- The enhancement of direct amide synthesis reaction rate over TiO2@SiO2@NiFe2O4 magnetic catalysts in the continuous flow under radiofrequency heating
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A series of TiO2@SiO2@NiFe2O4 composite magnetic catalyst with a core-double shell structure was synthesized by a sol-gel method. The morphology of the catalysts was studied by XRD, SEM, N2 physisorption and their magnetic properties were examined with magnetometry, and specific absorption rate measurements. The catalytic activity was determined in a direct amide synthesis reaction between aniline and phenylbutyric acid at 150 °C in a fixed bed flow reactor under radiofrequency heating. The intermediate silica layer of the catalyst increased the porosity of the outer titania layer and the specific absorbance rate of the catalyst. The initial reaction rate increased by 61% as compared to a similar core-shell TiO2@NiFe2O4 catalyst showing the detrimental effect of nickel ferrite on titania. The reaction rate was further increased by a factor of 3.5 after a sulfation treatment due to an optimum Lewis acid site strength. The highest specific reaction rate over TiO2@SiO2@NiFe2O4 was observed at a 7.5 wt% sulfate loading which was 2.6 times higher as compared to a mechanical mixture of the same composition. The initial reaction rate decreased by 36% after a period of 55 h on stream. The catalyst activity was restored after a treatment with a H2O2 solution.
- Liu, Yawen,Cherkasov, Nikolay,Gao, Pengzhao,Fernández, Javier,Lees, Martin R.,Rebrov, Evgeny V.
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- Visible-Light-Promoted Iron-Catalyzed N-Arylation of Dioxazolones with Arylboronic Acids
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A visible-light-promoted and simple iron salt-catalyzed N-arylation was achieved efficiently under external photosensitizer-free conditions. Arylboronic acids and bench-stable dioxazolones were used for this cross-coupling reaction. This reaction features high reactivity, wide substrate scope, good functional group tolerance, simple operation procedure, and mild reaction conditions. Preliminary mechanistic investigations were conducted to support a radical pathway. This method may contribute to shift the paradigm of iron-catalyzed C-N bond construction and nitrene transfer chemistry.
- Tang, Jing-Jing,Yu, Xiaoqiang,Yamamoto, Yoshinori,Bao, Ming
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p. 13955 - 13961
(2021/11/20)
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- Tungsten-Catalyzed Transamidation of Tertiary Alkyl Amides
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Transamidation has recently emerged as a straightforward and convenient means to diversify amides. However, the kinetically and thermodynamically demanding transamidation of notoriously robust, fully alkyl-substituted tertiary amides still remains a longstanding challenge. Here, we describe a method for the activation of tertiary alkyl amides to streamline transamidation using simple tungsten(VI) chloride as a catalyst and chlorotrimethylsilane as an additive. The highly electrophilic and oxophilic tungsten catalyst enables the selective scission of a C-N bond of tertiary alkyl amides to effect transamidation of a myriad of structurally and electronically diverse tertiary alkyl amides and amines. Mechanistic study implies that the synergistic effect of the catalyst and the additive could pronouncedly induce the nucleophilic acyl substitution of tertiary alkyl amide with amine to realize transamidation.
- Feng, Fang-Fang,Liu, Xuan-Yu,Cheung, Chi Wai,Ma, Jun-An
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p. 7070 - 7079
(2021/06/30)
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- Direct amide formation in a continuous-flow system mediated by carbon disulfide
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Amide bonds are ubiquitous in nature. They can be found in proteins, peptides, alkaloids, etc. and they are used in various synthetic drugs too. Amide bonds are mainly made by the use of (i) hazardous carboxylic acid derivatives or (ii) expensive coupling agents. Both ways make the synthetic technology less atom economic. We report a direct flow-based synthesis of amides. The developed approach is prominently simple and various aliphatic and aromatic amides were synthetized with excellent yields. The reaction in itself is carried out in acetonitrile, which is considered as a less problematic dipolar aprotic solvent. The used coupling agent, carbon disulfide, is widely available and has a low price. The utilized heterogeneous Lewis acid, alumina, is a sustainable material and it can be utilized multiple times. The technology is considerably robust and shows excellent reusability and easy scale-up is carried out without the need of any intensive purification protocols.
- Orsy, Gy?rgy,Fül?p, Ferenc,Mándity, István M.
