- Advantage of anaerobic conditions in the highly enantioselective synthesis of α,α-dialkyl-α-amino acids by chiral phase-transfer catalysis
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Intervention of the enolate oxidation in the catalytic asymmetric phase-transfer alkylation of protected α-amino acid derivatives under aerobic conditions has been addressed, and anaerobic conditions have been introduced to obtain synthetically satisfactory chemical yields as well as a high level of enantioselectivity.
- Ooi,Takeuchi,Ohara,Maruoka
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Read Online
- CuO-decorated magnetite-reduced graphene oxide: a robust and promising heterogeneous catalyst for the oxidative amidation of methylarenes in waterviabenzylic sp3C-H activation
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A magnetite-reduced graphene oxide-supported CuO nanocomposite (rGO/Fe3O4-CuO) was preparedviaa facile chemical method and characterized by Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), UV-vis spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), Brunauer-Emmett-Teller (BET) analysis, vibrating-sample magnetometry (VSM), and thermogravimetric (TG) analysis. The catalytic activity of the rGO/Fe3O4-CuO nanocomposite was probed in the direct oxidative amidation reaction of methylarenes with free amines. Various aromatic and aliphatic amides were prepared efficiently at room temperature from cheap raw chemicals usingtert-butyl hydroperoxide (TBHP) as a “green” oxidant and low-toxicity TBAI in water. This method combines the oxidation of methylarenes and amide bond formation into a single operation. Moreover, the synthesized nanocomposites can be separated from the reaction mixtures using an external magnet and reused in six consecutive runs without a noticeable decrease in the catalytic activity.
- Ebrahimi, Edris,Khalafi-Nezhad, Ali,Khalili, Dariush,Rousta, Marzieh
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p. 20007 - 20020
(2021/11/12)
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- Product selectivity controlled by manganese oxide crystals in catalytic ammoxidation
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The performances of heterogeneous catalysts can be effectively tuned by changing the catalyst structures. Here we report a controllable nitrile synthesis from alcohol ammoxidation, where the nitrile hydration side reaction could be efficiently prevented by changing the manganese oxide catalysts. α-Mn2O3 based catalysts are highly selective for nitrile synthesis, but MnO2-based catalysts including α, β, γ, and δ phases favour the amide production from tandem ammoxidation and hydration steps. Multiple structural, kinetic, and spectroscopic investigations reveal that water decomposition is hindered on α-Mn2O3, thus to switch off the nitrile hydration. In addition, the selectivity-control feature of manganese oxide catalysts is mainly related to their crystalline nature rather than oxide morphology, although the morphological issue is usually regarded as a crucial factor in many reactions.
- Hui, Yu,Luo, Qingsong,Qin, Yucai,Song, Lijuan,Wang, Hai,Wang, Liang,Xiao, Feng-Shou
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p. 2164 - 2172
(2021/09/20)
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- Visible light-mediated synthesis of amides from carboxylic acids and amine-boranes
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Here, a photocatalytic deoxygenative amidation protocol using readily available amine-boranes and carboxylic acids is described. This approach features mild conditions, moderate-to-good yields, easy scale-up, and up to 62 examples of functionalized amides with diverse substituents. The synthetic robustness of this method was also demonstrated by its application in the late-stage functionalization of several pharmaceutical molecules.
- Chen, Xuenian,Kang, Jia-Xin,Ma, Yan-Na,Miao, Yu-Qi
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supporting information
p. 3595 - 3599
(2021/06/06)
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- Design of gp120 HIV-1 entry inhibitors by scaffold hopping via isosteric replacements
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We present the development of alternative scaffolds and validation of their synthetic pathways as a tool for the exploration of new HIV gp120 inhibitors based on the recently discovered inhibitor of this class, NBD-14136. The new synthetic routes were based on isosteric replacements of the amine and acid precursors required for the synthesis of NBD-14136, guided by molecular modeling and chemical feasibility analysis. To ensure that these synthetic tools and new scaffolds had the potential for further exploration, we eventually tested few representative compounds from each newly designed scaffold against the gp120 inhibition assay and cell viability assays.
- Ahmed, Shahad,Altieri, Andrea,Belov, Dmitry S.,Curreli, Francesca,Debnath, Asim K.,Iusupov, Ildar R.,Kurkin, Alexander V.,Manasova, Ekaterina V.,Markov, Pavel O.,Spiridonov, Evgeniy A.
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- Activated Mont K10-Carbon supported Fe2O3: A versatile catalyst for hydration of nitriles to amides and reduction of nitro compounds to amines in aqueous media
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The iron oxide was successfully supported on activated clay/carbon through an experimentally viable protocol for both hydrations of nitrile to amide and reduction of nitro compounds to amines. The as-prepared catalyst has been extensively characterised by XPS, SEM-EDX, TEM, TGA, BET surface area measurements and powdered X-ray diffraction (PXRD). A wide variety of substrates could be converted to the desired products with good to excellent yields by using water as a green solvent for both the reactions. The catalyst was recyclable and reusable up to six consecutive cycles without compromising its catalytic proficiency. Graphical abstract: Activated Mont K10 carbon-supported Fe2O3 is a very efficient and versatile heterogeneous catalytic system for hydration of nitriles to amides and reduction of nitro compounds to amines and can be reused up to six consecutive cycles without significant loss in catalytic activity.[Figure not available: see fulltext.].
- Rahman, Taskia,Borah, Geetika,Gogoi, Pradip K
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- Manganese-Pincer-Catalyzed Nitrile Hydration, α-Deuteration, and α-Deuterated Amide Formation via Metal Ligand Cooperation
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A simple and efficient system for the hydration and α-deuteration of nitriles to form amides, α-deuterated nitriles, and α-deuterated amides catalyzed by a single pincer complex of the earth-abundant manganese capable of metal-ligand cooperation is reported. The reaction is selective and tolerates a wide range of functional groups, giving the corresponding amides in moderate to good yields. Changing the solvent from tert-butanol to toluene and using D2O results in formation of α-deuterated nitriles in high selectivity. Moreover, α-deuterated amides can be obtained in one step directly from nitriles and D2O in THF. Preliminary mechanistic studies suggest the transformations contributing toward activation of the nitriles via a metal-ligand cooperative pathway, generating the manganese ketimido and enamido pincer complexes as the key intermediates for further transformations.
