- An insight into the synthesis, crystal structure, geometrical modelling of crystal morphology, Hirshfeld surface analysis and characterization of N-(4-methylbenzyl)benzamide single crystals
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A versatile approach for the synthesis of N-(4-methylbenzyl)benzamide, C15H15NO, using CuI as catalyst has been reported. Single crystals of the synthesized compound were grown using the slow evaporation solution technique. The crystal structure of the N-(4-methylbenzyl)benzamide crystals has been determined by single-crystal X-ray diffraction. The compound crystallizes in an orthorhombic lattice, noncentrosymmetric space group Pna21. The crystal structure is stabilized by intermolecular N-H?O hydrogen bonds and weak C-H?π interactions to form layers parallel to the a axis. A user-friendly approach based on centre of mass propagation vector theory was used to predict the crystal morphology. The framework developed here utilizes the concept of intermolecular bond strength to discern the crystal morphology. Fourier transform IR, NMR and high-resolution mass spectrometry analytical techniques were used for the identification of functional groups and confirmation of the structure of the title compound. All of the intermolecular interactions present in the crystal structure, including the C-H?π, C-H?O and N-H?O interactions, were investigated and confirmed by molecular Hirshfeld surface analysis. From linear optical spectroscopy, the transmittance, optical band gap and UV cutoff wavelength were determined. The photoluminescence emission spectrum was recorded for a grown crystal. Dielectric measurements were performed at room temperature for various frequencies. The mechanical strength of the (001) plane of the title compound was measured using the Vickers micro-hardness technique. A piezo-coefficient of 15pCN-1 was found along the (001) plane of the title crystals. The thermal stability and melting point were also investigated. In addition, density functional theory simulations were used to calculate the optimized molecular geometry and the UV-vis spectrum, and to determine the highest occupied molecular orbital/lowest unoccupied molecular orbital energy gap. The results show that N-(4-methylbenzyl)benzamide is a potential candidate for multifunctional optical and piezoelectric crystals.
- Goel, Sahil,Yadav, Harsh,Singh, Nidhi,Singh, Budhendra,Bdikin, Igor,Rao, Devarapalli Chenna,Gopalaiah, Kovuru,Kumar, Binay
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- Acetonitrile and benzonitrile as versatile amino sources in copper-catalyzed mild electrochemical C-H amidation reactions
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A mild, efficient electrochemical approach to the site-selective direct C-H amidation of benzene and its derivatives with acetonitrile and benzonitrile has been developed. It has been shown that joint electrochemical oxidation of various arenes in the presence of a copper salt as a catalyst and nitriles leads to the formation of N-phenylacetamide from benzene and N-benzylacetamides from benzyl derivatives (up to 78% yield). A favorable feature of the process is mild conditions (room temperature, ambient pressure, no strong oxidants) that meet the criteria of green chemistry.
- Budnikova, Yulia,Kononov, Alexander,Rizvanov, Ildar,Strekalova, Sofia
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p. 37540 - 37543
(2021/12/07)
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- Reductive N-alkylation of primary amides using nickel-nanoparticles
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Here we report Ni-nanoparticles as reusable catalysts for reductive N-alkylation of amides. These Ni-nanoparticles based catalysts have been prepared by the template synthesis of tartaric acid and 2-methyl imidazole ligated Ni-complex on SiO2 and subsequent pyrolysis under argon. Applying optimal Ni-nanostructured catalyst, N-alkylation of aromatic and heterocyclic primary amides with different aldehydes in presence of molecular hydrogen was performed to access structurally diverse N-alkylated amides in good to excellent yields. In addition, the applicability of this N-alkylation protocol has been demonstrated for the selective functionalization of primary amide group in Levetiracetam drug.
- Alenad, Asma M.,Alshammari, Ahmad S.,Jagadeesh, Rajenahally V.,Murugesan, Kathiravan,Sohail, Manzar
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- Silver-Catalyzed Hydroboration of C-X (X = C, O, N) Multiple Bonds
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AgSbF6 was developed as an effective catalyst for the hydroboration of various unsaturated functionalities (nitriles, alkenes, and aldehydes). This atom-economic chemoselective protocol works effectively under low catalyst loading, base- A nd solvent-free moderate conditions. Importantly, this process shows excellent functional group tolerance and compatibility with structurally and electronically diverse substrates (>50 examples). Mechanistic investigations revealed that the reaction proceeds via a radical pathway. Further, the obtained N,N-diborylamines were showcased to be useful precursors for amide synthesis.
- Pandey, Vipin K.,Tiwari, Chandra Shekhar,Rit, Arnab
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supporting information
p. 1681 - 1686
(2021/03/03)
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- Dehydrogenative amide synthesis from alcohols and amines utilizing N-heterocyclic carbene-based ruthenium complexes as efficient catalysts: The influence of catalyst loadings, ancillary and added ligands
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The metal-catalyzed dehydrogenative coupling of alcohols and amines to access amides has been recognized as an atom-economic and environmental-friendly process. Apart from the formation of the amide products, three other kinds of compounds (esters, imines and amines) may also be produced. Therefore, it is of vital importance to investigate product distribution in this transformation. Herein, N-heterocyclic carbene-based Ru (NHC/Ru) complexes [Ru-1]-[Ru-5] with different ancillary ligands were prepared and characterized. Based on these complexes, we selected condition A (without an added NHC precursor) and condition B (with an added NHC precursor) to comprehensively explore the selectivity and yield of the desired amides. After careful evaluation of various parameters, the Ru loadings, added NHC precursors and the electronic/steric properties of ancillary NHC ligands were found to have considerable influence on this catalytic process.
