- Experimental and theoretical investigation of benzyl-N-pyrrolylketene, one- step procedure for preparing of new β-lactams by [2 +2] cycloaddition reaction
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3-Phenyl-2-(1-H-pyrrol-1-yl) propanoic acid has been used as a ketene source in synthesizing of monocyclic-2-azetidinones. Hindrance in ketene and imines successfully controlled the diastereoselectivity of the reaction. For example, in some cases only one isomer was achieved. By using Mukaiyama reagent, the leaving group in acid was activated and the by-products were separated by simple aqueous work-up. DFT calculation indicated that the benzyl-N-pyrrolylketene has nonconjugated structure and the pyrrolyl ring is perpendicular to the ketene plane in both the twisted and planar structures.
- Behzadi, Masoumeh,Saidi, Kazem,Islami, Mohammad Reza,Khabazzadeh, Hojatollah
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Read Online
- Stereoselective synthesis of new β-lactams from the main functional group of indomethacin
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New β-lactams were synthesized in moderate yields from indomethacin, which is currently used as a drug to relieve pain such as arthritis, muscle and bone damage. The reaction was carried out by [2 + 2] cycloaddition of the in situ formed indomethacinyl ke
- Amiri, Mojgan,Islami, Mohammad Reza,Mortazavi, Zahra Fahimeh al-Sadat
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- Cobalt-Catalyzed Deoxygenative Hydroboration of Nitro Compounds and Applications to One-Pot Synthesis of Aldimines and Amides
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The commercially available and bench-stable Co(acac)2 ligated with bis[(2-diphenylphosphino)phenyl] ether (dpephos) was employed for selective room temperature hydroboration of nitro compounds with HBPin (TOF up to 4615 h?1), tolerating halide, hydroxy, amino, ether, ester, lactone, amide and heteroaromatic functionalities. These reactions offered a direct access to a variety of N-borylamines RN(H)BPin, which were in situ treated with aldehydes and carboxylic acids to produce a series of aldimines and secondary carboxamides without the need for dehydrating and/or coupling reagents. Combination of these transformations in a sequential one-pot manner allowed for direct and selective synthesis of aldimines and secondary carboxamides from readily available and inexpensive nitro compounds.
- Gudun, Kristina A.,Zakarina, Raikhan,Segizbayev, Medet,Hayrapetyan, Davit,Slamova, Ainur,Khalimon, Andrey Y.
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p. 601 - 611
(2021/11/30)
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- Nanomagnetic catalysis (Fe3O4@S–TiO2): a novel magnetically nano catalyst for the synthesis of new highly substituted tetrahydropyridine derivatives under solvent-free conditions
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A novel nanomagnetic catalyst (Fe3O4@S–TiO2) was prepared by the hydrothermal method. At the first, Fe3O4 nanoparticles were synthesized, then iron oxide nanoparticles (IONPs) were dispersed in ethano
- Nezami, Zahra,Eshghi, Hossein
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p. 1997 - 2008
(2021/01/20)
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- Visible-Light-Induced Cycloaddition of α-Ketoacylsilanes with Imines: Facile Access to β-Lactams
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We report the synthesis of β-lactams from α-ketoacylsilanes and imines, which proceeds via a formal [2+2] photochemical cycloaddition with in situ generation of siloxyketene. This mild and operationally simple reaction proceeds in an atom-economic fashion with broad substrate scope, including aldimines, ketimines, hydrazones, and fused nitrogen heterocycles, affording a variety of important β-lactams with satisfactory diastereoselectivities in most cases. This reaction also features good functional-group tolerance, facile scalability and product diversification. Experimental and computational studies suggest that α-ketoacylsilanes can serve as photochemical precursors by engaging in a 1,3 silicon shift to the distal carbonyl group.
- Ye, Jian-Heng,Bellotti, Peter,Paulisch, Tiffany O.,Daniliuc, Constantin G.,Glorius, Frank
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supporting information
p. 13671 - 13676
(2021/05/11)
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- Sulfated polyborate: A dual catalyst for the reductive amination of aldehydes and ketones by NaBH4
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An efficient, quick, and environment-friendly one-pot reductive amination of aldehydes or ketones was developed. In ethanol at 70 °C, a imination catalyzed by sulfated polyborate and further reduced by sodium borohydride yields various amines. The present method has many significant benefits, including a shorter reaction time, excellent yields, and a hassle-free, straightforward experimental process. The reaction has a wide range of applications due to its flexibility, including secondary amine for reductive amination.
- Ganwir, Prerna,Chaturbhuj, Ganesh
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supporting information
(2021/05/19)
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- Aza-peterson olefinations: Rapid synthesis of (E)-alkenes
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An aza-Peterson olefination methodology to access 1,3-dienes and stilbene derivatives from the corresponding allyl- or benzyltrimethylsilane is described. Silanes can be deprotonated using Schlosser's base and added to N -phenyl imines or ketones to directly give the desired products in high yields.
- Britten, Thomas K.,Basson, Ashley J.,Roberts, Dean D.,McLaughlin, Mark G.
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p. 3535 - 3544
(2021/06/03)
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- Rhodium catalyzed multicomponent dehydrogenative annulation: one-step construction of isoindole derivatives
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A strategy for one-pot synthesis of isoindoles is describedviaa catalytic multicomponent dehydrogenative annulation of diarylimines, vinyl ketones and simple amines. In the presence of a rhodium catalyst and Cu oxidant, four C-H and two N-H bonds are activated along with the formation of one new C-C and two new C-N bonds, leading to a series of isoindole derivatives in good to very high isolated yields.
- Cheng, Biao,Lyu, Hairong,Quan, Yangjian,Xie, Zuowei
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supporting information
p. 7930 - 7933
(2021/08/17)
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- Arene diruthenium(II)-mediated synthesis of imines from alcohols and amines under aerobic condition
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The utility and selectivity of the newly synthesized dinuclear arene Ru(II) complex were demonstrated towards the synthesis of imines from coupling of alcohols and amines in the aerobic condition. Analytical and various spectral methods have been used to establish the unprecedented formation of the new thiolato-bridged dinuclear ruthenium complex. The molecular structure of the titled complex was evidenced with aid of X-ray crystallographic technique. A wide range of imines were obtained in good-to-excellent yields up to 98% and water as the by-product through an acceptorless dehydrogenative coupling of alcohols with amines. The catalytic reaction operated a concise atom economical without any oxidant with 1 mol% of the catalyst load. Further, the role of base, solvent and catalyst loading of the coupling reaction has been investigated. A plausible mechanism has been described and was found to proceed via the formation of an aldehyde intermediate. Short synthesis of antibacterial drug N-(salicylidene)-2-hydroxyaniline illustrated the utility of the present protocol.
