- Zeolite-Catalyzed Isomerization of Aromatic Amines to Methyl-Aza-Aromatics
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The scope and mechanism of the isomerization of arylamines to methyl-substituted aromatic heterocycles have been studied.Aniline, toluidines, naphthylamines and m-phenylenediamine all reacted to the corresponding ortho-methyl-substituted aza-aromatiics when exposed to high NH3 pressure and elevated temperature in the presence of acid catalysts.Zeolites with a three-dimensional pore structure, especially H-ZSM-5, showed the best performance.Optimum reaction conditions are around 600 K and 10 MPa.Two mechanisms which had been proposed earlier for this apparent N-ortho C exchange reaction proved untenable.Neither incorporation of the N atom into the aromatic ring nor a mechanism based on an intramolecular Ritter reaction could explain the required high NH3 pressure or the product distribution.Two new mechanisms are proposed which can explain all observations.In both mechanisms, reaction starts with addition of NH3 to the arylamine, followed by ring opening.In one mechanism an alkyno-imine intermediate is formed; in the other mechanism an enamino-imine intermediate is formed through a reverse aldol reaction.In both cases ring closure and NH3 elimination lead to the required aromatic heterocycles.The high NH3 pressure is explained by the need to add NH3 to the aromatic ring, and the high temperature by the need to desorb NH3 from the acid sites.
- Stamm, T.,Kouwenhoven, H. W.,Seebach, D.,Prins, R.
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- Copper-catalysed reductive amination of nitriles and organic-group reductions using dimethylamine borane
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A heterogeneous copper catalyst, formed in situ, has been shown to dehydrocouple commercially available amine boranes whilst transferring hydrogen for the reduction of selected organic functional groups in an aqueous medium. The catalytic system has also been shown to promote the reductive amination of aryl nitriles. This journal is
- Van Der Waals, Dominic,Pettman, Alan,Williams, Jonathan M. J.
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- Microbial deoxygenation of N-oxides with Baker's yeast-NaOH
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The microbial deoxygenation of a series of aromatic and heteroaromatic N-oxide compounds, including quinoline N-oxides, isoquinoline N-oxides, 2-aryl-2H-benzotriazole 1-oxides, benzo[c]cinnoline N-oxide and azoxybenzenes, has been performed with bakers'yeast-NaOH.
- Baik, Woonphil,Kim, Dong Ik,Koo, Sangho,Rhee, Jong Uk,Shin, Sung Hee,Kim, Byeong Hyo
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- Intermetallic Nanocatalysts from Heterobimetallic Group 10-14 Pyridine-2-thiolate Precursors
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Intermetallic compounds are atomically ordered inorganic materials containing two or more transition metals and main-group elements in unique crystal structures. Intermetallics based on group 10 and group 14 metals have shown enhanced activity, selectivity, and durability in comparison to simple metals and alloys in many catalytic reactions. While high-temperature solid-state methods to prepare intermetallic compounds exist, softer synthetic methods can provide key advantages, such as enabling the preparation of metastable phases or of smaller particles with increased surface areas for catalysis. Here, we study a generalized family of heterobimetallic precursors to binary intermetallics, each containing a group 10 metal and a group 14 tetrel bonded together and supported by pincer-like pyridine-2-thiolate ligands. Upon thermal decomposition, these heterobimetallic complexes form 10-14 binary intermetallic nanocrystals. Experiments and density functional theory (DFT) computations help in better understanding the reactivity of these precursors toward the synthesis of specific intermetallic binary phases. Using Pd2Sn as an example, we demonstrate that nanoparticles made in this way can act as uniquely selective catalysts for the reduction of nitroarenes to azoxyarenes, which highlights the utility of the intermetallics made by our method. Employing heterobimetallic pincer complexes as precursors toward binary nanocrystals and other metal-rich intermetallics provides opportunities to explore the fundamental chemistry and applications of these materials.
- Adamson, Marquix A. S.,Chen, Yunhua,Daniels, Carena L.,Dorn, Rick W.,Fan, Huajun,Knobeloch, Megan,Rossini, Aaron J.,Vela, Javier,Wu, Hao,Yox, Philip,Zhou, Guoquan
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- Simple and efficient reduction of aromatic nitro compounds using recyclable polymer-supported formate and magnesium
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Aromatic nitro compounds were chemoselectively reduced to the corresponding amines using recyclable polymer-supported formate as a hydrogen donor in the presence of low-cost magnesium powder at room temperature. Use of the immobilized hydrogen donor affords the product amine in excellent yield (90-97%) without the need for any Chromatographic purification steps. This method was found to be highly facile with selectivity over several other functional groups, such as halogen, alkene, nitrile, carbonyl, ester, amide, methoxy, phenol, and hydroxyl groups. CSIRO 2005.
- Abiraj, Keelara,Srinivasa, Gejjalagere R.,Gowda, D. Channe
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- Process development of 4-[N-methyl-N-(tetrahydropyran-4-yl)aminomethyl]aniline dihydrochloride: A key intermediate for TAK-779, a small-molecule nonpeptide CCR5 antagonist
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A new and efficient synthesis of 4-[N-methyl-N-(tetrahydropyran-4-yl)aminomethyl]aniline dihydrochloride, a key intermediate for the CCR5 antagonist TAK-779, is described. Reductive alkylation of methylamine with tetrahydro-4H-pyran-4-one followed by alkylation of N-methyl-N-(tetrahydropyran-4-yl)amine with 4-nitrobenzylbromide and reduction of N-(4-nitrobenzyl)-N-(tetrahydropyran-4-yl)amine results in a 78% isolated yield from the starting materials by a scalable method, using only commercially available reagents.
- Hashimoto, Hideo,Ikemoto, Tomomi,Itoh, Tatsuya,Maruyama, Hideaki,Hanaoka, Tadashi,Wakimasu, Mitsuhiro,Mitsudera, Hiroyuki,Tomimatsu, Kiminori
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- Rapid, efficient and selective reduction of aromatic nitro compounds with hydrazine hydrate in the presence of the plain and supported platinum nanoparticles as catalysts
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The current study aimed at application of the plain and supported platinum nanoparticles as a heterogenous catalyst for the reduction of aromatic nitro compounds. Monodispersed platinum nanoparticles were synthesized by reduction of H2PtCl6 by ethanol in the presence of polyvinyl pyrrolidone as a stabilizer, and then were immobilized on four types of zeolites. The obtained catalyst granules were characterized by X-ray diffractometry and transmission electron microscopy. The study then focused on elaboration of the catalytic activity of the nano catalysts under different operational conditions. It was found that reaction is adequately rapid at ambient temperature, and by utilizing a sufficient amount of catalyst, can be completed in nearly 30 min. Among the utilized zeolitic supports, zeolite 4A had the highest performance, but the mechanism of its synergetic effect on the activity of platinum nano catalyst was not found and requires more investigation.
- Mehdizadeh, Soofia,Ahmadi, Seyed Javad,Sadjadi, Sodeh,Outokesh, Mohammad
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- Sodium dithionite reduction of nitroarenes using viologen as an electron phase-transfer catalyst
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Various aromatic nitro compounds were reduced conveniently to the corresponding aniline derivatives with sodium dithionite using dioctyl viologen as an electron-transfer catalyst in dichloromethane- water two-phase system.
- Park, Kwanghee Koh,Oh, Chang Hun,Joung, Won Kyou
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- Mild and general procedure for Pd/C-catalyzed hydrodechlorination of aromatic chlorides
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A mild and efficient one-pot hydrodechlorination using a Pd/C-Et3N system proceeds at room temperature, which is general for the dechlorination of a variety of aromatic chlorides.
- Sajiki, Hironao,Kume, Akira,Hattori, Kazuyuki,Hirota, Kosaku
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- GRAPHITE CATAlYZED REDUCTION OF AROMATIC AND ALIPHATIC NITRO COMPOUNDS WITH HYDRAZINE HYDRATE
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Aromatic and aliphatic nitro compounds were readily reduced to amino compounds in excellant yields with graphite and hydrazine hydrate.
- Han, Byung Hee,Shin, Dae Hyun,Cho, Sung Yun
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- Metal-assisted lossen rearrangement
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A new reaction mechanism for the Lossen rearrangement of hydroxamic acids catalyzed by basic salts is presented. It is shown that the rearrangement proceeds in metal complexes of deprotonated hydroxamic acids. The deprotonation can occur either at the oxygen atom (observed for the zinc complexes) or at the nitrogen atom (observed for the potassium complexes). Both anionic forms are characterized by infrared multiphoton dissociation spectroscopy. The rearrangements proceed from the reactive N-deprotonated metal hydroxamates and lead to metal carbamates. The mechanism is elucidated by computational chemistry, mass-spectrometric studies, and preparative experiments.
- Jasikova, Lucie,Hanikyrova, Eva,Skriba, Anton,Jasik, Juraj,Roithova, Jana
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- Nickel oxide nanoparticles grafted on reduced graphene oxide (rGO/NiO) as efficient photocatalyst for reduction of nitroaromatics under visible light irradiation
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Nickel oxide nanoparticles were grafted on reduced graphene oxide via simultaneous reduction of graphene oxide and nickel salt in a single step reaction. The synthesized material (rGO/NiO) was found to be efficient visible light active photocatalyst for the reduction of nitroaromatic derivatives to their corresponding amino compounds. Hydrazine monohydrate provided necessary protons and electrons for the targeted reaction. After completion of the reaction, the photocatalyst could readily be recovered by simple external magnet and could be reused for six runs without any significant loss of its activity. More importantly, the photocatalyst did not show any leaching during the reaction as confirmed by ICP-AES analysis of the recovered catalyst.
- Al-Nafiey, Amer,Kumar, Anurag,Kumar, Malika,Addad, Ahmed,Sieber, Brigitte,Szunerits, Sabine,Boukherroub, Rabah,Jain, Suman L.
