- Palladium-catalyzed C-H acylation of arenes using thioethers as directing groups
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A highly efficient protocol for regioselective synthesis of diaryl ketones by palladium-catalyzed direct acylation of arenes using thioethers as directing groups is reported. The possible pathway of direct acylation between thioethers and α-oxocarboxylic acids is discussed. The direct acylation of thioethers via Pd-catalyzed C-H bond activation was described. Copyright
- Xu, Bo,Liu, Wei,Kuang, Chunxiang
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- Structural changes in concentrated solutions of alkali metal monosubstituted benzophenone radical anions as deduced front1H NMR measurements
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The radical anions of monosubstituted benzophenones (including 2-, 3- and 4-methyl-, 4-tert-butyl- and 4-phenylbenzophenone) with lithium, sodium and potassium as countercations in tetrahydrofuran (THF) were studied by paramagnetic solvent 1H NMR shift measurements in the concentration range ca 0.1-1.0 M. In addition to the cation effects, marked positional isomer and substituent effects were found for (1) molar paramagnetism, (2) magnetic state, (3) solubility, (4) structural stability with respect to concentration or addition of cosolvents and (5) rapidity of attainment of their equilibrium structure. The major conclusions which can be drawn are (a) the solvation behavior of the countercation is governed by the anion, (b) an alkyl group in the 4-position makes the structure of the lithium and sodium monosubstituted benzophenone radical anions concentration dependent and (c) in most cases, alkali metal aromatic ketone radical anions generated by electron transfer from the corresponding naphthalene radical anion attain their equilibrium structure rapidly. The data are interpreted on the basis of the involvement of spin-triplet interactions within 'dimers' or higher clusters. Copyright
- Micha-Screttas, Maria,Heropoulos, Georgios A.,Steele, Barry R.
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- Application of mobilized gold nanoparticles as sole catalyst for the oxidation of secondary alcohols into ketones
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Oxidation of alcohols into corresponding ketones is efficiently catalyzed by heterogeneous gold nanoparticles. Use of H2O2 instead of O2 (g) is the main feature of our methodology since maintaining the required pressure of O2 (g) at elevated temperature is not easy. The reaction does not require any co-catalyst. After completion of the reaction, the catalyst could be recovered by centrifugation and reused several times with only a slight decrease in activity. Thus our present protocol, which is comprised of green reagent, solvent and catalyst, is completely clean.
- Kidwai, Mazaahir,Bhardwaj, Saurav
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- Structural characterization of bismuth(III) and antimony(III) chlorotriflates: Key intermediates in catalytic Friedel-Crafts transformations
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Chlorotriflates of antimony and bismuth ClnM(OSO 2CF3)3-n (n = 1 or 2) are believed to be metallic intermediates of major importance in Friedel-Crafts reactions that use Bi(OSO2CF3)3, Sb(OSO2CF 3)3, the systems BiCl3/CF3SO 2OH or SbCl3/CF3SO2OH as catalysts. Unknown until now, the compounds ClBi(OSO2CF3)2 (1) and Cl2Sb(OSO2CF3) (2) have been synthesized by reaction of MCl3 (M = Bi, Sb) with triflic acid. After crystallization from THF, 1 and 2 were investigated in the solid state by X-ray crystallography. Their use as catalysts in benzoylation of toluene, acylation of m-xylene, and sulfonylation of toluene led to conclusive results, thus giving weight to their key role as intermediates in Friedel-Crafts reactions. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004.
- Mazieres, Stephane,Le Roux, Christophe,Peyronneau, Magali,Gornitzka, Heinz,Roques, Nicolas
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- Palladium NCN and CNC pincer complexes as exceptionally active catalysts for aerobic oxidation in sustainable media
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The oxidation of secondary benzyl alcohols is catalyzed by two palladacycles at atmospheric pressure in PEG-400, a sustainable reaction media. Recycling of the active catalytic species is performed up to the 5th run, and catalyst loadings decreased down to 10-8 mol%, thus achieving unprecedented TON and TOF values. In addition, the same conditions proved to be effective for the aerobic oxidation of benzyl methylene compounds, a scarcely explored process by palladium catalysts.
- Urgoitia, Garazi,Sanmartin, Raul,Herrero, Maria Teresa,Dominguez, Esther
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- Towards applications of metal-organic frameworks in catalysis: Friedel-Crafts acylation reaction over IRMOF-8 as an efficient heterogeneous catalyst
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A highly porous metal-organic framework (IRMOF-8) was synthesized by a solvothermal method, and used as an efficient heterogeneous catalyst for the Friedel-Crafts acylation reaction. The solid catalyst was characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FT-IR), atomic absorption spectrophotometry (AAS), and nitrogen physisorption measurements. High conversions were achieved in the presence of a catalytic amount of the IRMOF-8 (1-5 mol%) without the need for an inert atmosphere. The solid catalyst could be facilely separated from the reaction mixture by simple centrifugation, and could be reused without a significant degradation in catalytic activity. No contribution from homogeneous catalysis of active acid species leaching into the reaction solution was detected.
- Nguyen, Lien T.L.,Nguyen, Chi V.,Dang, Giao H.,Le, Ky K.A.,Phan, Nam T.S.
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- N-Acylsuccinimides: Twist-controlled, acyl-transfer reagents in Suzuki-Miyaura cross-coupling by N-C amide bond activation
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The palladium-catalyzed Suzuki-Miyaura cross-coupling of N-acylsuccinimides as versatile acyl-transfer reagents via selective amide N-C bond cleavage is reported. The method is user-friendly since it employs commercially-available, air-stable reagents and catalysts. The cross-coupling is enabled by half-twist of the amide bond in N-acylsuccinimides. These highly effective, crystalline acyl-transfer reagents present major advantages over perpendicularly twisted N-acylglutarimides, including low price of the succinimide activating ring, selective metal insertion under redox neutral conditions and high stability of the amide bond towards reaction conditions. Mechanistic studies indicate that oxidative addition is the rate limiting step in this widely applicable protocol.