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p. 7814 - 7818
(2020/12/28)
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- Antagonism of quorum sensing phenotypes by analogs of the marine bacterial secondary metabolite 3-methyl-N-(20-phenylethyl)-butyramide
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Quorum sensing (QS) antagonists have been proposed as novel therapeutic agents to combat bacterial infections. We previously reported that the secondary metabolite 3-methyl-N-(20-phenylethyl)-butyramide, produced by a marine bacterium identifie
- Meschwitz, Susan M.,Teasdale, Margaret E.,Mozzer, Ann,Martin, Nicole,Liu, Jiayuan,Forschner-Dancause, Stephanie,Rowley, David C.
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- Synergistic Copper-Catalyzed Reductive Aminocarbonylation of Alkyl Iodides with Nitroarenes
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We have developed a Cu-catalyzed reductive aminocarbonylation of alkyl iodides using nitroarenes as the nitrogen source. The reaction proceeds with a single copper catalyst playing dual roles of synergistically mediating both carbonylation of alkyl iodide
- Zhao, Siling,Mankad, Neal P.
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supporting information
p. 10106 - 10110
(2019/12/24)
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- Organic ligand-free carbonylation reactions with unsupported bulk Pd as catalyst
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Herein, surprising results for bulk Pd-catalyzed carbonylation reactions are presented. Three types of carbonylation reactions can be realized efficiently under organic ligand-free conditions, namely, hydroaminocarbonylation of olefins, aminocarbonylation of aryl iodides and oxidative carbonylation of amines, which almost cover all the known mechanisms in carbonylation reactions. Notably, the bulk Pd catalyst system exhibited better catalytic activity than the classical homogeneous PdCl2/(2-OMePh)3P catalyst system. This study will create a momentous and new field of green carbonylation reactions.
- Liu, Shujuan,Wang, Hongli,Dai, Xingchao,Shi, Feng
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supporting information
p. 3457 - 3462
(2018/08/06)
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- 2-substituted aniline as a simple scaffold for LuxR-regulated QS modulation
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The ability of the 2-substituted aniline motif to serve as a scaffold for designing potential LuxR-regulated quorum sensing (QS) modulators has been investigated, using docking experiments and biological evaluation of a series of 15 specially synthesized compounds. Aniline, 2-acetyl-aniline and 2-nitroaniline were considered, as well as their N-acylated derivatives. Docking experiments showed that the 2-substituted aniline motif fits within the LuxR binding site at the place of the lactone moiety of AHL, and the biological evaluation revealed QS antagonisitic activity for several compounds, validating the hypothesis that this scaffold acts on QS. Structure activity relationships are discussed regarding interactions with the key residues of the LuxR binding site, showing significant variations in the H-bonding pattern.
- Li, Sizhe,Wawrzyniak, Julien,Queneau, Yves,Soulère, Laurent
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- Direct amide synthesis over core-shell TiO2@NiFe2O4 catalysts in a continuous flow radiofrequency-heated reactor
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Core-shell composite magnetic catalysts TiO2@NiFe2O4 with a titania loading of 9-32 wt% have been synthesised by a sol-gel method for direct amide synthesis in a radiofrequency (RF, induction)-heated continuous flow reactor. The catalyst calcination temperature was optimised in the range of 350-500 °C and the highest activity was observed for the catalyst calcined at 500 °C due to conversion of titania into the catalytically active anatase phase. No reaction between the magnetic core and the titania shell was observed up to the calcination temperature of 1000 °C and no sintering of the titania shell was observed after calcination at 500 °C. The comparison of direct amide synthesis in a continuous flow fixed bed reactor under conventional and RF heating demonstrated that the RF heating mode increased the apparent reaction rate by 60% and decreased the deactivation rate due to a better temperature uniformity. The titania weight normalised reaction rate in the RF-heated reactor was constant for titania loadings above 17 wt%, while it decreased by a factor of 3 at lower titania loadings because of interactions between the ferrite core on the thin layer of the catalyst. The catalyst deactivation study showed that the deactivation rate could be accurately described by first order kinetics and that the main reason of deactivation was coking. The catalyst regeneration via calcination at 400 °C resulted in catalyst sintering, while treatment with a hydrogen peroxide solution at 90 °C fully recovered the catalytic activity.
- Liu, Yawen,Gao, Pengzhao,Cherkasov, Nikolay,Rebrov, Evgeny V.