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- One-Pot Synthesis of Secondary Amines from Nitroarenes and Aldehydes on Supported Copper Catalysts in a Flow Reactor: The Effect of the Support
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The effect of the support on the properties of copper catalysts supported on γ-Al2O3, SiO2, and TiO2–SiO2 with a ~5 wt % Cu content was studied in the one-pot synthesis of N-heptyl-p-toluidine from p-nitrotoluene and n-heptanal. The catalysts were characterized by elemental analysis, X-ray diffraction analysis, transmission electron microscopy, temperature-programmed reduction, and low-temperature nitrogen adsorption. The reaction was carried out in a flow reactor with the use of molecular hydrogen as a reducing agent. It was established that the nature of the support exerts a profound effect on the yield of the target secondary amine; in this case, 5%Cu/Al2O3 was found the most active catalyst. A combination of high catalyst activity in the hydrogenation of a nitro group to an amino group with the presence of acid sites, which facilitate imine formation as a result of the interaction of n-heptanal with p-toluidine, on the catalyst surface is necessary for reaching the greatest yield of N-heptyl-p-toluidine. The study of reaction mechanism on the 5%Cu/Al2O3 catalyst showed that p-nitrotoluene inhibits the hydrogenation of n-heptanal, and aldehyde hydrogenation into alcohol begins only after the conversion of the major portion of p-nitrotoluene as a result of the selective adsorption of the nitroarene under the conditions of the simultaneous presence of p-nitrotoluene and n-heptanal in the reaction mixture.
- Artyukha,Nuzhdin,Bukhtiyarova,Derevyannikova,Gerasimov, E. Yu.,Gladkii, A. Yu.,Bukhtiyarov
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- Photocatalytic formation of a carbamate through ethanol-assisted carbonylation of p-nitrotoluene
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The nitroarene p-nitrotoluene is converted with a selectivity higher than 85% to the corresponding carbamate at room temperature and atmospheric pressure, using photoexcited particles of TiO2 as catalyst and EtOH as carbonylating species. The Royal Society of Chemistry 2005.
- Maldotti, Andrea,Amadelli, Rossano,Samiolo, Luca,Molinari, Alessandra,Penoni, Andrea,Tollari, Stefano,Cenini, Sergio
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- Nanocrystalline Pt-CeO2 as an efficient catalyst for a room temperature selective reduction of nitroarenes
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We have developed a new synthesis strategy to prepare Pt nanoparticles with size between 2 and 5 nm supported on CeO2 nanoparticles with size between 30 and 60 nm by the hydrothermal method in the presence of the surfactant cetyltrimethyl ammonium bromide (CTAB) and a polymer (PVP). It was found that the catalyst is highly active for the chemoselective hydrogenation of nitro compounds in aqueous medium in the presence of molecular hydrogen at room temperature (25 °C). The catalyst was characterized by XRD, ICP-AES, XPS, BET-surface area measurements, SEM, TEM and EXAFS. Different reaction parameters like reaction time, catalyst ratio, Pt loading etc. were studied in detail. The investigation revealed that the site of Pt plays a crucial role in the activity by favouring the reduction of nitro-compounds. The catalyst shows >99.9% conversion of nitro-compounds with 99% selectivity of amino compounds. The reusability of the catalyst was tested by conducting the experiment with the same catalyst and it was found that the catalyst does not change its activity and selectivity even after five reuses. This journal is
- Shukla, Astha,Singha, Rajib Kumar,Sasaki, Takehiko,Bal, Rajaram
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- Mesoporous Au-TiO2 nanoparticle assemblies as efficient catalysts for the chemoselective reduction of nitro compounds
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In this article, we demonstrate novel mesoporous Au-loaded TiO2 nanoparticle assemblies (Au-MTA) as high-effective catalysts for the selective transformation of nitroaromatics into the corresponding aryl amine products. These materials feature
- Tamiolakis, Ioannis,Fountoulaki, Stella,Vordos, Nikolaos,Lykakis, Ioannis N.,Armatas, Gerasimos S.
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- Nitroarene reduction using Raney nickel alloy with ammonium chloride in water
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Aromatic nitroarenes are reduced in high yields using a user-friendly combination of Raney nickel alloy and ammonium chloride in water at 80-90°C.
- Bhaumik, Kankan,Akamanchi
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- Selective Synthesis of Primary Anilines from NH3 and Cyclohexanones by Utilizing Preferential Adsorption of Styrene on the Pd Nanoparticle Surface
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Dehydrogenative aromatization is one of the attractive alternative methods for directly synthesizing primary anilines from NH3 and cyclohexanones. However, the selective synthesis of primary anilines is quite difficult because the desired primary aniline products and the cyclohexanone substrates readily undergo condensation affording the corresponding imines (i.e., N-cyclohexylidene-anilines), followed by hydrogenation to produce N-cyclohexylanilines as the major products. In this study, primary anilines were selectively synthesized in the presence of supported Pd nanoparticle catalysts (e.g., Pd/HAP, HAP=hydroxyapatite, Ca10(PO4)6(OH)2) by utilizing competitive adsorption unique to heterogeneous catalysis; in other words, when styrene was used as a hydrogen acceptor, which preferentially adsorbs on the Pd nanoparticle surface in the presence of N-cyclohexylidene-anilines, various structurally diverse primary anilines were selectively synthesized from readily accessible NH3 and cyclohexanones. The Pd/HAP catalyst was reused several times though its catalytic performance gradually declined.
- Koizumi, Yu,Jin, Xiongjie,Yatabe, Takafumi,Miyazaki, Ray,Hasegawa, Jun-ya,Nozaki, Kyoko,Mizuno, Noritaka,Yamaguchi, Kazuya
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- Magnetically Recyclable Metal–Organic Framework@Fe3O4 Composite-Catalyzed Facile Reduction of Nitroarene Compounds in Aqueous Medium
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A kind of Metal–organic framework (MOF) composite namely Cu-BTC@Fe3O4 (BTC?=?1,3,5-benzenetricarboxylate) was prepared and showed good catalytic activity toward the reduction of nitroarenes. This reaction proceeded smoothly under mild reaction conditions in aqueous medium using sodium borohydride as the reduction agent, affording the corresponding anilines in good to excellent yields. In addition, the catalyst could be easily recovered with an external permanent magnet and be reused for successive six runs with slight decrease in its activity.
- Yang, Sen,Zhang, Zhi-Hui,Chen, Qun,He, Ming-Yang,Wang, Liang
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- Negishi-type coupling of bromoarenes with dimethylzinc
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Treatment of bromoarenes with dimethylzinc in the presence of a palladium catalyst provides a high-yielding route to methylarenes. The process accommodates a wide range of aromatic substituents and, in the majority of cases, is free of side reactions.
- Herbert, John M.
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- SELECTIVE AND SEQUENTIAL REDUCTION OF NITROAROATICS BY MONTMORILLONITESILYLAMINEPALLADIUM(II) COMPLEX
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Nitroaromatics are sequently and selectively hydrogenated in quantitative yields at room temperature and atmospheric pressure by interlamellarmontmorillonitepalladium(II) complex, a heterogenised homogenous catalyst.
- Mukkanti, K.,Rao, Y. V. Subba,Choudary, B. M.
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- Pd Nanoparticles Assembled on Metalporphyrin-Based Microporous Organic Polymer as Efficient Catalyst for Tandem Dehydrogenation of Ammonia Borane and Hydrogenation of Nitro Compounds
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Abstract: Metalporphyrin-based porous polymers supporting high dispersed Pd nanoparticle (NP) catalysts (HUST-1-Pd) were prepared with a novel solvent-knitting hyper-crosslinked polymer method using 5-, 10-, 15-, and 20-tetraphenylporphyrin (TPP) as building blocks. The N2 sorption isotherms of the catalysts show that the HUST-1-Pd possesses many ultra-micropores and continuous mesopores. The NPs are assembled on tetraphenylporphyrin structures and show Pd-N4 composition-dependent catalysis for methanolysis of ammonia borane (AB) and hydrogenation of aromatic nitro compounds to primary amines in methanol solutions at room temperature. The nano-palladium reduced by NaBH4 has efficient catalytic activity for AB methanolysis. A variety of R-NO2 derivatives were reduced selectively into R-NH2 via palladium catalyzed tandem reactions with 5–30?min of reaction time with conversion yields reaching up to 90%. The derivatives also give excellent recycling performance (more than 10 times). Furthermore, the turnover frequency (TOF) can reach 87,209?h?1. The HUST-1-Pd compounds represent a unique metal catalyst for hydrogenation reactions in a green environment without using pure hydrogen. Graphic Abstract: A monodisperse Pd NPs embed in porphyrin-based microporous organic polymer was reported to catalyse the tandem dehydrogenation of ammonia borane and hydrogenation of R-NO2 to R-NH2 at room temperature. The catalyst is efficient and reusable in an environment-friendly process with short reaction times and high yields.[Figure not available: see fulltext.]
- Zou, Zhijuan,Jiang, Yaya,Song, Kunpeng
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- Carbonylation of nitro and azo compounds in the presence of iron carbonyl catalysts
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The reactions of nitro and azo compounds with carbon monoxide were studied in the presence of iron carbonyl catalysts. It was shown that these catalytic systems differ substantially from Pd- and Rh-containing catalysts. In the case of the iron catalysts, the products of coupling of molecules are formed as intermediates and azo compounds are the final reaction products. The reactions involving the palladium and rhodium catalysts proceed without the intermediate formation of the coupling products and lead to isocyanates or carbamates. When combined using PdCh and Fe(CO)5/Al2Oj, the catalysts inhibit each other, especially in the presence of pyridine.
- Lapidus,Pelrovskii,Manov-Yuvenskii,Zelinsky
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- One-pot tandem catalysis over Pd@MIL-101: boosting the efficiency of nitro compound hydrogenation by coupling with ammonia borane dehydrogenation
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The hydrogenation efficiency of nitro compounds was found to be greatly boosted by coupling with dehydrogenation of ammonia borane. The Pd@MIL-101 with tiny Pd NPs is exceptionally efficient and recyclable in the tandem reactions and diverse nitro compounds can be selectively reduced to the corresponding amines in 1.5-5 min with quantitative yields.