- Osumi, Yuki,Liu, Chengwei,Szostak, Michal
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- Sulfated fibrous ZrO2/Al2O3 core and shell nanocomposites: A novel strong acid catalyst with hierarchically macro-mesoporous nanostructure
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A series of solid strong acid catalysts were synthesized from fibrous ZrO2/Al2O3 core and shell nanocomposites. In this series, the zirconium molar percentage was varied from 2% to 50%. The ZrO2/Al2O3 nanocomposites and their solid strong acid counterparts were characterised by a variety of techniques including 27Al magic angle spinning nuclear magnetic resonance (MAS-NMR), scanned electronic microscopy (SEM), transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS), nitrogen adsorption and infrared emission spectroscopy (IES). NMR results show that the interaction between zirconia species and alumina strongly correlates with pentacoordinated aluminium sites. This can also be detected by the change in binding energy of the 3d electrons of the zirconium. The acidity of the obtained solid acids was tested by using them as catalysts for the benzoylation of toluene. It was found that a sample with a 50% zirconium molar percentage possessed the highest surface acidity equalling that of pristine sulfated zirconia despite the reduced mass of zirconia.
- Liu, Erming,Locke, Ashley J.,Frost, Ray L.,Martens, Wayde N.
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- Diaryl ketone synthesis by [RuHCl(CO)(PPh3)3]- catalyzed coupling reaction of arylboronic acids with aryl aldehydes
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[RuHCl(CO)(PPh3)3] was found to be an efficient catalyst for the coupling reaction of arylboronic acids with aryl aldehydes. The reaction proceeded smoothly in the presence of K2CO3 and H2O to give diaryl ketones in good yields. Diaryl ketones were obtained from primarily formed alcohols via Rucatalyzed transfer hydrogenation reaction.
- Fukuyama, Takahide,Okamoto, Hiromi,Ryu, Ilhyong
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- Bismuth(III) bis(trifluoromethanesulfonyl)amide
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Bismuth(III) bis(trifluoromethanesulfonyl)amide (Bi(NTf2)3, 3) has been prepared from the reaction of protiodemetallation of tri-p-tolylbismuth by a stoichiometric amount of bis(trifluoromethanesulfonyl)amine (1). The intermediates BiPh3-n(NTf2)n (n=2 (4), 1 (5)) resulting from the reaction of 1 with triphenylbismuth have also been isolated. The amide 3 was able to catalyze the benzoylation and the benzenesulfonylation of toluene.
- Picot, Alexandre,Repichet, Sigrid,Le Roux, Christophe,Dubac, Jacques,Roques, Nicolas
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- Imidazolylmethylbenzophenones as highly potent aromatase inhibitors
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Suppression of tumor and plasma estrogen levels by inhibition of aromatase is one of the most effective treatments for post-menopausal breast cancer patients. Starting from an easy, synthetically accessible, benzophenone scaffold, a new class of potent aromatase inhibitors was synthesized, endowed with high selectivity with respect to 17α-hydroxylase/17,20-lyase (CYP17). Compounds 1b and 1d proved to be among the most potent inhibitors described so far.
- Gobbi, Silvia,Cavalli, Andrea,Negri, Matthias,Schewe, Katarzyna E.,Belluti, Federica,Piazzi, Lorna,Hartmann, Rolf W.,Recanatini, Maurizio,Bisi, Alessandra
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- Light/Palladium-Promoted Benzylic C?H Acylation Using a Benzoyl Group as the Photo-Directing Group
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2-Methylphenyl ketones undergo site-selective acylation at the benzylic position when treated with acid anhydride under UV irradiation in the presence of a palladium catalyst. The benzoyl carbonyl group serves as the photo-directing group so that the ortho benzylic C?H bond is activated site-selectively.
- Masuda, Yusuke,Ishida, Naoki,Murakami, Masahiro
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- N-Acyl-glutarimides: Effect of Glutarimide Ring on the Structures of Fully Perpendicular Twisted Amides and N-C Bond Cross-Coupling
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N-Acyl-glutarimides have emerged as the most reactive precursors for N-C(O) bond cross-coupling reactions to date, wherein the reactivity is driven by ground-state destabilization of the amide bond. Herein, we report a full study on the effect of a glutarimide ring on the structures, electronic properties, and reactivity of fully perpendicular N-acyl-glutarimide amides. Most notably, this report demonstrates the generality of deploying N-acyl-glutarimides to achieve full twist of the acyclic amide bond, and results in the discovery of N-acyl-glutarimide amide with an almost perfect twist value, τ = 89.1°. X-ray structures of five new N-acyl-glutarimides are reported. Reactivity studies in the Suzuki-Miyaura cross-coupling and transamidation reactions provide insight into the reactivity of N-acyl-glutarimides in metal-catalyzed and transition-metal-free reactions. The effect of distortion, structures, and rotational barriers around the N-C(O) axis is discussed. The ability to achieve full distortion of the amide bond significantly expands the range of reagents available for N-C(O) cross-coupling reactions.
- Bisz, Elwira,Chen, Hao,Dziuk, B?a?ej,Lalancette, Roger,Liu, Chengwei,Rahman, Md. Mahbubur,Szostak, Michal,Szostak, Roman,Wang, Qi
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- REVERSAL OF THE BENZOPHENONE REACTIVITY UPON η2 -COMPLEXATION TO BIS( η5 -CYCLOPENTADIENYL)ZIRCONIUM
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Reversal of the carbonyl activity of benzophenone, serving as electron donor in single-electron transfer processes and acting as a proton acceptor through the 'carbonyl'carbon atom, is observed upon η2 -complexation to zirconocene.
- Rosenfeldt, Frank,Erker, Gerhard
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- Asymmetric Transfer Hydrogenation of Diaryl Ketones with Ethanol Catalyzed by Chiral NCP Pincer Iridium Complexes
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The use of a chiral (NCP)Ir complex as the precatalyst allowed for the discovery of asymmetric transfer hydrogenation of diaryl ketones with ethanol as the hydrogen source and solvent. This reaction was applicable to various ortho-substituted diaryl keontes, affording benzhydrols in good yields and enantioselectivities. This protocol could be carried out in a gram scale under mild reaction conditions. The utility of the catalytic system was highlighted by the synthesis of the key precursor of (S)-neobenodine.
- Huang, Zheng,Liu, Guixia,Qian, Lu,Tang, Xixia,Wang, Yulei
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supporting information
(2022/02/23)
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- COMPLEXES OF N-HETEROCYCLIC CARBENES FOR TRANSITION METAL CATALYSIS
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Described herein is a new class of highly active Pd(II)-NHC complexes bearing anilines as throw-away ligands. These catalysts are well-defined, air- and moisture-stable and can be easily purified by chromatographic techniques. High activity and generality has been exemplified in the Suzuki-Miyaura cross-coupling by C-N, C-O and C-Cl cleavage. Facile syntheses of these catalysts is also described.