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p. 100997 - 101007
(2016/11/09)
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- The Use of Ureates as Activators for Samarium Diiodide
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A novel mode of SmI2 activation has been developed using ureates as reaction promoters. Several ureates formed by treatment of the corresponding ureas with n-BuLi have been shown to activate SmI2 to a substantial extent toward the reduction of 1-chlorodecane. Complexes formed from SmI2 and various ureates have been shown to be useful for the reduction of a variety of organohalides, including substrates of low reactivity such as aryl fluorides. Because of ease of synthesis and low molecular weight, the conjugate base of triethylurea (TEU-) was of primary focus. Visible spectroscopy and reactivity data are consistent with the hypothesis that the same complex is being formed when SmI2 is combined with either 2 or 4 equiv of TEU-, in spite of the greater reactivity of SmI2/4 TEU- with some alkyl halides. We propose that the active reductant is an N,O chelate formed between SmI2 and 2 equiv of TEU-.
- McDonald, Chriss E.,Ramsey, Jeremy D.,McAtee, Christopher C.,Mauck, Joseph R.,Hale, Erin M.,Cumens, Justin A.
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p. 5903 - 5914
(2016/07/23)
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- Selective palladium-catalyzed aminocarbonylation of olefins with aromatic amines and nitroarenes
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Various olefins can be smoothly transformed in the presence of a Pd-based catalyst system and (hetero)aromatic amines or nitroarenes to synthetically interesting amides in good yields and often with high regioselectivity (see scheme). Combining this atom-efficient procedure with established functionalizations of the resulting products allows the efficient preparation of quinolines. Copyright
- Fang, Xianjie,Jackstell, Ralf,Beller, Matthias
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supporting information
p. 14089 - 14093
(2014/01/06)
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- Direct amide formation using radiofrequency heating
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We present a simple method for direct and solvent-free formation of amides from carboxylic acids and amines using radiofrequency heating. The direct energy coupling of the AC magnetic field via nickel ferrite magnetic nanoparticles enables fast and controllable heating, as well as enabling facile work-up via magnetic separation.
- Houlding, Thomas K.,Tchabanenko, Kirill,Rahman, Md. Taifur,Rebrov, Evgeny V.
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p. 4171 - 4177
(2013/07/05)
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- The uncatalyzed direct amide formation reaction - Mechanism studies and the key role of carboxylic acid h-bonding
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Calorimetric studies of the mixing of a series of carboxylic acids and amines have been carried out to measure heat output, which has been compared with their ability to react to form carboxylate ammonium salts and amides. In order to identify which species (salt or H-bonded species) were formed, 1H NMR studies were also carried out by mixingcarboxylic acids and amines in [D8]toluene and monitoring the resulting reactions. These experiments were also compared to DFT computational studies, from which the relative merits of different mechanistic schemes for direct amide formation could be assessed. A reaction mechanism involving zwitterionic intermediates could be eliminated on the basis of calculated energies in toluene, however, a neutral intermediate pathway, involving carboxylic acid dimerization by mutual hydrogen bonding was found to be accessible and may explain how the direct amide formation reaction occurs. Such a mechanism is not inconsistent with kinetic modelling of direct amide formation under different reactions conditions. It Takes Two to Amide: Direct amide formation between carboxylic acids andamines has attracted a lot of curiosity, but there is little clarification on the interplay between ammonium carboxylate salt formation vs. amide bond formation. These studies shed light on these competing processes and a new mechanism is proposed for direct amide formation, elucidating the key role of carboxylic acid dimers.
- Charville, Hayley,Jackson, David A.,Hodges, George,Whiting, Andrew,Wilson, Mark R.
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supporting information; experimental part
p. 5981 - 5990
(2011/12/15)
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- Pd-catalyzed carbonylation of diazo compounds at atmospheric pressure: A catalytic approach to ketenes
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The carbonylation of carbenes through catalytic cycles is highly desirable due to the importance of ketene-mediated reactions in organic synthesis. In this investigation, a highly efficient and mild catalytic approach toward ketene intermediates has been developed based on Pd-catalyzed carbonylation of diazo compounds with CO. When α-diazocarbonyl compounds or N-tosylhydrazone salts are heated in the presence of a palladium catalyst under atmospheric pressure of CO, ketene intermediates are formed in situ, where they undergo further reactions with various nucleophiles such as alcohols, amines, or imines. The Pd-catalyzed tandem carbonylation-Staudinger cycloaddition gives β-lactam derivatives in good yields with excellent trans diastereoselectivity. The results from DFT calculation on the reaction mechanism suggest that Pd is involved in the [2 + 2] cycloaddition process and affects the diastereoselectivity of the β-lactam products by assisting isomerization of the addition intermediate. On the other hand, the acylketenes generated from the Pd-catalyzed carbonylation of α-diazoketones react with imines in a formal [4 + 2] cycloaddition manner to afford 1,3-dioxin-4-one derivatives. This straightforward carbonylation provides a new approach toward highly efficient catalytic generation of ketene species under mild conditions.