- Wang, Wan-Qiang,Wang, Zhi-Qin,Sang, Wei,Zhang, Rui,Cheng, Hua,Chen, Cheng,Peng, Da-Yong
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- Direct synthesis of amides and imines by dehydrogenative homo or cross-coupling of amines and alcohols catalyzed by Cu-MOF
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Oxidative dehydrogenative homo-coupling of amines to imines and cross-coupling of amines with alcohols to amides was achieved with high to moderate yields at room temperature in THF using Cu-MOF as an efficient and recyclable heterogeneous catalyst under mild conditions. Different primary benzyl amines and alcohols could be utilized for the synthesis of a wide variety of amides and imines. The Cu-MOF catalyst could be recycled and reused four times without loss of catalytic activity.
- Anbardan, Soheil Zamani,Bozcheloei, Abolfazl Hassani,Mokhtari, Javad,Yari, Ahmad
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p. 20788 - 20793
(2021/07/01)
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- 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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- An unprecedented cobalt-catalyzed selective aroylation of primary amines with aroyl peroxides
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A novel and facile cobalt-catalyzed selective aroylation of primary amines with aroyl peroxides was developed for the synthesis of aryl amides. It was unprecedented that C[sbnd]N bond formation product was selectively generated without the common N[sbnd]O bond formation product. Aroyl peroxides act as the sole aroylation reagent without additional base or oxidant. The reactions proceeded under mild conditions and showed broad substrates scope with a series of primary amines and aroyl peroxides.
- Li, Dong,Li, Jiale,Li, Juanjuan,Yuan, Songdong,Zhang, Qian
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supporting information
(2020/09/16)
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- Triethyl Phosphite/Benzoyl Peroxide Mediated Reductive Dealkylation of O-Benzoylhydroxylamines: A Cascade Synthesis of Secondary Amides
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A new triethyl phosphite/benzoyl peroxide (BPO) mediated system has been developed for the synthesis of secondary amides with good to excellent yields in a single step. This unprecedented cascade process involves sequential reduction of N–O bond and benzoylation followed by dealkylation of N–C bond of O-benzoylhydroxylamines (O-BHA). The methodology is versatile as it tolerates a variety of aromatic and aliphatic O-BHA as substrates to access secondary amides.
- Aegurla, Balakrishna,Mandle, Ram D.,Shinde, Prasad G.,Parit, Ratan S.,Kamble, Sanjay P.,Sudalai, Arumugam,Senthilkumar, Beeran
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supporting information
p. 4235 - 4238
(2020/07/04)
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- Graphene oxide: A convenient metal-free carbocatalyst for facilitating amidation of esters with amines
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Herein, we report a graphene oxide (GO) catalyzed condensation of non-activated esters and amines, that can enable diverse amides to be synthesized from abundant ethyl esters forming only volatile alcohol as a by-product. GO accelerates ester to amide conversion in the absence of any additives, unlike other catalysts. A wide range of ester and amine substrates are screened to yield the respective amides in good to excellent yields. The improved catalytic activity can be ascribed to the oxygenated functionalities present on the graphene oxide surface which forms H-bonding with the reactants accelerating the reaction. Improved yields and a wide range of functional group tolerance are some of the important features of the developed protocol.
- Patel, Khushbu P.,Gayakwad, Eknath M.,Shankarling, Ganapati S.
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p. 2661 - 2668
(2020/02/20)
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- Direct amidation of non-activated carboxylic acid and amine derivatives catalyzed by TiCp2Cl2
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This paper described a mild and efficient direct amidation of non-activated carboxylic acid and amine derivatives catalyzed by TiCp2Cl2. Arylacetic acid derivatives reacted with different amines to afford the corresponding amides in good to excellent yield except of aniline. Aryl formic acids failed to react with aniline but smoothly reacted with aliphatic amines and benzylamine in moderate to good yield, fatty acids reacting with benzyl and aliphatic amines give amides in good to excellent yield. Chiral amino acids derivatives were transformed into amides without racemization in moderate yield. The possible mechanism of direct amidation catalyzed by TiCp2Cl2 was discussed. This catalytic method is very suitable for the amidation of low sterically hindered arylacetic acid, fatty acids with different low sterically hindered amines except aniline, as well as the amidation of aryl formic acid with benzyl and aliphatic amines.
- Wang, Hui,Dong, Wei,Hou, Zhipeng,Cheng, Lidan,Li, Xiufen,Huang, Longjiang
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- Microwave-assisted catalytic method for a green synthesis of amides directly from amines and carboxylic acids
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Amide bonds are among the most interesting and abundant molecules of life and products of the chemical pharmaceutical industry. In this work, we describe a method of the direct synthesis of amides from carboxylic acids and amines under solvent-free conditions using minute quantities of ceric ammonium nitrate (CAN) as a catalyst. The reactions are carried out in an open microwave reactor and allow the corresponding amides to be obtained in a fast and effective manner when compared to other procedures of the direct synthesis of amides from acids and amines reported so far in the literature. The amide product isolation procedure is simple, environmentally friendly, and is performed with no need for chromatographic purification of secondary amides due to high yields. In this report, primary amines were used in most examples. However, the developed procedure seems to be applicable for secondary amines as well. The methodology produces a limited amount of wastes, and a catalyst can be easily separated. This highly efficient, robust, rapid, solvent-free, and additional reagent-free method provides a major advancement in the development of an ideal green protocol for amide bond formation.
- Kolanowski, Jacek L.,Markiewicz, Wojciech T.,Zarecki, Adam P.