- Tamilthendral, Veerappan,Ramesh, Rengan,Malecki, Jan Grzegorz
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- Ionic-Liquid-Catalyzed Synthesis of Imines, Benzimidazoles, Benzothiazoles, Quinoxalines and Quinolines through C?N, C?S, and C?C Bond Formation
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We report the tetramethyl ammonium hydroxide catalyzed oxidative coupling of amines and alcohols for the synthesis of imines under metal-free conditions by utilizing oxygen from air as the terminal oxidant. Under the same conditions, with ortho-phenylene diamines and 2-aminobenzenethiols the corresponding benzimidazoles and benzothiazoles were obtained. Quinoxalines were obtained from ortho-phenylene diamines and 1-phenylethane-1,2-diol, the conditions were then extended to the synthesis of quinoline building blocks by reaction of 2-amino benzyl alcohols either with 1-phenylethan-1-ol or acetophenone derivatives. The formation of C?N, C?S and C?C bonds was achieved under metal-free conditions. A broad range of amines (aromatic, aliphatic, cyclic and heteroaromatic) as well as benzylic alcohols including heteroaryl alcohols reacted smoothly and provided the desired products. The mild reaction conditions, commercially available catalyst, metal-free, good functional-group tolerance, broad range of products (imines, benzimidazoles, benzothiazoles, quinoxalines and quinolines) and applicability at gram scale reactions are the advantages of the present strategy.
- Adimurthy, Subbarayappa,Badhani, Gaurav,Joshi, Abhisek
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p. 6705 - 6716
(2021/12/31)
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- Switchable Imine and Amine Synthesis Catalyzed by a Well-Defined Cobalt Complex
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Switchable imine and amine synthesis catalyzed by a tripodal ligand-supported well-defined cobalt complex is presented herein. A large variety of primary alcohols and amines were selectively converted to imines or amines in good to excellent yields. It is discovered that the base plays a crucial role on the selectivity. A catalytic amount of base leads to the imine formation, while an excess loading of base results in the amine product. This strategy on product selectivity also strongly depends on the organometallic catalysts in use. We expect that the present study could provide useful insights toward selective organic synthesis and catalyst design.
- Paudel, Keshav,Xu, Shi,Hietsoi, Oleksandr,Pandey, Bedraj,Onuh, Chuka,Ding, Keying
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supporting information
p. 418 - 426
(2021/02/01)
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- Amino-functionalized zirconium and cerium MOFs: Catalysts for visible light induced aerobic oxidation of benzylic alcohols and microwaves assisted N-Alkylation of amines
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Herein we report that mixed zirconium-cerium-MOFs with amino-functionalized linkers (2-amino-1,4-benzenedicarboxylate, BDC-NH2, and 4-aminonaphthalene-2,6-dicarboxylate, NDC-NH2) act as effective non-noble-metal-based heterogeneous c
- Iglesias, Marta,Pintado-Sierra, Mercedes,Rasero-Almansa, Antonia,Sánchez, Félix,Valverde-González, Antonio
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- Direct synthesis of imines from nitro compounds and biomass-derived carbonyl compounds over nitrogen-doped carbon material supported Ni nanoparticles
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The selective synthesis of imines from biomass-derived chemicals over heterogeneous non-noble metal catalysts is of great importance for organic transformation. Herein, non-noble heterogeneous nitrogen-doped carbon supported Ni catalysts (abbreviated as Ni/CN-MgO-T, whereTrepresents the pyrolysis temperature) have been facilely prepared from the simple pyrolysis of Ni precursors and biomass, and Ni/CN-MgO-600 with the smallest size of Ni nanoparticles demonstrated the highest catalytic activity. The reductive coupling of nitroarenes and carbonyl compounds could be performed under mild conditions (80 °C, and 10 bar H2), affording structurally-diverse imines with high to excellent yields (84.2-98.1%). Thanks to the mild reaction conditions, the developed method showed good tolerance to other functional groups such as nitriles, halogen and vinyl groups.
- Li, Bo,Wang, Yanxin,Chi, Quan,Yuan, Ziliang,Liu, Bing,Zhang, Zehui
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p. 4464 - 4471
(2021/03/15)
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- Highly chemoselective synthesis of imine over Co/Zn bimetallic MOFs derived Co3ZnC-ZnO embed in carbon nanosheet catalyst
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One-pot direct synthesis of imines via reductive amination of nitroarenes with aromatic aldehydes remains a great challenge due in part to its over-hydrogenation of imines to secondary amines. Herein, a novel Co3ZnC and ZnO supported on N-doped carbon nanosheet catalyst with the thickness of ca. 5.0 nm was fabricated through the direct pyrolysis of a Co/Zn bimetallic MOFs at 500 °C (named as Co3ZnC-ZnO/NC-500). Surprisingly, the developed Co3ZnC-ZnO/NC-500 catalyst delivers 99.9 % conversion of nitrobenzene and 98.5 % selectivity to N-benzylideneaniline in one-pot reductive amination of nitrobenzene with benzaldehyde. Various characterizations (including as SEM, XRD, TEM, AFM, XPS, Raman and N2 adsorption–desorption) have revealed that the generated small size of Co3ZnC alloy, abundant structural defects, larger specific surface area (105.5 m2·g?1) as well as more basic sites are responsible for the outstanding catalytic activity of Co3ZnC-ZnO/NC-500 catalyst for tandem reaction. Moreover, the Co3ZnC-ZnO/NC-500 catalyst exhibits high stability during the recycling experiments without the loss of its catalytic activity. Notably, the results of contrast experiments have demonstrated that the intentional introduction of ZnO in Co3ZnC-ZnO/NC-500 catalyst plays a key role in the selectivity to N-benzylideneaniline in the tandem reaction. This study provides a new guideline for designing tandem catalysts with high selectivity.
- Li, Guangming,Li, Jingfang,Li, Weizuo,Li, Xuewei,Mao, Guijie,She, Wei,Wang, Jing
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- Tunable Synthesis of α-Amino Boronic Esters from Available Aldehydes and Amines through Sequential One-Pot Dehydration and Copper-Catalyzed Borylacylation
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Copper-catalyzed multicomponent borylacylation of imines with acid chlorides and bis(pinacolato)diboron was developed for the preparation of synthetically useful and pharmacologically relevant α-amino boronic acid derivatives. Starting from a range of acid chlorides and imines with aryl, heteroaryl, and alkyl substituents, most of these ligand-free reactions proceeded smoothly at room temperature in moderate to good yields. Furthermore, a facile and convenient one-pot, multistep access to the direct synthesis of α-amino boronic acid derivatives from available aldehydes and amines was also developed.
- Xia, Qi,Chang, Hua-Rong,Li, Juan,Wang, Jia-Yi,Peng, Yan-Qing,Song, Gong-Hua
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p. 2716 - 2724
(2020/01/31)
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- Diethylsilane as a Powerful Reagent in Au Nanoparticle-Catalyzed Reductive Transformations
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Diethylsilane (Et2SiH2), a simple and readily available dihydrosilane, that exhibits superior reactivity, as compared to monohydrosilanes, in a series of reductive transformations catalyzed by recyclable and reusable Au nanoparticles (1 mol-%) supported on TiO2. It reduces aldehydes or ketones almost instantaneously at ambient conditions. It can be used in a one pot rapid reductive amination procedure, in which premixing of aldehyde and amine is required prior to the addition of the reducing agent and the catalyst, even in a protic solvent. An unprecedented method for the synthesis of N-arylisoindolines is also shown in the reductive amination between o-phthalaldehyde and anilines. In this transformation, it is proposed that the intermediate N,2-diphenylisoindolin-1-imines are reduced stepwise to the isoindolines. Finally, Et2SiH2 readily reduces amides into amines in excellent yields and shorter reaction times relative to previously known analogous nano Au(0)-catalyzed protocols.