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Paragraph 29-30
(2021/07/17)
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- C(acyl)-C(sp2) and C(sp2)-C(sp2) Suzuki-Miyaura cross-coupling reactions using nitrile-functionalized NHC palladium complexes
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Application of N-heterocyclic carbene (NHC) palladium complexes has been successful for the modulation of C-C coupling reactions. For this purpose, a series of azolium salts (1a-f) including benzothiazolium, benzimidazolium, and imidazolium, bearing a CN-substituted benzyl moiety, and their (NHC)2PdBr2 (2a-c) and PEPPSI-type palladium (3b-f) complexes have been systematically prepared to catalyse acylative Suzuki-Miyaura coupling reaction of acyl chlorides with arylboronic acids to form benzophenone derivatives in the presence of potassium carbonate as a base and to catalyse the traditional Suzuki-Miyaura coupling reaction of bromobenzene with arylboronic acids to form biaryls. All the synthesized compounds were fully characterized by Fourier Transform Infrared (FTIR), and 1H and 13C NMR spectroscopies. X-ray diffraction studies on single crystals of 3c, 3e and 3f prove the square planar geometry. Scanning Electron Microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), metal mapping analyses and thermal gravimetric analysis (TGA) were performed to get further insights into the mechanism of the Suzuki-Miyaura cross coupling reactions. Mechanistic studies have revealed that the stability and coordination of the complexes by the CN group are achieved by the removal of pyridine from the complex in catalytic cycles. The presence of the CN group in the (NHC)Pd complexes significantly increased the catalytic activities for both reactions.
- ?akir, Sinem,Karabiyik, Hande,Kavukcu, Serdar Batikan,Rethinam, Senthil,Türkmen, Hayati
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p. 37684 - 37699
(2021/12/09)
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- Suzuki-Miyaura cross-coupling of esters by selective O-C(O) cleavage mediated by air- And moisture-stable [Pd(NHC)(μ-Cl)Cl]2precatalysts: Catalyst evaluation and mechanism
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The cross-coupling of aryl esters has emerged as a powerful platform for the functionalization of otherwise inert acyl C-O bonds in chemical synthesis and catalysis. Herein, we report a combined experimental and computational study on the acyl Suzuki-Miyaura cross-coupling of aryl esters mediated by well-defined, air- and moisture-stable Pd(ii)-NHC precatalysts [Pd(NHC)(μ-Cl)Cl]2. We present a comprehensive evaluation of [Pd(NHC)(μ-Cl)Cl]2 precatalysts and compare them with the present state-of-the-art [(Pd(NHC)allyl] precatalysts bearing allyl-type throw-away ligands. Most importantly, the study reveals [Pd(NHC)(μ-Cl)Cl]2 as the most reactive precatalysts discovered to date in this reactivity manifold. The unique synthetic utility of this unconventional O-C(O) cross-coupling is highlighted in the late-stage functionalization of pharmaceuticals and sequential chemoselective cross-coupling, providing access to valuable ketone products by a catalytic mechanism involving Pd insertion into the aryl ester bond. Furthermore, we present a comprehensive study of the catalytic cycle by DFT methods. Considering the clear advantages of [Pd(NHC)(μ-Cl)Cl]2 precatalysts on several levels, including facile one-pot synthesis, superior atom-economic profile to all other Pd(ii)-NHC catalysts, and versatile reactivity, these should be considered as the 'first-choice' catalysts for all routine applications in ester O-C(O) bond activation.
- Cavallo, Luigi,Nolan, Steven P.,Poater, Albert,Szostak, Michal,Yang, Shiyi,Zhou, Tongliang
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p. 3189 - 3197
(2021/05/25)
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- Palladium(II) Complexes of a Neutral CCC-Tris(N-heterocyclic carbene) Pincer Ligand: Synthesis and Catalytic Applications
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Treatment of tris-azolium precursor 1 with palladium acetate under thermal conditions provided a CCC-pincer palladium(II) complex (2) bearing three NHCs (one imidazolylidene and two triazolylidenes) and one iodide ligand. Further treatment of complex 2 with an excess of AgSbF6 generates tris(carbene) dicationic palladium complex 3 in which the iodine ligands are exchanged with SbF6 anions and the metal center is stabilized by one acetonitrile ligand. Complexes 2 and 3 were tested in several cross coupling reactions showing high conversions under low catalyst loadings and mild reaction conditions. Additionally, complexes 2 and 3 performed well in the hydrosilylation of terminal alkynes with good selectivity toward the E-isomer.
- Angeles-Beltrán, Deyanira,Mendoza-Espinosa, Daniel,Rendón-Nava, David,Rheingold, Arnold L.
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supporting information
p. 2166 - 2177
(2021/07/20)
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- Self-Assembled 2,3-Dicyanopyrazino Phenanthrene Aggregates as a Visible-Light Photocatalyst
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In this study, 2,3-dicyanopyrazino phenanthrene (DCPP), a commodity chemical that can be prepared at an industrial scale, was used as a photocatalyst in lieu of Ru or Ir complexes in C-X (X = C, N, and O) bond-forming reactions under visible-light irradiation. In these reactions, [DCPP]n aggregates were formed in situ through physical π-πstacking of DCPP monomers in organic solvents. These aggregates exhibited excellent photo- and electrochemical properties, including a visible light response (430 nm), long excited-state lifetime (19.3 μs), high excited-state reduction potential (Ered([DCPP]n*/[DCPP]n·-) = +2.10 V vs SCE), and good reduction stability. The applications of [DCPP]n aggregates as a versatile visible-light photocatalyst were demonstrated in decarboxylative C-C cross-coupling, amidation, and esterification reactions.