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supporting information
(2020/04/23)
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- Well-defined N-heterocyclic carbene/ruthenium complexes for the alcohol amidation with amines: The dual role of cesium carbonate and improved activities applying an added ligand
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Dehydrogenative amide bond formation from alcohols and amines has been regarded as an atom-economic and sustainable process. Among various catalytic systems, N-heterocyclic carbene (NHC)-based Ru catalytic systems have attracted growing interest due to the outstanding properties of NHCs as ligands. Herein, an NHC/Ru complex (1) was prepared and its structure was further confirmed with X-ray crystallography. In the presence of Cs2CO3, two NHC/Ru-based catalytic systems were disclosed to be active for this amide synthesis. System A, which did not contain any added ligand, required a catalyst loading of 1.00 mol%. Interestingly, improved catalytic performance was realized by the addition of an NHC precursor (L). Optimization of the amounts of L and other conditions gave rise to system B, a much more potent system with the Ru loading as low as 0.25 mol%. Moreover, an NHC-Ru-carbonate complex 6 was identified from the refluxing toluene of 1 and Cs2CO3, and further investigations revealed that 6 was an important intermediate for this catalytic reaction. Based on the above results, we claimed that the role of Cs2CO3 was to facilitate the formation of key intermediate 6. On the other hand, it provided the optimized basicity for the selective amide formation.
- Wang, Wan-Qiang,Yuan, Ye,Miao, Yang,Yu, Bao-Yi,Wang, Hua-Jing,Wang, Zhi-Qin,Sang, Wei,Chen, Cheng,Verpoort, Francis
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- The synthesis and structure of pyridine-oxadiazole iridium complexes and catalytic applications: Non-coordinating-anion-tuned selective C–N bond formation
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Several novel pyridine-oxadiazole iridium complexes were synthesized and characterized through X-ray crystallography. The designed iridium complexes revealed surprisingly high catalytic activity in C–N bondformation of amides and benzyl alcohols with the assistance of non-coordinating anions. In an attempt to achieve borrowing hydrogen reactions of amides with benzyl alcohols, N,N'-(phenylmethylene)dibenzamide products were unexpectedly isolated under non-coordinating anion conditions, whereas N-benzylbenzamide products were achieved in the absence of non-coordinating anions. The mechanism explorations excluded the possibility of “silver effect” (silver-assisted or bimetallic catalysis) and revealed that the reactivity of iridium catalyst was varied by non-coordinating anions. This work provided a convenient and useful methodology that allowed the iridium complex to be a chemoselective catalyst and demonstrated the first example of non-coordinating-anion-tuned selective C–N bond formation
- Yao, Wei,Zhang, Yilin,Zhu, Haiyan,Ge, Chenyang,Wang, Dawei
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p. 701 - 705
(2019/09/30)
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- Efficient Cobalt Catalyst for Ambient-Temperature Nitrile Dihydroboration, the Elucidation of a Chelate-Assisted Borylation Mechanism, and a New Synthetic Route to Amides
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N,N-Diborylamines have emerged as promising reagents in organic synthesis; however, their efficient preparation and full synthetic utility have yet to be realized. To address both shortcomings, an effective catalyst for nitrile dihydroboration was sought. Heating CoCl2 in the presence of PyEtPDI afforded the six-coordinate Co(II) salt, [(PyEtPDI)CoCl][Cl]. Upon adding 2 equiv of NaEt3BH, hydride transfer to one chelate imine functionality was observed, resulting in the formation of (κ4-N,N,N,N-PyEtIPCHMeNEtPy)Co. Single-crystal X-ray diffraction and density functional theory calculations revealed that this compound possesses a low-spin Co(II) ground state featuring antiferromagnetic coupling to a singly reduced imino(pyridine) moiety. Importantly, (κ4-N,N,N,N-PyEtIPCHMeNEtPy)Co was found to catalyze the dihydroboration of nitriles using HBPin with turnover frequencies of up to 380 h-1 at ambient temperature. Stoichiometric addition experiments revealed that HBPin adds across the Co-Namide bond to generate a hydride intermediate that can react with additional HBPin or nitriles. Computational evaluation of the reaction coordinate revealed that the B-H addition and nitrile insertion steps occur on the antiferromagnetically coupled triplet spin manifold. Interestingly, formation of the borylimine intermediate was found to occur following BPin transfer from the borylated chelate arm to regenerate (κ4-N,N,N,N-PyEtIPCHMeNEtPy)Co. Borylimine reduction is in turn facile and follows the same ligand-assisted borylation pathway. The independent hydroboration of alkyl and aryl imines was also demonstrated at 25 °C. With a series of N,N-diborylamines in hand, their addition to carboxylic acids allowed for the direct synthesis of amides at 120 °C, without the need for an exogenous coupling reagent.
- Ghosh, Chandrani,Kim, Suyeon,Mena, Matthew R.,Kim, Jun-Hyeong,Pal, Raja,Rock, Christopher L.,Groy, Thomas L.,Baik, Mu-Hyun,Trovitch, Ryan J.
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supporting information
p. 15327 - 15337
(2019/10/22)
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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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- A metal-free approach for the synthesis of amides/esters with pyridinium salts of phenacyl bromides via oxidative C–C bond cleavage
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An efficient, simple, and metal-free synthetic approach for the N- and O-benzoylation of various amines/benzyl alcohols with pyridinium salts of phenacyl bromides is demonstrated to generate the corresponding amides and esters. This protocol facilitates the oxidative cleavage of a C–C bond followed by formation of a new C–N/C–O bond in the presence of K2CO3. Various pyridinium salts of phenacyl bromides can be readily transformed into a variety of amides and esters which is an alternative method for the conventional amidation and esterification in organic synthesis. High functional group tolerance, broad substrate scope and operational simplicity are the prominent advantages of the current protocol.
- Manasa, Kesari Lakshmi,Tangella, Yellaiah,Krishna, Namballa Hari,Alvala, Mallika
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p. 1864 - 1871
(2019/08/12)
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- An efficient transformation of methyl ethers and nitriles to amides catalyzed by Iron(III) perchlorate hydrate
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An efficient and inexpensive synthesis of N-substituted amides from the reaction of nitriles with methyl ethers catalyzed by Fe(ClO4)3·H2O is described. Fe(ClO4)3·H2O is an economically efficient catalyst for the Ritter Reaction under solvent-free conditions. A range of methyl ethers (benzyl, sec-alkyl and tert-butyl ethers) were reacted with nitriles to provide the corresponding amides in high–excellent yields.