- Ben-David, Yehoshoa,Diskin-Posner, Yael,Kar, Sayan,Milstein, David,Zhou, Quan-Quan,Zou, You-Quan
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p. 10239 - 10245
(2021/08/24)
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- Cu(II)-promoted oxidative C-N bond cleavage of N-benzoylamino acids to primary aryl amides
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A novel protocol for CuCl2-promoted oxidative C-N bond cleavage of N-benzoyl amino acids was developed. It is the first example of using accessible amino acid as an ammonia synthetic equivalent for the synthesis of primary aryl amides via CuCl2-promoted oxidative C-N bond cleavage reaction. The present protocol shows excellent functional group tolerance and provides an alternative method for the synthetic of primary aryl amides in 84-96% yields.
- Zhou, Liandi,Liu, Wei,Zhao, Yongli,Chen, Junmin
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- Green and efficient Beckmann rearrangement by Cu(II) contained nano-silica triazine based dendrimer in water
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In this research, a Cu(II) contained nano-silica triazine based dendrimer was prepared, characterized, and utilized as a retrievable catalytic system (Cu(II)-TrDen@nSiO2) for green formation of primary amides in water at room temperature. The structure of nanoparticles was fully characterized by using scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), Fourier transform infrared spectroscopy (FT-IR), and thermogravimetry analysis (TGA). The results revealed that the nanoparticles have spherical morphology and an average size of around 40 nm. The analysis also illustrated that the copper nanoparticles had been successfully loaded on the nitrogen-rich dendritic structure with a uniform distribution. The inductively coupled plasma analysis showed that about 0.67 mmol/g of Cu was loaded on the Cu(II)-TrDen@nSiO2 support. Mild reaction conditions, excellent yields, environment-friendly synthesis, and easily prepared starting materials are the key features of the present method. The catalyst is easily removed from the reaction media using a simple filtration and can be re-used at least five times without any considerable loss of its catalytic activity.
- Bahreininejad, Mohammad Hasan,Moeinpour, Farid
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p. 893 - 901
(2021/01/12)
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- Process Development of the Copper(II)-Catalyzed Dehydration of a Chiral Aldoxime and Rational Selection of the Co-Substrate
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The access towards chiral nitriles remains crucial in the synthesis of several pharmaceuticals. One approach is based on metal-catalyzed dehydration of chiral aldoximes, which are generated from chiral pool-derived aldehydes as substrates, and the use of a cheap and readily available nitrile as co-substrate and water acceptor. Dehydration of N-acyl α-amino aldoximes such as N-Boc-l-prolinal oxime catalyzed by copper(II) acetate provides access to the corresponding N-acyl α-amino nitriles, which are substructures of the pharmaceuticals Vildagliptin and Saxagliptin. In this work, a detailed investigation of the formation of the amide as a by-product at higher substrate loadings is performed. The amide formation depends on the electronic properties of the nitrile co-substrate. We could identify an acceptor nitrile which completely suppressed amide formation at high substrate loadings of 0.5 m even when being used with only 2 equivalents. In detail, utilization of trichloroacetonitrile as such an acceptor nitrile enabled the synthesis of N-Boc-cyanopyrrolidine in a high yield of 92 % and with full retention of the absolute configuration.
- Gr?ger, Harald,Nonnhoff, Jannis
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- Does electrophilic activation of nitroalkanes in polyphosphoric acid involve formation of nitrile oxides?
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The mechanistic rationale involving activation of nitroalkanes towards interaction with nucleophilic reagents in the presence of polyphosphoric acid (PPA) was re-evaluated. Could nitrile oxide moieties be formed during this process? This experiment demonstrates that at least in some cases this could happen, as generated nitrile oxides were successfully intercepted as adducts of [3 + 2] cycloadditions. This journal is
- Aksenov, Alexander V.,Aksenov, Dmitrii A.,Aksenov, Nicolai A.,Kirilov, Nikita K.,Kurenkov, Igor A.,Nobi, Mezvah A.,Rubin, Michael,Skomorokhov, Anton A.,Sorokina, Elena A.
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p. 35937 - 35945
(2021/12/02)
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- Ring Opening/Site Selective Cleavage in N-Acyl Glutarimide to Synthesize Primary Amides
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A LiOH-promoted hydrolysis selective C-N cleavage of twisted N-acyl glutarimide for the synthesis of primary amides under mild conditions has been developed. The reaction is triggered by a ring opening of glutarimide followed by C-N cleavage to afford primary amides using 2 equiv of LiOH as the base at room temperature. The efficacy of the reactions was considered and administrated for various aryl and alkyl substituents in good yield with high selectivity. Moreover, gram-scale synthesis of primary amides using a continuous flow method was achieved. It is noted that our new methodology can apply under both batch and flow conditions for synthetic and industrial applications.
- Govindan, Karthick,Lin, Wei-Yu
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supporting information
p. 1600 - 1605
(2021/03/03)
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- Unlocking Amides through Selective C–N Bond Cleavage: Allyl Bromide-Mediated Divergent Synthesis of Nitrogen-Containing Functional Groups
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We report a new set of reactions based on the unlocking of amides through simple treatment with allyl bromide, creating a common platform for accessing a diverse range of nitrogen-containing functional groups such as primary amides, sulfonamides, primary amines, N-acyl compounds (esters, thioesters, amides), and N-sulfonyl esters. The method has potential industrial applicability, as demonstrated through gram-scale syntheses in batch and in a continuous flow system.
- Govindan, Karthick,Chen, Nian-Qi,Chuang, Yu-Wei,Lin, Wei-Yu
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supporting information
p. 9419 - 9424
(2021/11/30)
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- CuO-catalyzed conversion of arylacetic acids into aromatic nitriles with K4Fe(CN)6 as the nitrogen source
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Readily available CuO was demonstrated to be effective as the catalyst for the conversion of arylacetic acids to aromatic nitriles with non-toxic and inexpensive K4Fe(CN)6 as the nitrogen source via the complete cleavage of the C[tbnd]N triple bond. The present method allowed a series of arylacetic acids including phenylacetic acids, naphthaleneacetic acids, 2-thiopheneacetic acid and 2-furanacetic acid to be converted into the targeted products in low to high yields.
- Ren, Yun-Lai,Shen, Zhenpeng,Tian, Xinzhe,Xing, Ai-Ping,Zhao, Zhe
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- Aerobic oxidation of primary amines to amides catalyzed by an annulated mesoionic carbene (MIC) stabilized Ru complex
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Catalytic aerobic oxidation of primary amines to the amides, using the precatalyst [Ru(COD)(L1)Br2] (1) bearing an annulated π-conjugated imidazo[1,2-a][1,8]naphthyridine-based mesoionic carbene ligand L1, is disclosed. This catalytic protocol is distinguished by its high activity and selectivity, wide substrate scope and modest reaction conditions. A variety of primary amines, RCH2NH2 (R = aliphatic, aromatic and heteroaromatic), are converted to the corresponding amides using ambient air as an oxidant in the presence of a sub-stoichiometric amount of KOtBu in tBuOH. A set of control experiments, Hammett relationships, kinetic studies and DFT calculations are undertaken to divulge mechanistic details of the amine oxidation using 1. The catalytic reaction involves abstraction of two amine protons and two benzylic hydrogen atoms of the metal-bound primary amine by the oxo and hydroxo ligands, respectively. A β-hydride transfer step for the benzylic C-H bond cleavage is not supported by Hammett studies. The nitrile generated by the catalytic oxidation undergoes hydration to afford the amide as the final product. This journal is
- Yadav, Suman,Reshi, Noor U Din,Pal, Saikat,Bera, Jitendra K.