- Yang, Qihao,Chen, Yu-Zhen,Wang, Zhiyong U.,Xu, Qiang,Jiang, Hai-Long
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- Effect of pressure on the reaction between 3-methyl-1-p-tolyl-triazene and benzoic acid; a kinetic study
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Rates of reaction between 3-methyl- 1p-tolytriazene and benzoic acid were measured with variation of pressure in chloroform and acetonitrile. Activation volumes were found to be -15 and -4 cm3 mol-1, respectively. The reaction mechanism is discussed in the context of these values. Johann Ambrosius Barth 1996.
- Laila, Abdulhameed,Isaacs, Neil S.
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- Sulfamide chemistry applied to the functionalization of self-assembled monolayers on gold surfaces
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Aniline-terminated self-assembled monolayers (SAMs) on gold surfaces have successfully reacted with ArSO2NHOSO2Ar (Ar = 4-MeC6H4 or 4-FC6H4) resulting in monolayers with sulfamide moieties
- Pantaine, Lo?c,Humblot, Vincent,Coeffard, Vincent,Vallée, Anne
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- Palladium-catalyzed reduction of nitroaromatic compounds to the corresponding anilines
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Reduction of a variety of nitroaromaticcompoundswith triethylsilane in thepresence of catalytic amounts ofpalladium chloride in ethanol resulted in the formation of the corresponding anilines in excellent yields. Copyright
- Mirza-Aghayan, Maryam,Boukherroub, Rabah,Rahimifard, Mahshid,Bolourtchian, Mohammad
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- Promoting effect of na2SeO3 on the activity of MoO3 catalyst for nitroarenes reduction to amines with sodium borohydride
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Sodium selenite enhances the catalytic activity of molybdenum(VI) oxide during the reduction of nitroarenes (XC6H4NO2, X = 4-CN, 4-CO2Et, H, 4-Cl, 2-Me, 3-Me, 4-Me, 4-OMe) with sodium borohydride to arenamines (86-98 % yields) under mild conditions. X= 4-CN, 4-CO2Et, H, 4-Cl, 2-Me, 3-Me, 4-Me, 4-OMe in 86-98 % yields.
- Yanada, Kazuo,Yanada, Reiko,Meguri, Haruo
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- Transition metal imide/organic imine metathesis reactions: Unexpected observations
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Mixtures of [Ti(NBut)Cl2(py)3] 1 and PhC(NAr)H (Ar = C6H3Me2-2,6 or C6H4Me-4) gave quantitative conversion to [Ti(NAr)Cl2(py)3] and PhC(NBut)H, the products of Ti=N-But/C=NAr transition metal imide/organic imine metathesis; examination of the kinetics for Ar = C6H4Me-4 showed that the rate limiting step for this process is zero order in [1], demonstrating that these reactions do not involve metal imide particiption in the rate limiting step.
- McInnes, Jacqueline M.,Mountford, Philip
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- One-Pot Synthesis of Heterobimetallic Metal–Organic Frameworks (MOFs) for Multifunctional Catalysis
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A one-pot synthesis of bimetallic metal–organic frameworks (Co/Fe-MOFs) was achieved by treating stoichiometric amounts of Fe and Co salts with 2-aminoterephthalic acid (NH2-BDC). Monometallic Fe (catalyst A) and Co (catalyst F) were also prepared along with mixed-metal Fe/Co catalysts (B–E) by changing the Fe/Co ratio. For mixed-metal catalysts (B–E) SEM energy-dispersive X-ray (EDX) analysis confirmed the incorporation of both Fe and Co in the catalysts. However, a spindle-shaped morphology, typically known for the Fe-MIL-88B structure and confirmed by PXRD analysis, was only observed for catalysts A–D. To test the catalytic potential of mixed-metal MOFs, reduction of nitroarenes was selected as a benchmark reaction. Incorporation of Co enhanced the activity of the catalysts compared with the parent NH2-BDC-Fe catalyst. These MOFs were also tested as electrocatalysts for the oxygen evolution reaction (OER) and the best activity was exhibited by mixed-metal Fe/Co-MOF (Fe/Co batch ratio=1). The catalyst provided a current density of 10 mA cm?2 at 410 mV overpotential, which is comparable to the benchmark OER catalyst (i.e., RuO2). Moreover, it showed long-term stability in 1 m KOH. In a third catalytic test, dehydrogenation of sodium borohydride showed high activity (turnover frequency=87 min?1) and hydrogen generation rate (67 L min?1 g?1 catalyst). This is the first example of the synthesis of bimetallic MOFs as multifunctional catalysts particularly for catalytic reduction of nitroarenes and dehydrogenation reactions.
- Iqbal, Bushra,Saleem, Murtaza,Arshad, Salman Noshear,Rashid, Jamshaid,Hussain, Naveed,Zaheer, Muhammad
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- PROTONATION OF REAGENTS AND ACID-BASE CATALYSIS IN ACYLATION
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The kinetic characteristics of the model reaction of electron transfer and the reaction of acylation of aromatic amines by aromatic acid anhydrides were investigated as a function of the concentration of acid catalyst and a correlation was established between the type of this function and the characteristics of protonation of the amines.The rate constants of the catalytic and noncatalytic flows of the forward and reverse reactions in the phthalic anhydride-p-toluidine system were determined as a function of the molarity and proton-acceptor properties of the solvent.The mechanism of acid-base catalysis was examined as a sequence of proton and electron transfer processes. Keywords: catalysis, kinetics, protonation.
- Kalnin'sh, K. K.
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- Dinuclear Palladium(II) Complexes Containing Anilide Anions as Bridging Ligands
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The reactions of with aniline and its derivatives (L) in benzene at room temperature afforded 3)L>, (hfac), and (hfac)2 depending on the reactants mole ratio.On the other hand, the reactions of various complexes with L in refluxing benzene (in most cases) gave rise to the anilide-bridged dinuclear complexes 2, which in turn reacted with primary amines and pyridine (L') to produce 2(β-dik)2.
- Okeya, Seichi,Yoshimatsu, Hisako,Nakamura, Yukio,Kawaguchi, Shinichi
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- Iodide Reduction of Sulfilimines. 2. Evidence for Concurrent Stepwise and Concerted Mechanisms for the Decomposition of Sulfurane Intermediates
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The iodide reduction of N-(substituted ethyl or phenyl)-S,S-dimethylsulfilimmonium salts (aqueous solution, 25 deg C, μ = 1.0 with KCl) is first order in proton activity and iodide concentration in the pH range 0.5-5.The solvent deuterium isotope effects for the reduction reaction vary in the range kH/kD = 0.26-0.48 as the nitrogen substituent is changed from ethyl- to trifluoroethylamine.Electron-withdrawing groups in the leaving group decrease the rate of the reaction and give βl.g. values of ca. 0.7 for cyanoethyl- and trifluoroethylamine leaving groups and ca. 0.1 for the more basic ethylamine derivatives; a βl.g. of 0.58 is observed for aniline derivatives.General acid catalysis is observed in the reduction of the acidic ethylamine and aniline derivatives with Broensted α values of 0.59 and 0.39 for cyanoethyl- and trifluoroethylamine leaving groups, respectively; for anilines, the Broensted α values decreased from 0.67 to 0.50 as the leaving group is changed from 4-methyl- to 3-nitroaniline.The value of βl.g. decreases with decreasing strength of the catalyzing acid and the term pxy = (δβl.g./δpKaHA) = (δα/δKal.g.) ca. -0.06 to -0.1.The solvent deuterium isotope effect on the general catalyzed reduction reaction increases with increasing acid strength; for the cyanoethylamine derivative, kBH/kBD = 1.47-2.32 for acetic and chloroacetic acids, respectively.A mechanism is suggested involving concurrent stepwise and concerted mechanisms for the reduction reaction; the mechanism observed seems to depend on the nature of the catalyzing acid.
- Young, Paul R.,Huang, H. C.
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- Catalytic Deoxygenation of Nitroarenes Mediated by High-Valent Molybdenum(VI)-NHC Complexes
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The high-valent molybdenum(VI) N-heterocyclic carbene complexes, (NHC)MoO2 (1) and (NHC)MoO(NtBu) (2) (NHC = 1,3-bis(3,5-di-tert-butyl-2-phenolato)-benzimidazol-2-ylidene), are investigated toward their catalytic potential in the deoxygenation of nitroarenes. Using pinacol as the sacrificial and green reductant, both complexes are shown to be very active (pre)catalysts for this transformation allowing a reduction of the catalyst loading down to 0.25 mol %. Mechanistic investigations show μ-oxo bridged molybdenum(V) complexes [(NHC)MoO]2O (4) and [(NHC)Mo(NtBu)]2O (5) as well as zwitterionic pinacolate benzimidazolium complex 6, with a doubly protonated NHC ligand, to be potentially active species in the catalytic cycle. Both 4 and 5 can be prepared independently by the deoxygenation of 1 and 2 using triethyl phosphine (PEt3) or triphenyl phosphine (PPh3) and were shown to exhibit an unusual multireferenced ground state with a very small singlet-triplet gap at room temperature. Computational studies show that the spin state plays an unneglectable role in the catalytic process, efficiently lowering the reaction barrier of the deoxygenation step. Mechanistic details, putting special emphasis on the fate of the catalyst will be presented and potential routes how nitroarene reduction is facilitated are evaluated.
- Liu, Shenyu,Amaro-Estrada, Jorge Ivan,Baltrun, Marc,Douair, Iskander,Schoch, Roland,Maron, Laurent,Hohloch, Stephan
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- Recyclable aluminium oxy-hydroxide supported Pd nanoparticles for selective hydrogenation of nitro compounds via sodium borohydride hydrolysis
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The reduction of aromatic/aliphatic nitro compounds to primary amines with high yields was easily realized by transfer hydrogenation comprising commercially available aluminium oxy-hydroxide-supported Pd nanoparticles (0.5 wt% Pd, Pd/AlO(OH)) as catalysts and NaBH4 as the hydrogen reservoir at room temperature in a water/methanol mixture (v/v = 7/3). The presented catalytic methodology is highly efficient for the reduction of various nitro compounds as well as reusable. A variety of R-NO2 derivatives were tested by performing the Pd/AlO(OH) catalysed reduction reaction and all the nitro compounds were selectively reduced to their corresponding primary amines in reaction times ranging from 0.75 to 13 min with yields reaching up to 99%. This process can be assessed as an eco-friendly method involving both reusable catalysts (Pd/AlO(OH) NPs) and hydrogen sources (NaBH4).