- Yin, Guibo,Yan, Bin,Chen, Junqing,Ji, Min
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p. 1355 - 1363
(2019/04/30)
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- Base-Promoted Amidation and Esterification of Imidazolium Salts via Acyl C-C bond Cleavage: Access to Aromatic Amides and Esters
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Imidazolium salts have been effectively employed as suitable acyl transfer agents in amidation and esterification in organic synthesis. The weak acyl C(O)-C imidazolium bond was exploited to generate acyl electrophiles, which further react with amines and alcohols to afford amides and esters. The broad substrate scope of anilines and benzylic amines and base-promoted conditions are the benefits of this route. Interestingly, phenol, benzylic alcohols, and a biologically active alcohol can also be subjected to esterification under the optimized conditions.
- Karthik, Shanmugam,Muthuvel, Karthick,Gandhi, Thirumanavelan
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p. 738 - 751
(2019/01/24)
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- FeCl2·4H2O catalyzed ritter reaction with nitriles and halohydrocarbons
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An efficient and inexpensive synthesis of N-substituted amides from the Ritter reaction of nitriles with various halohydrocarbons catalyzed by FeCl2·4H2O is described. FeCl2·4H2O economically efficiently catalyzed the Ritter reaction under solvent-free conditions. A range of halohydrocarbons (benzyl, tert-butyl and sec-alkyl halohydrocarbons) were coupled with nitriles to provide the corresponding amides in high to excellent yields.
- Feng, Cheng-Liang,Yin, Gui-Bo,Yan, Bin,Chen, Jun-Qing,Ji, Min
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p. 345 - 353
(2019/02/12)
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- Graphene Oxide: A Metal-Free Carbocatalyst for the Synthesis of Diverse Amides under Solvent-Free Conditions
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An environmentally friendly, inexpensive, carbocatalyst, graphene oxide (GO) promoted efficient, metal-free transamidation of various carboxamides with aliphatic, cyclic, and aromatic amines is demonstrated. The protocol is equally applicable to phthalimide, urea, and thioamide determining its adaptability. The oxygenated functionalities such as carbonyl (?C=O), epoxy (?O?), carboxyl (?COOH) and hydroxyl (?OH), present on graphene oxide surface impart acidic properties to the catalyst. The graphene oxide being heterogeneous in nature, work efficiently under solvent-free reaction conditions providing desired products in good to excellent yields. The one-pot synthesis of 2,3-Dihydro-5H-benzo[b]-1,4-thiazepin-4-one moiety by GO catalyzed Aza Michael addition followed by intramolecular transamidation is also described. A plausible reaction mechanistic pathway involving H-bonding is discussed. The graphene oxide can be recycled and reused up to five cycles without much loss in catalytic activity. (Figure presented.).
- Patel, Khushbu P.,Gayakwad, Eknath M.,Patil, Vilas V.,Shankarling, Ganapati S.
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supporting information
p. 2107 - 2116
(2019/03/26)
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- An open-source approach to automation in organic synthesis: The flow chemical formation of benzamides using an inline liquid-liquid extraction system and a homemade 3-axis autosampling/product-collection device
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Several open-source hardware and software technologies (RAMPS, Python, PySerial, OpenCV) were used to control an automated flow chemical synthesis system. The system was used to effect the synthesis of a series of benzamides. An inexpensive Raspberry Pi single board computer provided an electronic interface between the control computer and the RAMPS motor driver boards.
- O'Brien, Matthew,Hall, April,Schrauwen, John,van der Made, Joyce
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supporting information
p. 3152 - 3157
(2018/03/21)
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- Highly Efficient Copper-Catalyzed Amidation of Benzylic Hydrocarbons Under Neutral Conditions
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A ligand free method has been developed for the amidation of benzylic hydrocarbons. A range of benzylic amides has been prepared with the use of dicumyl peroxide and a copper catalyst in good to excellent yields.
- Howard, Eva-Louise,Guzzardi, Norman,Tsanova, Viliyana G.,Stika, Angeliki,Patel, Bhaven
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supporting information
p. 794 - 797
(2018/02/21)
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- Fe(ClO 4) 3 ·h 2 O-Catalyzed Ritter Reaction: A Convenient Synthesis of Amides from Esters and Nitriles
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An efficient and inexpensive synthesis of N-substituted amides from the Ritter reaction of nitriles with esters catalyzed by Fe(ClO 4) 3 ·H 2 O is described. Fe(ClO 4) 3 ·H 2 O is an economically efficient catalyst for the Ritter reaction under solvent-free conditions. Reactions of a range of esters (benzyl, sec-alkyl, and tert-butyl esters) with nitriles (primary, secondary, tertiary, and aryl nitriles) were performed to provide the corresponding amides in high to excellent yields.
- Feng, Chengliang,Yan, Bin,Yin, Guibo,Chen, Junqing,Ji, Min
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p. 2257 - 2264
(2018/10/20)
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- Convenient synthesis of amides by Zn(ClO4)2·6H2O catalysed Ritter reaction with nitriles and halohydrocarbons
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A convenient and high yielding procedure for the synthesis of amides by the Ritter reaction of nitriles and halohydrocarbons in the presence of Zn(ClO4)2·6H2O as a highly stable, effective and available catalyst is described.
- Feng, Chengliang,Yin, Guibo,Yan, Bin,Chen, Junqing,Ji, Min
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supporting information
p. 383 - 386
(2018/08/21)
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- Tetramethyl Orthosilicate (TMOS) as a Reagent for Direct Amidation of Carboxylic Acids
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Tetramethyl orthosilicate (TMOS) is shown to be an effective reagent for direct amidation of aliphatic and aromatic carboxylic acids with amines and anilines. The amide products are obtained in good to quantitative yields in pure form directly after workup without the need for any further purification. A silyl ester as the putative activated intermediate is observed by NMR methods. Amidations on a 1 mol scale are demonstrated with a favorable process mass intensity.