- Zhang, Zhenhua,Liu, Yiyang,Ling, Lin,Li, Yuxue,Dong, Yian,Gong, Mingxing,Zhao, Xiaokun,Zhang, Yan,Wang, Jianbo
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supporting information; experimental part
p. 4330 - 4341
(2011/06/21)
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- Clean, reusable and low cost heterogeneous catalyst for amide synthesis
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We have developed a heterogeneous silica catalyst that can effectively catalyse amide synthesis from acid and amine, without production of toxic by-products and with the advantage of being readily available, low cost, environmentally benign and reusable. The Royal Society of Chemistry 2009.
- Comerford, James W.,Clark, James H.,MacQuarrie, Duncan J.,Breeden, Simon W.
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supporting information; experimental part
p. 2562 - 2564
(2009/10/16)
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- Novel intramolecular reactivity of oximes: Synthesis of cyclic and spiro-fused imines
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(Chemical Equation Presented) Under conventional heat (135-145°C) or microwave irradiation and 1 equiv of acetic anhydride, ortho-substituted aryl-oximes undergo a novel sp3 C-H activated cyclization to produce the corresponding isoindoles, and
- Savarin, Cecile G.,Grise, Christiane,Murry, Jerry A.,Reamer, Robert A.,Hughes, David L.
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p. 981 - 983
(2007/10/03)
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- A novel approach for the direct conversion of alkylsulfonyl derivatives into alkylcarbonyl derivatives via tin-free radical carbonylation
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A novel radical approach for the direct conversion of RSO2X into RCOX in a single step is devised; the present approach is very simple, highly efficient, and minimizes formation of by-product. The Royal Society of Chemistry.
- Kim, Sangmo,Lim, Kyoung-Chan,Kim, Sunggak
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p. 4507 - 4509
(2008/04/01)
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- Catalytic one-pot synthesis of N-phenyl alkyl amides from alkene and aniline in the presence of cobalt on charcoal under carbon monoxide
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N-Phenyl alkyl amides were synthesized by the cobalt on charcoal-catalyzed one-pot reaction of alkene and aniline under carbon monoxide; this is the first heterogeneous catalytic formation of N-phenyl alkyl amides.
- Lee, Sang Ick,Son, Seung Uk,Chung, Young Keun
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p. 1310 - 1311
(2007/10/03)
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- Mechanism of the reaction of carbodiimides with carboxylic acids
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The kinetic parameters of the reaction of diphenylcarbodiimide with various carboxylic acids have been determined at a temperature interval of 20-160 deg C.The classical scheme for the reaction of carbodiimides with carboxylic acids is extended.It has been found that, at high temperatures, amides and isocyanates are the end products of the reactions.N-Acylureas, initially formed from aromatic carbodiimides and carboxylic acids, dissociate into isocyanates and amides at temperatures above 60 deg C.N-Acylureas formed by the reaction of carboxylic acids with aliphatic carbodiimides prove to be more stable: their dissociation temperature is about 50 deg C higher.Both the formation and dissociation of N-acylureas are much faster when the parent acid is stronger.
- Schotman, A. H. M.
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p. 319 - 324
(2007/10/02)
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- A FACILE SYNTHESIS OF CARBOXYLIC ESTERS AND CARBOXAMIDES BY THE USE OF 1,1'-DIMETHYLSTANNOCENE AS A CONDENSING REAGENT
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Various carboxylic esters or carboxamides are prepared in good yields under nearly neutral conditions from equimolar amounts of free carboxylic acids and alcohols or amines, respectively, by the use of 1,1'-dimethylstannocene as a condensing reagent.
- Mukaiyama, Teruaki,Ichikawa, Junji,Asami, Masatoshi
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p. 683 - 686
(2007/10/02)
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