- Mechanism of the Palladium-Catalyzed Synthesis of Münchnones: The Role of Ligands in N-Acyl Iminium Salt Carbonylation
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The palladium-catalyzed carbonylative coupling of imines, acid chlorides, and dipolarophiles can provide efficient routes to prepare nitrogen-containing heterocycles. One challenge in developing this reaction, and in the creation of more active catalyst systems, is the lack of data on how this complex transformation proceeds. To address this, we report here the results of our mechanistic studies on this system, and in particular the formation of mesoionic münchnones. This includes the synthesis of key catalytic intermediates, model reactions, and kinetic studies that support the role of these compounds in catalysis. Together, these studies provide a clear picture of the impact of catalyst structure, ligands, and palladium nanoparticles on facilitating the carbonylation of in situ generated iminium salts, and suggest an avenue for the creation of more active catalyst systems.
- Tjutrins, Jevgenijs,Dhawan, Rajiv,Lu, Yingdong,Arndtsen, Bruce A.
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Read Online
- A simple flowcell for reactionmonitoring by NMR
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A simple, cheap and flexible flowcell based on a standard 5mmNMR tube, designed for the monitoring of reactions but of wide applicability, is described. No modification of the NMR instrument is needed, allowing the system to be employed with any conventional NMR probe and magnet. The system is robust and economical in use of reagents, and can be used for studying both homogeneous and heterogeneous reactions.
- Khajeh,Bernstein,Morris
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Read Online
- Catalysis of aldehyde imination by hydrogen bonding with a simple organic disulfonamide receptor
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The disulfonamide receptor 1 catalyzes imine formation from aldehyde and amine, apparently by binding the transition state for the rate-determining nucleophilic attack of amine on the aldehyde.
- Kavallieratos, Konstantinos,Crabtree, Robert H.
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Read Online
- Synthesis of chromeno[3,4-b]piperazines by an enol-ugi/reduction/cyclization sequence
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Keto piperazines and aminocoumarins are privileged building blocks for the construction of geometrically constrained peptides and therefore valuable structures in drug discovery. Combining these two heterocycles provides unique rigid polycyclic peptidomimetics with drug-like properties including many points of diversity that could be modulated to interact with different biological receptors. This work describes an efficient multicomponent approach to condensed chromenopiperazines based on the novel enol-Ugi reaction. Importantly, this strategy involves the first reported post-condensation transformation of an enol-Ugi adduct.
- Bornadiego, Ana,Neo, Ana G.,Marcos, Carlos F.
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supporting information
(2021/05/31)
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- Cyclometalated Half-Sandwich Iridium(III) Complexes: Synthesis, Structure, and Diverse Catalytic Activity in Imine Synthesis Using Air as the Oxidant
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Four air-stable cyclometalated half-sandwich iridium complexes 1-4 with C,N-donor Schiff base ligands were prepared through C-H activation in moderate-to-good yields. These complexes have been well characterized, and their exact structure was elaborated on by single-crystal X-ray analysis. The iridium(III) complexes 1-4 showed good catalytic activity in the imine synthesis under open-flask conditions (air as the oxidant) from primary amine oxidative homocoupling, secondary amine dehydrogenation, and the cross-coupling reaction of amine and alcohol. Substituents bonded on the ligands of the iridium complexes displayed little effect on the catalytic efficiency. The stability and good catalytic efficiency of the iridium catalysts, mild reaction conditions, and substrate universality showed their potential application in industrial production.
- Li, Rong-Jian,Ling, Chun,Lv, Wen-Rui,Deng, Wei,Yao, Zi-Jian
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p. 5153 - 5162
(2021/05/04)
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- Nickel Complexes Bearing N,N,O-Tridentate Salicylaldiminato Ligand: Efficient Catalysts for Imines Formation via Dehydrogenative Coupling of Primary Alcohols with Amines
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Treatment of salicylaldiminato ligand L1H-L2H (L1H = 2,4-di-tert-butyl-6-((quinolin-8-ylimino)methyl)phenol; L2H = 2,4-di-tert-butyl-6-(((2-(diethylamino)ethyl)imino)methyl)phenol) with Ni(OAc)2·4H2O in refluxing ethanol afforded nickel complexes [(L1)Ni(OAc)] (1) and [(L2)Ni(OAc)] (2), respectively. Reaction of L3H (L3H = (2,4-di-tert-butyl-6-(((2-(pyridin-2-yl)ethyl)imino)methyl)phenol)) with Ni(OAc)2·4H2O in the presence of excess triethylanmine gave the dual ligands coordinated nickel complex [(L2)2Ni] (3). Complexes 1-3 were well characterized by high-resolution mass spectrometry, infrared spectroscopy, elemental analysis, and X-ray diffraction analysis. All the three Ni(II) complexes exhibited efficient activity and good selectivity in the acceptorless dehydrogenative coupling of alcohols and amines to produce imines and diimines. The present protocol provides an atom-economical and sustainable route for the synthesis of various imine derivatives by employing an earth-abundant nickel salt and easily prepared salicylaldiminato ligands.
- Han, Zhangang,Hao, Zhiqiang,Lin, Jin,Lu, Guo-Liang,Zhang, Junhua,Zhang, Xiaoying
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p. 3843 - 3853
(2021/11/18)
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- Half-Sandwich Ruthenium Complexes Bearing Hemilabile κ2-(C,S)?Thioether-Functionalized NHC Ligands: Application to Amide Synthesis from Alcohol and Amine
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Amide synthesis is one of the most crucial transformations in chemistry and biology. Among various catalytic systems, N-heterocyclic carbene (NHC)-based ruthenium (Ru) catalyst systems have been proven to be active for direct synthesis of amides by sustainable acceptorless dehydrogenative Coupling of primary alcohols with amines. Most often, these catalytic systems usually use monodentate NHC and thus require an additional ligand to obtain high reactivity and selectivity. In this work, a series of cationic Ru(II)(η6-p-cymene) complexes with thioether-functionalized N-heterocyclic carbene ligands (imidazole and benzimidazole-based) have been prepared and fully characterized. These complexes have then been used in the amidation reaction and the most promising one (i. e. 3 c) has been applied on a large range of substrates. High conversions albeit with moderate yields have generally been obtained.