- Braddock, D. Christopher,Lickiss, Paul D.,Rowley, Ben C.,Pugh, David,Purnomo, Teresa,Santhakumar, Gajan,Fussell, Steven J.
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supporting information
p. 950 - 953
(2018/02/23)
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- Base-promoted amide synthesis from aliphatic amines and ynones as acylation agents through C-C bond cleavage
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A new protocol for the synthesis of amides via base-promoted cleavage of the C(sp)-C(CO) bond of ynones with aliphatic primary and secondary amines under transition-metal-, ligand-, and oxidant-free conditions has been developed. This method exhibits a wide substrate scope, high functional group tolerance and exclusive chemoselectivity, as well as mild reaction conditions.
- Cheng, Guolin,Lv, Weiwei,Kuai, Changsheng,Wen, Si,Xiao, Shangyun
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supporting information
p. 1726 - 1729
(2018/02/21)
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- Efficient N-Heterocyclic Carbene/Ruthenium Catalytic Systems for the Alcohol Amidation with Amines: Involvement of Poly-Carbene Complexes?
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The atom-economic direct amidation of alcohols with amines has been recently highlighted as an attractive and promising transformation. Among the versatile reported catalytic systems, in situ generated N-heterocyclic carbene (NHC)/ruthenium (Ru) catalytic systems have demonstrated their advantages such as easy operation and use of commercial Ru compounds. However, the existing catalyst loadings are relatively high, and additional insights for the in situ catalyst generation are still not well-documented. In this work, a variety of benzimidazole-based NHC precursors were initially synthesized. Through the screening of various NHC precursors and other reaction conditions, active in situ catalytic systems were discovered for the efficient amide synthesis. Notably, the catalyst loading is as low as 0.5 mol %. Furthermore, additional experiments were performed to validate the rationale for the superiority of the current catalytic systems over our previous system. It was observed that the ligand structure is one of the reasons for the higher activity. In addition, the higher ratio of the NHC precursor/[Ru] is another important factor for the improvement. Further HR-MS analysis identified the formation of two mono-NHC-Ru species as major species and two Ru species bearing multiple NHC ligands as minor species. Hopefully, the efficient and readily-accessible catalytic systems reported herein could demonstrate great potential for further practical applications.
- Cheng, Hua,Xiong, Mao-Qian,Zhang, Ni,Wang, Hua-Jing,Miao, Yang,Su, Wei,Yuan, Ye,Chen, Cheng,Verpoort, Francis
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p. 4338 - 4345
(2018/09/06)
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- Ruthenium-based catalytic systems incorporating a labile cyclooctadiene ligand with N-heterocyclic carbene precursors for the atom-economic alcohol amidation using amines
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Transition-metal-catalyzed amide-bond formation from alcohols and amines is an atom-economic and eco-friendly route. Herein, we identified a highly active in situ N-heterocyclic carbene (NHC)/ruthenium (Ru) catalytic system for this amide synthesis. Various substrates, including sterically hindered ones, could be directly transformed into the corresponding amides with the catalyst loading as low as 0.25 mol.%. In this system, we replaced the p-cymene ligand of the Ru source with a relatively labile cyclooctadiene (cod) ligand so as to more efficiently obtain the corresponding poly-carbene Ru species. Expectedly, the weaker cod ligand could be more easily substituted with multiple mono-NHC ligands. Further high-resolution mass spectrometry (HRMS) analyses revealed that two tetra-carbene complexes were probably generated from the in situ catalytic system.
- Chen, Cheng,Miao, Yang,De Winter, Kimmy,Wang, Hua-Jing,Demeyere, Patrick,Yuan, Ye,Verpoort, Francis
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- In situ Generated Ruthenium Catalyst Systems Bearing Diverse N-Heterocyclic Carbene Precursors for Atom-Economic Amide Synthesis from Alcohols and Amines
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The transition-metal-catalyzed direct synthesis of amides from alcohols and amines is herein demonstrated as a highly environmentally benign and atom-economic process. Among various catalyst systems, in situ generated N-heterocyclic carbene (NHC)-based ruthenium (Ru) halide catalyst systems have been proven to be active for this transformation. However, these existing catalyst systems usually require an additional ligand to achieve satisfactory results. In this work, through extensive screening of a diverse variety of NHC precursors, we discovered an active in situ catalyst system for efficient amide synthesis without any additional ligand. Notably, this catalyst system was found to be insensitive to the electronic effects of the substrates, and various electron-deficient substrates, which were not highly reactive with our previous catalyst systems, could be employed to afford the corresponding amides efficiently. Furthermore, mechanistic investigations were performed to provide a rationale for the high activity of the optimized catalyst system. NMR-scale reactions indicated that the rapid formation of a Ru hydride intermediate (signal at δ=?7.8 ppm in the 1H NMR spectrum) after the addition of the alcohol substrate should be pivotal in establishing the high catalyst activity. Besides, HRMS analysis provided possible structures of the in situ generated catalyst system.
- Cheng, Hua,Xiong, Mao-Qian,Cheng, Chuan-Xiang,Wang, Hua-Jing,Lu, Qiang,Liu, Hong-Fu,Yao, Fu-Bin,Chen, Cheng,Verpoort, Francis
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p. 440 - 448
(2018/02/06)
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- Nickel-Catalyzed Phosphine Free Direct N-Alkylation of Amides with Alcohols
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Herein, we developed an operational simple, practical, and selective Ni-catalyzed synthesis of secondary amides. Application of renewable alcohols, earth-abundant and nonprecious nickel catalyst facilitates the transformations, releasing water as byproduct. The catalytic system is tolerant to a variety of functional groups including nitrile, allylic ether, and alkene and could be extended to the synthesis of bis-amide, antiemetic drug Tigan, and dopamine D2 receptor antagonist Itopride. Preliminary mechanistic studies revealed the participation of a benzylic C-H bond in the rate-determining step.