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p. 7018 - 7028
(2021/11/17)
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- Nitromethane as a nitrogen donor in Schmidt-type formation of amides and nitriles
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The Schmidt reaction has been an efficient and widely used synthetic approach to amides and nitriles since its discovery in 1923. However, its application often entails the use of volatile, potentially explosive, and highly toxic azide reagents. Here, we report a sequence whereby triflic anhydride and formic and acetic acids activate the bulk chemical nitromethane to serve as a nitrogen donor in place of azides in Schmidt-like reactions. This protocol further expands the substrate scope to alkynes and simple alkyl benzenes for the preparation of amides and nitriles.
- Jiao, Ning,Liu, Jianzhong,Qiu, Xu,Song, Song,Wei, Jialiang,Wen, Xiaojin,Zhang, Cheng,Zhang, Ziyao
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supporting information
p. 281 - 285
(2020/01/28)
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- Half-sandwich ruthenium(II) complexes containing biphenylamine based Schiff base ligands: Synthesis, structure and catalytic activity in amidation of various aldehydes
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New half-sandwich ruthenium (II) complexes [η6?p-cymene)Ru (L1-3)Cl] (1–3) containing biphenylamine based Schiff base ligands (HL1-3) have been synthesized and characterized by analytical and spectroscopic methods. Additionally, the solid state structure of 2 has been determined by single crystal X-ray diffraction study. The complex 2 serves as a catalyst for the amidation of various aldehydes to amides in good yield.
- Nagalakshmi, Veerasamy,Nandhini, Raja,Brindha, Veerappan,Krishnamoorthy, Bellie Sundaram,Balasubramani, Kasthuri
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- Ru-based complexes as heterogeneous potential catalysts for the amidation of aldehydes and nitriles in neat water
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Five novel heterogeneous mononuclear complex-anchored Ru(III) have been efficiently sono-synthesized and characterized by utilizing several analytical techniques. The assembled complexes could be utilized as effective, robust and recyclable (up to eight consecutive runs) catalysts for one-pot transformation of a vast array of nitriles and aldehydes to primary amides in H2O under aerobic conditions. Moreover, some unreported di- and tetra-amide derivatives were obtained also under the optimal conditions. The results of ICP/OES analysis demonstrated that there is no detected leaching of the recycled catalyst, which suggests the real heterogeneity of the present protocol. The present Ru-complexes exhibited superiority compared to other reported catalysts for amide preparation in terms of low catalyst load, short reaction time, low operating temperature, no hazardous additives required, and high values of TON (990) and TOF (1980 h11).
- Arafa, Wael Abdelgayed Ahmed
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supporting information
p. 1056 - 1064
(2020/11/09)
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- Ruthenium(III) 2-(aminofluoreneazo)phenolate complexes: Synthesis, characterization, catalytic activity in amidation reaction and Fluorescence quenching studies
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A series of ruthenium(III)2-(aminofluoreneazo)phenolate complexes with general formula [RuCl(PPh3)2(L1-5)] (1–5) (L = 2-(aminofluoreneazo)phenolate ligands) have been synthesized. The characterization of the synthesized complexes was accomplished by elemental analysis, spectroscopic (FT-IR, UV–Vis, Fluorescence and EPR) and ESI-MStechniques. The catalytic performance of one of the synthesized complexes 3 for the amidation of aldehyde in the presence of NaHCO3/NH2OH·HCl has been evaluated. The fluorescence emission of complexes [RuCl(PPh3)2(L2)] (2) and [RuCl(PPh3)2(L3) (3)] are effectively quenched by 1,4-benzoquinone and 1,4-naphthoquinone in acetonitrile medium.
- Thirumal, Muniyappan,Venkatachalam, Galmari,Venkattappan, Anbazhagan
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- Cu(II)–metformin immobilized on graphene oxide: an efficient and recyclable catalyst for the Beckmann rearrangement
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Abstract: In this study, for the first time, the copper(II) nanoparticles (NPs) have been immobilized on metformin-functionalized graphene oxide and then its catalytic applications have been investigated in synthesis of amides from aldoximes (Beckmann rearrangement). The chemical structure of prepared catalyst has been characterized by various analyses like FT-IR, TGA, TEM, SEM, EDX, and ICP. All analyses confirm the successful and stable immobilization of copper NPs on functionalized graphene oxide. This synthesized heterogeneous nanocatalyst showed excellent catalytic activity with high product yields and short reaction times. Also, the suggested catalyst could be recycled ten times without a drastic decrease in its catalytic activity. Graphic abstract: [Figure not available: see fulltext.].
- Solaiman Hamed, Ahmed,Mohammad Ali, Ehab
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p. 701 - 714
(2019/11/03)
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- Preparation method of aromatic amide compound
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The present invention provides a preparation method of an aromatic amide compound. In an organic solvent, under the effect of a catalyst, an aromatic acid compound and an amine source are subjected toa dehydration reaction to obtain the aromatic amide compound, wherein the aromatic acid compound is an aromatic acid, a substituted aromatic acid, a heterocyclic aromatic acid or a substituted heterocyclic aromatic acid; and the substituent group of amide is any substituent group of H, a C1-C8 straight-chain alkyl or branched-chain alkyl group, a benzene ring or an aromatic ring. The aromatic amide compound is an important chemical intermediate, and the synthesis method is mild in reaction condition and high in yield.
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Paragraph 0044-0045
(2020/07/15)
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- Fe3O4@GlcA@Cu-MOF: A Magnetic Metal-Organic Framework as a Recoverable Catalyst for the Hydration of Nitriles and Reduction of Isothiocyanates, Isocyanates, and Isocyanides
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A novel magnetic metal-organic framework (Fe3O4@GlcA@Cu-MOF) has been prepared and characterized by spectroscopic, microscopic, and magnetic techniques. This magnetically separable catalyst exhibited high catalytic activity for nitrile hydration and the ability to reduce isothiocyanates, isocyanates, and isocyanides with excellent activity and selectivity without any additional reducing agent.