- He, Min,Yu, Xiaoqiang,Wang, Yi,Li, Fei,Bao, Ming
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p. 5016 - 5025
(2021/04/12)
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- Evaluation of Cyclic Amides as Activating Groups in N-C Bond Cross-Coupling: Discovery of N-Acyl-δ-valerolactams as Effective Twisted Amide Precursors for Cross-Coupling Reactions
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The development of efficient methods for facilitating N-C(O) bond activation in amides is an important objective in organic synthesis that permits the manipulation of the traditionally unreactive amide bonds. Herein, we report a comparative evaluation of a series of cyclic amides as activating groups in amide N-C(O) bond cross-coupling. Evaluation of N-acyl-imides, N-acyl-lactams, and N-acyl-oxazolidinones bearing five- and six-membered rings using Pd(II)-NHC and Pd-phosphine systems reveals the relative reactivity order of N-activating groups in Suzuki-Miyaura cross-coupling. The reactivity of activated phenolic esters and thioesters is evaluated for comparison in O-C(O) and S-C(O) cross-coupling under the same reaction conditions. Most notably, the study reveals N-acyl-δ-valerolactams as a highly effective class of mono-N-acyl-activated amide precursors in cross-coupling. The X-ray structure of the model N-acyl-δ-valerolactam is characterized by an additive Winkler-Dunitz distortion parameter ?(τ+χN) of 54.0°, placing this amide in a medium distortion range of twisted amides. Computational studies provide insight into the structural and energetic parameters of the amide bond, including amidic resonance, N/O-protonation aptitude, and the rotational barrier around the N-C(O) axis. This class of N-acyl-lactams will be a valuable addition to the growing portfolio of amide electrophiles for cross-coupling reactions by acyl-metal intermediates.
- Bisz, Elwira,Chen, Hao,Dziuk, B?a?ej,Ejsmont, Krzysztof,Lalancette, Roger,Pyle, Daniel J.,Rahman, Md. Mahbubur,Szostak, Michal,Szostak, Roman,Wang, Qi
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p. 10455 - 10466
(2021/07/31)
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- Protocol for Palladium/ N-Heterocyclic Carbene-Catalyzed Suzuki-Miyaura Cross-Coupling of Amides by N-C(O) Activation
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Amides are among the most important and ubiquitous functional groups in organic chemistry and process development. In this Practical Synthetic Procedure, a protocol for the Suzuki-Miyaura cross-coupling of amides by selective N-C(O) bond activation catalyzed by commercially available, air-and moisture-stable palladium/N-heterocyclic carbene (NHC) complexes is described. The procedure described involves [Pd(IPr)(cin)Cl] [IPr = 2,6-(diisopropylphenyl)imidazol-2-ylidene, cin = cinnamyl] at 0.10 mol% at room temperature and is performed on decagram scale. Furthermore, a procedure for the synthesis of amide starting materials is accomplished via selective N-tert-butoxycarbonylation, which is the preferred method over N-Acylation. The present protocol carries advantages of operational simplicity, commercial availability of catalysts, and excellent conversions at low catalyst loadings. The method is generally useful for activation of N-C(O) amide bonds in a broad spectrum of amide precursors. The protocol should facilitate the implementation of amide cross-coupling reactions.
- Lei, Peng,Li, Guangchen,Ling, Yun,An, Jie,Nolan, Steven P.,Szostak, Michal
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p. 682 - 687
(2020/11/23)
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- Carbonylative Suzuki-Miyaura Coupling Reactions of Aryl Iodides with Readily Available Polymer-Immobilized Palladium Nanoparticles
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Polysilane/alumina-supported palladium nanoparticle catalyzed carbonylative Suzuki-Miyaura coupling reactions under ligand-free conditions have been developed to synthesize diaryl ketones. High yields and selectivities were achieved even with low catalyst loading under atmospheric pressure of CO gas. A variety of aryl iodides and arylboronic acids could be utilized to afford the diaryl ketones in excellent yields. Moreover, the ligand-free immobilized palladium nanoparticles could be recovered by simple filtration and the catalytic activity could be maintained for several runs.
- Yasukawa, Tomohiro,Zhu, Zhiyuan,Yamashita, Yasuhiro,Kobayashi, Shu
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p. 502 - 504
(2020/09/21)
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- Poly(ethylene glycol) dimethyl ether mediated oxidative scission of aromatic olefins to carbonyl compounds by molecular oxygen
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A simple, and practical oxidative scission of aromatic olefins to carbonyl compounds using O2as the sole oxidant with poly(ethylene glycol) dimethyl ether as a benign solvent has been developed. A wide range of monosubstituted,gem-disubstituted, 1,2-disubstituted, trisubstituted and tetrasubstituted aromatic olefins was successfully converted into the corresponding aldehydes and ketones in excellent yields even with gram-scale reaction. Some control experiments were also conducted to support a possible reaction pathway.
- Yu, Tao,Guo, Mingqing,Wen, Simiaomiao,Zhao, Rongrong,Wang, Jinlong,Sun, Yanli,Liu, Qixing,Zhou, Haifeng
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p. 13848 - 13852
(2021/04/22)
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- Method for preparing aldehyde ketone compound through olefin oxidation
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The invention provides a method for preparing an aldehyde ketone compound by olefin oxidation, which relates to an olefin oxidative cracking reaction in which oxygen participates. The method comprises the following specific steps: in the presence of a solvent and an oxidant, carrying out oxidative cracking on an olefin raw material to obtain a corresponding aldehyde ketone product. Compared with the traditional method, the method does not need to add any catalyst or ligand, does not need to use high-pressure oxygen, has the advantages of simple and mild reaction conditions, environment friendliness, low cost, high atom economy and the like, is wide in substrate application range and high in yield, and has a wide application prospect in the aspects of synthesis of aldehyde ketone medical intermediates and chemical raw materials.
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Paragraph 0019
(2021/04/07)
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- Photo-induced oxidative cleavage of C-C double bonds for the synthesis of biaryl methanoneviaCeCl3catalysis
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A Ce-catalyzed strategy is developed to produce biaryl methanonesviaphotooxidative cleavage of C-C double bonds at room temperature. This reaction is performed under air and demonstrates high activity as well as functional group tolerance. A synergistic Ce/ROH catalytic mechanism is also proposed based on the experimental observations. This protocol should be the first successful Ce-catalyzed photooxidation reaction of olefins with air as the oxidant, which would provide inspiration for the development of novel Ce-catalyzed photochemical synthesis processes.
- Xie, Pan,Xue, Cheng,Du, Dongdong,Shi, SanShan
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supporting information
p. 6781 - 6785
(2021/08/20)
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- Fe-S Catalyst Generated in Situ from Fe(III)- And S3?--Promoted Aerobic Oxidation of Terminal Alkenes
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An iron-sulfur complex formed by the simple mixture of FeCl3 with S3?- generated in situ from K2S is developed and applied to selective aerobic oxidation of terminal alkenes. The reaction was carried out under an atmosphere of O2 (balloon) and could proceed on a gram scale, expanding the application of S3?- in organic synthesis. This study also encourages us to explore the application of an Fe-S catalyst in organic reactions.