- Achard, Thierry,Bellemin-Laponnaz, Stéphane,Chen, Weighang,Egly, Julien,Maisse-Fran?ois, Aline
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supporting information
(2022/01/20)
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- Enantioselective Reductive Cyanation and Phosphonylation of Secondary Amides by Iridium and Chiral Thiourea Sequential Catalysis
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The combination of transition-metal catalysis and organocatalysis increasingly offers chemists opportunities to realize diverse unprecedented chemical transformations. By combining iridium with chiral thiourea catalysis, direct enantioselective reductive cyanation and phosphonylation of secondary amides have been accomplished for the first time for the synthesis of enantioenriched chiral α-aminonitriles and α-aminophosphonates. The protocol is highly efficient and enantioselective, providing a novel route to the synthesis of optically active α-functionalized amines from the simple, readily available feedstocks. In addition, the reactions are scalable and the thiourea catalyst can be recycled and reused.
- Chen, Dong-Huang,Sun, Wei-Ting,Zhu, Cheng-Jie,Lu, Guang-Sheng,Wu, Dong-Ping,Wang, Ai-E,Huang, Pei-Qiang
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supporting information
p. 8827 - 8831
(2021/03/16)
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- A Versatile Approach to Dynamic Amide Bond Formation with Imine Nucleophiles
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Dynamic covalent chemistry has rapidly become an important approach to access supramolecular structures. While the products generated in these reactions are held together by covalent bonds, the reversible nature of the transformations can limit the utility of many these systems in creating robust materials. We describe herein a method to form stable and commonly employed amide bonds by exploiting the reversible coupling of imines and acyl chlorides. The reaction employs easily accessible reagents, is dynamic under ambient conditions, without catalysts, and can be trapped with simple hydrolysis. This offers an approach to create broad families of amide products under thermodynamic control, including the selective formation of amide macrocycles or polymers.
- Arndtsen, Bruce A.,Erguven, Huseyin,Keyzer, Evan N.
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supporting information
(2020/05/05)
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- Air-Stable Half-Sandwich Iridium Complexes as Aerobic Oxidation Catalysts for Imine Synthesis
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Several N,O-coordinate half-sandwich iridium complexes, 1-5, containing constrained bulky β-enaminoketonato ligands were prepared and clearly characterized. Single-crystal X-ray diffraction characterization of these complexes indicates that the iridium center adopts a distorted octahedral geometry. Complexes 1-5 showed good catalytic efficiency in the oxidative homocoupling of primary amines, dehydrogenation of secondary amines, and the oxidative cross-coupling of amines and alcohols, which furnished various types of imines in good yields and high selectivities using O2 as an oxidant under mild conditions. No distinctive substituent effects of the iridium catalysts were observed in these reactions. The diverse catalytic activity, broad substrate scope, mild reaction conditions, and high yields of the products made this catalytic system attractive in industrial processes.
- Deng, Wei,Fan, Xiao-Nan,Ou, Hui-Dan,Yao, Zi-Jian
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supporting information
(2020/04/02)
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- Efficient Co-Catalyzed Double Hydroboration of Nitriles: Application to One-Pot Conversion of Nitriles to Aldimines
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The commercially available and bench-stable Co(acac)2/dpephos system is employed as a precatalyst for selective and efficient room temperature hydroboration of organic nitriles with HBPin to produce a series of N,N-diborylamines [RN(BPin)2], which react in situ with aldehydes to give aldimines. Formation of aldimines from N,N-diborylamines does not require a dehydrating agent, is applicable to a wide range of N,N-diborylamine and aldehyde substrates and is highly chemoselective, being unaffected by various common functional groups, such as alkenes, alkynes, secondary amines, ketones, esters, amides, carboxylic acids, pyridines, nitriles, and nitro compounds. The overall transformation represents a synthetically valuable approach to aldimines from nitriles and can be performed in a sequential one-pot manner, tolerating ester, lactone, carboxamide and unactivated alkene functionalities.
- Gudun, Kristina A.,Slamova, Ainur,Hayrapetyan, Davit,Khalimon, Andrey Y.
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p. 4963 - 4968
(2020/04/17)
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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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- Direct Synthesis of Amides by Acceptorless Dehydrogenative Coupling of Benzyl Alcohols and Ammonia Catalyzed by a Manganese Pincer Complex: Unexpected Crucial Role of Base
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Amide synthesis is one of the most important transformations in chemistry and biology. The direct use of ammonia for the incorporation of nitrogen functionalities in organic molecules is an attractive and environmentally benign method. We present here a new synthesis of amides by acceptorless dehydrogenative coupling of benzyl alcohols and ammonia. The reaction is catalyzed by a pincer complex of earth-abundant manganese in the presence of a stoichiometric base, making the overall process economical, efficient, and sustainable. Interesting mechanistic insights based on detailed experimental observations, indicating the crucial role of the base, are provided.
- Daw, Prosenjit,Kumar, Amit,Espinosa-Jalapa, Noel Angel,Ben-David, Yehoshoa,Milstein, David
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supporting information
p. 12202 - 12206
(2019/08/20)
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- Bi-functional catalyst of porous N-doped carbon with bimetallic FeCu for solvent-free resultant imines and hydrogenation of nitroarenes
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The efficient and stable catalyst applied to the transformation of amines into the corresponding imines and hydrogenation of nitroarenes under mild reaction conditions is reported. The catalytic performance of porous N-doped carbon with FeCu (FeCu@NPC) catalyst are tested by aromatic alcohol-based N-alkylated of amines with solvent-free and hydrogenation of nitroarenes via N2H4·H2O. The results proved that the yield of these two reactions are all over 99.9% under optimum condition. Moreover, the synergistic effect of the catalyst for N-alkylated reaction was investigated through the kinetic study. The catalyst can be easily separated from reaction system by an external magnetism, and can be recycled and reutilized for at least 4 runs with conversions are all over 75%. The study of the catalyst indicated that it was suitable for the reactions in industry. Hence, the catalysis process by the inexpensive metals-based catalyst is green and sustainable.
- Wang, Kaizhi,Gao, Wenbing,Jiang, Pengbo,Lan, Kai,Yang, Ming,Huang, Xiaokang,Ma, Lei,Niu, Fang,Li, Rong
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- Au nanoparticle-immobilized L-cysteine-paired porous ionic copolymer as an efficient catalyst for additive-free oxidative coupling of alcohols and amines
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Herein, an L-cysteine-paired ionic copolymer (DVB-[MimLcy]n) with mesoporosity was prepared by free radical copolymerization of divinylbenzene (DVB) and imidazolium ionic liquids (ILs), followed by anion-exchange with L-cysteine. Because of the rich functional groups of –NH2, –SH, and –COO– and the porous framework, the DVB-[MimLcy]3 was revealed to be an ideal stabilizer for metal nanoparticles (NPs). Highly uniform dispersed small Au NPs (2–3 nm) immobilized on DVB-[MimLcy]3 (Aua/DVB-[MimLcy]3) can act as an efficient heterogeneous catalyst for additive-free synthesis of imines through coupling of a broad range of alcohols and organic amines and can be easily recovered and steadily reused several times.