- Ghorbani-Choghamarani, Arash,Taherinia, Zahra
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supporting information
p. 902 - 909
(2020/11/30)
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- Tuning acylthiourea ligands in Ru(II) catalysts for altering the reactivity and chemoselectivity of transfer hydrogenation reactions, and synthesis of 3-isopropoxy-1H-indole through a new synthetic approach
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Ru(II)-p-cymene complexes (1–3) containing picolyl based pseudo-acylthiourea ligands (L1-L3) were synthesized and characterized. The crystallographic study confirmed the molecular structures of all the ligands (L1-L3) and complex 3. The catalytic activity of the complexes was tested mainly towards TH of carbonyl compounds and nitroarenes. The influence of steric and electronic effects of the ligands on the chemoselectivity and reactivity were reported. The catalytic activity was enhanced and chemoselectivity was switched after tuning the ligands in the catalysts, compared to their corresponding unmodified Ru(II)-p-cymene complexes. The catalysis was extended to a broad range of substrates including some challenging systems like furfural, benzoylpyridine, benzoquinone, chromanone, etc. The strategy of tuning the bifunctional ligands in the catalysts for effective and selective catalysis worked nicely. Further, the catalysis was extended to one pot synthesis of 3-isopropoxyindole from 2-nitrocinnamaldehyde, the first synthetic route similar to Baeyer Emmerling indole synthesis. All the catalytic experiments exhibited high conversion and selectivity.
- Sathishkumar, Pushpanathan N.,Prabha, Padinhattath Sachind,Bhuvanesh, Nattamai S.P.,Karvembu, Ramasamy
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- Optimization of the synthesis of het/aryl-amidoximes using an efficient green chemistry
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This work focuses on optimizing an efficient green synthesis of arylamidoximes from appropriate nitrile and hydroxylamine hydrochloride in water and triethylamine (1.6 mol equivalent) as a base at room temperature for 6 h. This new green synthetic methodology is compared with previously known methods. The main advantages of this new process reported are good yield, easier work-up and short reaction times. Moreover, some of the synthesized arylamidoximes converted to 1,2,4-oxadiazole derivatives 13a,b and 14via the reaction with (4-acetylphenoxy)acetic acid 12.
- Albayati, Mustafa R.,Mohamed, Mamdouh F. A.,Moustafa, Amr H.
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p. 1217 - 1231
(2020/03/19)
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- Pyridine-Enabled C-N Bond Activation for the Rapid Construction of Amides and 4-Pyridylglyoxamides by Cooperative Palladium/Copper Catalysis
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A pyridine-enabled C-N bond activation of peptidomimetics employing cooperative palladium/copper catalysis in water is developed. Diverse amides and 4-pyridylglyoxamides are simultaneously synthesized through two steps from commercially available materials in a rapid, environmentally friendly, and high atom-economical manner.
- Song, Liangliang,Claessen, Sander,Van Der Eycken, Erik V.
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p. 8045 - 8054
(2020/07/15)
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- Base-Mediated Amination of Alcohols Using Amidines
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Novel and efficient base-mediated N-alkylation and amidation of amidines with alcohols have been developed, which can be carried out in one-pot reaction conditions, which allows for the synthesis of a wide range of N-alkyl amines and free amides in good to excellent yields with high atom economy. In contrast to borrowing hydrogen/hydrogen autotransfer or oxidative-type N-alkylation reactions, in which alcohols are activated by transition-metal-catalyzed or oxidative aerobic dehydrogenation, the use of amidines provides an effective surrogate of amines. This circumvents the inherent necessity in N-alkylation of an oxidant or a catalyst to be stabilized by ligands.
- Chen, Jianbin,Fang, Yanchen,Jia, Xiaofei,Jiang, Shaohua,Li, Zehua,Liang, Zuyu,Lu, Fenghong,Qi, Shuo,Ren, Chaoyu,Yu, Shuangming,Zhang, Chunyan,Zhang, Guoying,Zhang, Sheng
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p. 7728 - 7738
(2020/07/15)
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- N-(Hydroxybenzyl)benzamide Derivatives: Aqueous pH-Dependent Kinetics and Mechanistic Implications for the Aqueous Reactivity of Carbinolamides
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The rate constants for the aqueous reaction, between pH 0 and 14, have been determined for a series of amide substituted N-(hydroxybenzyl)benzamide derivatives, in H2O, at 25 °C, I = 1.0 M (KCl). The N-(hydroxybenzyl)benzamide derivatives were found to react via three distinct mechanisms with the kinetically dominant mechanism being dependent on the pH of the reaction solution. It has been shown that the carbinolamides react via a specific-base-catalyzed mechanism (E1cB-like) under basic and pH neutral conditions. At lower pH values, an acid-catalyzed mechanism was kinetically dominant and, last, a water reaction was postulated at pH values where neither the hydroxide-dependent nor the general-acid-catalyzed mechanism was dominant. Contrary to earlier studies with N-(hydroxymethyl)benzamide compounds, no evidence for mechanistic variation based upon the nature of the amidic substituent was observed for any of the N-(hydroxybenzyl)benzamide derivatives studied between pH values of 0-14. The rate for the acid-catalyzed reaction (kH, ρ = -1.17), the apparent second-order hydroxide rate constant (k1′, ρ = 0.87), the hydroxide-independent rate (k1, ρ = 0.65), and the pKa's of the hydroxyl group of the carbinolamide (ρ = 0.23) are reported.
- Koyanagi, Takaoki,Nagorski, Richard W.,Przybyla, David E.,Rafie, Mohammad I.,Siena, Paul M.
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supporting information
(2020/02/04)
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- Supported palladium catalyzed aminocarbonylation of aryl iodides employing bench-stable CO and NH3surrogates
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A simple, efficient and phosphine free protocol for carbonylative synthesis of primary aromatic amides under polystyrene supported palladium (Pd?PS) nanoparticle (NP) catalyzed conditions has been demonstrated. Herein, instead of using two toxic and difficult to handle gases simultaneously, we have employed the solid, economical, bench stable oxalic acid as the CO source and ammonium carbamate as the NH3source in a single pot reaction. For the first time, we have applied two non-gaseous surrogates simultaneously under heterogeneous catalyst (Pd?PS) conditions for the synthesis of primary amides using an easy to handle double-vial (DV) system. The developed strategy showed a good functional group tolerance towards a wide range of aryl iodides and afforded primary aromatic amides in good yields. The Pd?PS catalyst was easy to separate and can be recycled up to four consecutive runs with small loss in catalytic activity. We have successfully extended the scope of the methodology to the synthesis of isoindole-1,3-diones from 1,2-dihalobenzene, 2-halobenzoates and 2-halobenzoic acid following double and single carbonylative cyclization approaches.