- Ai, Jing-Jing,Huang, Cheng-Mi,Li, Jian,Liu, Bei-Bei,Rao, Weidong,Wang, Fei,Wang, Shun-Yi
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supporting information
p. 4705 - 4709
(2021/06/28)
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- Photo-induced oxidative cleavage of C-C double bonds of olefins in water
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The carbonyl compounds, synthesized by the oxidative cleavage of their corresponding olefins, are of great significance in organic synthesis, especially aryl ketones. We have developed a gentle and effective protocol, using acid red 94 as the organic metal-free photocatalyst, O2 as the oxidant, and water as the solvent. Under visible light irradiation, aryl ketone derivatives were obtained in moderate to excellent yields, showing good economic and environmental advantages.
- Zhang, Yilan,Yue, Xiaoguang,Liang, Chenfeng,Zhao, Jianming,Yu, Wenbo,Zhang, Pengfei
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supporting information
(2021/08/27)
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- Synthesis and application of SBA-Pr-Py@Pd in Suzuki-type cross-coupling reaction
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SBA-Pr-Py was synthesized by functionalization of SBA-15 with 4-pyridine carbaldehyde, and then it was grafted by palladium ions to give SBA-Pr-Py@Pd nanocatalyst, which was used in cross-coupling reaction. In this process, aryl boronic acid is treated with various acyl halides using SBA-Pr-Py@Pd catalyst to provide aryl ketones under mild conditions. Graphical abstract: [Figure not available: see fulltext.].
- Mohammadi Ziarani, Ghodsi,Ebrahimi, Zahra,Mohajer, Fatemeh,Badiei, Alireza
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p. 4583 - 4594
(2021/08/06)
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- Complexes: Easily Synthesized, Highly Active Pd(II)-NHC Precatalysts for Cross-Coupling Reactions
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We report the synthesis, characterization, and reactivity of [(NHC)PdCl2(aniline)] complexes. These well-defined, air- and moisture-stable catalysts are highly active in the Suzuki-Miyaura cross-coupling of amides by N-C(O) activation as well as in the Suzuki-Miyaura cross-coupling of esters, aryl chlorides, and Buchwald-Hartwig amination. Most crucially, this study introduces broadly available anilines as stabilizing ligands for well-defined Pd(II)-NHC catalysts. The availability of various aniline scaffolds, including structural and electronic diversity, has a significant potential in fine-tuning of challenging cross-couplings by Pd-NHCs. The parent catalyst in this class, [Pd(IPr)(AN)Cl2], has been commercialized in collaboration with Millipore Sigma, offering broad access for reaction screening and optimization.
- Xia, Qinqin,Shi, Shicheng,Gao, Pengcheng,Lalancette, Roger,Szostak, Roman,Szostak, Michal
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p. 15648 - 15657
(2021/10/25)
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- A novel two-dimensional metal-organic framework as a recyclable heterogeneous catalyst for the dehydrogenative oxidation of alcohol and theN-arylation of azole compounds
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A novel metal-organic framework (MOF) with two-dimensional (2D) crystal structure was developed using Cu(NO3)2·3H2O and 2,2′,5,5′-tetramethoxy-[1,1′-biphenyl]-4,4′-dicarboxylic acid. Further, its structure was characterized using infrared spectroscopy, thermogravimetry, X-ray diffraction, and X-ray crystallography. The activated Cu-MOF was used to catalyze the dehydrogenative oxidation of alcohol andN-arylation of azole compounds. Furthermore, it could be easily recovered and reused.
- Liu, Chengxin,Cui, Jin,Wang, Yufang,Zhang, Mingjie
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p. 11739 - 11744
(2021/03/31)
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- Pd-Catalysed carbonylative Suzuki-Miyaura cross-couplings using Fe(CO)5under mild conditions: generation of a highly active, recyclable and scalable ‘Pd-Fe’ nanocatalyst
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The dual function and role of iron(0) pentacarbonyl [Fe(CO)5] has been identified in gaseous CO-free carbonylative Suzuki-Miyaura cross-couplings, in which Fe(CO)5supplied COin situ, leading to the propagation of catalytically active Pd-Fe nanoparticles. Compared with typical carbonylative reaction conditions, CO gas (at high pressures), specialised exogenous ligands and inert reaction conditions were avoided. Our developed reaction conditions are mild, do not require specialised CO high pressure equipment, and exhibit wide functional group tolerance, giving a library of biaryl ketones in good yields.
- Zhu, Zhuangli,Wang, Zhenhua,Jian, Yajun,Sun, Huaming,Zhang, Guofang,Lynam, Jason M.,McElroy, C. Robert,Burden, Thomas J.,Inight, Rebecca L.,Fairlamb, Ian J. S.,Zhang, Weiqiang,Gao, Ziwei
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supporting information
p. 920 - 926
(2021/02/09)
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- Suzuki coupling of aroyl-MIDA boronate esters – A preliminary report on scope and limitations
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Recent methodological reports for synthesizing acyl-MIDA boronate esters compel an investigation of their potential use as substrates in a standard Suzuki-Miyaura cross-coupling reaction. Here we report the production of benzophenones by C[sbnd]C cross coupling between a benzoyl-MIDA boronate ester and a multitude of aryl bromide substrates in adequate yields following optimization under ambient conditions outside of a glove box. Under these standard conditions, none of several acyl-MIDA boronate esters (in an alkyl series) serves as a competent coupling partner. The substrate scope is also limited by the finding that the corresponding trifluoroborates of both acyl- and aroyltrifluroborates are not suitable substrates. For reasons of availability and synthetic difficulty in procuring other aroyl-MIDA boronates, this preliminary study examines the reactivity of benzoyl-MIDA boronate with several aryl bromide substrates.
- Lai, Samson,Lin, Wen Xuan,Perrin, David M.,Takaesu, Noah
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supporting information
(2021/05/31)
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- Acylboronates in polarity-reversed generation of acyl palladium(II) intermediates
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We report a catalytic cross-coupling process between aryl (pseudo)halides and boron-based acyl anion equivalents. This mode of acylboronate reactivity represents polarity reversal, which is supported by the observation of tetracoordinated boronate and acyl palladium(II) species by 11B, 31P NMR, and mass spectrometry. A broad scope of aliphatic and aromatic acylboronates has been examined, as well as a variety of aryl (pseudo)halides.