- Louka, Anastasia,Kidonakis, Marios,Saridakis, Iakovos,Zantioti-Chatzouda, Elisavet-Maria,Stratakis, Manolis
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p. 3508 - 3514
(2020/06/02)
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- Cu/Ni-doped sulfated zirconium oxide immobilized on CdFe2O4 NPs: a cheap, sustainable and magnetically recyclable inorgano-catalyst for the efficient preparation of α-aminonitriles in aqueous media
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Abstract: A new multifunctional bimetallic nanocatalyst was prepared by immobilization of Cu/Ni-doped sulfated zirconium oxide on magnetic cadmium ferrite (CdFe2O4@SiO2@ZrO2/SO42?/Cu/Ni) and used as an efficient recyclable catalyst for one-pot as well as stepwise preparation of α-aminonitriles under mild conditions. The magnetic nanocatalyst was characterized by FTIR, TGA, VSM, XRD, EDX, FE-SEM, and TEM analyses. Also, the surface acidity of the catalyst was measured by pyridine adsorption assay. The catalyst possesses various active sites which could catalyst a variety of aromatic and aliphatic aldehydes to the corresponding α-amionitriles under moderate to high yields in the presence of aniline. Furthermore, transformation of ketones to the desired α-amionitriles and some bis-aminonitriles was also performed by this method. The catalyst could be readily recovered from the reaction mixture and reused for several times without significant loss of activity. Graphic abstract: A general and efficient method has been developed for transformation of a variety of aliphatic, aromatic aldehydes and ketones to the corresponding α-aminonitriles using a multifunctional recyclable CdFe2O4@SiO2@ZrO2/SO42?/Cu/Ni nanocatalyst.[Figure not available: see fulltext.]
- Nasseri, Mohammad Ali,Ramezani-Moghadam, Simin,Kazemnejadi, Milad,Allahresani, Ali
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p. 4233 - 4256
(2020/07/08)
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- Catalyst- And solvent-free efficient access to: N -alkylated amines via reductive amination using HBpin
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A sustainable approach which works under catalyst- and solvent-free conditions for the synthesis of structurally diverse secondary amines has been uncovered. This one-pot protocol works efficiently at room temperature and is compatible with a wide range of sterically and electronically diverse aldehydes and primary amines. Notably, this simple process offers scalability, excellent functional group tolerance, chemoselectivity, and is also effective at the synthesis of biologically relevant molecules. This journal is
- Bauri, Somnath,Pandey, Vipin K.,Rit, Arnab
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supporting information
p. 3853 - 3857
(2020/07/27)
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- Simple synthesis of the novel Cu-MOF catalysts for the selective alcohol oxidation and the oxidative cross-coupling of amines and alcohols
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A novel porous metal–organic framework {Cu2(bbda)0.5(Hbbda)1.5(OAc)1.5.8H2O} (UoB-5) was synthesized under ultrasound irradiation by employing a new Schiff base ligand H2bbda (4,4'(1,4-phenylene bis (azanylylidene)) bis (methanylylidene))dibenzoic acid) and was fully characterized. The microporous nature of UoB-5 was confirmed by gas-sorption measurements. This framework acted as a highly effective heterogeneous catalyst for the alcohol oxidation reaction with tert-butyl hydroperoxide (t-BuOOH) as an oxidant. The presence of coordinatively unsaturated metal sites in UoB-5 could be the reason for high performance in this reaction. Furthermore, using the long linker with the free -NC group and uncoordinated -N atom on the wall of the pores created UoB-5 an excellent candidate for the catalytic activities without activation of the framework. It was confirmed with the heterogeneous catalytic experiments on the one-pot tandem synthesis of imines from benzyl alcohols and anilines. Eventually, the new Cu-MOF (UoB-5) could be an alternative catalyst as a more economically favorable and environmentally friendly in the catalysis field.
- Ghamari Kargar, Pouya,Aryanejad, Sima,Bagherzade, Ghodsieh
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- Polyoxometalate catalyzed imine synthesis: Investigation of mechanistic pathways
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The syntheses of imines by oxidative coupling of primary alcohols and amines were achieved by using 2 molpercent polyoxometalate (POM) Na12[WZn3(H2O)2(ZnW9O34)2] (Zn–WZn3) catalyst in the presence of t-BuOK and di-oxygen with excellent conversion (up to 100percent) and selectivity (up to 100percent). Non-noble metal-based POM catalyst in the presence of base represents a new reaction protocol for the selective synthesis of imine from both aromatic and aliphatic primary amines with functional group tolerance. Control experiment shows the formation of di-oxygen bind Zn–WZn3 activated species. The electron-density of POM is mostly situated on the surface oxygen atoms of W–O–W bonds which can engage the alcoholic OH group and helps for the imine selectivity in the second step of imine synthesis.
- Adhikary, Subhasis D.,Mandal, Debaprasad
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supporting information
(2020/05/25)
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- Insight into Ce Doping Induced Oxygen Vacancies over Ce-Doped Mno2 Catalysts for Imine Synthesis
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The pursuit of modern sustainable chemistry has stimulated the development of innovative catalytic processes that enable chemical transformations to be performed under mild and clean conditions with high efficiency. Here, an amorphous sheet-like MnO2 (Ce-doped MnO2: CMBO) was obtained after Ce doping, which exhibits excellent catalytic performance for the oxidation coupling of alcohol and aniline. Conversion of 99% and a selectivity of 99% could be achieved within 6 h at 60 oC under air atmosphere, and the formation rate of target product was up to 30.2 μmol·h–1·m–2. Based on a series of characterizations, it was found that the doping of Ce into the MnO2 could increase the concentration of the oxygen vacancies, thus forming abundant active surface oxygen species and favoring the mobility of lattice oxygen, which are the main reasons for the greatly enhanced catalytic performance of CMBO. This work indicates that increasing oxygen vacancy by element doping may serve as a facile and efficient way to enhance catalytic performance of transition metal oxide.
