- A Carbazolyl Porphyrin-Based Conjugated Microporous Polymer for Metal-Free Photocatalytic Aerobic Oxidation Reactions
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Herein, a carbazolyl porphyrin-based π-conjugated microporous polymer was prepared via simple FeCl3-catalyzed oxidative polymerization. The resulting polymer (TCPP-CMP) exhibits high surface area, permanent pores, good stability, broad light absorption range and suitable redox potentials. As expected, TCPP-CMP is a highly effective metal-free and heterogeneous photocatalyst for a variety of aerobic oxidation reactions, including oxidative coupling of primary amines, oxidative dehydrogenation of secondary amines, and oxidation of sulfides into sulfoxides using molecular oxygen under visible light irradiation. Importantly, natural sunlight is able to promote the aerobic oxidation of benzylamine and thioanisole via TCPP-CMP photocatalyst with high conversion and selectivity, which are comparable with reactions conducted under artificial light. In addition, heterogeneous TCPP-CMP has good recyclability, which retained its activity even after four cycles. The current work lays the foundation for future applications of TCPP-CMP as metal-free heterogeneous photocatalyst for aerobic oxidation reactions.
- Jiang, Jun,Liang, Zhongxiu,Xiong, Xiaoyan,Zhou, Xiantai,Ji, Hongbing
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Read Online
- 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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- 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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- Method for preparing N -benzyl allylamine by high-efficiency photo-catalytic oxidation of xylylenediamine
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The invention belongs to the technical field of photocatalytic oxidation, and particularly relates to a method for preparing N -allylamine by high-efficiency photo-catalytic oxidation of xylylenediamine. The flavin photosensitizer is used as a catalyst, a
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Paragraph 0020-0049
(2021/11/03)
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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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- 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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- 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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p. 5705 - 5710
(2021/07/06)
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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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- 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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- 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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- 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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- 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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- Deaminative Olefination of Methyl N-Heteroarenes by an Amine Oxidase Inspired Catalyst
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We explored the bioinspired o-quinone cofactor catalyzed aerobic primary amine dehydrogenation for a cascade olefination reaction with nine different methyl N-heteroarenes, including pyrimidines, pyrazines, pyridines, quinolines, quinoxolines, benzimidazoles, benzoxazoles, benzthiazoles, and triazines. An o-quinone catalyst phd (1,10-phenanthroline-5,6-dione) combined with a Br?nsted acid catalyzed the reaction. N-Heteroaryl stilbenoids were synthesized in high yields and (E)-selectivities under mild conditions using oxygen (1 atm) as the sole oxidant without needing transition-metal salt, ligand, stoichiometric base, or oxidant.
- Thorve, Pradip Ramdas,Maji, Biplab
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supporting information
p. 542 - 547
(2021/01/26)
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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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- 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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- Thiazolo[5,4-d]thiazole-Based Donor–Acceptor Covalent Organic Framework for Sunlight-Driven Hydrogen Evolution
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2D covalent organic frameworks (COFs) could have well-defined arrangements of photo- and electro-active units that serve as electron or hole transport channels for solar energy harvesting and conversion, but their insufficient charge transfer and rapid ch
- Li, Wenqian,Huang, Xiaofeng,Zeng, Tengwu,Liu, Yahu A.,Hu, Weibo,Yang, Hui,Zhang, Yue-Biao,Wen, Ke
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supporting information
p. 1869 - 1874
(2020/12/30)
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- Half-Sandwich Ruthenium Complexes Bearing Hemilabile κ2-(C,S)?Thioether-Functionalized NHC Ligands: Application to Amide Synthesis from Alcohol and Amine
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Amide synthesis is one of the most crucial transformations in chemistry and biology. Among various catalytic systems, N-heterocyclic carbene (NHC)-based ruthenium (Ru) catalyst systems have been proven to be active for direct synthesis of amides by sustainable acceptorless dehydrogenative Coupling of primary alcohols with amines. Most often, these catalytic systems usually use monodentate NHC and thus require an additional ligand to obtain high reactivity and selectivity. In this work, a series of cationic Ru(II)(η6-p-cymene) complexes with thioether-functionalized N-heterocyclic carbene ligands (imidazole and benzimidazole-based) have been prepared and fully characterized. These complexes have then been used in the amidation reaction and the most promising one (i. e. 3 c) has been applied on a large range of substrates. High conversions albeit with moderate yields have generally been obtained.