- Bains, Rohit,Das, Pralay,Kumar, Ajay,Ram, Shankar,Shaifali,Sheetal
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supporting information
p. 7193 - 7200
(2020/10/02)
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- Aerobic oxidation of primary benzylic amines to amides and nitriles catalyzed by ruthenium carbonyl clusters carrying N,O-bidentate ligands
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Four trinuclear ruthenium carbonyl clusters, (6-BrPyCHRO)2Ru3(CO)8 (R = 4-OCH3C6H4, 1a; R = 4-BrC6H4, 1b) and (2-OC6H4-HCN-C6H4R)2Ru3(CO)8 (R = 4-OCH3, 2a; R = 4-Br, 2b), were synthesized from the reactions of Ru3(CO)12 with the corresponding N,O-bidentate ligands (two pyridyl alcohols and two Schiff bases) respectively in a ratio of 1:2. Three new complexes 1b, 2a and 2b have been fully characterized by elemental analysis, FT-IR, NMR and X-ray crystallography. The catalytic activity of these ruthenium complexes for the aerobic oxidation of primary benzylic amines to amides and nitriles in the presence of t-BuOK was investigated, of which the Schiff base complex 2a was found to exhibit the highest activity.
- Dong, Qing,Han, Zhangang,Hao, Zhiqiang,Li, Ying,Lin, Jin,Lu, Guo-Liang,Meng, Lizhen,Yan, Xinlong
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p. 3480 - 3487
(2020/04/02)
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- Appraisal of Ruthenium(II)complexes of (4-phenoxyphenylazo)ligands for the synthesis of primary amides by dint of hydroxylamine hydrochloride and aldehydes
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A new family of O, N donor-functionalized (4-phenoxyphenylazo)-2-naphthol/4-substituted phenol-based ligands (HL1-HL4)has been synthesized. The prepared ligands were successfully utilized for the access of a series of ruthenium(II)carbonyl complexes of the type [Ru(L)Cl(CO)(EPh3)3](E = phosphine/arsine), (L = 1-(4-phenoxyphenylazo)-2-naphthol (HL1), 2-(4-phenoxyphenylazo)-4-chlorophenol (HL2), 2-(4-phenoxyphenylazo)-4-methylphenol (HL3)and 2-(4-phenoxyphenylazo)-4-methoxyphenol (HL4)). All of the ruthenium(II)carbonyl complexes and ligands have been fully characterized by FT-IR, UV–visible, 1H NMR, 31P NMR, mass spectrometry and CHN analysis. The ligands have been analyzed by 13C NMR. The UV–visible spectroscopic study reveals that both the ligands and Ru(II)complexes exhibit excellent charge transfer transitions. This is the basic criteria for the oxidative amidation reaction, which is an influential strategy for the transformation of oxygenated organic compounds to the profitable amides. However, this catalytic process makes more impact on the application of new divalent ruthenium(II)azo compounds as catalyst in a single-pot conversion of aldehydes to amides in the presence of NaHCO3.
- Vinoth, Govindasamy,Indira, Sekar,Bharathi, Madheswaran,Sounthararajan, Muniyan,Sakthi, Dharmalingam,Bharathi, Kuppannan Shanmuga
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- (η6-Benzene)Ru(II) half-sandwich complexes of pyrazolated chalcogenoethers for catalytic activation of aldehydes to amides transformation
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The reaction of [(η6-C6H6)RuCl(μ-Cl)]2 with chalcogenoether substituted 1H-pyrazole ligands (L1-L3) in methanol have yielded three novel Ru(II) half-sandwich complexes [(η6-C6H6)RuCl(L)]PF6 (1–3) in high yield under the ambient reaction conditions. The NMR, MS and FT-IR analytical techniques were used to identify their structures. The molecular structures of the complexes 2 and 3 were established with X-ray crystallographic analysis and revealed a pseudo-octahedral half sandwich piano-stool geometry around ruthenium in each complex. Complexes 1–3 are thermally robust and were found to be insensitive towards the air and moisture. All the complexes were found to be catalytically active and produced the excellent yields of amides (up to 95%) from corresponding aldehydes. In contrast to the previous reported catalytic systems for aldehyde to amide transformation, the present complexes 1–3 are very efficient and have several advantages in terms of low catalyst loading, reaction time, temperature and wide applicability for various substituted aldehydes. Owing to the stronger σ-donor coordination properties of selenium containing ligands, the complex 2 was found to be more efficient as compare to the sulphur and tellurium analogues.
- Sharma, Kamal Nayan,Ali, Munsaf,Srivastava, Avinash Kumar,Joshi, Raj Kumar
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- Half-sandwich ruthenium(II)complexes containing O, N bidentate azo ligands: Synthesis, structure and their catalytic activity towards one-pot conversion of aldehydes to primary amides and transfer hydrogenation of ketones
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The ruthenium(II)complexes of the general formula [Ru(η6?p?cymene)(Cl)(L1?5)](L = O, N-donors of biphenylazo derivatives), formed by reacting 2?(biphenylazo)phenol (HL1 ? HL4)and 1?(biphenylazo)naphthol ligands (HL5)with [{η6?p?cymene)RuCl}2(μ?Cl)2]have been synthesized. The compositions of the complexes have been established by IR, UV–Vis, 1H NMR spectral methods and X-ray crystallography. The synthesized complex could act as an efficient, reusable homogeneous catalyst for transformation of aldehydes to the corresponding primary amides in the presence of NH2OH·HCl, thus resulting an expansion of Beckmann rearrangement. The effect of solvent, base, temperature, time, catalyst loading and recyclability was also investigated. They also effectively catalyze the transfer hydrogenation reaction of various ketones with 2-propanol.
- Nandhini, Raja,Venkatachalam, Galmari
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- (Ar-tpy)RuII(ACN)3: A Water-Soluble Catalyst for Aldehyde Amidation, Olefin Oxo-Scissoring, and Alkyne Oxygenation
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The synthetic chemists always look for developing new catalysts, sustainable catalysis, and their applications in various organic transformations. Herein, we report a new class of water-soluble complexes, (Ar-tpy)RuII(ACN)3, utilizing designed terpyridines possessing electron-donating and -withdrawing aromatic residues for tuning the catalytic activity of the Ru(II) complex. These complexes displayed excellent catalytic activity for several oxidative organic transformations including late-stage C-H functionalization of aldehydes with NH2OR to valuable primary amides in nonconventional aqueous media with excellent yield. Its diverse catalytic power was established for direct oxo-scissoring of a wide range of alkenes to furnish aldehydes and/or ketones in high yield using a low catalyst loading in the water. Its smart catalytic activity under mild conditions was validated for dioxygenation of alkynes to highly demanding labile synthons, 1,2-diketones, and/or acids. This general and sustainable catalysis was successfully employed on sugar-based substrates to obtain the chiral amides, aldehydes, and labile 1,2-diketones. The catalyst is recovered and reused with a moderate turnover. The proposed mechanistic pathway is supported by isolation of the intermediates and their characterization. This multifaceted sustainable catalysis is a unique tool, especially for late-stage functionalization, to furnish the targeted compounds through frequently used amidation and oxygenation processes in the academia and industry.