- Shen, Haidong,Bu, Jun,Wang, Wenbin,Wu, Chen,Cao, Yueling,Zhang, Baoliang,Zhang, Qiuyu,Zhang, Hepeng
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supporting information
p. 1353 - 1359
(2020/08/25)
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- Tuning effect of amorphous Fe2O3on Mn3O4for efficient atom-economic synthesis of imines at low temperature: Improving [O] transfer cycle of Mn3+/Mn2+in Mn3O4
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A facile and scaled-up synthesis route to efficient and environment-friendly metal oxide catalysts with desirable properties is of great practical importance, owing to their excellent performance as heterogeneous catalysts in organic synthesis. Herein, a novel amorphous Fe2O3 modified Mn3O4 catalyst (Fe5Mn5-100) has been prepared by adopting a simple co-precipitation method following low temperature baking. Fe5Mn5-100 showed exceptionally high catalytic activity for the atom-economic production of imine from benzyl alcohol with aniline, giving a 98% imine yield at 60 °C in only 3 h, which is higher than all of the reported non-noble and noble metal catalysts. Importantly, Fe5Mn5-100 could still exhibit extraordinary catalytic performance on a large-scale reaction without any solvent, including the frequently used toxic mesitylene, xylene or toluene. Interestingly, the amorphous Fe2O3-100 provided no catalytic activity, and pure Mn3O4-100 showed very inferior catalytic activity towards this reaction. Further detailed characterizations and experimental results revealed that amorphous Fe2O3 plays an important role in expediting the [O] transfer cycle of Mn3+/Mn2+ in Mn3O4, and enhances the oxidation ability and acidity of Fe5Mn5-100. This discovery would provide a new avenue for the atom-economic and environment-friendly industrial synthesis of imine. This journal is
- Cao, Xiao,Gou, Galian,Long, Yu,Luo, Shicheng,Luo, Yutong,Ma, Jiantai,Qin, Jiaheng,Wang, Kaizhi,Wu, Wei
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p. 5628 - 5640
(2020/09/17)
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- A Cu-BTC metal-organic framework (MOF) as an efficient heterogeneous catalyst for the aerobic oxidative synthesis of imines from primary amines under solvent free conditions
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A Cu-BTC (MOF-199) [copper(ii)-benzene-1,3,5-tricarboxylate] catalyst has been synthesized and evaluated for imine synthesis from amine compounds under neat conditions. The performance of the Cu-BTC MOF was significantly higher than that of the CuO supported on Al2O3, TiO2 and SiO2 catalysts. The role of surface Lewis acid sites on the catalyst in the formation of imine products was illustrated by the pyridine-IR studies. The recovered Cu-BTC catalyst demonstrated consistent activity for five cycles under similar experimental conditions. The physicochemical properties of the catalysts were analyzed by XRD, BET-SA, FT-IR, UV-DRS, SEM, TEM, XPS and pyridine adsorbed DRIFT spectroscopy.
- Venu, Boosa,Shirisha, Varimalla,Vishali, Bilakanti,Naresh, Gutta,Kishore, Ramineni,Sreedhar, Inkollu,Venugopal, Akula
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supporting information
p. 5972 - 5979
(2020/04/27)
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- Uniform Cu/chitosan beads as a green and reusable catalyst for facile synthesis of iminesviaoxidative coupling reaction
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A nonprecious metal and biopolymer-based catalyst, Cu/chitosan beads, has been successfully prepared by using a software-controlled flow system. Uniform, spherical Cu/chitosan beads can be obtained with diameters in millimeter-scale and narrow size distribution (0.78 ± 0.04 mm). The size and morphology of the Cu/chitosan beads are reproducible due to high precision of the flow rate. In addition, the application of the Cu/chitosan beads as a green and reusable catalyst has been demonstrated using a convenient and efficient protocol for the direct synthesis of iminesviathe oxidative self- and cross-coupling of amines (24 examples) with moderate to excellent yields. Importantly, the beads are stable and could be reused more than ten times without loss of the catalytic performance. Furthermore, because of the bead morphology, the Cu/chitosan catalyst has greatly simplified recycling and workup procedures.
- Bunchuay, Thanthapatra,Chantiwas, Rattikan,Chutimasakul, Threeraphat,Intanin, Apichai,Na Nakhonpanom, Pakamon,Tantirungrotechai, Jonggol,Tirdtrakool, Warinda
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p. 21009 - 21018
(2020/06/22)
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- Thioglycerol-Stabilized Rhodium Nanoparticles in Biphasic Medium as Catalysts in Multistep Reactions
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Small rhodium nanoparticles (ca. 3.5 nm) were prepared by the decomposition of an organometallic precursor under hydrogen pressure in glycerol using 1-thioglycerol as stabilizer. Full characterization in the solid state [HR-TEM, EDX, XPS] showed a fcc structure for the Rh0/RhI nanoparticles capped with thiolate ligand. Reduction of different functionalities, including nitro groups and imines, was applied to tandem reductive amination of aldehydes with primary and secondary amines, and to the synthesis of N-substituted anilines from nitrobenzene. In addition, thiolate-capped RhNPs could be recovered and reused up to 5 runs without loss of activity nor selectivity.
- Guerrero-Ríos, Itzel,Portales-Martínez, Benjamín,Reina, Antonio,Serrano-Maldonado, Alejandro
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supporting information
(2020/07/04)
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- Visible light photocatalytic aerobic oxidative synthesis of imines from alcohols and amines on dye-sensitized TiO2
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A general visible light photocatalytic protocol for the synthesis of imines via a two-step one-pot route on alizarin red S (ARS)-sensitized TiO2 was uncovered. This efficient synthesis protocol involves one step of the highly selective formation of aldehydes from the oxidation of alcohols with O2 on ARS-sensitized TiO2 photocatalyst, and a subsequent step of condensation of newly formed aldehydes with various amines on TiO2 to afford imines in one pot. Anatase TiO2 provides a versatile platform for catalytic amounts of ARS (0.67 mol%) to facilitate the electron transfer from dye traversing its conduction band to O2 under green LED irradiation. Moreover, the Lewis acid sites of TiO2 can promote the formation of imines from aldehydes and amines in very high isolated yields. We took advantage of both the photocatalytic and catalytic properties of TiO2 to significantly expand the scope of imines. Our work suggests that the synthetic applications of TiO2 photocatalysis can be achievable under mild conditions by exploring the excellent functionalities of TiO2.
- Xu, Hui,Shi, Ji-Long,Hao, Huimin,Li, Xia,Lang, Xianjun
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p. 128 - 135
(2019/01/04)
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- Method for preparing imine by utilizing copper catalyst to catalyze cross coupling of amine and alcohol
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The invention discloses a method for preparing imine by utilizing a copper catalyst to catalyze cross coupling of amine and alcohol. The method comprises the following steps: under the condition of nooxidant, adopting Cu/Al2O3 as a catalyst to catalyze the cross coupling of the amine and the alcohol so as to prepare the imine. The method disclosed by the invention has beneficial effects that thereaction system is simple, cocatalysts such as organic ligand, alkaline, and free radical of nitroxide do not need to be added, and simultaneously under the condition of no oxidant, the method utilizes Cu/Al2O3 to catalyze cross coupling of the amine and the alcohol so as to prepare the imine; the problem that the imine is easily peroxidated can be effectively solved; in addition, the catalyst Cu/Al2O3 used by the method is simple in preparation, is highly-effective and stable and is low in price.