- Das, Jagadish,Banerjee, Debasis
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p. 3378 - 3384
(2018/03/26)
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- Unmasking Amides: Ruthenium-Catalyzed Protodecarbonylation of N-Substituted Phthalimide Derivatives
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The unprecedented transformation of a wide range of synthetically appealing phthalimides into amides in a single-step operation has been achieved in high yields and short reaction times using a ruthenium catalyst. Mechanistic studies revealed a unique, homogeneous pathway involving five-membered ring opening and CO2 release with water being the source of protons.
- Yuan, Yu-Chao,Kamaraj, Raghu,Bruneau, Christian,Labasque, Thierry,Roisnel, Thierry,Gramage-Doria, Rafael
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supporting information
p. 6404 - 6407
(2017/12/08)
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- A process for preparing N - alkyl amide method (by machine translation)
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The invention discloses a method for preparing N - alkyl amide of the method. In the reaction container, joins the nitrile, oxime, transition metal catalyst iridium complex [Cp * IrCl2 ]2 , Toluene; the reaction mixture in 100 °C reaction under 6 hours, cooling to room temperature; then the alcohol and alkali compound is added, the reaction mixture in the 130 °C react again under 12 hours later, then through the column separation, to obtain the target compound. The invention from the fully commercialized nitrile, proceed wowo and mellow, in the participation of transition metal iridium catalyst, to directly obtain N - alkyl amide, the reaction exhibits three significant advantages: 1) the use of the commercialization of the starting material; 2) low catalyst load; 3) is environment-friendly and easy to control. Therefore, the reaction in accordance with the requirement of green chemistry, has broad prospects of development. (by machine translation)
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Paragraph 0036; 0037; 0038; 0039; 0040
(2017/08/19)
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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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- Sulfur–Fluoride Exchange (SuFEx)-Mediated Synthesis of Sterically Hindered and Electron-Deficient Secondary and Tertiary Amides via Acyl Fluoride Intermediates
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Amide bond formation is one of the most executed reactions in chemistry and biology. This is largely due to the ubiquity of the amide functional group in biological molecules, natural products and pharmaceutically important drugs. We report here the development of “SuFExAmide”: a new sulfur–fluoride exchange (SuFEx) click chemistry based protocol for the efficient amidation of carboxylic acids via acyl fluoride intermediates. We have developed benzene-1,3-disulfonyl fluoride as a cost effective, powerful and versatile coupling agent, which delivers challenging secondary and tertiary amides in excellent yields from sterically hindered and electron-deficient amines. The straightforward method offers significant benefits over existing protocols in terms of substrate scope, efficiency and ease of operation and is demonstrated by the synthesis of 44 amides, including GNF6702, an antiprotozoal drug candidate. In the majority of cases, the amide products are obtained in high yield without the need for excess reagents or chromatographic purification.
- Smedley, Christopher J.,Barrow, Andrew S.,Spiteri, Christian,Giel, Marie-Claire,Sharma, Pallavi,Moses, John E.
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p. 9990 - 9995
(2017/08/01)
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- Method for synthesizing N-alkylamide
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The invention discloses a method for synthesizing N-alkylamide. In a reaction container, adding nitrile, a complex of a transition-metal catalyst gold, a solvent tetrahydrofuran and H2O; reacting a reaction mixture for several hours at the temperature of 130-140 DEG C, cooling the reaction mixture to room temperature, performing vacuum pressure reduction to remove the solvent; adding a compound alcohol, alkali, the complex of a transition-metal catalyst iridium, a solvent toluene, reacting the reaction mixture for several hours at the temperature of 130 DEG C, through column separation, obtaining a target compound. According to the invention, with participation of the transition-metal catalyst, commercial nitrile is hydrolyzed to generate an amide intermediate, and then is subjected to an alkylation reaction with alcohol to obtain N-alkylamide. The reaction has three obvious advantages: 1) the commercial nitrile and alcohol which is almost nontoxic are taken as initial raw materials; 2) only water is generated as a by-product in the reaction, so that the reaction has no harm on environment; and 3) reaction atom economy is high. The reaction accords with green chemistry requirement, and has wide development prospect.
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- Clean synthesis of primary to tertiary carboxamides by CsOH-catalyzed aminolysis of nitriles in water
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Using CsOH as the only catalyst and utilizing its "cesium effect", a clean synthesis of a wide range of primary, secondary, and tertiary carboxamides was achieved by aminolysis reactions of nitriles with ammonia, primary, or secondary amines in water. Studies on the control reactions revealed that the reactions with ammonia most probably proceed via an aminolysis path by the initial addition of ammonia to Cs-activated nitriles to form unsubstituted amidine intermediates, while the reactions with primary or secondary amines may proceed via a hydration/transamidation path by the initial hydration of the Cs-activated nitriles to form primary carboxamide intermediates followed by their transamidation with amines through the formation of substituted amidine intermediates.
- Li, Yang,Chen, Haonan,Liu, Jianping,Wan, Xujun,Xu, Qing
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supporting information
p. 4865 - 4870
(2016/10/06)
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- Lewis acid-driven reaction pathways in synergistic cooperative catalysis over gold/palladium bimetallic nanoparticles for hydrogen autotransfer reaction between amide and alcohol
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Metal nanoparticle catalysts, especially gold and its bimetallic nanoparticle catalysts, have been widely used in organic transformations as powerful and green catalysts. The concept of employing two distinct catalysts in one reaction system, such as in cooperative and synergistic catalysis, is a powerful strategy in homogeneous catalysis. However, the adaption of such a strategy to metal nanoparticle catalysis is still under development. Recently, we have found that cooperative catalytic systems of gold/palladium bimetallic nanoparticles and Lewis acid can be used for the N-alkylation of primary amides through hydrogen autotransfer reaction between amide and alcohol. Herein, the results of a detailed investigation into the effects of Lewis acids on this hydrogen autotransfer reaction are reported. It was found that the choice of Lewis acid affected not only the reaction pathway leading to the desired product, but also other reaction pathways that produced several intermediates and by-products. Weak Lewis acids, such as alkaline-earth metal triflates, were found to be optimal for the desired N-alkylation of amides.