- Du, Shengyu,Zhang, Chenjun,Jiang, Yuchen,Jiang, Pingping,Leng, Yan
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- Time-Dependent Switching of Constitutional Dynamic Libraries and Networks from Kinetic to Thermodynamic Distributions
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The distribution of the constituents of a constitutional dynamic library (CDL) may undergo time-dependent changes as a function of the kinetics of the processes generating the CDL from its components. Thus, the constitutional dynamic network (CDN) representing the connections between the constituents changes from a kinetic distribution to the thermodynamic one as a function of time. We investigated the behavior of dynamic covalent libraries (DCLs) of four constituents generated by reversible formation of C═N bonds between four components, 2 aldehydes and 2 amino compounds, both in absence and in the presence of metal cations. The associated [2 × 2] networks underwent time-dependent changes from the initial kinetic distribution to the final thermodynamic one, involving an orthogonal switch from one diagonal to the other diagonal of the square [2 × 2] network leading to a very large change in distribution. The DCL constituents could be switched from kinetic products (imines) to thermodynamic products (oximes or acylhydrazones) based on the reactivities of the components and the thermodynamic stabilities of the constituents without addition of any external effector, solely on the basis of the intrinsic properties of the self-contained system. Such processes were achieved for purely organic DCLs/CDNs as well as for inorganic ones containing two metal cations, the latter changing from the silver(I) complex of an imine (kinetic product) to the zinc(II) complex of a hydrazone (thermodynamic product). The results bear relationship to out-of-equilibrium systems concerning kinetic behavior in adaptive chemistry.
- He, Meixia,Lehn, Jean-Marie
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supporting information
p. 18560 - 18569
(2019/11/21)
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- Activation of primary amines by copper(i)-based lewis acid promoters in the solventless synthesis of secondary propargylamines
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Primary amines are activated by copper(I)-based Lewis acid promoters in an A 3 -coupling one-pot solventless reaction with aldehydes and phenylacetylene for the synthesis of secondary propargylamines. The reaction is promoted by a CuSO 4 /NaI system, a practical precursor of the in situ generated effective CuI/I 2 system, that worked well, but only in a restricted number of examples. Substitution of I 2 with CeCl 3 ·7H 2 O in a one-pot two-step reaction provided good yields and a wider applicability, with the added value given by a safer procedure.
- Cimarelli, Cristina,Navazio, Federica,Rossi, Federico V.,Del Bello, Fabio,Marcantoni, Enrico
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p. 2387 - 2396
(2019/05/27)
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- α-Acyl-α-diazoacetates in Transition-Metal-Free β-Lactam Synthesis
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Thermally promoted reaction of α-acyl-α-diazoacetates with imines has been investigated. The transformation, earlier reported predominantly under transition metal catalyzed conditions, delivers α-alkoxycarbonyl-substituted β-lactams with outstanding diastereoselectivity. DFT calculations performed in order to evaluate energetically feasible reaction pathways revealed the intermediacy of 1,3-oxazin-4-one intermediates hitherto never implicated in the Staudinger synthesis of β-lactams.
- Synofzik, Judith,Dar'In, Dmitry,Novikov, Mikhail S.,Kantin, Grigory,Bakulina, Olga,Krasavin, Mikhail
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p. 12101 - 12110
(2019/10/02)
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- Synthesis and evaluation of Zn(II) dithiocarbamate complexes as potential antibacterial, antibiofilm, and antitumor agents
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Four complexes having the formula [Zn(L)2] [L1 = (C18H20NS2 –), N-(4-isopropyl-benzyl)-(benzyl)-dithiocarbamate], [L2 = (C10H12NS2 –), N-(benzyl)-(ethyl)-dithiocarbamate], [L3 = (C19H22ONS2 –), N-(4-isopropyl-benzyl)-(4-methoxy-benzyl)-dithiocarbamate], and [L4 = (C16H16NS2 –), N-(benzyl)-(4-methyl-benzyl)-dithiocarbamate] have been contemplated, synthesized, and characterized by elemental analysis and IR, 1H, 13C NMR and UV–visible absorption spectra. All Zn(II) complexes have similar geometry and coordination number. Complex A2 (with ligand L2) crystallizes in triclinic system with space group P-1 having distorted square pyramidal geometry which was stabilized by weak C–H···π and C–H···S intramolecular interactions. The antibacterial, antibiofilm, and antitumor activities of the complexes have been screened and A2 and A3 showed their prominence. Interestingly, both A2 and A3 showed more killing potential against multi-drug resistant gram-positive isolates with MIC indices of 16 μg mL?1 and 16 μg mL?1, respectively, against both MRSA and MSSA, while the antitumor agent A3 showed its prominence with GI50 and LC50 41.15 and 133.73 μg mL?1, respectively.
- Maurya, Vinay Kumar,Singh, Ashish Kumar,Singh, Ravi Pratap,Yadav, Shivangi,Kumar, Krishna,Prakash, Pradyot,Prasad, Lal Bahadur
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p. 3338 - 3358
(2019/11/26)
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- Selective aerobic oxidation of halides and amines with an inorganic-ligand supported zinc catalyst
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A practical, efficient and environmentally benign catalytic protocol for the oxidative cross-coupling reaction of halides with amines, oxidative self-coupling of amines and oxidation of halides was developed with inorganic-ligand supported ZnPOM (NH4)4[ZnMo6O18(OH)6] using molecular oxygen. This method mainly utilizes an inorganic polymolybdate ligand to support the Zn2+ ion, avoiding the use of complicated organic ligands.
- Wang, Jingjing,Zhai, Yongyan,Wang, Ying,Yu, Han,Zhao, Wenshu,Wei, Yongge
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p. 13323 - 13327
(2018/10/15)
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- Visible-Light-Driven Photocatalytic Oxidation of Organic Chlorides Using Air and an Inorganic-Ligand Supported Nickel-Catalyst Without Photosensitizers
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Engineering photoredox-triggered chemical transformation via visible light has been an emerging area in organic synthesis. However, most of the well-established photocatalysts are based upon either transition metal complexes involved with noble metals and organic ligands or photosensitive organic dyes, the development of pure inorganic molecular photocatalysts that could provide better stability and durability is greatly retarded. Herein we discover that the Anderson polyoxometalate (POM) Na4[NiMo6O18(OH)6] (1), which consists of pure inorganic framework built from a central NiII core supported by six MoVIO6 inorganic scaffold/ligands, can be used as a powerful photocatalyst. Upon irradiation with visible light (>400 nm), the compound can catalyze, in high efficiency, a wide range of reactions, including the oxidative cross-coupling reaction of chlorides with amines, as well as oxidation of chlorides using molecular oxygen, affording various imines, aldehydes, and ketones, respectively in high selectivity and good yields. Owing to the robust inorganic framework, this catalyst exhibits excellent stability during the catalysis and reusability with little loss of the catalytic activity, thus providing an alternative without use of complicated organic ligands and expensive noble metal-based photosensitizers.