- Achard, Thierry,Bellemin-Laponnaz, Stéphane,Chen, Weighang,Egly, Julien,Maisse-Fran?ois, Aline
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supporting information
(2022/01/20)
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- Construction of 5H-Dibenzo[c,e]azepine Framework from Dibenzothiophene Dioxides and N-Benzylimines through SNAr Reactions
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Treatment of a mixture of dibenzothiophene dioxides and benzaldehyde N-benzylimines with potassium hexamethyldisilazide induces sequential intermolecular and intramolecular SNAr reactions to eventually form the corresponding 5H-dibenzo[c,e]azep
- Furukawa, Tomoki,Kaga, Atsushi,Saito, Hayate,Yanagi, Tomoyuki,Yorimitsu, Hideki
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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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- Visible-light-induced oxidative coupling reaction of benzylic amines using iridium(III) complex of pincer type imidazo[1,5-a]pyridine ligand
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We have designed and synthesized an iridium(III) complex of pincer type imidazo[1,5-a]pyridine ligand. The complex has a broad absorption band and shows the yellow emission in solution. When the complex was used as a photocatalyst in the visible-light-ind
- Yagishita, Fumitoshi,Nagamori, Tatsuya,Shimokawa, Sota,Hoshi, Keita,Yoshida, Yasushi,Imada, Yasushi,Kawamura, Yasuhiko
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supporting information
(2020/03/10)
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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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- 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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- 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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- Method for preparing imine through photocatalytic amine oxidative coupling
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The invention discloses a method for preparing imine through photocatalytic amine oxidative coupling. According to the method, benzylamine and derivatives thereof are used as raw materials, oxygen isused as an oxidizing agent, a porous organic polymer for
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Paragraph 0020-0021
(2020/01/12)
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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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p. 1757 - 1765
(2020/01/06)
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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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- 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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- NaCl as Catalyst and Water as Solvent: Highly E-Selective Olefination of Methyl Substituted N-Heteroarenes with Benzyl Amines and Alcohols
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Oxidative coupling of benzylamines and alcohols with methyl substituted N-heteroarenes such as quinolines and quinoxalines has been achieved using chloride, a sea abundant anion as the catalyst for practical synthesis of a wide range of E-disubstituted olefins in aqueous medium. Detailed mechanistic studies and control experiments were carried out to deduce the reaction mechanism which indicated that in situ formed ClO2- is the active form of the catalyst. We have successfully carried out a 1 g scale reaction using this methodology, and five pharmaceutically relevant conjugated olefins were also synthesized by this method in moderate to good yields.
- Hazra, Susanta,Tiwari, Vikas,Verma, Ashutosh,Dolui, Pritam,Elias, Anil J.
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supporting information
p. 5496 - 5501
(2020/07/14)
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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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p. 753 - 761
(2019/11/03)
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- Nickel(ii) and nickel(0) complexes as precursors of nickel nanoparticles for the catalytic hydrogenation of benzonitrile
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The use of the nickel(ii) complex [(TEEDA)NiCl2] (1; TEEDA= N,N,N′,N′-tetraethyl-ethylendiamine) and nickel(0) complex [Ni(COD)2] (5) as pre-catalysts in the additive-free catalytic hydrogenation of benzonitrile (BN) is reported. In the presence of 1 (1 mol%), BN was hydrogenated under relatively mild reaction conditions (100 °C, 120 psi H2, 72 h) to the corresponding secondary imine, N-benzylidenebenzylamine (BBA), in very good yield (83%). As a counterpart, 5 (1 mol%) selectively hydrogenated BN to benzylamine (BA) in excellent yield (96%) under similar reaction conditions (80 °C, 120 psi H2, 24 h). In both cases, nickel nanoparticles (Ni-NPs) were identified as the catalytically active species. These Ni-NPs were formed in situ from 1 and 5 without external additives or additional stabilizers. The use of complex 5 was extended to the hydrogenation of different (hetero) aromatic and aliphatic nitriles.
- Rodríguez, Alejandro A.,Gardu?o, Jorge A.,García, Juventino J.