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Paragraph 0036; 0037; 0039
(2019/02/04)
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- Amorphous Fe2O3 improved [O] transfer cycle of Ce4+/Ce3+ in CeO2 for atom economy synthesis of imines at low temperature
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CeO2 based catalysts have been investigated in various catalytic reactions due to its unique reversible Ce3+/Ce4+ redox pair and physicochemical property, but its poor cycle efficiency and low reservoir limit its wide application in the fine chemicals industry. In this work, a novel amorphous Fe2O3 modified CeO2 catalytic system was developed by a facile co-precipitation method. The as-prepared samples were characterized in detail, and were employed for catalyzing the one-pot synthesis of imine from benzyl alcohol and aniline under air atmosphere at low temperature. The as-prepared sample with molar ratio of Fe:Ce = 8:2 dried at 100 °C (named Fe8Ce2-100) exhibited superhigh activity for atom economy synthesis of imine, which was much higher than the reported CeO2 catalyst, even higher than some noble metal catalysts. It is worth noting that pure amorphous Fe2O3-100 could not catalyze this reaction at all, and both pure CeO2-100 and the mechanical mixed sample with the same molar ratio of Fe:Ce exhibited much more inferior catalytic activity than Fe8Ce2-100. Combining characterization results and the catalytic activities of different catalysts at various reaction conditions, the enhanced catalytic activity of Fe8Ce2-100 could be ascribed to the novel synergistic effect between CeO2 and amorphous Fe2O3. Amorphous Fe2O3 plays the role of engine to greatly improve the [O] transfer cycle of Ce4+/Ce3+, as well as enhances the redox and amphoteric properties of the catalysts. This work firstly determines amorphous Fe2O3 can participate and facilitate the catalytic cycle for organic reaction, and may provide a significant strategy for designing polymetallic oxide catalyst towards organic aerobic transformation.
- Qin, Jiaheng,Long, Yu,Wu, Wei,Zhang, Wei,Gao, Zekun,Ma, Jiantai
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p. 161 - 174
(2019/02/15)
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- The preparation and photocatalytic activity of Ag-Pd/g-C3N4 for the coupling reaction between benzyl alcohol and aniline
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In this study, the carrier g-C3N4 was prepared by melamine, and the Ag-Pd/g-C3N4 catalyst was synthesized by the NaBH4 reduction method. Different characterization techniques, including SEM, TEM, XRD, UV–vis DRS, XPS, photoluminescence spectra (PL) and BET, were employed to investigate the morphology and optical properties of the as-prepared samples. The Ag-Pd/g-C3N4 catalyst was used for the synthesis of imine from a benzyl alcohol and aniline. The results show that when the total loading of Ag and Pd is 2 wt%, and the mass ratio of Ag and Pd is 1:1, the activity of the catalyst is the highest (The highest conversion of aniline is 86.7% and the product selectivity is >99%.). The reaction is optimized by changing the type of solvent, the type and amount of base, the type of catalyst, and the amount of reactants. The optimal reaction conditions are 6 ml of n-hexane, 1.4 mmol of Cs2CO3, 50 mg of the Ag-Pd/g-C3N4 (2 wt%, 1:1), and 2:1 mol ratio of benzyl alcohol and aniline. Under optimal reaction conditions, alcohol derivatives and amine derivatives were investigated to determine the suitable range of the catalyst for alcohols and amines. Then, the effects of different light intensities and wavelengths on the reaction were explored. Additionally, the catalyst's recycling ability was tested, and it was found to be relatively stable. The effect of reactive groups on the mechanism shows that the reaction is mainly achieved by the synergy between h+, e? and ·O2?.
- Ma, Jingjing,Yu, Xiujuan,Liu, Xiaoling,Li, Haiying,Hao,Li, Jingyi
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- H2-Generation from Alcohols by the MOF-Based Noble Metal-Free Photocatalyst Ni/CdS/TiO2@MIL-101
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The synthesis of important classes of chemical compounds from alcohols helps to conserve Earth's fossil carbon resources, since alcohols can be obtained from indigestible and abundantly available biomass. The utilisation of visible light for the activation of alcohols permits alcohol-based C-N and C-C bond formation under mild conditions inaccessible with thermally operating hydrogen liberation catalysts. Herein, we report on a noble metal-free photocatalyst able to split alcohols into hydrogen and carbonyl compounds under inert gas atmosphere without the requirement of electron donors, additives, or aqueous reaction media. The reusable photocatalyst mediates C-N multiple bond formation using the oxidation of alcohols and subsequent coupling with amines. The photocatalyst consists of a CdS/TiO2 heterojunction decorated with co-catalytic Ni nanoparticles and is prepared on size-optimised colloidal metal-organic framework (MOF) crystallites.
- Tilgner, Dominic,Klarner, Mara,Hammon, Sebastian,Friedrich, Martin,Verch, Andreas,De Jonge, Niels,Kümmel, Stephan,Kempe, Rhett
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p. 842 - 847
(2019/08/26)
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- Crystal phase effect of iron oxides on the aerobic oxidative coupling of alcohols and amines under mild conditions: A combined experimental and theoretical study
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Selective catalytic oxidation using air as the terminal oxidant is an ecofriendly route for the synthesis of fine and commodity chemicals. However, the catalyst generally faces the challenges of the inertness of molecular oxygen, limited substrate scope, poor selectivity, and high cost. Moreover, the toxicity of the catalyst should also be considered when the products are used in pharmaceutical or biotechnological areas. Here, upon investigating the dependence of catalytic oxidation on the crystal phases of iron oxides, we find that naked γ-Fe2O3 particles exhibit excellent catalytic activity, selectivity, and stability in a series of imine synthetic reactions. The performance of γ-Fe2O3 particles is significantly better than that of α-Fe2O3 and Fe3O4 under mild reaction conditions, and the γ-Fe2O3 catalyst can be separated from the reaction mixture magnetically. Both experimental and theoretical calculation results show that γ-Fe2O3 possesses supercapability for oxygen activation. The inverse spinel structure of γ-Fe2O3 has abundant cation vacancies, which confers unique electronic properties on surface Fe species. These Fe species tend to transfer electrons to molecular oxygen to form O2? or O22? species. These oxygen species are favorable for the dehydrogenation of alcohols, which is responsible for the high activity of γ-Fe2O3 in this coupling reaction.
- Geng, Longlong,Jian, Wei,Jing, Pei,Zhang, Wenxiang,Yan,Bai, Fu-Quan,Liu, Gang
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p. 145 - 152
(2019/08/01)
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- Oxygen-vacancies-engaged efficient carrier utilization for the photocatalytic coupling reaction
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Defects can greatly optimize the solar light harvesting capability and electronic structure of oxide materials. However, it remains challenging to achieve a defect engineering strategy under mild conditions. Meanwhile, the simultaneous exploitation of photogenerated holes (h+) and electrons (e?) to promote both photooxidation and photoreduction in a coupled system has rarely been reported. For the first time, we reveal an oxygen-vacancies-mediated photocatalytic strategy in which the electrons and holes are fully utilized for nitrobenzene reduction coupled with benzyl alcohol oxidation. The oxygen vacancies (OVs) generated in situ on the surface of TiO2 greatly extend light absorption into the visible region and promote the photogenerated electron transport for efficient photocatalysis. The experimental and theoretical results together indicate that chemisorption on the TiO2 surface decreases the oxidation potential of benzyl alcohol and causes an upward shift in its HOMO, which facilitates the oxidation reaction of benzyl alcohol to benzaldehyde. The in situ generated surface OVs also act as a bridge to enable the trapping and transferring of the photoinduced electrons to the nitrobenzene. This work provides a new perspective of utilizing the chemisorption between the reactant and catalyst to achieve a defect engineering strategy for synergetic photocatalysis.