- Yu, Han,Wang, Jingjing,Zhai, Yongyan,Zhang, Mengqi,Ru, Shi,Han, Sheng,Wei, Yongge
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p. 4274 - 4279
(2018/09/10)
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- Dynamic Covalent Metathesis in the C=C/C=N Exchange between Knoevenagel Compounds and Imines
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Fast and reversible dynamic covalent C=C/C=N exchange takes place without catalyst in nonpolar solvents between barbiturate-derived Knoevenagel (Kn) compounds and imines. A detailed study of the reaction indicates that it proceeds by an associative organo-metathesis mechanism involving the formation of a four-membered ring azetidine intermediate by addition of the imine C=N group to the C=C bond of the Kn compound. This intermediate could be generated cleanly and stabilized at low temperature by condensation of the o,p-dinitrophenyl Kn derivative with the cyclic imine 1-azacyclohexene. It was characterized by extensive NMR and mass spectrometric studies. The process described represents a genuine dynamic covalent organo-metathesis through a four-membered ring adduct as intermediate. It paves the way for the exploration of a wide set of dynamic systems involving (strongly) polarized C=C bonds and various imines, extending also into covalent dynamic polymers and polymolecular assemblies.
- Gu, Ruirui,Flidrova, Karolina,Lehn, Jean-Marie
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p. 5560 - 5568
(2018/05/01)
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- Mechanistic Studies on the Michael Addition of Amines and Hydrazines to Nitrostyrenes: Nitroalkane Elimination via a Retro-aza-Henry-Type Process
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In this article we report on the mechanistic studies of the Michael addition of amines and hydrazines to nitrostyrenes. Under the present conditions, the corresponding N-alkyl/aryl substituted benzyl imines and N-methyl/phenyl substituted benzyl hydrazones were observed via a retro-aza-Henry-type process. By combining organic synthesis and characterization experiments with computational chemistry calculations, we reveal that this reaction proceeds via a protic solvent-mediated mechanism. Experiments in deuterated methanol CD3OD reveal the synthesis and isolation of the corresponding deuterated intermediated Michael adduct, results that support the proposed slovent-mediated pathway. From the synthetic point of view, the reaction occurs under mild, noncatalytic conditions and can be used as a useful platform to yield the biologically important N-methyl pyrazoles in a one-pot manner, simple starting with the corresponding nitrostyrenes and the methylhydrazine.
- Kallitsakis, Michael G.,Tancini, Peter D.,Dixit, Mudit,Mpourmpakis, Giannis,Lykakis, Ioannis N.
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p. 1176 - 1184
(2018/02/09)
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- Direct access to: N -alkylated amines and imines via acceptorless dehydrogenative coupling catalyzed by a cobalt(ii)-NNN pincer complex
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A simple, phosphine-free Co(ii)-NNN pincer complex catalyzed direct N-alkylation of anilines with alcohols via hydrogen auto-transfer (HA) and selective acceptorless dehydrogenative coupling (ADC) of benzylamines with alcohols affording imines with the liberation of molecular hydrogen and water is reported.
- Midya, Siba P.,Pitchaimani, Jayaraman,Landge, Vinod G.,Madhu, Vedichi,Balaraman, Ekambaram
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p. 3469 - 3473
(2018/07/29)
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- A General Way to Construct Arene-Fused Seven-Membered Nitrogen Heterocycles
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Imines react with seven-membered cyclic anhydrides (prepared from the corresponding dicarboxylic acids by a recently discovered in-situ cyclodehydration protocol) by the Castagnoli–Cushman reaction pathway to give privileged seven-membered arene-fused nitrogen-heterocyclic compounds with reagent-controlled diversity of the skeleton and peripheral groups.
- Bakulina, Olga,Chizhova, Maria,Dar'in, Dmitry,Krasavin, Mikhail
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p. 362 - 371
(2018/01/27)
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- Unusually Reactive Cyclic Anhydride Expands the Scope of the Castagnoli-Cushman Reaction
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In the course of synthesizing and testing various "azole-including" cyclic anhydrides in the Castagnoli-Cushman reaction with imines, a remarkably reactive, pyrrole-based anhydride has been identified. It displayed a remarkably efficient reaction with N-alkyl and N-aryl imines, in particular, with "enolizable" α-C-H imines which typically fail to react with a majority of known cyclic anhydrides. The reactivity of this anhydride has been justified by an efficient resonance stabilization of its enol form. This finding expands the existing arsenal of highly reactive cyclic anhydrides and further confirms the importance of anhydride enolization for an efficient Castagnoli-Cushman reaction.
- Chizhova, Maria,Khoroshilova, Olesya,Dar'In, Dmitry,Krasavin, Mikhail
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p. 12722 - 12733
(2018/10/15)
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- Direct Synthesis of Amides by Dehydrogenative Coupling of Amines with either Alcohols or Esters: Manganese Pincer Complex as Catalyst
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The first example of base-metal-catalysed synthesis of amides from the coupling of primary amines with either alcohols or esters is reported. The reactions are catalysed by a new manganese pincer complex and generate hydrogen gas as the sole byproduct, thus making the overall process atom-economical and sustainable.
- Kumar, Amit,Espinosa-Jalapa, Noel Angel,Leitus, Gregory,Diskin-Posner, Yael,Avram, Liat,Milstein, David
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supporting information
p. 14992 - 14996
(2017/10/25)
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- Mechanochemical lignin-mediated strecker reaction
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A mechanochemical Strecker reaction involving a wide range of aldehydes (aromatic, heteroaromatic and aliphatic), amines, and KCN afforded a library of α-aminonitriles upon mechanical activation. This multicomponent process was efficiently activated by li
- Dabral, Saumya,Turberg, Mathias,Wanninger, Andrea,Bolm, Carsten,Hernández, José G.