- Joarder, Dripta De,Gayen, Subrata,Sarkar, Rajarshi,Bhattacharya, Rajarshi,Roy, Sima,Maiti, Dilip K.
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p. 8468 - 8480
(2019/07/03)
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- Ti-superoxide catalyzed oxidative amidation of aldehydes with saccharin as nitrogen source: Synthesis of primary amides
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A new heterogeneous catalytic system (Ti-superoxide/saccharin/TBHP) has been developed that efficiently catalyzes oxidative amidation of aldehydes to produce various primary amides. The protocol employs saccharin as amine source and was found to tolerate a wide range of substrates with different functional groups. Moderate to excellent yields, catalyst reusability and operational simplicity are the main highlights. A possible mechanism and the role of the catalyst in oxidative amidation have also been discussed.
- Kamble, Rohit B.,Mane, Kishor D.,Rupanawar, Bapurao D.,Korekar, Pranjal,Sudalai,Suryavanshi, Gurunath
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p. 724 - 728
(2020/01/23)
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- Amidation of aldehydes using mono-cationic half-sandwich rhodium(III) complexes with functionalized phenylhydrazone ligands
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A series of mono-cationic half-sandwich rhodium(III) complexes have been synthesized in methanol using phenylhydrazone-derived ligands (L1–L6) and the starting precursor [(η5-C5Me5)2Rh2(μ-Cl)2Cl2] in a 2:1 molar ratio. The N,N′-phenylhydrazone complexes have been isolated as tetraphenylborate salts. All complexes were characterized by elemental analysis, FT-IR, UV–visible, NMR spectroscopy and mass spectrometry. The molecular structure of complex [(η5-C5Me5)Rh(L1)Cl](BPh4) (1) was confirmed by single-crystal X-ray structure analysis. Complex [(η5-C5Me5)Rh(L3)Cl](BPh4) (3) was used as an efficient catalyst for the amide formation reaction, with up to 99% conversion after 2 h in toluene at 110 °C in the presence of hydroxyl amine hydrochloride and sodium bicarbonate.
- Devika, Neelakandan,Ananthalakshmi, Subbiah,Raja, Nandhagopal,Gupta, Gajendra,Therrien, Bruno
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- A carboxylic acid continuous method of preparing amide (by machine translation)
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The invention discloses a continuous process for preparing amides of carboxylic acid method, it comprises the following steps: raw material carboxylic acid with the catalyst is dissolved in a solvent as a material A, acyl acyl reagent or reagent is dissolved in a solvent as a material B, amine reagent or an amine reagent is dissolved in the water as the material C, material A and material B respectively through the infusion pump delivering it into a tubular reactor I acyl reaction, the obtained intermediate product acyl chloride by the infusion pump 3 conveying the material into the tubular reactor C together with the amination reaction II, the reaction mixture after flowing out of the tubular reactor II, through after treatment to obtain the target amide. The invention adopts the technical, can ensure that the whole process is continuous, controllable, raw materials less dose, high safety, and can be easily realized and hermetical, continuous, automated production; the invention through the use of low-cost proton acid catalytic reaction, its low cost, after treatment is simple, easy to separate and remove, from the source to avoid the generation of the carcinogen, consistent with the requirement of environmental protection. (by machine translation)
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- Chemoselective Synthesis of Aryl Ketones from Amides and Grignard Reagents via C(O)-N Bond Cleavage under Catalyst-Free Conditions
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Conversion of a wide range of N-Boc amides to aryl ketones was achieved with Grignard reagents via chemoselective C(O)-N bond cleavage. The reactions proceeded under catalyst-free conditions with different aryl, alkyl, and alkynyl Grignard reagents. α-Ketoamide was successfully converted to aryl diketones, while α,β-unsaturated amide underwent 1,4-addition followed by C(O)-N bond cleavage to provide diaryl propiophenones. N-Boc amides displayed higher reactivity than Weinreb amides with Grignard reagents. A broad substrate scope, excellent yields, and quick conversion are important features of this methodology.
- Sureshbabu, Popuri,Azeez, Sadaf,Muniyappan, Nalluchamy,Sabiah, Shahulhameed,Kandasamy, Jeyakumar
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p. 11823 - 11838
(2019/10/02)
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- Method used for direct synthesis of 4-chlorobenzonitrile from para-chlorobenzoic acid and urea
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The invention provides a method used for direct synthesis of 4-chlorobenzonitrile from para-chlorobenzoic acid and urea, and belongs to the technical field of organic chemistry, and organic fine chemical product. the method comprises following steps: para-chlorobenzoic acid and urea are reacted to obtain an intermediate reaction mixture containing 4-Chlorobenzamide, and the intermediate reaction mixture containing 4-Chlorobenzamide is subjected to dehydration reaction so as to obtain a mixture containing 4-chlorobenzonitrile; the mixture containing 4-chlorobenzonitrile is subjected to underpressure distillation to obtain crude nitrile, and the crude nitrile is subjected to water washing, filtering, drying, and underpressure distillation to obtain finished product 4-chlorobenzonitrile. Theroute is short; operation is simple; reaction conditions are convenient to control; production cost is low; environment pollution is low; the quality of synthesized 4-chlorobenzonitrile is stable; theintermediate reaction mixture containing 4-Chlorobenzamide is subjected to supersonic wave or microwave catalytic dehydration, so that the yield and purity of 4-chlorobenzonitrile are increased obviously.
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Paragraph 0017; 0020; 0023; 0026; 0028
(2019/11/14)
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- Hydration of nitriles using a metal-ligand cooperative ruthenium pincer catalyst
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Nitrile hydration provides access to amides that are important structural elements in organic chemistry. Here we report catalytic nitrile hydration using ruthenium catalysts based on a pincer scaffold with a dearomatized pyridine backbone. These complexes catalyze the nucleophilic addition of H2O to a wide variety of aliphatic and (hetero)aromatic nitriles in tBuOH as solvent. Reactions occur under mild conditions (room temperature) in the absence of additives. A mechanism for nitrile hydration is proposed that is initiated by metal-ligand cooperative binding of the nitrile.