- G?ksu, Haydar
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- Studies on the Mechanism of Transfer Hydrogenation of Nitroarenes by Formate Salts Catalyzed by Pd/C
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The hydrogenation of nitroarenes to aminoarenes using formate salts as hydrogen donors and Pd/C as catalyst in a liquid/liquid/solid system was found to be a true hydrogen transfer process.The mechanism of the reaction comprises successive adsorption of a
- Wiener, Harold,Blum, Jochanan,Sasson, Yoel
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- Palladium Immobilized on a Polyimide Covalent Organic Framework: An Efficient and Recyclable Heterogeneous Catalyst for the Suzuki–Miyaura Coupling Reaction and Nitroarene Reduction in Water
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An efficient and recyclable Pd nano-catalyst was developed via immobilization of Pd nanoparticles on polyimide linked covalent organic frameworks (PCOFs) that was facilely prepared through condensation of melamine and 3,3′,4,4′-biphenyltetracarboxylic dianhydride. The Pd nanoparticles (Pd NPs) catalyst was thoroughly characterized by FT-IR, XRD, SEM, TEM. Furthermore, the catalytic activity of Pd NPs catalyst was evaluated by Suzuki–Miyaura coupling reaction and nitroarene reduction in water, respectively. The excellent yields of corresponding products revealing revealed that the Pd NPs catalyst could be applied as an efficient and reusable heterogeneous catalyst for above two reactions. Graphical Abstract: [Figure not available: see fulltext.]
- Dong, Zhenhua,Pan, Hongguo,Gao, Pengwei,Xiao, Yongmei,Fan, Lulu,Chen, Jing,Wang, Wentao
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p. 299 - 306
(2021/05/10)
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- Selective Reduction of Nitroarenes to Arylamines by the Cooperative Action of Methylhydrazine and a Tris(N-heterocyclic thioamidate) Cobalt(III) Complex
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We report an efficient catalytic protocol that chemoselectively reduces nitroarenes to arylamines, by using methylhydrazine as a reducing agent in combination with the easily synthesized and robust catalyst tris(N-heterocyclic thioamidate) Co(III) complex [Co(κS,N-tfmp2S)3], tfmp2S = 4-(trifluoromethyl)-pyrimidine-2-thiolate. A series of arylamines and heterocyclic amines were formed in excellent yields and chemoselectivity. High conversion yields of nitroarenes into the corresponding amines were observed by using polar protic solvents, such as MeOH and iPrOH. Among several hydrogen donors that were examined, methylhydrazine demonstrated the best performance. Preliminary mechanistic investigations, supported by UV-vis and NMR spectroscopy, cyclic voltammetry, and high-resolution mass spectrometry, suggest a cooperative action of methylhydrazine and [Co(κS,N-tfmp2S)3] via a coordination activation pathway that leads to the formation of a reduced cobalt species, responsible for the catalytic transformation. In general, the corresponding N-arylhydroxylamines were identified as the sole intermediates. Nevertheless, the corresponding nitrosoarenes can also be formed as intermediates, which, however, are rapidly transformed into the desired arylamines in the presence of methylhydrazine through a noncatalytic path. On the basis of the observed high chemoselectivity and yields, and the fast and clean reaction processes, the present catalytic system [Co(κS,N-tfmp2S)3]/MeNHNH2 shows promise for the efficient synthesis of aromatic amines that could find various industrial applications.
- Ioannou, Dimitris I.,Gioftsidou, Dimitra K.,Tsina, Vasiliki E.,Kallitsakis, Michael G.,Hatzidimitriou, Antonios G.,Terzidis, Michael A.,Angaridis, Panagiotis A.,Lykakis, Ioannis N.
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supporting information
p. 2895 - 2906
(2021/02/27)
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- Rhodium nanoparticles supported on 2-(aminomethyl)phenols-modified Fe3O4 spheres as a magnetically recoverable catalyst for reduction of nitroarenes and the degradation of dyes in water
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A magnetic nanostructured catalyst (Fe3O4@SiO2-Amp-Rh) modified with 2-(aminomethyl)phenols (Amp) was designed and prepared, which is used to catalyze the reduction of aromatic nitro compounds into corresponding amines and the degradation of dyes. The 2-aminomethylphenol motif plays a vital role in the immobilization of rhodium nanoparticles to offer extraordinary stability, which has been characterized by using various techniques, including transmission electron microscopy (TEM), thermal gravimetric analyzer (TGA), X-Ray Diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). A variety of nitroaromatic derivatives have been reduced to the corresponding anilines in water with up to yields of 99% within 1?h at room temperature. In addition, the catalyst system is effective in catalyzing the reduction of toxic pollutant 4-nitrophenol and the degradation of MO, MB and RhB dyes. Importantly, this catalyst Fe3O4@SiO2-Amp-Rh can be easily recovered by an external magnetic field because of the presence of magnetic core of Fe3O4, and the activity of Fe3O4@SiO2-Amp-Rh does not decrease significantly after 7 times’ recycling, which indicates that the catalyst performed high reactivity as well as stability. Graphical abstract: [Figure not available: see fulltext.]
- Chen, Tian,Chen, Zhangpei,Hu, Jianshe,Lv, Kexin,Reheman, Aikebaier,Wang, Gongshu
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-
- Synthesis and characterization of chitosan pyridyl imine palladium (CPIP) complex as green catalyst for organic transformations
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In this work, the modification of chitosan using 2-acetyl pyridine has been used to prepare an intermediate, chitosan pyridyl imine (CPI), in first step and then in second step it is further reacted with Pd(OAc)2 to develop chitosan pyridyl imine palladium (CPIP) complex catalyst in a very simplistic way. The formed CPIP has been extensively characterized with respect to raw chitosan utilizing methods including FT-IR, pyrolysis GC–MS, XRD, XPS, FE-SEM, EDS, TGA-DTG and DSC. TG-DSC study suggested that the catalyst is thermally stable up to 300?°C. This catalyst shows an excellent activity in the reduction of toxic pollutant nitrobenzene to less toxic aniline. CPIP complex has also been found to give magnificent results in Suzuki–Miyaura and Heck cross-coupling reactions, and therefore, using this green catalyst, the toxic phosphine ligand can be excluded from cross-coupling reactions. This study furnishes an economic and eco-friendly catalyst for organic transformation in sustainable chemistry.
- Chundawat, Narendra Singh,Pathan, Sultan,Singh, Girdhar Pal,Deuri, Arup Saha,Zarrintaj, Payam,Chauhan, Narendra Pal Singh
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p. 2835 - 2850
(2021/02/11)
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- Magnetically‐recoverable Schiff base complex of Pd(II) immobilized on Fe3O4@SiO2 nanoparticles: an efficient catalyst for the reduction of aromatic nitro compounds to aniline derivatives
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Fe3O4@SiO2/Schiff base/Pd(II) is reported as a magnetically recoverable heterogeneous catalyst for the chemoselective reduction of aromatic nitro compounds to the corresponding amines through catalytic transfer hydrogenation (CTH). In this regard, a small amount of the nanocatalyst (0.52?mol% Pd) and hydrazine hydrate, showing safe characteristics and perfect ability as the hydrogen donor, were added to the nitro substrates. The experiments described the successful reduction of aromatic nitro compounds with good to excellent yields and short reaction times. The catalyst, due to its magnetic property, could be simply separated from the reaction mixture by a permanent magnet and reused in seven consecutive reactions without considerable loss in its activity. Moreover, the leaching of Pd was only 3.6% after the seventh run. Thus, the most striking feature of this method is to use a small amount of the magnetic nanocatalyst along with a cheap and safe hydrogen source to produce the important amine substances selectively, which makes the method economical, cheap, environmentally friendly, and simple. Graphic abstract: [Figure not available: see fulltext.]
- Azadi, Sedigheh,Esmaeilpour, Mohsen,Sardarian, Ali Reza
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p. 809 - 821
(2021/07/20)
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- Highly porous copper-supported magnetic nanocatalysts: made of volcanic pumice textured by cellulose and applied for the reduction of nitrobenzene derivatives
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Herein, a novel designed heterogeneous catalytic system constructed of volcanic pumice magnetic particles (VPMPs), cellulose (CLS) as a natural polymeric matrix, and copper nanoparticles (Cu NPs) is presented. Also, to enhance the inherent magnetic property of VPMP, iron oxide (Fe3O4) nanoparticles have been prepared and incorporated in the structureviaanin situprocess. As its first and foremost excellent property, the designed composite is in great accordance with green chemistry principles because it contains natural ingredients. Another brilliant point in the architecture of the designed composite is the noticeable porosity of VPMP as the core of the composite structure (surface area: 84.473 m2g?1). This great porosity leads to the use of a small amount (0.05 g) of the particles for catalytic purposes. However, the main characterization methods, such as Fourier-transform infrared and energy-dispersive X-ray spectroscopy, thermogravimetric analysis, and electron microscopy, revealed that the spherical metallic particles (Fe and Cu oxides) were successfully distributed onto the surface of the VPMP and CLS matrices. Further, vibrating-sample magnetometer analysis confirmed the enhancement of the magnetic property (1.5 emu g?1) of the composite through the addition of Fe3O4nanoparticles. Further, the prepared (Fe3O4@VPMP/CLS-Cu) nanocomposite has been applied to facilitate the reduction reaction of hazardous nitrobenzene derivatives (NBDs) to their aniline analogs, with 98% conversion efficiency in eight minutes under mild conditions. Moreover, the good reusability of the catalytic system has been verified after recycling it ten times without any significant decrease in the performance.