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- Transition-Metal-Controlled Inorganic Ligand-Supported Non-Precious Metal Catalysts for the Aerobic Oxidation of Amines to Imines
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Most state-of-art transition-metal catalysts usually require organic ligands, which are essential for controlling the reactivity and selectivity of reactions catalyzed by transition metals. However, organic ligands often suffer from severe problems including cost, toxicity, air/moisture sensitivity, and being commercially unavailable. Herein, we show a simple, mild, and efficient aerobic oxidation procedure of amines using inorganic ligand-supported non-precious metal catalysts 1, (NH4)n[MMo6O18(OH)6] (M=Cu2+; Fe3+; Co3+; Ni2+; Zn2+, n=3 or 4), synthesized by a simple one-step method in water at 100 °C, demonstrating that the catalytic activity and selectivity can be significantly improved by changing the central metal atom. In the presence of these catalysts, the catalytic oxidation of primary and secondary amines, as well as the coupling of alcohols and amines, can smoothly proceed to afford various imines with O2 (1 atm) as the sole oxidant. In particular, the catalysts 1 have transition-metal ion core, and the planar arrangement of the six MoVI centers at their highest oxidation states around the central heterometal can greatly enhance the Lewis acidity of catalytically active sites, and also enable the electrons in the center to delocalize onto the six edge-sharing MO6 units, in the same way as ligands in traditional organometallic complexes. The versatility of this methodology maybe opens a path to catalytic oxidation through inorganic ligand-coordinated metal catalysis.
- Yu, Han,Zhai, Yongyan,Dai, Guoyong,Ru, Shi,Han, Sheng,Wei, Yongge
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supporting information
p. 13883 - 13887
(2017/10/13)
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- Dual Heterogeneous Catalyst Pd-Au@Mn(II)-MOF for One-Pot Tandem Synthesis of Imines from Alcohols and Amines
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A new Mn(II) metal-organic framework (MOF) 1 was synthesized by the combination of 4,4,4-trifluoro-1-(4-(pyridin-4-yl)phenyl)butane-1,3-dione (L) and Mn(OAc)2 in solution. 1 features a threefold-interpenetrating NbO net containing honeycomb-like channels, in which the opposite Mn(II)···Mn(II) distance is 23.5075(10) ?. Furthermore, 1 can be an ideal platform to support Pd-Au bimetallic alloy nanoparticles to generate a composite catalytic system of Pd-Au@Mn(II)-MOF (2). 2 can be a highly active bifunctional heterogeneous catalyst for the one-pot tandem synthesis of imines from benzyl alcohols and anilines and from benzyl alcohols and benzylamines.
- Chen, Gong-Jun,Ma, Hui-Chao,Xin, Wen-Ling,Li, Xiao-Bo,Jin, Fa-Zheng,Wang, Jing-Si,Liu, Ming-Yang,Dong, Yu-Bin
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supporting information
p. 654 - 660
(2017/01/13)
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- A metallopeptoid as an efficient bioinspired cooperative catalyst for the aerobic oxidative synthesis of imines
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Enzymatic catalysis is largely based on intramolecular cooperativity between a metal center and functional organic molecules located on one scaffold. Inspired by this concept we have designed the metallopeptoid trimer BT, which is a unique intramolecular cooperative oxidation catalyst incorporating two catalytic centers, phenanthroline-copper and TEMPO, as well as one non-catalytic benzyl group. Herein we explore the capability of BT to act as an efficient catalyst for the oxidative synthesis of imines, which are versatile intermediates in the fine chemicals and pharmaceutical industries. We demonstrate that BT, combined with CuI, can catalyze the production of benzyl, aryl, heteroaryl, allylic and aliphatic imines from various alcohols and amines with a turn-over-number up to 45 times higher than this achieved when phenanthroline, copper and TEMPO are mixed in solution. Moreover, in low catalyst(s) loading, BT enables transformations that are not possible when a mixture of the individual catalysts is employed.
- Chandra Mohan, Darapanani,Sadhukha, Arghya,Maayan, Galia
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p. 139 - 144
(2017/10/16)
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- Aerobic oxidative coupling of alcohols and amines towards imine formation by a dicopper(I,I) catalyst
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A dicopper(I,I) complex [Cu2(L1) (Cl)2] (1), bearing a Cu2Cl2 core spanned by a naphthyridine–diimine ligand is synthesized by the treatment of CuCl with 2,7–bis(N–mesitylmethylimino)–1,8–naphthyridine (L1). The catalytic efficacy of 1 is assessed for aerobic oxidative synthesis of imines from alcohols and amines. The title complex is found to be an excellent catalyst for a wide variety of alcohols and amines. Kinetic experiments revealed the involvement of both copper ions in the aerobic oxidation process. The general utility of naphthyridine based ligands to favour a possible bimetallic pathway for a catalytic reaction is demonstrated here.
- Dutta, Indranil,De, Subhabrata,Yadav, Sudhir,Mondol, Ranajit,Bera, Jitendra K.
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p. 117 - 124
(2017/09/30)
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- A Metal-Free Approach to 1,2-Diamines via Visible Light-Driven Reductive Coupling of Imines with Perylene as a Photoredox Catalyst
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A simple, metal-free, and versatile approach to 1,2-diamines has been developed based on reductive coupling reactions of various imines, where perylene, an aromatic hydrocarbon, was used as a photoredox catalyst under visible light irradiation using a white light-emitting diode. The use of 1 mol % perylene enabled almost complete conversion of the imines, leading to the formation of their corresponding 1,2-diamines, which were isolated in good yields. The ratios between dl and meso diamines ranged from 31:69 to 82:18 depending on the substituents of the imines.
- Okamoto, Shusuke,Ariki, Risako,Tsujioka, Hiroki,Sudo, Atsushi
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p. 9731 - 9736
(2017/09/23)
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- Polarity-Reversed Allylations of Aldehydes, Ketones, and Imines Enabled by Hantzsch Ester in Photoredox Catalysis
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The polarity reversal (umpolung) reaction is an invaluable tool for reversing the chemical reactivity of carbonyl and iminyl groups, which subsequent cross-coupling reactions to form C?C bonds offers a unique perspective in synthetic planning and implementation. Reported herein is the first visible-light-induced polarity-reversed allylation and intermolecular Michael addition reaction of aldehydes, ketones, and imines. This chemoselective reaction has broad substrate scope and the engagement of alkyl imines is reported for the first time. The mechanistic investigations indicate the formation of ketyl (or α-aminoalkyl) radicals from single-electron reduction, where the Hantzsch ester is crucial as the electron/proton donor and the activator.
