucial to the efficient charge separation and excellent photocatalytic activity.
- Liu, Hang,Xu, Caiyun,Li, Dandan,Jiang, Hai-Long
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supporting information
p. 5379 - 5383
(2018/04/02)
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- Oxygen-Rich Carbon Quantum Dots as Catalysts for Selective Oxidation of Amines and Alcohols
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Metal-free carbocatalysis has been widely utilized for aerobic oxidative reactions. Here, we report that oxygen-rich carbon quantum dots (O-CQDs) demonstrate a catalytic performance superior to graphene oxide, if used as a metal-free nanocatalyst for the direct transformation of amines and alcohols, under mild and solvent-free conditions. O-CQDs show a yield of 75 % for the oxidative coupling of amine to imine (with 5 wt % catalyst loading) and a conversion of 3.8 % for benzyl alcohol (with 2 wt % catalyst loading). The catalytic activities of thermally treated O-CQDs are further improved for benzylamine, for example, indicated by a yield of up to 98 % with 4 wt % catalyst loading. In addition, O-CQDs show a photoenhanced catalytic ability of amine (98 % yield with 5 wt % catalyst loading for 6 h reaction). Characterizations and simulations show that numerous carboxyl oxygen functional groups and unpaired electrons at the edge sites of O-CQDs are likely involved in the aerobic oxidation of amines.
- Ye, Jianglin,Ni, Kun,Liu, Jie,Chen, Guanxiong,Ikram, Mujtaba,Zhu, Yanwu
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p. 259 - 265
(2018/01/17)
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