- Fazeli, Atefeh,Maleki, Ali,Qazi, Fateme Sadat,Saeidirad, Mahdi,Shalan, Ahmed Esmail,Taheri-Ledari, Reza
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p. 25284 - 25295
(2021/08/05)
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- Highly efficient hydrogenation reduction of aromatic nitro compounds using MOF derivative Co-N/C catalyst
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The direct hydrogenation reduction of aromatic nitro compounds to aromatic amines with non-noble metals is an attractive area. Herein, the pyrolysis of Co(2-methylimidazole)2 metal-organic framework successfully produces a magnetic Co-N/C nanocomposite, which exhibits a porous structure with a high specific area and uniform Co nanoparticle distribution in nitrogen-doped graphite. In addition, the Co-N/C catalysts possess high cobalt content (23%) with highly active β-Co as the main existing form and high nitrogen content (3%). These interesting characteristics endow the Co-N/C nanocomposite with excellent catalytic activity for the hydrogenation reduction of nitro compounds under mild conditions. In addition, the obtained Co-N/C nanocomposites possess a broad substrate scope and good cycle stability for the reduction of halogen-substituted or carbonyl substituted phenyl nitrates. This journal is
- Dai, Yuyu,Li, Xiaoqing,Wang, Likai,Xu, Xiangsheng
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p. 22908 - 22914
(2021/12/24)
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- Generation of a Sulfinamide Species from Facile N-O Bond Cleavage of Nitrosobenzene by a Thiolate-Bridged Diiron Complex
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The activation of nitrosobenzene promoted by transition-metal complexes has gained considerable interest due to its significance for understanding biological processes and catalytic C-N bond formation processes. Despite intensive studies in the past decades, there are only limited cases where electron-rich metal centers were commonly employed to achieve the N-O or C-N bond cleavage of the coordinated nitrosobenzene. In this regard, it is significant and challenging to construct a suitable functional system for examining its unique reactivity toward reductive activation of nitrosoarene. Herein, we present a {Fe2S2} functional platform that can activate nitrosobenzene via an unprecedented iron-directed thiolate insertion into the N-O bond to selectively generate a well-defined diiron benzenesulfinamide complex. Furthermore, computational studies support a proposal that in this concerted four-electron reduction process of nitrosobenzene the iron center serves as an important electron shuttle. Notably, compared to the intact bridging nitrosoarene ligand, the benzenesulfinamide moiety has priority to convert into aniline in the presence of separate or combined protons and reductants, which may imply the formation of the sulfinamide species accelerates reduction process of nitrosoarene. The reaction pattern presented here represents a novel activation mode of nitrosobenzene realized by a thiolate-bridged diiron complex.
- Chen, Yifeng,Qu, Jingping,Wang, Baomin,Xu, Sunlin,Yang, Dawei,Ye, Shengfa
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supporting information
p. 17374 - 17387
(2021/10/25)
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- Ligand compound for copper catalyzed aryl halide coupling reaction, catalytic system and coupling reaction
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The invention provides a ligand compound capable of being used for copper catalyzed aryl halide coupling reaction, the ligand compound is a three-class compound containing a 2-(substituted or non-substituted) aminopyridine nitrogen-oxygen group, and the invention also provides a catalytic system for the aryl halide coupling reaction. Thecatalytic system comprises a copper catalyst, a compound containing a 2-(substituted or non-substituted) aminopyridine nitrogen-oxygen group adopted as a ligand, alkali and a solvent, and meanwhile, the invention also provides a system for the aryl halide coupling reaction adopting the catalyst system. The compound containing the 2-(substituted or non-substituted) aminopyridine nitrogen oxygen group can be used as the ligand for the copper catalyzed aryl chloride coupling reaction, and the ligand is stable under a strong alkaline condition and can well maintain catalytic activity when being used for the copper-catalyzed aryl chloride coupling reaction. In addition, the copper catalyst adopting the compound as the ligand can particularly effectively promote coupling of copper catalyzed aryl chloride and various nucleophilic reagents which are difficult to generate under conventional conditions, C-N, C-O and C-S bonds are generated, and numerous useful small molecule compounds are synthesized. Therefore, the aryl halide coupling reaction has a very good large-scale application prospect by adopting the copper catalysis system of the ligand.
- -
-
Paragraph 0111-0119
(2021/05/29)
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- METHOD FOR PRODUCING AMINO AROMATIC COMPOUND
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To provide a novel method for producing an amino aromatic compound.SOLUTION: A method for producing a compound (B) having at least one amino group on an aromatic ring, includes at least a step in which a compound (A) at least having an aromatic ring and one group represented by -CR=CH2 [R is a hydrogen atom or a C1-3 alkyl group] on the aromatic ring is reacted with sodium azide in the presence of acid.SELECTED DRAWING: None
- -
-
Paragraph 0040-0045
(2021/03/03)
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- Room-temperature copper-catalyzed electrophilic amination of arylcadmium iodides with ketoximes
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We started our study by preparation two ketoximes. Later, there were studies to reveal these ketoximes' effects in the electrophilic amination reaction with organocadmium reagents. Primarily, it was observed that arylcadmium iodides could not be reacted with ketoximes at room temperature in the absence of a catalyst. CuCN was a suitable catalyst for this electrophilic amination reaction of arylcadmium iodides and allowed the preparation of functionalized aniline derivatives in good yields under mild reaction conditions. We obtained the results indicated that the yield of primary arylamines was strongly dependent on the steric and electronic effects of organocadmium reagent and amination agent. In the case of both amination reagents, meta-substituted arylamines were obtained in higher yields than para-substituted arylamines. We observed that acetone O-(4-chlorophenylsulfonyl)oxime, 1, as an aminating agent, was more successful than acetone O-(2-Naphthylsulfonyl)oxime, 2, in the synthesis of functionalized arylamines by electrophilic amination of corresponding aryl cadmium iodides. In this method, there is no cadmium release to the environment.
- Korkmaz, Adem
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p. 3119 - 3125
(2021/05/10)
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- High yielding electrophilic amination with lower order and?higher order organocuprates: Application of acetone O-(4-Chlorophenylsulfonyl)oxime in the construction of the C?N bond at room temperature
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Electrophilic amination reaction was performed with lower order and?higher order organocuprates using acetone O-(4-Chlorophenylsulfonyl)oxime (1). It was proceeded smoothly at room temperature in the presence of organocuprates to provide the corresponding primary amines in good yields with 10 and 60 min, respectively. The primary amine yields of the electrophilic amination of bromomagnesium organocyanocuprates and dibromomagnesium diorganocyanocuprates were obtained 52–72% and 58–83%, respectively. We observed that higher order organocuprates were more successful than lower order organocuprates in the synthesis of functionalized arylamines by electrophilic amination.
- Duran, Serdar,Korkmaz, Adem
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p. 2077 - 2087
(2021/05/27)
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- Manganese Catalyzed Hydrogenation of Azo (N=N) Bonds to Amines
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We report the first example of homogeneously catalyzed hydrogenation of the N=N bond of azo compounds using a complex of an earth-abundant-metal. The hydrogenation reaction is catalyzed by a manganese pincer complex, proceeds under mild conditions, and yields amines, which makes this methodology a sustainable alternative route for the conversion of azo compounds. A plausible mechanism involving metal-ligand cooperation and hydrazine intermediacy is proposed based on mechanistic studies. (Figure presented.).
- Ben-David, Yehoshoa,Das, Uttam Kumar,Diskin-Posner, Yael,Kar, Sayan,Milstein, David
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supporting information
p. 3744 - 3749
(2021/07/09)
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- Mechanochemical synthesis of aromatic sulfonamides
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A three-component Pd-catalysed aminosulfonylation reaction of K2S2O5 and amine with aryl bromides or aromatic carboxylic acids was developed. This strategy was developed to utilise mechanical energy and accommodate primary as well as secondary aliphatic and aromatic amines to provide a new shortcut to a wide range of sulfonamides. Studies on the scope and limitations of the reaction indicated its tolerance of a vast range of functional groups and many structural patterns. The reactions were scaled up to gram quantities.
- Mkrtchyan, Satenik,Iaroshenko, Viktor O.
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supporting information
p. 11029 - 11032
(2021/11/03)
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- The graphite-catalyzed: ipso -functionalization of arylboronic acids in an aqueous medium: metal-free access to phenols, anilines, nitroarenes, and haloarenes
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An efficient, metal-free, and sustainable strategy has been described for the ipso-functionalization of phenylboronic acids using air as an oxidant in an aqueous medium. A range of carbon materials has been tested as carbocatalysts. To our surprise, graphite was found to be the best catalyst in terms of the turnover frequency. A broad range of valuable substituted aromatic compounds, i.e., phenols, anilines, nitroarenes, and haloarenes, has been prepared via the functionalization of the C-B bond into C-N, C-O, and many other C-X bonds. The vital role of the aromatic π-conjugation system of graphite in this protocol has been established and was observed via numerous analytic techniques. The heterogeneous nature of graphite facilitates the high recyclability of the carbocatalyst. This effective and easy system provides a multipurpose approach for the production of valuable substituted aromatic compounds without using any metals, ligands, bases, or harsh oxidants.
- Badgoti, Ranveer Singh,Dandia, Anshu,Parewa, Vijay,Rathore, Kuldeep S.,Saini, Pratibha,Sharma, Ruchi
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p. 18040 - 18049
(2021/05/29)
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- A convenient Hofmann reaction of carboxamides and cyclic imides mediated by trihaloisocyanuric acids
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A simple, efficient and pot-economic approach in a single vessel has been developed for conversion of aromatic and aliphatic carboxamides into primary amines with one fewer carbom atom (Hofmann reaction) in 38–89 % yield by reacting with trichloro- or tribromoisocyanuric acid and sodium hydroxide in aqueous acetonitrile. Under the same reaction conditions, cyclic imides gave amino acids (69–83 %). The role of the trihaloisocyanuric acids is the in situ generation of N-haloamides, key-intermediates for the Hofmann reaction. The scalability of the methodology was demonstrated by a multigram-scale transformation of phthalimide into anthranilic acid in 77 % yield.
- Bastos, Gustavo A.,de Mattos, Marcio C.S.
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- Synthesis of Substituted Anilines from Cyclohexanones Using Pd/C-Ethylene System and Its Application to Indole Synthesis
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The synthesis of anilines and indoles from cyclohexanones using a Pd/C-ethylene system is reported. A simple combination of NH4OAc and K2CO3 under nonaerobic conditions was found to be the most suitable to perform this reaction. Hydrogen transfer between cyclohexanone and ethylene generates the desired products. The reaction tolerates a variety of substitutions on the starting cyclohexanones.