- Qi, Li,Chen, Yiyun
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supporting information
p. 13312 - 13315
(2016/10/30)
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- Trans-Symmetric Dynamic Covalent Systems: Connected Transamination and Transimination Reactions
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The development of chemical transaminations as a new type of dynamic covalent reaction is described. The key 1,3-proton shift is under complete catalytic control and can be conducted orthogonally to, or simultaneous with, transimination in the presence of an amine to rapidly yield two-dimensional dynamic systems with a high degree of complexity evolution. The transamination-transimination systems are proven to be fully reversible, stable over several days, compatible with a range of functional groups, and highly tunable. Kinetic studies show transamination to be the rate-limiting reaction in the network. Furthermore, it was discovered that readily available quinuclidine is a highly potent catalyst for aldimine transaminations. This study demonstrates how connected dynamic reactions give rise to significantly larger systems than the unconnected counterparts, and shows how reversible isomerizations can be utilized as an effective diversity-generating element. Constant exchange: The development of chemical transaminations as a new type of dynamic covalent reactions is described (see figure). This study demonstrates how connected dynamic reactions give rise to significantly larger systems than the unconnected counterparts, and shows how reversible isomerizations can be utilized as an effective diversity-generating element.
- Schaufelberger, Fredrik,Hu, Lei,Ramstr?m, Olof
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p. 9776 - 9783
(2015/06/30)
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- Factors influencing the regioselectivity of the oxidation of asymmetric secondary amines with singlet oxygen
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Aerobic amine oxidation is an attractive and elegant process for the α functionalization of amines. However, there are still several mechanistic uncertainties, particularly the factors governing the regioselectivity of the oxidation of asymmetric secondary amines and the oxidation rates of mixed primary amines. Herein, it is reported that singlet-oxygen-mediated oxidation of 1° and 2° amines is sensitive to the strength of the α-C-H bond and steric factors. Estimation of the relative bond dissociation energy by natural bond order analysis or by means of one-bond C-H coupling constants allowed the regioselectivity of secondary amine oxidations to be explained and predicted. In addition, the findings were utilized to synthesize highly regioselective substrates and perform selective amine cross-couplings to produce imines.
- Ushakov, Dmitry B.,Plutschack, Matthew B.,Gilmore, Kerry,Seeberger, Peter H.
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supporting information
p. 6528 - 6534
(2015/04/22)
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- Visible light-induced selective photocatalytic aerobic oxidation of amines into imines on Cu/graphene
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Graphene can stabilize metallic copper nanoparticles and enable them to exhibit excellent photocatalytic activity for aerobic oxidation of various primary and secondary amines into the corresponding imines. The copper nanoparticles stabilized on graphene absorb the energy of visible light via localized surface plasmon resonance, and produce energetic hot electrons that activate the reactants adsorbed on the surface of copper nanoparticles. The formation of imines involves selective oxygenation of amines to aldehydes and subsequent condensation with amines to form imines.
- Zhai, Zhao-Yang,Guo, Xiao-Ning,Jin, Guo-Qiang,Guo, Xiang-Yun
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p. 4202 - 4207
(2015/08/03)
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- Size of gold nanoparticles driving selective amide synthesis through aerobic condensation of aldehydes and amines
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Metal nanoparticles (NPs) have attracted much attention in many fields due to their intrinsic characteristics. It is generally accepted that smaller NPs (1.5-3 nm) are more active than larger NPs, and reverse cases are very rare. We report here the direct aerobic oxidative amide synthesis from aldehydes and amines catalyzed by polymer-incarcerated gold (Au) NPs. A unique correlation between imine/amide selectivity and size of NPs was discovered; Au-NPs of medium size (4.5-11 nm) were found to be optimal. High yields were obtained with a broad range of substrates, including primary amines. Au-NPs of medium size could be recovered and reused several times without loss of activity, and they showed good activity and selectivity in amide formation from alcohols and amines. Superior activity and selectivity of gold nanoparticles (Au-NPs) of medium size (4.5-11 nm) were found for the direct and selective aerobic oxidative amide synthesis from various combinations of aldehydes and amines. This is an example of an unusual correlation between the size of NPs and their activity/selectivity. These catalysts could be recovered and reused several times without loss of activity.
- Miyamura, Hiroyuki,Min, Hyemin,Soulé, Jean-Fran?ois,Kobayashi, Shu
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supporting information
p. 7564 - 7567
(2015/06/25)
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- Facile synthesis of litchi shaped cuprous oxide and its application in the aerobic oxidative synthesis of imines
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In the present work, uniform litchi shaped cuprous oxide (Cu2O) nanoaggregates were synthesized via a facile method by employing copper(ii) chloride, sodium hydroxide, ethylene glycol and ascorbic acid in the absence of surfactants at room temperature. With further increase of the reaction temperature, broken hollow copper nanoaggregates were obtained. The structure of a Cu2O nanoaggregate was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Transmission Electron Microscopy (TEM), Brunauer-Emmett-Teller (BET) analysis and High Resolution Transmission Electron Microscopy (HRTEM). The as-obtained Cu2O nanoaggregates showed efficient catalytic activities in the aerobic oxidative synthesis of imines.
- Bai, Lei,Dang, Zheng
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p. 10341 - 10345
(2015/02/05)
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- Palladium-catalyzed [4 + 2] cycloaddition of aldimines and 1,4-dipolar equivalents via amphiphilic allylation
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The combination of Pd catalyst and diethylzinc with triethylborane promotes the amphiphilic allylation of aldimines with 2,3-bismethylenebutane-1,4-diol derivatives to serve as bis-allylic zwitterion species to form 3,4-bismethylenepiperidines via a formal [4 + 2] cycloaddition reaction. 3,4-Bismethylenepiperidine rings are applicable for the synthesis of isoquinoline derivatives via the Diels-Alder reaction followed by an oxidation reaction with DDQ.
- Hirata, Goki,Yamada, Naoshi,Sanada, Shohei,Onodera, Gen,Kimura, Masanari
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supporting information
p. 600 - 603
(2015/03/04)
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- Lanthanide coordination polymer constructed from 2,2′-bipyridyl-4,4′-dicarboxylic acid: Structure, catalysis and fluorescence
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Two new isostructural lanthanide coordination polymers (Ln-CPs) [Ln2(bpdc)3(DMF)2] (Ln = Tb for 1, Eu for 2) with two kinds of one-dimensional channels along the a axis, were synthesized by 2,2′-bipyridyl-4,4′-dicarboxylic acid (H2bpdc) under solvothermal conditions. With exposed Lewis acid Ln3+ centers, 1 as a heterogeneous catalyst shows good catalytic reactivity and selectivity for the Strecker reaction affording medium to excellent conversion yields. Luminescent studies illustrate that 1 and 2 show intensive green and red luminescence triggered by efficient antenna effect of ligands under UV light, respectively. Moreover, 1 exhibits sensitive fluorescent response to Cu2+ in DMF solution.