- Trofimova, Alina,Holownia, Aleksandra,Tien, Chieh-Hung,?irvinskas, Martynas J.,Yudin, Andrei K.
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supporting information
p. 3294 - 3299
(2021/05/07)
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- Supported Palladium-Catalyzed Carbonylative Synthesis of Diaryl Ketones from Aryl Bromides and Arylboronic Acids
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A palladium supported on graphitic carbon nitride (Pd/g-C3N4) catalyzed carbonylative reaction of aryl bromides and arylboronic acids by has been developed for the construction of diaryl ketones. Using benzene-1,3,5-triyl triformate (TFBen) as the CO source, the reaction proceeded well to give various diaryl ketones in moderate to good yields.
- Xu, Tiefeng,Wang, Qi,Yang, Zeyi,Yi, Lili,Wang, Jian-Shu,Lu, Wangyang,Ying, Jun,Wu, Xiao-Feng
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supporting information
p. 2027 - 2030
(2021/06/21)
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- Bipyridinium and Phenanthrolinium Dications for Metal-Free Hydrodefluorination: Distinctive Carbon-Based Reactivity
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The development of novel Lewis acids derived from bipyridinium and phenanthrolinium dications is reported. Calculations of Hydride Ion Affinity (HIA) values indicate high carbon-based Lewis acidity at the ortho and para positions. This arises in part from extensive LUMO delocalization across the aromatic backbones. Species [C10H6R2N2CH2CH2]2+ (R=H [1 a]2+, Me [1 f]2+, tBu [1 g]2+), and [C12H4R4N2CH2CH2]2+ (R=H [2 a]2+, Me [2 b]2+) were prepared and evaluated for use in the initiation of hydrodefluorination (HDF) catalysis. Compound [2 a]2+ proved highly effective towards generating catalytically active silylium cations via Lewis acid-mediated hydride abstraction from silane. This enabled the HDF of a range of aryl- and alkyl- substituted sp3(C?F) bonds under mild conditions. The protocol was also adapted to effect the deuterodefluorination of cis-2,4,6-(CF3)3C6H9. The dications are shown to act as hydride acceptors with the isolation of neutral species C16H14N2 (3 a) and C16H10Me4N2 (3 b) and monocationic species [C14H13N2]+ ([4 a]+) and [C18H21N2]+ ([4 b]+). Experimental and computational data provide further support that the dications are initiators in the generation of silylium cations.
- Burton, Katherine I.,Elser, Iris,Waked, Alexander E.,Wagener, Tobias,Andrews, Ryan J.,Glorius, Frank,Stephan, Douglas W.
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supporting information
p. 11730 - 11737
(2021/07/16)
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- Catalytic Aldehyde and Alcohol Arylation Reactions Facilitated by a 1,5-Diaza-3,7-diphosphacyclooctane Ligand
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We report a catalytic method to access secondary alcohols by the coupling of aryl iodides. Either aldehydes or alcohols can be used as reaction partners, making the transformation reductive or redox-neutral, respectively. The reaction is mediated by a Ni catalyst and a 1,5-diaza-3,7-diphosphacyclooctane. This P2N2ligand, which has previously been unrecognized in cross-coupling and related reactions, was found to avoid deleterious aryl halide reduction pathways that dominate with more traditional phosphines and NHCs. An interrupted carbonyl-Heck type mechanism is proposed to be operative, with a key 1,2-insertion step forging the new C-C bond and forming a nickel alkoxide that may be turned over by an alcohol reductant. The same catalyst was also found to enable synthesis of ketone products from either aldehydes or alcohols, demonstrating control over the oxidation state of both the starting materials and products.
- Isbrandt, Eric S.,Nasim, Amrah,Newman, Stephen G.,Zhao, Karen
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supporting information
p. 14646 - 14656
(2021/09/18)
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- N-Acylcarbazoles and N-Acylindoles: Electronically Activated Amides for N-C(O) Cross-Coupling by Nlpto Ar Conjugation Switch
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The development of new amide precursors for selective, catalytic activation of carbon-nitrogen bonds in amides is a fundamental objective of this emerging reactivity manifold. We report the palladium-catalyzed Suzuki-Miyaura cross-coupling of N-acylcarbazoles and N-acylindoles with arylboronic acids by a highly selective N-C(O) cleavage. The key amide bond ground-state destabilization stems from Nlp to Ar conjugation and enables us for the first time to achieve reactivity similar to that for N-acylsulfonamide and N-acylcarbamate activation in simple anilides.
- Buchspies, Jonathan,Rahman, Md. Mahbubur,Szostak, Roman,Szostak, Michal
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p. 4703 - 4709
(2020/06/17)
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- Water Phase, Room Temperature, Ligand-Free Suzuki–Miyaura Cross-Coupling: A Green Gateway to Aryl Ketones by C–N Bond Cleavage
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We report herein a green strategy for synthesis of aryl ketones from twisted amides by using Pd(OAc)2 as catalysts. This method shows high functional group tolerance to offer a variety of ketones in good yields under mild conditions (up to 94 %). Notably, this methodology demonstrates the first water phase, room temperature, ligand-free Suzuki–Miyaura coupling through C–N bond cleavage, which is environmentally friendly and might facilitate the development of amide based green chemistry.
- Zhang, Yuqi,Wang, Zijia,Tang, Zhao,Luo, Zhongfeng,Wu, Hongxiang,Liu, Tingting,Zhu, Yulin,Zeng, Zhuo
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p. 1620 - 1628
(2020/03/04)
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- Palladium-Catalyzed Suzuki Coupling of N-Acyloxazolidinones via Selective Cleavage of C–N Bonds
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By implementing a palladium-catalyzed Suzuki coupling reaction of N-acyloxazolidinones with arylboronic acid, we herein report on the preparation of substituted diaryl ketones via selective cleavage of exocyclic C–N Bonds. The reaction was carried out under mild reaction conditions with excellent functional group compatibility in good yields (up to 93 %).