- Maeda, Katsumi,Matsubara, Ryosuke,Hayashi, Masahiko
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supporting information
p. 1530 - 1534
(2021/03/08)
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- Selective primary aniline synthesis through supported Pd-catalyzed acceptorless dehydrogenative aromatization by utilizing hydrazine
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By utilizing hydrazine (N2H4) as the nitrogen source in the presence of a hydroxyapatite-supported Pd nanoparticle catalyst (Pd/HAP), various primary anilines can be selectively synthesized from cyclohexanonesviaacceptorless dehydrogenative aromatization. The strong nucleophilicity of N2H4and the stability of the hydrazone intermediates can effectively suppress the formation of the undesired secondary aniline byproducts.
- Lin, Wei-Chen,Yamaguchi, Kazuya,Yatabe, Takafumi
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supporting information
p. 6530 - 6533
(2021/07/07)
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- Selective Carbon-Carbon Bond Amination with Redox-Active Aminating Reagents: A Direct Approach to Anilines?
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Amines are among the most fundamental motifs in chemical synthesis, and the introduction of amine building blocks via selective C—C bond cleavage allows the construction of nitrogen compounds from simple hydrocarbons through direct skeleton modification. Herein, we report a novel method for the preparation of anilines from alkylarenes via Schmidt-type rearrangement using redox-active amination reagents, which are easily prepared from hydroxylamine. Primary amines and secondary amines were prepared from corresponding alkylarenes or benzyl alcohols under mild conditions. Good compatibility and valuable applications of the transformation were also displayed.
- Qiu, Xu,Wang, Yachong,Su, Lingyu,Jin, Rui,Song, Song,Qin, Qixue,Li, Junhua,Zong, Baoning,Jiao, Ning
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p. 3011 - 3016
(2021/09/13)
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- Minimization of Back-Electron Transfer Enables the Elusive sp3 C?H Functionalization of Secondary Anilines
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Anilines are some of the most used class of substrates for application in photoinduced electron transfer. N,N-Dialkyl-derivatives enable radical generation α to the N-atom by oxidation followed by deprotonation. This approach is however elusive to monosubstituted anilines owing to fast back-electron transfer (BET). Here we demonstrate that BET can be minimised by using photoredox catalysis in the presence of an exogenous alkylamine. This approach synergistically aids aniline SET oxidation and then accelerates the following deprotonation. In this way, the generation of α-anilinoalkyl radicals is now possible and these species can be used in a general sense to achieve divergent sp3 C?H functionalization.
- Zhao, Huaibo,Leonori, Daniele
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supporting information
p. 7669 - 7674
(2021/03/08)
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- Reductive Formylation of Nitroarenes using HCOOH over Bimetallic C?N Framework Derived from the Integration of MOF and COF
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CoZn embedded C?N framework is prepared by the carbonization of CoZn containing MOF integrated with COF porous architecture in Ar atmosphere. The graphitic nature of porous carbon is confirmed from Raman analysis. The porosity and nanostructure information are retrieved from N2-sorption and transmission electron microscopic analysis, respectively. The incorporation of different metals and their oxidation states and types of nitrogen present in the C?N framework are confirmed from X-ray photoelectron spectroscopy. The basicity of the materials is determined from a CO2-temperature programmed desorption. ZnCo embedded C?N framework exhibits excellent activity in the selective reductive formylation using HCOOH. For comparison, more than 15 materials are prepared, and their activities are compared. Several control experiments are performed to establish a structure-activity relation. The recycling experiment, hot-filtration test, and poisoning experiment demonstrate the metal embedded porous C?N framework‘s recyclability and stability. A reaction mechanism for the reductive N-formylation of nitroaromatics is presented based on structure-activity relationship, control reactions, and physicochemical characterizations. The development of interesting MOF-COF-derived metal nanoclusters embedded C?N framework for selective reductive formylation of nitroaromatics using formic acid will be highly attractive to catalysis researchers and industrialists.
- Kumar Kar, Ashish,Srivastava, Rajendra
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p. 3174 - 3183
(2021/05/27)
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- Unlocking Amides through Selective C–N Bond Cleavage: Allyl Bromide-Mediated Divergent Synthesis of Nitrogen-Containing Functional Groups
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We report a new set of reactions based on the unlocking of amides through simple treatment with allyl bromide, creating a common platform for accessing a diverse range of nitrogen-containing functional groups such as primary amides, sulfonamides, primary amines, N-acyl compounds (esters, thioesters, amides), and N-sulfonyl esters. The method has potential industrial applicability, as demonstrated through gram-scale syntheses in batch and in a continuous flow system.
- Govindan, Karthick,Chen, Nian-Qi,Chuang, Yu-Wei,Lin, Wei-Yu
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p. 9419 - 9424
(2021/11/30)
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- Discovery and characterization of an acridine radical photoreductant
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Photoinduced electron transfer (PET) is a phenomenon whereby the absorption of light by a chemical species provides an energetic driving force for an electron-transfer reaction1–4. This mechanism is relevant in many areas of chemistry, including the study of natural and artificial photosynthesis, photovoltaics and photosensitive materials. In recent years, research in the area of photoredox catalysis has enabled the use of PET for the catalytic generation of both neutral and charged organic free-radical species. These technologies have enabled previously inaccessible chemical transformations and have been widely used in both academic and industrial settings. Such reactions are often catalysed by visible-light-absorbing organic molecules or transition-metal complexes of ruthenium, iridium, chromium or copper5,6. Although various closed-shell organic molecules have been shown to behave as competent electron-transfer catalysts in photoredox reactions, there are only limited reports of PET reactions involving neutral organic radicals as excited-state donors or acceptors. This is unsurprising because the lifetimes of doublet excited states of neutral organic radicals are typically several orders of magnitude shorter than the singlet lifetimes of known transition-metal photoredox catalysts7–11. Here we document the discovery, characterization and reactivity of a neutral acridine radical with a maximum excited-state oxidation potential of ?3.36 volts versus a saturated calomel electrode, which is similarly reducing to elemental lithium, making this radical one of the most potent chemical reductants reported12. Spectroscopic, computational and chemical studies indicate that the formation of a twisted intramolecular charge-transfer species enables the population of higher-energy doublet excited states, leading to the observed potent photoreducing behaviour. We demonstrate that this catalytically generated PET catalyst facilitates several chemical reactions that typically require alkali metal reductants and can be used in other organic transformations that require dissolving metal reductants.
- MacKenzie, Ian A.,Wang, Leifeng,Onuska, Nicholas P. R.,Williams, Olivia F.,Begam, Khadiza,Moran, Andrew M.,Dunietz, Barry D.,Nicewicz, David A.
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- A polyamine dendritic polymer-copper complex: A reusable catalyst for the additive-free amination of aryl bromides, and iodides
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A porphyrin-initiated amine-functionalized polyepichlorohydrin dendritic polymer (PPECH-Amine) was effectively synthesized, and its water-soluble copper complex (PPECH-Amine-Cu) was developed by treating it with copper acetate. PPECH-Amine and PPECH-Amine-Cu were characterised by different spectroscopic and microscopic techniques. PPECH-Amine-Cu was identified as a reusable catalyst for the amination of bromo- and iodo-benzene derivatives in aqueous media. Due to the presence of residual amino groups in the PPECH-Amine-Cu catalyst, the protocol does not need any additional base additive, as ammonia itself acts as a base and a coupling partner. Due to the good water-soluble nature of this catalyst, it can be easily separated and reused up to six reaction cycles without any loss in its activity.
- Avudaiappan,Palmurukan,Unnikrishnan,Sreekumar
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p. 1477 - 1484
(2020/02/05)
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- Copper and L-(?)-quebrachitol catalyzed hydroxylation and amination of aryl halides under air
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L-(?)-Quebrachitol, a natural product obtained from waste water of the rubber industry, was utilized as an efficient ligand for the copper-catalyzed hydroxylation and amination of aryl halides to selectively give phenols and aryl amines in water or 95percent ethanol. In addition, the hydroxylation of 2-chloro-4-hydroxybenzoic acid was validated on a 100-g scale under air.
- Bao, Xuefei,Chen, Guoliang,Dong, Jinhua,Du, Fangyu,Li, Hui,Liang, Xinjie,Wu, Ying,Zhang, Yongsheng
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supporting information
(2020/08/03)
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- A new ligand for copper-catalyzed amination of aryl halides to primary(hetero)aryl amines
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N,N′-Bis(3,5-dimethoxyphenyl)cyclopentane-1,1-dicarboxamide was found as a new ligand for copper-catalyzed amination of aryl iodides, bromides and chlorides to afford various primary (hetero)aryl amines. These reactions proceeded efficiently under mild conditions when inexpensive aqueous ammonia (28% NH3 in H2O) was used as the amino source.
- Chen, Dong,Dong, Xinrui,Jiang, Shang,Jiang, Sheng,Qiu, Yatao,Wu, Xiaoxing
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supporting information
(2020/02/11)
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- Catalytic Reductions Without External Hydrogen Gas: Broad Scope Hydrogenations with Tetrahydroxydiboron and a Tertiary Amine
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Facile reduction of aryl halides with a combination of 5% Pd/C, B2(OH)4, and 4-methylmorpholine is reported. Aryl bromides, iodides, and chlorides were efficiently reduced. Aryl dihalides containing two different halogen atoms underwent selective reduction: I over Br and Cl, and Br over Cl. Beyond these, aryl triflates were efficiently reduced. This combination was broadly general, effectuating reductions of benzylic halides and ethers, alkenes, alkynes, aldehydes, and azides, as well as for N-Cbz deprotection. A cyano group was unaffected, but a nitro group and a ketone underwent reduction to a low extent. When B2(OD)4 was used for aryl halide reduction, a significant amount of deuteriation occurred. However, H atom incorporation competed and increased in slower reactions. 4-Methylmorpholine was identified as a possible source of H atoms in this, but a combination of only 4-methylmorpholine and Pd/C did not result in reduction. Hydrogen gas has been observed to form with this reagent combination. Experiments aimed at understanding the chemistry led to the proposal of a plausible mechanism and to the identification of N,N-bis(methyl-d3)pyridin-4-amine (DMAP-d6) and B2(OD)4 as an effective combination for full aromatic deuteriation. (Figure presented.).