- Wang, Shengyan,Xu, Jianing,Zheng, Jifu,Chen, Xiaodong,Shan, Liang,Gao, Lijuan,Wang, Li,Yu, Miao,Fan, Yong
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supporting information
p. 81 - 86
(2015/09/15)
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- IBX works efficiently under solvent free conditions in ball milling
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IBX (2-iodoxybenzoic acid), discovered in 1893, is an oxidant in synthetic chemistry whose extensive use is impeded by its explosiveness at high temperature and poor solubility in common organic solvents except DMSO. Since the discovery of Dess-Martin Periodinane in 1983, several modified IBX systems have been reported. However, under ball milling conditions, IBX works efficiently with various organic functionalities at ambient temperature under solvent free conditions. Also, the waste IBA (2-iodosobenzoic acid) produced from the reactions was in situ oxidized to IBX in the following step using oxone and thus reused for multiple cycles by conserving its efficiency (only ~6% loss after 15 cycles). This work describes an overview of a highly economical synthetic methodology which overcomes the problems of using IBX, efficiently in gram scale and in a non-explosive way. This journal is the Partner Organisations 2014.
- Achar, Tapas Kumar,Maiti, Saikat,Mal, Prasenjit
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p. 12834 - 12839
(2014/04/03)
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- Catalytic activity of MCM-41 and Al grafted MCM-41 for oxidative self and cross coupling of amines
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The catalytic activity of MCM-41 mesoporous silica (MS) and Al grafted MCM-41 (Al-MS) with varied amount of Al were studied for oxidative self and cross coupling of benzyl amines to imines. The role of Al, its amount, acidity of the catalyst, effect of reaction conditions (especially presence of solvent and excess air) and amines nature on the oxidative coupling reactions were investigated. Surface OH groups play an effective role in amine activation by hydrogen bonding, whereas the acid sites generated by incorporation of optimum amount of Al further improve the activity. The Al in optimum amount (Si/Al: 20) showed good catalytic activity in self coupling of benzyl amine as compared to MS and Al-MS with high Al loading. A suitable polar solvent and presence of excess air significantly promote the activity of MS and Al-MS for amine coupling reactions. The MS without Al was also found to be efficient catalyst for oxidative self and cross coupling of amines. The presence of Al in Al-MS (in optimum amount, i.e., Si/Al: 20) made the self coupling of benzyl amine faster than MS, whereas the cross coupling reactions with Al-MS were observed to be slightly slower than MS, which is probably due to competitive adsorption of amine substrate and amine nucleophile over acidic sites. The activity of MS and Al-MS catalysts for self and cross coupling reactions was also dependent of the amines nature (basicity and nucleophilicity).
- Tayade, Kamlesh N.,Mishra, Manish
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p. 114 - 125
(2014/01/06)
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- Morphology-tuned exceptional catalytic activity of porous-polymer-supported Mn3O4 in aerobic sp3 C-H bond oxidation of aromatic hydrocarbons and alcohols
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Mn3O4 nanomaterials with different morphologies (sphere, nanowire, and octahedron) embedded into functionalized nanoporous polymers were developed by a facile one-pot solvothermal technique at different temperatures. These Mn3O4-based hybrid materials could behave as heterogeneous nanocatalysts to perform sp3 C-H bond oxidation of aromatic hydrocarbons and alcohols with molecular oxygen as an economic oxidant. Catalytic activity could be effectively tuned by changing the morphology of incorporated Mn3O4 in nanoporous polymer. These Mn3O4-based hybrid materials exhibited remarkable catalytic performance for sp3 C-H bond oxidation as compared with bare Mn3O4 nanoparticles. Mn3O4 with octahedral morphology in nanoporous polymer exhibited the highest catalytic activity on account of its more exposed crystallographic planes and edges. These Mn3O4-based nanocatalysts could be recycled and reused for consecutive catalytic cycles without a significant loss of catalytic activity. Exceptional crystal facets: Nanoporous-polymer-supported Mn3O4 nanocatalysts (Mn@DVTA, DVTA=divinyltriallyl) with different morphologies are developed to catalyze aerobic sp3 C-H bond oxidation of aromatic hydrocarbons and alcohols. Among the different nanocatalysts, those with octahedral crystallite morphology exhibit outstanding catalytic performance.
- Mondal, John,Borah, Parijat,Sreejith, Sivaramapanicker,Nguyen, Kim Truc,Han, Xiguang,Ma, Xing,Zhao, Yanli
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p. 3518 - 3529
(2015/04/16)
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- Metal-Ligand cooperation on a diruthenium platform: Selective imine formation through acceptorless dehydrogenative coupling of alcohols with amines
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Metal-metal singly-bonded diruthenium complexes, bridged by naphthyridine-functionalized N-heterocyclic carbene (NHC) ligands featuring a hydroxy appendage on the naphthyridine unit, are obtained in a single-pot reaction of [Ru2(CH3COO)2(CO)4] with 1-benzyl-3-(5,7-dimethyl-1,8-naphthyrid-2-yl)imidazolium bromide (BIN-HBr) or 1-isopropyl-3-(5,7-dimethyl-1,8-naphthyrid-2-yl)imidazolium bromide (PIN-HBr), TlBF4, and substituted benzaldehyde containing an electron-withdrawing group. The modified NHC-naphthyridine-hydroxy ligand spans the diruthenium unit in which the NHC carbon and hydroxy oxygen occupy the axial sites. All the synthesized compounds catalyze acceptorless dehydrogenation of alcohols to the corresponding aldehydes in the presence of a catalytic amount of weak base 1,4-diazabicyclo[2.2.2]octane (DABCO). Further, acceptorless dehydrogenative coupling (ADHC) of the alcohol with amines affords the corresponding imine as the sole product. The substrate scope is examined with 1 (BIN, p-nitrobenzaldehyde). A similar complex [Ru2(CO) 4(CH3COO)(3-PhBIN)][Br], that is devoid of a hydroxy arm, is significantly less effective for the same reaction. Neutral complex 1 a, obtained by deprotonation of the hydroxy arm in 1, is found to be active for the ADHC of alcohols and amines under base-free conditions. A combination of control experiments, deuterium labeling, kinetic Hammett studies, and DFT calculations support metal-hydroxyl/hydroxide and metal-metal cooperation for alcohol activation and dehydrogenation. The bridging acetate plays a crucial role in allowing β-hydride elimination to occur. The ligand architecture on the diruthenium core causes rapid aldehyde extrusion from the metal coordination sphere, which is responsible for exclusive imine formation. Ligand lends a hand: Metal-hydroxy/hydroxide and metal-metal cooperation is demonstrated for acceptorless dehydrogenation of alcohols to give aldehydes. The ligand architecture ensures rapid extrusion of the aldehyde from the metal core, resulting in the formation of the corresponding imine as the sole coupled product with amines (see scheme; DABCO=1,4-diazabicyclo[2.2.2]octane).