- Miyamura, Hiroyuki,Isshiki, Satoshi,Min, Hyemin,Kobayashi, Shū
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p. 1662 - 1668
(2016/11/09)
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- Design and synthesis of ruthenium(II) OCO pincer type NHC complexes and their catalytic role towards the synthesis of amides
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The present contribution describes the synthesis and characterization of a family of robust ruthenium complexes, supported by a tridentate pincer ligand of the type bis-phenolate-N-heterocyclic carbene [ tBu(OCO) 2-] (NHC). Ruthenium(II) complexes (1-3) bearing bis-phenolate-N-heterocyclic carbene ligand were synthesized in good yields by the reaction of imidazolinium proligand (HL) with metal precursors [RuHCl(CO)(EPh3)2(B)] (E = P or As; B = PPh3, AsPh3 or Py) by transmetalation from the corresponding silver carbene complex. All the Ru(II)-NHC complexes have been characterized by elemental analyses, spectroscopic methods as well as ESI mass spectrometry. Based on the spectral results, an octahedral geometry was assigned for all the complexes. The tridentate nature of the tBu(OCO) 2- ligand as well as some level of steric protection provided by the t Bu groups may rationalize the excellent stability of the Ru-Ccarbene bond in the present systems. Moreover, for the explorations of catalytic potential of the synthesized compounds, all the three [Ru-NHC] complexes (1-3) were tested as catalysts for amidation of alcohols with amines. Notably, the complex 1 was found to be very efficient and versatile catalyst towards amidation of a wide range of alcohols with amines. [Figure not available: see fulltext.].
- Nirmala, Muthukumaran,Viswanathamurthi, Periasamy
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- Transamidation of carboxamides with amines over nanosized zeolite beta under solvent-free conditions
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A highly efficient approach to transamidation of carboxamides with amines over nanosized zeolite beta under solvent-free conditions has been successfully demonstrated. Transamidation of a variety of amides with amines produced the respective N-alkyl amides in moderate to excellent yields.
- Durgaiah, Chevella,Naresh, Mameda,Swamy, Peraka,Srujana, Kodumuri,Rammurthy, Banothu,Narender, Nama
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- Selective catalytic Hofmann: N -alkylation of poor nucleophilic amines and amides with catalytic amounts of alkyl halides
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Using only catalytic amounts of alkyl halides in the reactions of poor nucleophilic amines/amides and alcohols led to a selective Hofmann N-alkylation reaction catalytic in alkyl halides, providing a practical and efficient method for the practical synthesis of mono- or di-alkylated amines/amides in high selectivities. This new method avoids the use of large amounts of bases, alkyl halides, and solvents, and generates water as the only byproduct. Preliminary mechanistic studies showed that alkyl halides are key intermediates/catalysts regeneratable in the reaction cycle.
- Xu, Qing,Xie, Huamei,Zhang, Er-Lei,Ma, Xiantao,Chen, Jianhui,Yu, Xiao-Chun,Li, Huan
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supporting information
p. 3940 - 3944
(2016/07/21)
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- Copper-Catalyzed Ligand-Free Amidation of Benzylic Hydrocarbons and Inactive Aliphatic Alkanes
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An efficient copper-catalyzed amidation of benzylic hydrocarbons and inactive aliphatic alkanes with simple amides was developed. The protocol proceeded smoothly without any ligand, and a wide range of N-alkylated aromatic and aliphatic amides, sulfonamides, and imides were synthesized in good yields.
- Zeng, Hui-Ting,Huang, Jing-Mei
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supporting information
p. 4276 - 4279
(2015/09/15)
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- Combination of gold and iridium catalysts for the synthesis of N-alkylated amides from nitriles and alcohols
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An alternative and efficient approach for the synthesis of N-alkylated amides from nitriles and alcohols was proposed and accomplished. By the combination of [(IPr)Au(NTf2)] (IPr = 1,3-bis(diisopropylphenyl)imidazol-2-ylidene) and [CpIrCl2]2 (Cp = η5-pentamethylcyclopentadienyl), a series of nitriles were first hydrated to give amides, in which the resulting amides were further N-alkylated with a variety of alcohols as alkylating agents to afford N-alkylated amides with good to excellent yields. Compared with previous methods for the synthesis of N-alkylated amides from nitriles and alcohols as starting materials, this protocol could be accomplished with high atom economy under more environmentally benign conditions.
- Li, Feng,Ma, Juan,Lu, Lei,Bao, Xiaofeng,Tang, Wanying
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p. 1953 - 1960
(2015/04/27)
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- Copper(I)-Catalyzed Reductive Cross-Coupling of N-Tosylhydrazones with Amides: A Straightforward Method for the Construction of C(sp3)- N Amide Bonds from Aldehydes
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A method for the one-pot synthesis of substituted amides from aldehydes and amides is presented. Namely, condensation of aldehydes with N-tosylhydrazide generated the N-tosylhydrazones which were then reductively cross-coupled in situ with primary or secondary amides in the presence of a copper catalyst to afford secondary or tertiary amides, respectively. The reaction proceeded efficiently for a wide range of aldehydes and amides under the optimized conditions, i.e., 10 mol% of tetrakis(acetonitrile)copper(I) tetrafluoroborate [Cu(CH3CN)4BF4], 1 mol% of tetra-n-butylammonium iodide [(n-Bu)4NI], and sodium hydroxide [NaOH] as base in tetrahydrofuran (THF) at 80 C. As a result, the method provides a straightforward route for the synthesis of substituted amides from readily available aldehydes via a transition metal-catalyzed C(sp3)- N amide bond forming reaction.