- Korvinson, Kirill A.,Akula, Hari K.,Malinchak, Casina T.,Sebastian, Dellamol,Wei, Wei,Khandaker, Tashrique A.,Andrzejewska, Magdalena R.,Zajc, Barbara,Lakshman, Mahesh K.
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supporting information
p. 166 - 176
(2020/01/02)
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- Synthesis of: N -methylated amines from acyl azides using methanol
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The transformation of acyl azide derivatives into N-methylamines was developed using methanol as the C1 source via the one-pot Curtius rearrangement and borrowing hydrogen methodology. Following this protocol, various functionalised N-methylated amines were synthesized using the (NNN)Ru(ii) complex from carboxylic acids via an acyl azide intermediate. Several kinetic studies and DFT calculations were carried out to support the mechanism and also to determine the role of the Ru(ii) complex and base in this transformation.
- Chakrabarti, Kaushik,Dutta, Kuheli,Kundu, Sabuj
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p. 5891 - 5896
(2020/08/21)
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- Shape-dependent reactivity and chemoselectivity of nanogold towards nitrophenol reduction in water
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Although the catalytic activity of nano-gold surfaces for the reduction of nitro compounds has been known, the effect of their shape has been rarely evaluated. Here, the synthesis, characterization, and application of both gold nanoworms (GNW) and gold nanospheres (GNS) are described. Both GNW and GNS were characterized using SEM, TEM, UV–Vis, FTIR, and XPS spectroscopy. The catalytic efficiency of GNW with an average dimensions of 2 × 250 nm (D × L) towards the hydrogenation of nitrophenol, a pollutant present in industrial wastewater, is higher (TOF 3675 h?1) than that of spherical GNS (10 ± 1 nm), for which TOF is 1838 h?1 in water using NaBH4 as the reductant. The selectivity of 4-aminophenol is 100% for both GNS and GNW.
- Aziz, Md Abdul,Nafiu, Sodiq Adeyeye,Shaikh, M. Nasiruzzaman
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- Ultrasound-assisted rapid reduction of nitroaromatics to anilines using gallium metal
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The reduction of nitroaromatic compounds to anilines is widely used throughout organic synthesis. Typical methods of performing this transformation utilize hydrogenation over a pyrophoric catalyst or a finely divided reducing metal, which often affords heterogeneous mixtures that are difficult to purify. Herein, we report for the first time the use of gallium metal as a reducing agent in organic synthesis. The reaction proceeds under aerobic conditions and affords homogeneous mixtures for a convenient workup. Using this method, twelve anilines were obtained in 33% to quantitative yields with short reaction times of 10-60 minutes.
- Bento, Ian,Bernaldez, Mabel,Noguchi, Ryden,Kawakami, Joel
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supporting information
p. 1404 - 1407
(2020/03/31)
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- Pd modified prussian blue frameworks: Multiple electron transfer pathways for improving catalytic activity toward hydrogenation of nitroaromatics
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Prussian blue analogs (PBAs) exhibit potential as low-cost and eco-friendly nanocatalysts that can be fabricated with ease. However, the PBA framework structure suffers from poor electronic conductivity, which limits the catalytic efficiency for this clas
- Cha, Joo Hwan,Farha, Omar K.,Jang, Ho Won,Jeon, Se Yeon,Kirlikovali, Kent O.,Ostadhassan, Mehdi,Rasouli, Vamegh,Shokouhimehr, Mohammadreza,Varma, Rajender S.,Zhang, Kaiqiang
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- Atomically Dispersed Co Catalyst for Efficient Hydrodeoxygenation of Lignin-Derived Species and Hydrogenation of Nitroaromatics
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Single-atom catalysts (SACs) have attracted much attention due to their outstanding catalytic performance in heterogeneous catalysis. Here, we report a template sacrificial method to fabricate an atomically dispersed Co catalyst; three kinds of silica templates with different microstructures (MCM-41, SBA-15, and FDU-12) were employed and the effect of pore structure of the templates on the dispersity of Co was investigated. The catalysts fabricated with different templates presented different Co dispersities, leading to distinguishing catalytic performance. The optimized Co1?NC-(SBA) catalyst with atomically dispersed Co displayed outstanding catalytic activity for the hydrodeoxygenation (HDO) of lignin-derived species as well as the hydrogenation of various nitroaromatics. The reaction mechanism of the HDO of vanillin was investigated by using density functional theory calculations as well.
- Du, Congcong,Gao, Shutao,Gao, Yongjun,Huang, Jianyu,Meng, Tao,Qiao, Yuqing,Shang, Ningzhao,Shen, Tongde,Wang, Chun,Wang, Haijun,Wang, Junmin,Wang, Zhi,Wu, Qiuhua,Zhang, Longkang
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p. 8672 - 8682
(2020/09/18)
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- Tandem selective reduction of nitroarenes catalyzed by palladium nanoclusters
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We report a catalytic tandem reduction of nitroarenes by sodium borohydride (NaBH4) in aqueous solution under ambient conditions, which can selectively produce five categories of nitrogen-containing compounds: anilines, N-aryl hydroxylamines, azoxy-, azo- and hydrazo-compounds. The catalyst is in situ-generated ultrasmall palladium nanoclusters (Pd NCs, diameter of 1.3 ± 0.3 nm) from the reduction of Pd(OAc)2 by NaBH4. These highly active Pd NCs are stabilized by surface-coordinated nitroarenes, which inhibit the further growth and aggregation of Pd NCs. By controlling the concentration of Pd(OAc)2 (0.1-0.5 mol% of nitroarene) and NaBH4, the water/ethanol solvent ratio and the tandem reaction sequence, each of the five categories of N-containing compounds can be obtained with excellent yields (up to 98%) in less than 30 min at room temperature. This tunable catalytic tandem reaction works efficiently with a broad range of nitroarene substrates and offers a green and sustainable method for the rapid and large-scale production of valuable N-containing chemicals.
- Yan, Ziqiang,Xie, Xiaoyu,Song, Qun,Ma, Fulei,Sui, Xinyu,Huo, Ziyu,Ma, Mingming
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supporting information
p. 1301 - 1307
(2020/03/11)
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- Enhanced reduction of nitrobenzene derivatives: Effective strategy executed by Fe3O4/PVA-10%Ag as a versatile hybrid nanocatalyst
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Herein, we present an organic–inorganic hybrid nanocomposite constructed of polyvinyl alcohol (PVA), iron oxide (Fe3O4), and 10% of silver nanoparticles (Ag NPs). First, a convenient in situ method is introduced for the preparation of this efficient catalytic system (Fe3O4/PVA-10%Ag). Further, we study the high catalytic performance for the reduction of nitrobenzene (NB) derivatives as a hazardous species of chemicals and the significant biological activity (antibacterial effects) of the nanocomposite. However, high reaction yields (99%) have been obtained in short reaction times (~15 min). A plausible mechanism is suggested, and all the required characterizations of the presented nanocatalyst are investigated in this study.
- Rahimi, Jamal,Taheri-Ledari, Reza,Niksefat, Maryam,Maleki, Ali
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- Simple reversible fixation of a magnetic catalyst in a continuous flow system: Ultrafast reduction of nitroarenes and subsequent reductive amination using ammonia borane
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Continuous reductive amination of aldehydes with nitroarenes over a Pd-Pt-Fe3O4 catalyst was performed. We used NH3BH3 as not only a hydrogen source for nitro reduction, but also a reductant for imine reduction. Secondary aromatic amines were obtained in the continuous flow reaction in good to excellent yields.
- Byun, Sangmoon,Cho, Ahra,Kang, Dong Yun,Kim, B. Moon,Kim, Ha Joon,Kim, Hong Won,Kim, Seong Min,Lei, Cao,Park, Jin Kyoon
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p. 944 - 949
(2020/03/11)
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- Synthesis, characterization, and catalytic activity of half-sandwich ruthenium complexes with pyridine/phenylene bridged NHC = E (NHC = N-heterocyclic carbene, E = S, Se) ligands
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Three half-sandwichruthenium(II) complexes with pyridine/phenylene bridged NHC = E (NHC = N-heterocyclic carbene, E = S, Se) ligands [Ru(p-cymene)L](PF6)1–2 (1a–1c, L = ligand) were synthesized and characterized. All ruthenium complexes were fully characterized by 1H and 13C NMR spectra, mass spectrometry, and single-crystalX-ray diffraction methods. Moreover, the half-sandwich ruthenium complexes with NHC = E ligands showed highly catalytic activities towards to the tandem dehydrogenation of ammonia borane (AB) and hydrogenation of R–NO2 to R–NH2 at 353 K in water.
- Jia, Wei-Guo,Du, Teng-Teng,Gao, Li-Li,Du, Jun
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- Convenient conversion of hazardous nitrobenzene derivatives to aniline analogues by Ag nanoparticles, stabilized on a naturally magnetic pumice/chitosan substrate
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Herein, silver nanoparticles (Ag NPs), as an effective catalyst for the reduction process of nitrobenzene derivatives to non-hazardous and useful aniline derivatives, are conveniently synthesized on an inherently magnetic substrate. For this purpose, an efficient combination of volcanic pumice (VP), which is an extremely porous igneous rock, and a chitosan (CTS) polymeric network is prepared and suitably used for the stabilization of the Ag NPs. High magnetic properties of the fabricated Ag@VP/CTS composite, which have been confirmed via vibrating-sample magnetometer (VSM) analysis, are the first and foremost advantage of the introduced catalytic system since it gives us the opportunity to easily separate the particles and perform purification processes. Briefly, higher yields were obtained in the reduction reactions of nitrobenzenes (NBs) under very mild conditions in a short reaction time. Also, along with the natural biocompatible ingredients (VP and CTS) in the structure, excellent recyclability has been observed for the fabricated Ag@VP/CTS catalytic system, which convinces us to do scaling-up and suggests the presented system can be used for industrial applications. This journal is
- Taheri-Ledari, Reza,Mirmohammadi, Seyedeh Shadi,Valadi, Kobra,Maleki, Ali,Shalan, Ahmed Esmail
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p. 43670 - 43681
(2020/12/25)
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- Esterification of Tertiary Amides: Remarkable Additive Effects of Potassium Alkoxides for Generating Hetero Manganese–Potassium Dinuclear Active Species
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A catalyst system of mononuclear manganese precursor 3 combined with potassium alkoxide served as a superior catalyst compared with our previously reported manganese homodinuclear catalyst 2 a for esterification of not only tertiary aryl amides, but also tertiary aliphatic amides. On the basis of stoichiometric reactions of 3 and potassium alkoxide salt, kinetic studies, and density functional theory (DFT) calculations, we clarified a plausible reaction mechanism in which in situ generated manganese–potassium heterodinuclear species cooperatively activates the carbonyl moiety of the amide and the OH moiety of the alcohols. We also revealed details of the reaction mechanism of our previous manganese homodinuclear system 2 a, and we found that the activation free energy (ΔG≠) for the manganese–potassium heterodinuclear complex catalyzed esterification of amides is lower than that for the manganese homodinuclear system, which was consistent with the experimental results. We further applied our catalyst system to deprotect the acetyl moiety of primary and secondary amines.