- Yang, Xue,Tao, Huilin,Leow, Wan Ru,Li, Jingjun,Tan, Yanxi,Zhang, Yongfan,Zhang, Teng,Chen, Xiaodong,Gao, Shuiying,Cao, Rong
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p. 116 - 125
(2019/04/08)
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- Readily Available Primary Aminoboranes as Powerful Reagents for Aldimine Synthesis
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Primary aminoboranes (RNHBR2), which are readily available by spontaneous dehydrocoupling of amines and boranes cleanly react at room temperature with aldehydes to give aldimines. The overall transformation from amines to aldimines can be conveniently performed by a sequential one-pot reaction. This synthetic strategy is especially useful for electron poor and bulky amines which are reluctant to react with aldehydes under dehydration conditions. Using a Glorius robustness screen, we show that this methodology is chemoselective, and functional group tolerant. Computational and experimental data support the irreversible formation of the aldimine product in marked contrast with traditional methods.
- Junor, Glen P.,Romero, Erik A.,Chen, Xi,Jazzar, Rodolphe,Bertrand, Guy
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supporting information
p. 2875 - 2878
(2019/02/13)
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- A new bifunctional heterogeneous nanocatalyst for one-pot reduction-Schiff base condensation and reduction-carbonylation of nitroarenes
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In this work, synthesis of Pd-NHC-γ-Fe2O3-n-butyl-SO3H and its activity as a bifunctional heterogeneous nanocatalyst containing Pd-NHC and acidic functional groups, are described. This newly synthesized nanomagnetic catalyst is fully characterized by different methods such as FT-IR, XPS, TEM, VSM, ICP and TG analysis. At first, the catalytic activity of Pd-NHC-γ-Fe2O3-n-butyl-SO3H is evaluated for the reduction of nitroarenes in aqueous media using NaBH4 as a clean source of hydrogen generation at ambient temperature. Using the promising results obtained from the nitroarene reduction, this catalytic system is used for two one-pot protocols including reduction-Schiff base condensation and reduction-carbonylation of various nitroarenes. In these reactions the in situ formed amines are further reacted with aldehydes to yield imines or carbonylated to amides. The desired products are obtained in good to high yields in the presence of Pd-NHC-γ-Fe2O3-n-butyl-SO3H as a bifunctional catalyst. The catalyst is reused with the aid of a magnetic bar for up to six consecutive cycles without any drastic loss of its catalytic activity.
- Sobhani, Sara,Chahkamali, Farhad Omarzehi,Sansano, José Miguel
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p. 1362 - 1372
(2019/01/24)
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- 2,4,6-Trihydroxybenzoic Acid-Catalyzed Oxidative Ugi Reactions with Molecular Oxygen via Homo- And Cross-Coupling of Amines
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Metal-free, oxidative four-component Ugi reactions (U-4CRs) were conducted to synthesize dipeptides from two different amines, isocyanides, and carboxylic acids using 2,4,6-trihydroxybenzoic acid catalyst in O2 atmosphere. The organocatalytic U-4CRs proceed via oxidative cross-coupling of benzylamines with other aliphatic or aromatic amines to form imines, followed by condensation with isocyanides and carboxylic acids. The U-4CRs via cross-coupling of amines are rare, and the simple, metal-free procedures are advantageous for further applications in drug and heterocycle syntheses.
- Dong, Chun-Ping,Uematsu, Akinori,Kumazawa, Shun,Yamamoto, Yuki,Kodama, Shintaro,Nomoto, Akihiro,Ueshima, Michio,Ogawa, Akiya
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p. 11562 - 11571
(2019/10/03)
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- Pyridine-Stabilized Rhodium Nanoparticles in Ionic Liquids as Selective Hydrogenation and Transfer Hydrogenation Catalysts
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Rhodium nanoparticles (RhNPs) stabilized with pyridine-based ligands in the ionic liquid [BMIM][BF4] (RhNPs-I to III) were synthesized from the organometallic precursor [Rh(μ-OMe)COD]2 under dihydrogen pressure. The pyridine-stabilized RhNPs showed smaller size compared to the ligand free RhNPs-V and presented higher activity and selectivity in the hydrogenation of acetophenone to 1-phenylethanol. In the case of pyridine-capped RhNPs-I, the system was reused for several runs without loss of activity and selectivity. Nitrobenzene was reduced to aniline with dihydrogen in the presence of RhNPs-I with moderate activity. When the hydrogen source was formic acid-Et3N azeotrope (transfer hydrogenation) the reaction was completed within minutes with high selectivity. Under transfer hydrogenation conditions, it was possible to apply the catalytic system RhNPs-I in multistep processes for the generation of substituted arylic amines through the reductive N-alkylation of nitrobenzene and benzaldehyde; and the synthesis of substituted pyrroles through the nitroarene reduction/Paal-Knorr condensation.
- Serrano-Maldonado, Alejandro,Martin, Erika,Guerrero-Ríos, Itzel
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- One-pot solvothermal synthesized CoS2@MoS2 nanocomposites for selective reduction coupling reaction to synthesize imines
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Selective reduction coupling of nitroaromatics and aldehydes for imines synthesis has been investigated by using a series of bifunctional CoS2@MoS2 catalysts prepared by one-pot solvothermal method. Under optimal Co/Mo ratio of 0.75 and preparation temperature (180 °C), CoS2@MoS2–180-0.75 catalyst shows 96.5% nitrobenzene conversion, 93.0% imine selectivity and good versatility for substituted nitrobenzene and different aldehydes under mild conditions (60 °C, 1.5 MPa H2). The characterizations reveal that high nitroaromatics hydrogenation activity and good selectivity are mainly due to the formation of CoMoS phase, the coupling reaction between aniline derivatives and aldehydes is achieved by the appropriate acidity of CoS2@MoS2 nanocomposites.
- Han, Wenpeng,Wang, Junwei,Li, Xuekuan,Zhou, Ligong,Yang, Ying,Tang, Mingxing,Ge, Hui
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- Direct reductive coupling of nitroarenes and alcohols catalysed by Co-N-C/CNT@AC
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A non-noble heterogeneous catalyst-a Co, N and C composite encapsulated carbon nanotube grown in situ on the surface of activated carbon (Co-N-C/CNT@AC)-was fabricated via the pyrolysis-reduction process. Co-N-C/CNT@AC catalyzed the reductive coupling of structurally diverse nitroarenes and alcohols to imines and secondary amines under exogenous base- and solvent-free conditions. BET, TEM, SEM, XRD and XPS characterization showed that the exceptional catalytic property of Co-N-C/CNT@AC could be explained by its nanostructure, Co-N and basic N species. Our protocol had advantages of low cost, environment-friendliness, and good applicability. Furthermore, a reaction route of nitroarenes, amines and alcohols as the starting materials was proposed to improve the atom economy of the reductive coupling of nitroarenes with alcohols.