- Xu, Peng,Han, Fu-She,Wang, Yan-Hua
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supporting information
p. 3441 - 3446
(2016/01/25)
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- A Heterogeneous Niobium(V) Oxide Catalyst for the Direct Amidation of Esters
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This study reports the first example of a heterogeneous catalytic system for the direct amidation of various esters with amines. Of 25 types of catalyst, Nb2O5 shows the highest activity in the amidation of methyl benzoate with aniline. Nb2O5 gives high yields in the amidation of various esters and amines under solvent-free conditions, is reusable, and shows higher turnover numbers than previously reported homogeneous catalysts such as La(OTf)3. IR spectroscopic studies of ethyl acetate adsorbed on the catalysts show a strong acid-base interaction between the Nb5+ Lewis acid site and carbonyl oxygen, which can result in high reactivity of the ester with a nucleophile (amine) and, thus, high activity of Nb2O5. Kinetic results show that the activity of Nb2O5 does not markedly decrease with increasing aniline concentration, in contrast to reference catalysts TiO2 and La(OTf)3. The relatively low negative impact of basic molecules on the Lewis acid catalysis of Nb2O5 also enables its high activity.
- Ali, Md. Ayub,Siddiki, S. M. A. Hakim,Kon, Kenichi,Shimizu, Ken-Ichi
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p. 2705 - 2710
(2015/09/15)
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- Synergistic cascade catalysis by metal nanoparticles and Lewis acids in hydrogen autotransfer
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Of the many types of catalysis involving two or more catalysts, synergistic catalysis is of great interest because novel reactions or reaction pathways may be discovered when there is synergy between the catalysts. Herein, we describe a synergistic cascade catalysis, in which immobilized Au/Pd bimetallic nanoparticles and Lewis acids work in tandem to achieve the N-alkylation of primary amides to secondary amides with alcohols via hydrogen autotransfer. When Au/Pd nanoparticles were used with metal triflates, a significant rate acceleration was observed, and the desired secondary amides were obtained in excellent yields. The metal triflate is thought to not only facilitate the addition of primary amides to aldehydes generated in situ, but also enhance the returning of hydrogen from nanoparticles to hydrogen-accepting intermediates. This resulted in a more rapid turnover of the nanoparticle catalyst, and ultimately translated into an increase in the overall rate of the reaction. The two catalysts in this co-catalytic system work in a synergistic and cascade fashion, resulting in an efficient hydrogen autotransfer process.
- Choo, Gerald C. Y.,Miyamura, Hiroyuki,Kobayashi, Shuˉ
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p. 1719 - 1727
(2015/08/12)
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- Efficient conversion of acids and esters to amides and transamidation of primary amides using OSU-6
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OSU-6, an MCM-41 type hexagonal mesoporous silica with strong Bronsted acid properties, has been used to promote the high-yield conversion of carboxylic acids and esters to carboxamides as well as transamidations of primary amides in a one-pot solventless approach. A metal-free heterogeneous catalyst that promotes all of these processes has not been previously reported. OSU-6 enables these transformations to proceed in shorter times and at lower temperatures for a broad range of substrates. An added benefit is that the catalyst can be recycled and reused multiple times without significant loss of activity.
- Nammalwar, Baskar,Muddala, Nagendra Prasad,Watts, Field M.,Bunce, Richard A.
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p. 9101 - 9111
(2015/11/09)
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- An attractive route to transamidation catalysis: Facile synthesis of new o-aryloxide-N-heterocyclic carbene ruthenium(II) complexes containing trans triphenylphosphine donors
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Well-defined robust ruthenium(II) complexes 3a-d bearing o-aryloxide-N-heterocyclic carbene ligands with different wingtip substituents (3a (R = Me), 3b (R = Ph), 3c (R = iPr) and 3d (R = Mes)) in the imidazole ring were synthesized in good yields by the reaction of imidazolium proligands with metal precursor [RuHCl(CO)(PPh3)3] by transmetallation from the corresponding silver carbene complexes. All the Ru(II)-NHC complexes have been characterized by elemental analyses, spectroscopic methods as well as ESI mass spectrometry. The molecular structure of the complex 3a was identified by means of single-crystal X-ray diffraction analysis, which revealed that the complexes possess a distorted octahedral geometry. In order to explore the catalytic potential of the synthesized complexes, all the four [Ru-NHC] complexes [3a-d] were tested as catalysts for transamidation of carboxamides with amines. Notably, the complex 3a was found to be very efficient and versatile catalyst toward transamidation of a wide range of amides with amines.
- Nirmala, Muthukumaran,Prakash, Govindan,Viswanathamurthi, Periasamy,Malecki, Jan Grzegorz
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- C-N Coupling of Amides with Alcohols Catalyzed by N-Heterocyclic Carbene-Phosphine Iridium Complexes
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N-Heterocyclic carbene-phosphine iridium complexes (NHC-Ir) were developed/found to be a highly reactive catalyst for N-monoalkylation of amides with alcohols via hydrogen transfer. The reaction produced the desired product in high isolated yields using a wide range of substrates with low catalyst loading and short reaction times.
- Kerdphon, Sutthichat,Quan, Xu,Parihar, Vijay Singh,Andersson, Pher G.
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p. 11529 - 11537
(2015/12/04)
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- The direct synthesis of N-alkylated amides via a tandem hydration/N-alkylation reaction from nitriles, aldoximes and alcohols
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A novel strategy for the direct synthesis of N-alkylated amides from nitriles, aldoximes and alcohols was proposed and accomplished in the presence of a Cp*Ir complex. This journal is the Partner Organisations 2014.
- Wang, Nana,Zou, Xiaoyuan,Ma, Juan,Li, Feng
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p. 8303 - 8305
(2014/07/22)
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