- Akiyama, Shoko,Himo, Fahmi,Hirai, Takahiro,Katayama, Shoichiro,Kato, Daiki,Mai, Binh Khanh,Mashima, Kazushi,Nagae, Haruki
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- Cycloglutaramide-based ligand, synthetic method of ligand, application of ligand in coupling reaction for synthesizing arylamine derivative and catalytic system
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The invention discloses a cycloglutaramide-based ligand having a general formula I shown in the specification, a synthetic method of the ligand, an application of the ligand in a coupling reaction forsynthesizing an arylamine derivative, and a catalytic system. The compounds represented by the formula I can be used as a ligand in the coupling reaction of synthesizing the arylamine derivative by using an aryl halide under catalysis of copper, especially the coupling reaction of aryl halide and an amine source to form a C-N bond under catalysis. Under mild reaction conditions, the high-yield arylamine derivative is obtained, and the ligand has a simple structure, convenient preparation and a less use amount.
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Paragraph 0100-0105
(2020/03/12)
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- Recyclable Pd/C catalyzed one-step reduction of carbonyls to hydrocarbons under simple conditions without extra base
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The reductions of carbonyls for the synthesis of hydrocarbons were developed with hydrazine hydrate, hydrogen gas and ammonium formate respectively. The simple, mild and efficient conditions were provided by employing recyclable Pd/C as catalyst in normal solvents at 100 °C and the reactions proceeded smoothly to produce the corresponding products with good to excellent yields. And gram-scale reactions and recycling of the catalyst were also demonstrated. Furtherly, the mechanism has been proposed.
- Zhou, Xiao-Yu,Chen, Xia
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supporting information
(2019/12/06)
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- Selective Photoinduced Reduction of Nitroarenes to N-Arylhydroxylamines
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We report the selective photoinduced reduction of nitroarenes to N-arylhydroxylamines. The present methodology facilitates this transformation in the absence of catalyst or additives and uses only light and methylhydrazine. This noncatalytic photoinduced transformation proceeds with a broad scope, excellent functional-group tolerance, and high yields. The potential of this protocol reflects on the selective and straightforward conversion of two general antibiotics, azomycin and chloramphenicol, to the bioactive hydroxylamine species.
- Kallitsakis, Michael G.,Ioannou, Dimitris I.,Terzidis, Michael A.,Kostakis, George E.,Lykakis, Ioannis N.
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supporting information
p. 4339 - 4343
(2020/06/08)
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- Synthesis and polymerisation of α-alkylidene cyclic carbonates from carbon dioxide, epoxides and the primary propargylic alcohol 1,4-butynediol
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Using the bulk chemical 1,4-butynediol, readily available epoxides and carbon dioxide, a new series of unsubstituted exovinylene carbonates were synthesised. Chemoselective additions of diamines or diols to these cyclic carbonates allow the regiocontrolled synthesis of new functionalised polyurethanes and polycarbonates under mild conditions. This route to polyurethanes avoids the use of toxic isocyanates.
- Dabral, Saumya,Licht, Ulrike,Rudolf, Peter,Bollmann, Gérard,Hashmi, A. Stephen K.,Schaub, Thomas
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supporting information
p. 1553 - 1558
(2020/03/23)
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- Highly efficient one-pot multi-directional selective hydrogenation and N-alkylation catalyzed by Ru/LDH under mild conditions
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Atomic economy, non-toxicity, harmlessness and multidirectional selectivity advocated by green chemistry have increasingly become a hot and difficult research topic. Herein, we present a highly efficient, one-pot tandem and easy-to-operate method through which we could directly produce a broad range of multi-directional selective hydrogenated amines or N-alkyl aliphatic amines using aromatic nitro compounds as raw materials. Ru/LDH with characteristics of layered mesoporous structure, well dispersed small Ru nanoparticles and LDH stabilization to the Ru NPs was employed as the catalyst. It is remarkable that multi-directional superb chemoselectivity to aromatic amines, alicyclic amines as well as N-alkyl aliphatic amines could be achieved with excellent catalytic activity and recyclability by tuning reaction conditions over 5wt%Ru/LDH-2. Additionally, this catalytic system also exhibited attractive activity and multi-directional chemoselectivity in the hydrogenation of quinoline and its derivatives with solvents of different polarity. Chemoselectivity to 5,6,7,8-tetrahydroquinoline derivatives could reach as high as 95.6 %.
- Zhang, Sishi,Xu, Jie,Cheng, Hongmei,Zang, Cuicui,Sun, Bin,Jiang, Heyan,Bian, Fengxia
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supporting information
(2020/03/30)
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- Superhydrophobic nickel/carbon core-shell nanocomposites for the hydrogen transfer reactions of nitrobenzene and N-heterocycles
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In this work, catalytic hydrogen transfer as an effective, green, convenient and economical strategy is for the first time used to synthesize anilines and N-heterocyclic aromatic compounds from nitrobenzene and N-heterocycles in one step. Nevertheless, how to effectively reduce the possible effects of water on the catalyst by removal of the by-product water, and to further introduce water as the solvent based on green chemistry are still challenges. Since the structures and properties of carbon nanocomposites are easily modified by controllable construction, a one step pyrolysis process is used for controllable construction of micro/nano hierarchical carbon nanocomposites with core-shell structures and magnetic separation performance. Using various characterization methods and model reactions the relationship between the structure of Ni?NCFs (nickel-nitrogen-doped carbon frameworks) and catalytic performance was investigated, and the results show that there is a positive correlation between the catalytic performance and hydrophobicity of catalysts. Besides, the possible catalytically active sites, which are formed by the interaction of pyridinic N and graphitic N in the structure of nitrogen-doped graphene with the surfaces of Ni nanoparticles, should be pivotal to achieving the relatively high catalytic performance of materials. Due to its unique structure, the obtained Ni?NCF-700 catalyst with superhydrophobicity shows extraordinary performances toward the hydrogen transfer reaction of nitrobenzene and N-heterocycles in the aqueous state; meanwhile, it was also found that Ni?NCF-700 still retained its excellent catalytic activity and structural integrity after three cycles. Compared with traditional catalytic systems, our catalytic systems offer a highly effective, green and economical alternative for nitrobenzene and N-heterocycle transformation, and may open up a new avenue for simple construction of structure and activity defined carbon nanocomposite heterogeneous catalysts with superhydrophobicity.
- Duan, Zhiying,Liu, Fangfang,Pang, Shaofeng,Su, Qiong,Wang, Yanbin,Xie, Xin,Zhang, Ping,Zhang, Yujing,Zhou, Feng
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p. 1996 - 2010
(2020/04/07)
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- Copper-Mediated Diamination of Arylboronic Acids for the Synthesis of 2-Aryl Benzimidazoles Using Trimethylsilyl Azide as the Amino Sources with Aldehydes
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A direct and versatile copper-mediated three-component reaction of arylboronic acids, trimethylsilyl azide and aldehydes for the synthesis of benzimidazoles is reported. The reaction is well tolerated by a wide range of substituted aromatic aldehydes and aromatic boronic acids to produce the corresponding benzimidazoles in moderate to high yields. Mechanism investigations demonstrated that copper-promoted Chan-Evans-Lam coupling, C?H amination, and oxidative cycloaddition are involved in the tandem processes. (Figure presented.).
- Xie, Zeqiang,Zhou, Fengtao,Ding, Ke
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p. 3442 - 3446
(2020/07/30)
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- Acceptorless dehydrogenative oxidation of primary alcohols to carboxylic acids and reduction of nitroarenes via hydrogen borrowing catalyzed by a novel nanomagnetic silver catalyst
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A novel silver nano magnetic catalyst was devised for dehydrogenative oxidation of aromatic and aliphatic alcohols to the corresponding acid with water as the sole oxygen source and hydrogen gas as the only by-product. The designed catalytic system advantages from easy recovery of magnetic materials i.e. magnetic decantation, being economically viable and environmentally friendly. Furthermore, the catalytic reaction is able to reduce aryl nitro compounds in the absence of any reducing agent.
- Yazdani, Elahe,Heydari, Akbar
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supporting information
(2020/08/14)
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- Preparation method of alkyl aromatic compound based on alkenyl ether Friedel-Crafts reaction
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The invention discloses a preparation method of an alkyl aromatic compound based on an alkenyl ether Friedel-Crafts reaction, and belongs to the technical field of pharmaceutical and chemical intermediates and related chemistry. According to the method, alkenyl ether and an aromatic compound are used as raw materials, and green and efficient synthesis of the alkyl-substituted aromatic compound isrealized under the catalytic action of Lewis acid or protonic acid. The method has the advantages of high selectivity, mild reaction conditions, good functional group compatibility, the wide substraterange, environmental friendliness and the like. The alkyl-substituted aromatic compound is an important organic synthesis intermediate and has very wide application in the fields of organic synthesisand pharmacy, so that the alkyl-substituted aromatic compound has relatively high application value and social and economic benefits.
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Paragraph 0045-0047; 0055-0056; 0058
(2020/07/24)
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