- Jian, Junsheng,He, Zhanyu,Zhang, Yuqi,Liu, Tingting,Liu, Lizhen,Wang, Zijia,Wang, Hui,Wang, Sanyong,Zeng, Zhuo
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p. 4176 - 4180
(2020/07/13)
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- A Bifunctional Iron Nanocomposite Catalyst for Efficient Oxidation of Alkenes to Ketones and 1,2-Diketones
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We herein report the fabrication of a bifunctional iron nanocomposite catalyst, in which two catalytically active sites of Fe-Nx and Fe phosphate, as oxidation and Lewis acid sites, were simultaneously integrated into a hierarchical N,P-dual doped porous carbon. As a bifunctional catalyst, it exhibited high efficiency for direct oxidative cleavage of alkenes into ketones or their oxidation into 1,2-diketones with a broad substrate scope and high functional group tolerance using TBHP as the oxidant in water under mild reaction conditions. Furthermore, it could be easily recovered for successive recycling without appreciable loss of activity. Mechanistic studies disclose that the direct oxidation of alkenes proceeds via the formation of an epoxide as intermediate followed by either acid-catalyzed Meinwald rearrangement to give ketones with one carbon shorter or nucleophilic ring-opening to generate 1,2-diketones in a cascade manner. This study not only opens up a fancy pathway in the rational design of Fe-N-C catalysts but also offers a simple and efficient method for accessing industrially important ketones and 1,2-diketones from alkenes in a cost-effective and environmentally benign fashion.
- Ma, Zhiming,Ren, Peng,Song, Tao,Xiao, Jianliang,Yang, Yong,Yuan, Youzhu
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p. 4617 - 4629
(2020/05/19)
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- Chiral electron-rich PNP ligand with a phospholane motif: Structural features and application in asymmetric hydrogenation
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Despite the remarkable reactivity that was achieved by a series of transition-metal catalysts with a PNP type ligand, the electron-rich chiral PNP ligands have still been rarely reported because of the difficulties in synthesis and the nature of air-sensitivity. Herein, we report a novel chiral PNP ligand (Heng-PNP) with both a rigid backbone and a bulky tert-butyl group on the phospholane motif. We successfully obtained its divalent iron complex. The chiral environment of its Ir(III) complex was also discussed with quadrant analysis. This tridentate ligand was applied in iridium-catalyzed asymmetric hydrogenation of challenging diaryl ketones: up to 98% ee and 500 TON are achieved. Computational study showed that the twist of conjugate aryl group in the substrate (induced by the special chiral pocket of Ir/Heng-PNP complex) leads to the energy difference in the enantiodetermining step.
- Wang, Heng,Zhang, Yao,Yang, Tilong,Guo, Xiaochong,Gong, Quan,Wen, Jialin,Zhang, Xumu
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p. 8796 - 8801
(2020/11/13)
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- Carbonylative Suzuki-Miyaura cross-coupling by immobilized Ni?Pd NPs supported on carbon nanotubes
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In this study, a novel carbon nanotube (CNT) based nanocatalyst (Ni?Pd/CNT) was synthesized by modifying CNTs using Ni?Pd core-shell nanoparticles (NPs). Ni?Pd/CNT was used in catalytic carbonylative cross-coupling between 4-iodoanisole and phenylboronic acid. The Ni?Pd NPs possessed a magnetic nickel (Ni) core with a palladium (Pd) structural composite shell. Thus, the use of Ni had led to a reduced consumption of Pd without sacrificing the overall catalytic performance, simultaneously making it reusable as it could be conveniently recovered from the reaction mixture by using an external magnetic field. Immobilization of the Ni?Pd NPs on carbon nanotubes not only prevented their aggregation, but also significantly enhanced the accessibility of the catalytically active sites. The abovementioned approach based on carbon nanotubes and Ni?Pd NPs provided a useful platform for the fabrication of noble-metal-based nanocatalysts with easy accessibility and low cost, which may allow for an efficient green alternative for various catalytic reductions. This journal is
- Dujuan, Ouyang,Jixiang, Li,Mustapha, Mazli,Nan, Liu,Rouhi, Jalal,Wenhui, Duan,Yalan, Cai
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p. 27923 - 27931
(2020/11/07)
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- Friedel–Crafts benzylation of toluene catalyzed by ZnCl2/SiO2 heterogeneous catalyst to para- and ortho-mono-benzylated toluene
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A series of catalysts was prepared for the liquid-phase Friedel–Crafts benzylation of toluene with benzyl chloride (BC) by impregnating rice husk ash silica with ZnCl2 (3?wt%, 6?wt%, 9?wt%, and 12?wt%) via a wet impregnation method. The XRD analysis indicates that the catalysts were amorphous with ill-defined pore systems. The XPS analysis detected the coexistence of ZnO nanoparticles together with ZnCl2 on the catalyst surface, whereas the 29Si NMR analysis indicates the formation of Si–O–Zn bond. Quantitative conversion of benzyl chloride (100%) was achieved within 3?h at 353?K when a catalyst with 9?wt% ZnCl2 was used due to its narrow pore size and high surface area (635?m2?g?1). Para- and ortho-mono-benzylated toluene was obtained as the products. The reaction is proposed to take place via weak attraction between benzyl chloride and the Zn through its chlorine atom. The catalyst was recycled four times with minimum loss (8%) in activity. The benzylation of benzene, toluene, p-xylene, and anisole followed the classical mechanism of Friedel–Craft-type acid-catalyzed benzylation reaction. The BC conversion increased in the order of toluene = p-xylene > anisole > benzene. The catalyst was also screened to be active in the benzoylation of toluene with benzoyl chloride (BOC). The conversion of BOC was 45% with selectivity toward 2-methylbenzophenone (50%) and 3-methylbenzophenone (50%).
- Iqbal, Anwar,Tan, Kok-Hou,Shaari,Ahmad,Adam, Farook,Lee, Hwei Voon,Yusop, Rahimi M.,Abu Bakar,Lee, Hooi Ling,Pauzi, Hariy,Malik, Muhammad Fadhirul Izwan Abd,Jusoh, Ahmad Fadly,Wilson, Lee D.,Ahmad,Hazwan Hussain,Ibrahim, Mohamad Nasir Mohamad
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p. 1615 - 1626
(2020/03/05)
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- Oxidative C-S Bond Cleavage of Benzyl Thiols Enabled by Visible-Light-Mediated Silver(II) Complexes
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The oxidative cleavage reaction of the C-S bond using singlet oxygen is challenging because of its uncontrollable nature. We have developed a novel method for the singlet-oxygen-mediated selective C-S bond cleavage reaction using silver(II)-ligand complexes. Visible-light-induced silver catalysis enables the controlled oxidative cleavage of benzyl thiols to afford carbonyl compounds, such as aldehydes or ketones, which are important synthetic components.