- Liu, Di,Yang, Ping,Zhang, Hao,Liu, Minjie,Zhang, Wenfei,Xu, Dongmei,Gao, Jun
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p. 2129 - 2137
(2019/04/27)
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- Manganese catalyzed reductive amination of aldehydes using hydrogen as a reductant
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A one-pot two-step procedure was developed for the alkylation of amines via reductive amination of aldehydes using molecular dihydrogen as a reductant in the presence of a manganese pyridinyl-phosphine complex as a pre-catalyst. After the initial condensation step, the reduction of imines formed in situ is performed under mild conditions (50-100 °C) with 2 mol% of catalyst and 5 mol% of tBuOK under 50 bar of hydrogen. Excellent yields (>90%) were obtained for a large combination of aldehydes and amines (40 examples), including aliphatic aldehydes and amino-alcohols.
- Wei, Duo,Bruneau-Voisine, Antoine,Valyaev, Dmitry A.,Lugan, No?l,Sortais, Jean-Baptiste
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supporting information
p. 4302 - 4305
(2018/05/03)
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- Tert-Butyl Nitrite Promoted Oxidative Intermolecular Sulfonamination of Alkynes to Synthesize Substituted Sulfonyl Pyrroles from the Alkynylamines and Sulfinic Acids
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tert-Butyl nitrite promoted oxidative intermolecular sulfonamination of alkynes to synthesize substituted sulfonyl pyrroles from the alkynylamines and sulfinic acids via tandem addition/cyclization was developed. This reaction is performed well by employing tert-butyl nitrite as the oxidant, and various substituted sulfonyl pyrroles are formed in moderate to good yields with no requirement of metal catalysis.
- Qi, Zhenjie,Jiang, Yong,Wang, Yanyan,Yan, Rulong
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supporting information
p. 8636 - 8644
(2018/06/18)
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- Formic acid catalyzed one-pot synthesis of α-aminophosphonates: an efficient, inexpensive and environmental friendly organocatalyst
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Abstract: Aqueous formic acid is used for the synthesis of α-aminophosphonates through Kabachnik–Fields reaction applying aromatic amine, phosphite, and carbonyl compounds. Using formic acid as an efficient and low-cost organocatalyst provides environmental friendly, high yields, low reaction time and mild reaction condition. The isolated products were analyzed by IR, NMR, and mass techniques. Graphical abstract: [Figure not available: see fulltext.].
- Azarnia Mehraban, Jamshid,Jalali, Mahsa Sadat,Heydari, Akbar
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p. 2215 - 2223
(2018/08/04)
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- Cu-Catalyzed Tandem Aerobic Oxidative Cyclization for the Synthesis of 3,3′-Bipyrroles from the Homopropargylic Amines
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A Cu-catalyzed method for the synthesis of 3,3′-bipyrroles from homopropargylic amines through tandem aerobic oxidative cyclization involving the formation of C-C bond has been developed. The features of this reaction are a small number of Cu catalysis and simple starting substrates. Moreover, this procedure exhibits good functional group tolerance and a series of 3,3′-bipyrroles derivatives are obtained in moderate to good yields.
- Qi, Zhenjie,Jiang, Yong,Yuan, Bingxiang,Niu, Yanning,Yan, Rulong
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supporting information
p. 5048 - 5052
(2018/08/24)
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- One-pot cascade synthesis of pyrano/furanotetrahydroquinolines through povarov reaction catalyzed by Fe(NO3)3@Al2O3
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Fe(NO3)3@Al2O3 was synthesized as a green heterogeneous catalyst for Povarov reaction toward the one-pot cascade synthesis of cis- and trans-tetrahydroquinolines from aryl amines, aryl aldehydes, and electron-rich olefins (dihydropyran/dihydrofuran) under thermal conditions. The reaction is diastereoselective with trans product formed in preponderance. The products were characterized by 1H NMR, 13C NMR, IR, ESIMS, and elemental analysis. The characterization of Fe(NO3)3@Al2O3 was made by various techniques such as Fourier-transform infrared, inductively coupled plasma-atomic emission spectroscopy, X-ray diffraction, energy dispersive X-ray, scanning electron microscope, transmission electron micrographs, TGA, and vibrating sample magnetometer. High catalytic activity, easy recovery and reusability, eco-benign nature, and thermal and chemical stabilities are the key properties of the catalyst that makes it attractive from the viewpoint of green chemistry.
- Kaur, Ramneet,Khajuria, Rajni,Saini, Yeshwinder,Kapoor, Kamal K.
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- Cross-dehydrogenative coupling strategy for phosphonation and cyanation of secondary N-alkyl anilines by employing 2,3-dichloro-5,6-dicyanobenzoquinone
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The cross-dehydrogenative coupling strategy for metal-free phosphonation and cyanation of secondary N-alkyl anilines has been developed firstly under mild reaction conditions. Based on detailed optimization of reaction conditions, the substrate generality of N-alkyl anilines and various hydrogen phosphonates has been investigated, and a series of versatile α-aminophosphonates and α-aminonitriles were therefore furnished in good to excellent yields. A plausible collective reaction mechanism through dehydrogenation to imine formation, then to respective α-aminophosphonates and α-aminonitriles was proposed.
- Liu, Qing,Yu, Shuchen,Hu, Liangzhen,Hussain, Muhamad Ijaz,Zhang, Xiaohui,Xiong, Yan
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p. 7209 - 7217
(2018/11/10)
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- Design and stereoselective synthesis of novel β-lactone and β-lactams as potent anticancer agents on breast cancer cells
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To produce a novel class of anticancer compounds, an efficient method for synthesizing novel β-lactone and β-lactam frameworks was developed based on the reaction of a new ketene with C=O and C=N bonds. Functionalized 2-azetidinones were efficiently synthesized by employing 2,4-dichlorophenoxylketene, which was generated in situ. The reaction of the ketene with aldehydes was not successful and in all cases except for 4-nitrobenzaldehyde, a rearranged dimer of the ketene was obtained as a lactone. Anticancer cellular activity of all new β-lactams and lactones on breast cancer cells was studied. All new synthesized compounds exhibited potential anticancer activity which may guarantee their future application in moderate chemotherapy.