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p. 1082 - 1089
(2020/01/31)
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- Diastereo- A nd Enantioselective Synthesis of Homoallylic Amines Bearing Quaternary Carbon Centers
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A Cu-catalyzed method for the efficient enantio- A nd diastereoselective synthesis of chiral homoallylic amines bearing a quaternary carbon and an alkenylboron is disclosed. Transformations are promoted by a readily prepared (phosphoramidite)-Cu complex and involve bench-stable ?,?-disubstituted allyldiborons and benzyl imines; products are obtained in up to 82% yield, >20:1 dr, and >99:1 er. Reactions proceed via stereodefined boron-stabilized allylic Cu species formed by an enantioselective transmetalation. Utility of the 1-amino-3-alkenylboronate products is highlighted by a variety of synthetic transformations.
- Green, Jacob C.,Zanghi, Joseph M.,Meek, Simon J.
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supporting information
p. 1704 - 1709
(2020/02/20)
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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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- 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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supporting information
p. 11710 - 11719
(2020/07/27)
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- Non-emissive RuII Polypyridyl Complexes as Efficient and Selective Photosensitizers for the Photooxidation of Benzylamines
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Five new RuII polypyridyl complexes bearing N-(arylsulfonyl)-8-amidoquinolate ligands and three of their biscyclometalated IrIII congeners have been prepared and employed as photocatalysts (PCs) in the photooxidation of benzylamines with O2. In particular, the new RuII complexes do not exhibit photoluminescence, rather they harvest visible light efficiently and are very stable in solution under irradiation with blue light. Their non-emissive behavior has been related to the low electrochemical energy gaps and rationalized on the basis of theoretical calculations (DFT analysis) that predict low S0←T1 energy values. Moreover, the RuII complexes, despite being non-emissive, display excellent activities in the selective photocatalytic transformation of benzylamines into the corresponding imines. The presence of an electron-withdrawing group (-CF3) on the arene ring of the N-(arylsulfonyl)-8-amidoquinolate ligand improves the photocatalytic activity of the corresponding photocatalyst. Furthermore, all the experimental evidence, including transient absorption spectroscopy measurements suggest that singlet oxygen is the actual oxidant. The IrIII analogues are considerably more photosensitive and consequently less efficient photosensitizers (PSs).
- Yagüe, Cristina,Echevarría, Igor,Vaquero, Mónica,Fidalgo, Jairo,Carbayo, Arancha,Jalón, Félix A.,Lima, Jo?o C.,Moro, Artur J.,Manzano, Blanca R.,Espino, Gustavo
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supporting information
p. 12219 - 12232
(2020/09/01)
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- Catalytic activity of Mg-Al hydrotalcites and derived mixed oxides for imination reactionsviaan oxidative-dehydrogenation mechanism
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The catalytic activities of Mg-Al hydrotalcites and derived Mg-Al mixed oxides were studied for the imination of benzylic substrates (benzyl amine and benzyl alcohol), with aniline as a model reaction, to establish a green and cost-effective catalytic (precious metal free) process for imination and tandem reactions utilizing alcohols as reagents. The Mg-Al mixed oxide (Mg/Al ratio = 3.0) was found to be an efficient catalyst for imination reactions to synthesize cross-imines with high selectivity as well as for tandem reactions of alcohols. Basic sites of catalysts adsorb benzylic substrates through the hydrogen of their functional groups (-NH2/-OH) and activate (weaken) benzylic C-H bonds for hydride elimination. Thus, basic sites catalyze the reaction by activating benzylic substrates for oxidative-dehydrogenation (i.e., deprotonation followed by hydride elimination with the help of oxygen) to produce reactive imine/carbonyl intermediates, which undergo subsequent nucleophilic reactions with amine.
- Vala, Naresh,Joshi, Pradyuman A.,Mishra, Manish
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p. 8859 - 8868
(2020/06/08)
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- Anion-cation synergistic metal-free catalytic oxidative homocoupling of benzylamines by triazolium iodide salts
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Triazolium iodide salts are excellent catalysts for the selective oxidative coupling of benzylamines to yield imines. This metal-free reaction proceeds in quantitative spectroscopic yields when run in refluxing 1,2-dichlorobenzene and open to the air. No catalytic activity was observed with related triazolium tetrafluoroborate salts. Variation of catalyst and reaction atmosphere provides mechanistic insights, and revealed dioxygen as the terminal oxidant and the iodine/iodide couple as key redox component in the catalytic dehydrogenation pathway. While molecular iodine is competent as a catalyst in its own right, the triazolium cation triples the reaction rate and reaches turnover frequencies up to 30 h-1, presumably through beneficial interactions of the electron-poor azolium π system and I2, which facilitate the electron transfer from the substrate to iodine and concomitant formation of I-. This acceleration is specific for triazolium cations and represents a hybrid anion/cation catalytic process as a simple and straightforward route towards imine products, with economic advantages over previously reported metal-based catalytic systems.