- Guo, Beibei,Otten, Edwin,De Vries, Johannes G.
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p. 10647 - 10652
(2019/12/02)
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- Activation of nitriles by silver(I) N-heterocyclic carbenes: An efficient on-water synthesis of primary amides
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A first example of silver(I) N-heterocyclic carbene (Ag(I)-NHC) catalyzed on-water synthesis of primary amides by hydration of nitriles under mild reaction conditions is described. This organometallic catalytic system has excellent tolerance for various homo-aromatic, hetero-aromatic and aliphatic nitriles to afford primary amides in good yields in neat water.
- Thirukovela, Narasimha Swamy,Balaboina, Ramesh,Kankala, Shravankumar,Vadde, Ravindhar,Vasam, Chandra Sekhar
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supporting information
p. 2637 - 2641
(2019/03/21)
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- Solvent-Tailored Pd3P0.95 nano catalyst for amide-nitrile inter-conversion, the hydration of nitriles and transfer hydrogenation of the CO bond
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For the first time, a one pot thermolysis of [Pd(PPh3)2Cl2] prepared by reacting Ph3P with PdCl2 in a 2:1 molar ratio in MeOH at 280 °C in a trioctylphosphine (TOP) and oleylamine(OA)-octadecane(ODE) mixture (1:1) was used to prepare quantum dots (QDs; size ~2-3 nm) and nanoparticles (NPs; size ~13-14 nm), respectively, of composition Pd3P0.95. TEM, SEM-EDX, powder-XRD and XPS (for QDs only) were used to authenticate the two nanophases. 31P{1H}NMR experiments performed to monitor the progress of thermolysis reactions revealed that the phosphorus present in the Pd3P0.95 QDs had come from TOP, whereas in Pd3P0.95 NPs, its source is triphenylphosphine. The nature of the solvent did not affect the chemical composition of the nano-phase but controlled its size. Probably, solvent dependent, unique, single source precursors (SSPs) of palladium were generated in situ, and controlled the size. The catalytic activity of both Pd3P0.95 QDs and NPs was explored. The QDs were found to be efficient as a catalyst for the amide-nitrile interconversion at room temperature (yield up to 92% in 4 h), hydration of nitriles and transfer hydrogenation (TH) of carbonyl compounds with yields up to 96% in 3-4 h. The yields and reaction rates of amide-nitrile inter-conversion and TH when catalyzed by Pd3P0.95 QDs were found to be higher compared to the ones observed with the Pd/C catalyst. The binding energy of Pd(3d) in the X-ray photoelectron spectrum (XPS) of Pd3P0.95 indicated an electron transfer from the metal to phosphorus, resulting in electron deficient palladium, which facilitates the coordination of a substrate to Pd and drives the reaction. The reusability of Pd3P0.95 QDs for the interconversion was found to be up to 4-Times, while for the transfer hydrogenation of carbonyl compounds it was up to 6-Times, but with a diminished yield. Pd3P0.95 NPs were found to be less active (yield up to 36% in optimized reaction conditions) in comparison to Pd3P0.95 QDs. The mercury poisoning test suggested that the catalysis predominantly proceeded heterogeneously on the surface of the QDs. The PXRD and XPS results did not suggest a significant variation in the phase of QDs after the third catalytic cycle. The bleeding of Pd during catalysis (determined by flame AAS) and the agglomeration of QDs as supported by the SEM-EDX and TEM results are probably responsible for the reduction in the catalytic activity of QDs after reusing three times.
- Sharma, Alpesh K.,Joshi, Hemant,Bhaskar, Renu,Singh, Ajai K.
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supporting information
p. 10962 - 10970
(2019/07/31)
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- Ru (III) Schiff-base complex anchored on nanosilica as an efficient and retrievable catalyst for hydration of nitriles
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Transition metal catalyzed hydration of nitriles is an attractive methodology for amide synthesis, and hence recently attracted wide attention. It is one of the significant organic transformations as amides play a vital role in biological, pharmaceutical and industrial applications. In this work, we report the synthesis of a new solid supported Ru (III) Schiff base complex, Ru@imine-nanoSiO2 immobilized on nanosilica obtained from rice husk. The complex was characterized by FTIR, powder X-ray diffraction, BET surface area measurement, UV–vis, SEM–EDX, TEM, ESR, X-ray photoelectron spectroscopy and ICP-AES analysis. Using Ru@imine-nanoSiO2 as the catalyst, the hydration of nitriles in i-PrOH at 40?°C was studied which resulted in good isolated yields (60–99%). The catalyst can be recycled and reused up to 5th cycle without any loss in activity. The products were characterized by FTIR, GC–MS and 1H-NMR spectroscopy and compared with authentic samples.
- Sultana, Samim,Borah, Geetika,Gogoi, Pradip K.
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- Trash to treasure: Eco-friendly and practical synthesis of amides by nitriles hydrolysis in WepPA
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The hydration of nitriles to amides in a water extract of pomelo peel ash (WEPPA) was realized with moderate to excellent yields without using external transition metals, bases or organic solvents. This reaction features a broad substrate scope, wide functional group tolerance, prominent chemoselectivity, and good reusability. Notably, a magnification experiment in this bio-based solvent at 100 mmol further demonstrated its practicability.
- Sun, Yajun,Jin, Weiwei,Liu, Chenjiang
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supporting information
(2019/11/11)
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- Method for preparing derivatives of benzamide under microwave condition in aqueous phase
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The invention discloses a method for preparing derivatives of benzamide under a microwave condition in an aqueous phase. A coupling reaction is carried out between substituted benzoic acid and amine under the microwave condition in the aqueous phase. The method for preparing the derivatives of benzamide is environmentally friendly, easy and convenient to operate, safe, low in cost and efficient. Compared with the prior art, the method can be applicable to a large number of functional groups, is high in yield, produces fewer by-products, and further is easy to operate, safe, low in cost and environmentally friendly. A formula is shown in the description.
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Paragraph 0018; 0077
(2019/03/28)
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- One-Pot Anodic Conversion of Symmetrical Bisamides of Ethylene Diamine to Unsymmetrical gem-Bisamides of Methylene Diamine
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Symmetrical bisamides of ethylene diamine of type ArCONHCH2CH2NHCOAr undergo anodic C-C bond cleavage in acetonitrile-LiClO4 under controlled-potential electrolysis. The electrogenerated carbocation intermediates react with the solvent acetonitrile to afford unsymmetrical gem-bisamides of type ArCONHCH2NHCOMe in a one-pot reaction. The yields of the latter products are moderate (up to 60%). Other minor products involve two symmetrical gem-bisamides of type ArCONHCH2NHCOAr and MeCONHCH2NHCOMe and fragmentation products (e.g., ArCONHCHO, ArCONH2, and ArCN).