- Rashidi, Mahnoosh,Islami, Mohammad Reza,Esmaeili-Mahani, Saeed
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p. 835 - 841
(2018/01/22)
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- Grouping Effect of Single Nickel?N4 Sites in Nitrogen-Doped Carbon Boosts Hydrogen Transfer Coupling of Alcohols and Amines
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As a new type of heterogeneous catalyst with “homogeneous-like” activity, single-site transition-metal materials are usually treated as integrated but separate active centers. A novel grouping effect is reported for single Ni?N4 sites in nitrogen-doped carbon (Ni/NC), where an effective ligand-stabilized polycondensation method endows Ni/NC nanocatalysts with a high content of single-site Ni up to 9.5 wt %. The enhanced electron density at each single Ni?N4 site promotes a highly efficient hydrogen transfer, which is exemplified by the coupling of benzyl alcohol and aniline into N-benzylaniline with a turnover frequency (TOF) value of 7.0 molN-benzylaniline molmetal?1 h?1; this TOF outpaces that of reported stable non-noble-metal-based catalysts by a factor of 2.
- Su, Hui,Gao, Peng,Wang, Meng-Ying,Zhai, Guang-Yao,Zhang, Jun-Jun,Zhao, Tian-Jian,Su, Juan,Antonietti, Markus,Li, Xin-Hao,Chen, Jie-Sheng
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supporting information
p. 15194 - 15198
(2018/10/31)
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- Direct synthesis of imines by 9-azabicyclo-[3,3,1]nonan-N-oxyl/KOH-catalyzed aerobic oxidative coupling of alcohols and amines
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A simple and efficient method for preparation of imines by the oxidative coupling of benzyl alcohols with aromatic amines or aliphatic amines was developed. The reaction was catalyzed by 9-azabicyclo[3.3.1]nonan-N-oxyl (ABNO)/KOH with air as the economic and green oxidant. Under the optimal reaction conditions, a variety of imines were obtained in 80%-96% isolated yields.
- Wan, Yan,Ma, Jia-Qi,Hong, Chao,Li, Mei-Chao,Jin, Li-Qun,Hu, Xin-Quan,Hu, Bao-Xiang,Mo, Wei-Min,Sun, Nan,Shen, Zhen-Lu
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p. 1269 - 1272
(2017/10/26)
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- Manganese-Catalyzed and Base-Switchable Synthesis of Amines or Imines via Borrowing Hydrogen or Dehydrogenative Condensation
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The use of earth-abundant transition metals as a noble metal replacement in catalysis is especially interesting if different catalytic reactivity is observed. We report, here, on the selective manganese-catalyzed base-switchable synthesis of N-alkylated amines or imines. In both reactions, borrowing hydrogen/hydrogen autotransfer (N-alkyl amine formation) or dehydrogenative condensation (imine formation), we start from the same amines and alcohols and use the same Mn precatalyst. The key is the presence of a potassium base to prefer N-alkylation and a sodium base to permit imine formation. Both bases react with the manganese hydride via deprotonation. The potassium manganate hydride reacts about 40 times faster with an imine to give the corresponding amine than the sodium manganate hydride. The selectivity seems unique for manganese complexes. We observe a broad scope with a complete product overlap, all amine alcohol combinations can be converted into an N-alkyl amine or an imine, and a good functional group tolerance.
- Fertig, Robin,Irrgang, Torsten,Freitag, Frederik,Zander, Judith,Kempe, Rhett
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p. 8525 - 8530
(2018/09/06)
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- C-N Bond Formation Catalyzed by Ruthenium Nanoparticles Supported on N-Doped Carbon via Acceptorless Dehydrogenation to Secondary Amines, Imines, Benzimidazoles and Quinoxalines
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Ruthenium nanoparticles (NPs) supported on N-doped carbon (Ru/N?C) were prepared by the pyrolysis of cis-Ru(phen)2Cl2 loaded onto carbon powder (VULCAN XC72R) at 800 °C. Ru/N?C NPs (0.2 mol% Ru) selectively catalyzed either acceptorless dehydrogenation coupling (ADC) or auto-transfer-hydrogen (ATH) reactions of amines with alcohols to imines and secondary amines. Such selectivity could be controlled by the choice of alkali metal ion associated with the base. Under similar catalytic conditions, the ADC cross-coupling of diamines with primary alcohols or diols afforded the corresponding benzimidazoles and quinoxalines in good to excellent yields. This catalytic system displayed good activity, recyclability, and wide applicability to a diverse range of substrates.
- Guo, Bin,Li, Hong-Xi,Zhang, Shi-Qi,Young, David James,Lang, Jian-Ping
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p. 5627 - 5636
(2018/12/04)
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- Oxidative coupling of alcohols and amines to an imine over Mg-Al acid-base bifunctional oxide catalysts
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A series of Mg-Al mixed oxide catalysts are prepared and introduced as efficient irreducible catalysts for the oxidative coupling of alcohols and amines to imine. The structure and surface properties of Mg-Al oxides are modulated by changing the Mg/Al ratios, calcination temperature and treatment with probe molecules. Detailed characterization, including X-ray diffraction, 27Al magic angle spinning nuclear magnetic resonance spectroscopy, N2-adsorption, NH3-temperature-programmed desorption, CO2-temperature-programmed desorption and X-ray photoelectron spectroscopy are carried out to determine the physicochemical properties of these catalysts. The Mg-Al oxides with Mg/Al = 3 exhibit the highest activity in the reaction, which possess a large number of surface weak basic sites and a relatively small number of weak acidic sites. The role of the acidic and basic sites in the reaction process is systematically investigated, and are shown to serve as adsorption and activation sites for amines and alcohols, respectively. Under the synergistic effect of these acid-base centers, the oxidative coupling process successfully occurs on the surface of Mg-Al mixed oxides. Compared with the acidic sites, the weak basic sites play a more important role in the catalytic process. The acidic sites are the catalytic centers for the benzyl alcohol activation, which control the reaction rate of the oxidative coupling reaction.
- Song, Jinling,Yu, Guiyang,Li, Xi,Yang, Xuwei,Zhang, Wenxiang,Yan, Wenfu,Liu, Gang
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p. 309 - 318
(2018/02/20)
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- Method of synthesizing imine and amine compounds by means of borrowing-hydrogen reduction coupling
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The invention belongs to energy and chemical industry and particularly relates to a method of synthesizing imine and amine compounds by means of borrowing-hydrogen reduction coupling by using a nitrogen-doped hierarchical-porous biomass-based carbon material supported catalyst. The method includes the steps of: under a seal reaction condition, adding a nitro-aromatic hydrocarbon compound, benzyl alcohol compounds with different substituent groups, the supported catalyst, methylbenzene and potassium tert-butoxide; performing a reaction at 50-150 DEG C for 4-24 h, cooling the product to room temperature and filtering a reaction liquid to obtain the imine compound represented in the formula (1) or the amine compound represented in the formula (2). The raw materials of the catalyst are regenerable resources, are widely distributed, are green and environment-friendly, are easy to prepare and abundant in sources, and are low in cost; the catalyst can be recycled without deactivation and is stable to air, water and heat. By means of the supported metal catalyst, the conversion rate of the borrowing-hydrogen reduction coupling reaction on the nitro-compound and alcohol to prepare the iminecompounds is higher than 99%, and yield can reach 90-60%; the conversion rate of same to prepare the amine compounds is higher than 99%, and yield can reach 90-60%.
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Paragraph 0043; 0044; 0045; 0046; 0049
(2018/11/04)
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