- Albrecht, Martin,Byrne, Joseph P.
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supporting information
p. 7379 - 7387
(2020/10/13)
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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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- 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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- Cobalt-Catalyzed α-Arylation of Substituted α-Bromo α-Fluoro β-Lactams with Diaryl Zinc Reagents: Generalization to Functionalized Bromo Derivatives
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A cobalt-catalyzed cross-coupling of α-bromo α-fluoro β-lactams with diarylzinc or diallylzinc reagents is herein disclosed. The protocol proved to be general, chemoselective and operationally simple allowing the C4 functionalization of β-lactams. The substrate scope was expanded to α-bromo lactams and amides, α-bromo lactones and esters as well as N- and O-containing heterocycles.
- Br?se, Stefan,Chen, Hi-Yung,Cossy, Janine,Koch, Vanessa,Lei, Aiwen,Lorion, Mélanie M.,Nieger, Martin
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supporting information
p. 13163 - 13169
(2020/09/23)
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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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- Table salt as a catalyst for the oxidation of aromatic alcohols and amines to acids and imines in aqueous medium: Effectively carrying out oxidation reactions in sea water
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A simple, efficient, sustainable and economical method for the oxidation of alcohols and amines has been developed based on chloride, a sea abundant anionic catalyst for the practical synthesis of a wide range of carboxylic acids, ketones and imines. Oxidation of aromatic alcohols was carried out using NaCl (20 mol%) as the catalyst, NaOH (50 mol%) and aq. TBHP (4 equiv.) as the oxidant in 55-92% isolated yields. Oxidation of aromatic amines to imines was achieved by using only 20 mol% of NaCl and aq. TBHP (4 equiv.) in 32-93% isolated yields. The chlorine species formed during the reaction as the active oxidation catalyst has been identified as ClO2- for alcohols and ClO-/ClO2- for amines by control experiments. This method is mostly free from chromatographic purification, which makes it suitable for large-scale synthesis. We have scaled up to 30 gram scale the synthesis of carboxylic acids and imines in good yields and have also carried out efficiently this new method using filtered sea water as the solvent and catalyst.
- Hazra, Susanta,Kushawaha, Ajay Kishor,Yadav, Deepak,Dolui, Pritam,Deb, Mayukh,Elias, Anil J.
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supporting information
p. 1929 - 1934
(2019/04/29)
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- Photocatalytic Transformation of Amines to Imines by Meso-Porous Copper Sulfides
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Here we have demonstrated a visible-light-driven catalytic process for amine to imine transformations, using a hydrothermal procedure based mesoporous copper sulfide material. The surface chemistry of this heterogeneously catalyzed process, which was furt
- Dutta, Biswanath,Achola, Laura A.,Clarke, Ryan,Sharma, Vinit,He, Junkai,Kerns, Peter,Suib, Steven L.
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p. 4262 - 4265
(2019/08/20)
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- Unprecedented Copper(II) Complex with a Topoquinone-like Moiety as a Structural and Functional Mimic for Copper Amine Oxidase: Role of Copper(II) in the Genesis and Amine Oxidase Activity
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Copper amine oxidase (CAO), consisting of the topoquinone (TPQ) cofactor, catalyzes the oxidation of primary amines to aldehyde. We have successfully addressed this issue through isolation of a copper complex which mimics the active-site structure as well as the function of CAO. This inimitable complex, consisting of two TPQ-like side-arms, formed by ambient aerial oxidation of a precursor Schiff base complex, is the most efficient homogeneous catalyst for quantitative oxidation of primary benzylic amines to corresponding secondary imines under ambient conditions within 30 min. The longstanding contention of actual involvement of Cu(II) in the catalysis is resolved through quenching experiments of Cu(II) superoxo species and detailed density functional theory studies.
- Jangir, Ritambhara,Ansari, Mursaleem,Kaleeswaran, Dhananjayan,Rajaraman, Gopalan,Palaniandavar, Mallayan,Murugavel, Ramaswamy
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p. 10940 - 10950
(2019/11/13)
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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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supporting information
p. 6430 - 6434
(2019/04/10)
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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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- 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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- 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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- 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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