- Saha, Biswajit,Wahidurrahaman,Daw, Prosenjit,Sengupta, Gargi,Bera, Jitendra K.
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p. 6542 - 6551
(2014/06/09)
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- Pseudorotaxane orientational stereoisomerism driven by π-electron density
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Pseudo[2]rotaxane orientational isomers were formed in a stereocontrolled way by exploiting the electron-withdrawing (EW) or electron-donating (ED) effects of para-substituted dibenzylammonium axles threaded through the π-electron rich calixarene cavity, which allow the fine tuning of the weak π-π interactions.
- Gaeta, Carmine,Talotta, Carmen,Neri, Placido
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supporting information
p. 9917 - 9920
(2014/08/18)
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- Direct amidation from alcohols and amines through a tandem oxidation process catalyzed by heterogeneous-polymer-incarcerated gold nanoparticles under aerobic conditions
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We describe herein a highly elegant and suitable synthesis of amide products from alcohols and amines through a tandem oxidation process that uses molecular oxygen as a terminal oxidant. Carbon-black-stabilized polymer-incarcerated gold (PICB-Au) or gold/cobalt (PICB-Au/Co) nanoparticles were employed as an efficient heterogeneous catalyst depending on alcohol reactivity and generated only water as the major co-product of the reaction. A wide scope of substrate applicability was shown with 42 examples. The catalysts could be recovered and reused without loss of activity by using a simple operation. Gold standard: A highly efficient green method for amide synthesis from alcohols and amines catalyzed by gold nanoparticles stabilized by styrene-based copolymers has been developed (see scheme). Two catalysts have been used with high selectivity depending on the combination of substrates. These Au nanoparticle catalysts can be recovered and reused several times by simple operations. Copyright
- Soule, Jean-Francois,Miyamura, Hiroyuki,Kobayashi, Shu
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supporting information
p. 2614 - 2626
(2013/11/19)
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- Selective imine formation from alcohols and amines catalyzed by polymer incarcerated gold/palladium alloy nanoparticles with molecular oxygen as an oxidant
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Carbon black stabilized, polymer incarcerated gold/palladium alloy nanoparticles (PICB-Au/Pd) act as an efficient, reusable heterogeneous catalyst for imine synthesis from alcohols and amines through a tandem oxidative process using molecular oxygen as the terminal oxidant.
- Soule, Jean-Francois,Miyamura, Hiroyuki,Kobayashi, Shu
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supporting information
p. 355 - 357
(2013/02/23)
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- Bifunctional ruthenium(II) PCP pincer complexes and their catalytic activity in acceptorless dehydrogenative reactions
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New air-stable ruthenium complex 1, bearing the dibenzobarrelene-based cooperating ligand, was synthesized in 96% yield and fully characterized. The examination of its coordination chemistry revealed that the ruthenium center in 1 is slightly distorted from octahedral geometry, and 31P NMR is consistent with the formation of trans-spanned pincer complexes bearing strongly bent dibenzobarrelene-based ligands. The catalytic activity of the new complex was examined in acceptorless dehydrogenation of alcohols and acceptorless dehydrogenative coupling of alcohols with amines.
- Musa, Sanaa,Fronton, Sveta,Vaccaro, Luigi,Gelman, Dmitri
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p. 3069 - 3073
(2013/07/05)
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- Iron-catalyzed efficient synthesis of amides from aldehydes and amine hydrochloride salts
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A practical and efficient method for the synthesis of amides has been developed by iron-catalysed oxidative amidation of aldehydes with amine hydrochloride salts. A wide range of amides have been obtained in good to excellent yields under mild conditions. The application of this novel amide formation reaction to the synthesis of pharmaceutical compounds has been successfully demonstrated. Copyright
- Ghosh, Subhash Chandra,Ngiam, Joyce S. Y.,Chai, Christina L. L.,Seayad, Abdul M.,Dang, Tuan Thanh,Chen, Anqi
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body text
p. 1407 - 1412
(2012/07/13)
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- Direct reductive amination of aldehydes using lithium-arene(cat.) as reducing system. A simple one-pot procedure for the synthesis of secondary amines
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A simple one-pot procedure for the direct reductive amination of aldehydes using lithium powder and a catalytic amount of 4,4′-di-tert-butylbiphenyl (DTBB) or a polymer supported naphthalene as reducing system is described. The direct reductive amination of a variety of aldehydes with primary amines was achieved simply by adding a mixture of the corresponding carbonyl compound and the amine, over a solution of the lithium arenide in THF at room temperature. For most of the substrates tested the main reaction products were the secondary amines along with variable amounts of the corresponding alcohol and/or imine products. Theoretical DFT calculations have been applied in order to explain the differences in reactivity observed for aromatic substrates.
- Nador, Fabiana,Moglie, Yanina,Ciolino, Andrés,Pierini, Adriana,Dorn, Viviana,Yus, Miguel,Alonso, Francisco,Radivoy, Gabriel
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experimental part
p. 3156 - 3160
(2012/08/08)
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- Ni-Cu/γ-Al2O3 catalyzed N-alkylation of amines with alcohols
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A γ-Al2O3 supported Ni and Cu bimetallic nanoparticles catalyst (45 wt.% Ni, Ni/Cu mass ratio = 4.5/1.0) is prepared by electroless plating method for the N-alkylation of amines with alcohols under base and Lewis acidic cocatalyst conditions. The catalyst afforded fast conversions, high selectivity for amines and alcohols with various structures under an Ar atmosphere in o-xylene. Furthermore, catalyst still has a stable catalytic activity after two consecutive cycles regenerated.
- Sun, Jian,Jin, Xiaodong,Zhang, Fengwei,Hu, Wuquan,Liu, Juntao,Li, Rong
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experimental part
p. 30 - 33
(2012/07/17)
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