- Golub, Tatiana,Dou, Gui-Yuan,Zeng, Cheng-Chu,Becker, James Y.
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p. 7961 - 7964
(2019/10/11)
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- Selectivity-tunable amine aerobic oxidation catalysed by metal-free N,O-doped carbons
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Herein, we present a series of N,O-doped mesoporous carbons obtained at different pyrolysis temperatures as the first metal-free catalysts which successfully switch between imine and nitrile products for amine oxidation. Systematic characterization studies and control experiments revealed that the C-O group on the surface could function as a catalytically active site for nitrile synthesis and the N-doping environment was essential.
- Li, Yingguang,Shang, Sensen,Wang, Lianyue,Lv, Ying,Niu, Jingyang,Gao, Shuang
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supporting information
p. 12251 - 12254
(2019/10/21)
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- [VO(PS-BBMA)](SO4) catalyzed Α-oxygenation of benzylamines to amides in solvent free condition
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Polymer anchored [VO(PS-BBMA)]SO4 and unsupported [VO(BBMA)]SO4 catalysts were synthesized and characterized by elemental analyses, FT-IR, ESR, UV–vis diffuse reflectance spectroscopy (DRS), thermogravimetric analysis (TGA), and vibrating sample magnetometry (VSM). A protocol for the synthesis of benzamides from benzylamine has been developed using [VO(PS-BBMA]SO4 as an effective catalyst under solvent free conditions in presence of H2O2. The reactions provide good yields of the corresponding amide products with substrate scope and excellent functional group compatibility. The developed catalyst can be facilely recovered, heterogeneous, compared with unsupported analogue and reused six times without significant decrease in its activity.
- Renuka,Gayathri
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- Ionic liquid catalysed aerobic oxidative amidation and thioamidation of benzylic amines under neat conditions
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Tetrabutylammonium hydroxide (TBAOH) was discovered as a highly efficient and green catalyst for aerobic oxidation of the α-methylene carbon of primary amines as well as benzylic groups into the corresponding amides and ketones under neat conditions. We described herein, ionic liquid TBAOH catalysed aerobic oxidation of benzyl amines to benzamides and with elemental sulfur; the corresponding benzylbenzothioamides were obtained under metal-free, oxidant-free and base-free conditions. Applicability at the gram scale for the synthesis of the desired amides/ketones is also demonstrated with the present protocol.
- Joshi, Abhisek,Kumar, Rahul,Semwal, Rashmi,Rawat, Deepa,Adimurthy, Subbarayappa
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supporting information
p. 962 - 967
(2019/03/11)
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- Aerobic Activation of C-H Bond in Amines Over a Nanorod Manganese Oxide Catalyst
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The development of heterogeneous catalysts for the synthesis of pharmaceutically relevant compounds is always important for chemistry research. Here, we report a selective aerobic oxidation of aromatic and aliphatic amines to corresponding amides over a nanorod manganese oxide (NR-MnOx) catalyst. The kinetic studies reveal that the NR-MnOx catalyzed amine-to-amide reaction proceeds the oxidative dehydrogenation of the amines into nitriles, followed by hydrolysis of nitrile into amides. The NR?MnOx exhibits fast kinetics and high selectivities in these steps, as well as hinders the by-product formation. More importantly, the NR-MnOx catalyst is stable and reusable in the continuous recycle tests with water as a sole by-product, exhibiting superior sustainability and significant advancement to outperform the traditional amide production route in acidic or basic media with toxic by-products.
- Wang, Hai,Wang, Liang,Wang, Sai,Dong, Xue,Zhang, Jian,Xiao, Feng-Shou
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p. 401 - 406
(2018/08/11)
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- Copper-amino group complexes supported on silica-coated magnetite nanoparticles: Efficient catalyst for oxidative amidation of methyl arenes
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Magnetite nanoparticles coated with mesoporous silica, Fe3O4@SiO2, were prepared. Surface functionalization of this core-shell nanocomposite with (3-aminopropyl)trimethoxysilane (APTMS) followed by its reaction with Cu(OAc)2 was used to develop a new heterogeneous copper complex (Fe3O4@SiO2-APTMS-Cu). The structure and composition of the synthesized nanocatalyst were characterized by FTIR, SEM, VSM, TEM, XRD, and ICP analyses. The catalytic activity of the synthesized catalyst was probed in the oxidative amidation reaction of methyl arenes with amine hydrochloride salts. Various primary, secondary, and tertiary amides were prepared by this method. The magnetic properties of this catalyst lead to easy separation as well as providing significant catalyst recyclability. The catalyst is reusable 6 times without significant decrease in its catalytic activity.
- Karimi, Meghdad,Ghandi, Leila,Saberi, Dariush,Heydari, Akbar
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supporting information
p. 3900 - 3908
(2018/03/06)
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- Metal-Free Nitrogen- and Boron-Codoped Mesoporous Carbons for Primary Amides Synthesis from Primary Alcohols via Direct Oxidative Dehydrogenation
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Metal-free catalysts show environmental friendliness and cost-effectiveness, as well as less susceptibility to poisoning over metal and metal oxide catalysts. In this respect, we present the synthesis and characterization of metal-free mesoporous nitrogen- and boron-codoped nanocarbon (meso-N,B/C), which exhibits good catalytic performance with conversion of 89% and selectivity of 83% toward amide synthesis from primary alcohols using NH4OAc as an ammonia resource under an oxygen atmosphere. The facile codoping synthetic strategy was executed by pyrolysis of nitrogen-enriched ligand 4,5-diazafluorene-9-one azine (DAA) and H3BO3 as a nitrogen and boron content modulator, respectively. Significantly, control experiments revealed that the reaction proceeded through direct oxidative dehydrogenation of hemiaminal after aldehyde-ammonia condensation, which was remarkably different from that in the previous literature. Density functional theory (DFT) calculations further demonstrate that the selective preference for benzamide largely benefits from the strong adsorption and enhanced activity of oxygen molecules via the interaction with a B atom doped in the catalyst. The active sites in the meso-N,B/C catalyst are proposed to be B atom bonded with N within the graphitic carbon sheets. This founding opens up avenues for the development of modified carbon materials on metal-free catalysis.
- Shang, Sensen,Chen, Pei-Pei,Wang, Lianyue,Lv, Ying,Li, Wei-Xue,Gao, Shuang
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p. 9936 - 9944
(2018/10/15)
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