- Hong, Boseok,Aganda, Kim Christopher C.,Lee, Anna
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supporting information
p. 4395 - 4399
(2020/06/05)
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- Ruthenium-Catalyzed Dehydrogenation of Alcohols with Carbodiimide via a Hydrogen Transfer Mechanism
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Ruthenium-catalyzed oxidative dehydrogenation of alcohols using carbodiimide as an efficient hydrogen acceptor has been developed. The protocol exhibits wide substrate scope with good to excellent yields. The results of the kinetic analysis indicated that the reaction mechanism includes the hydrogen transfer process and that the addition of carbodiimide is essential for the reaction system, and the resulting amidine also could react as a hydrogen acceptor.
- Sueki, Shunsuke,Matsuyama, Mizuki,Watanabe, Azumi,Kanemaki, Arata,Katakawa, Kazuaki,Anada, Masahiro
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p. 4878 - 4885
(2020/06/02)
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- Scalable Aerobic Oxidation of Alcohols Using Catalytic DDQ/HNO3
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A selective, practical, and scalable aerobic oxidation of alcohols is described that uses catalytic amounts of 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) and HNO3, with molecular oxygen serving as the terminal oxidant. The method was successfully applied to the oxidation of a wide range of benzylic, propargylic, and allylic alcohols, including two natural products, namely, carveol and podophyllotoxin. The conditions are also applicable to the selective oxidative deprotection of p-methoxybenzyl ethers.
- Arseniyadis, Stellios,Clavier, Louis,Copin, Chloé,Fournier, Jean,Giffard, Jean-Fran?ois,Jean, Alexandre,Katsina, Tania,Macedo Portela Da Silva, Nayane,Tamion, Rodolphe
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supporting information
p. 856 - 860
(2020/07/14)
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- Photo-induced phosphorus radical involved semipinacol rearrangement reaction: Highly synthesis of γ-oxo-phosphonates
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Hydroxyphosphoric acids display the unique biological activities, and they have some attractive prospects as clinical drug moleculars. Herein, a new approach for the synthesis of γ-oxo-phosphonates (the precursor of hydroxyphosphoric acid) has been established through the semipinacol rearrangement tactic involved the photo-induced phosphorus radical process. Most important, this transformation is avoid of the external oxidants, and occurs very well under the sunlight irradiation, meanwhile the γ-oxo-phosphonate was easily derivatized to obtain γ-hydroxyphosphoric acid, thus highlights the synthesis value of this method.
- Wang, Chunhai,Huang, Xiaoling,Liu, Xueting,Gao, Suqian,Zhao, Bin,Yang, Shangdong
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supporting information
p. 677 - 680
(2019/08/27)
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- N-Acyl-5,5-Dimethylhydantoins: Mild Acyl-Transfer Reagents for the Synthesis of Ketones Using Pd-PEPPSI or Pd/Phosphine Catalysts
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N-Acyl-hydantoins have emerged as novel acyl-transfer reagents for the synthesis of ketones via selective N-C(O) cleavage. Herein, we report two new protocols for the cross-coupling of N-acyl-5,5-dimethylhydantoins using versatile and readily accessible Pd-PEPPSI or Pd/phosphine catalysts. The acyl Suzuki reactions afford biaryl ketones in good to excellent yields under operationally simple conditions using commercially available, bench- A nd air-stable twisted N-acyl-hydantoins as acyl donors. The method complements and expands on the previous protocol for the cross-coupling of N-acyl-hydantoins (Luo, Z.et al. Org. Process Res. Dev. 2018, 22, 1188).
- Liu, Chengwei,Szostak, Michal,Wang, Chang-An
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p. 1043 - 1051
(2020/07/15)
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- Binuclear Palladium Complex Immobilized on Mesoporous SBA-16: Efficient Heterogeneous Catalyst for the Carbonylative Suzuki Coupling Reaction of Aryl Iodides and Arylboronic Acids Using Cr(CO)6 as Carbonyl Source
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Abstract: In this study, a binuclear palladium complex immobilized on the organo-functionalized SBA-16 was prepared and structurally characterized by routine techniques. Characterizations indicated that the mesostructure of SBA-16 was maintained after the immobilization of palladium complex. Then, the prepared nanomaterial was applied as a heterogeneous catalyst in the carbonylative Suzuki coupling reaction of aryl iodides with arylboronic acids using Cr(CO)6 as carbonyl source. The catalyst was efficiently promoted the coupling reactions of various aryl iodides and arylboronic acids to give the corresponding diaryl ketones in excellent yields. Moreover, the catalyst was readily recovered by filtration and could be reused for seven cycles without losing its structural integrity and catalytic activity. Graphic Abstract: [Figure not available: see fulltext.].
- Niakan, Mahsa,Asadi, Zahra,Emami, Mohammad
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p. 404 - 418
(2020/01/03)
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- Carbonylative Suzuki coupling reactions catalyzed by ONO pincer–type Pd(II) complexes using chloroform as a carbon monoxide surrogate
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Benzoylhydrazone Schiff base–ligated three new ONO pincer–type palladium(II) complexes, [(PdL1(PPh3)] (1), [(PdL2(PPh3)] (2), and [(PdL3(PPh3)] (3), were synthesized by the reaction of the respective ligand, N-(2-hydroxybenzylidene)benzohydrazide (HL1), N-(2-hydroxy-3-methoxybenzylidene)benzohydrazide (HL2), or N-(5-bromo-2-hydroxybenzylidene) benzohydrazide (HL3), with Pd(OAc)2 and PPh3 in methanol and isolated as air-stable reddish-orange crystalline solids in high yields (78%–83%). All three complexes were fully characterized by elemental analysis, Fourier-transform infrared spectroscopy, UV–Visible, 1H nuclear magnetic resonance (NMR), 13C{1H} NMR, and 31P{1H} NMR spectroscopic studies. The molecular structure of all three complexes was established unambiguously by single-crystal X-ray diffraction studies which revealed a distorted square planar geometry of all three complexes. The ONO pincer–type ligands occupied three coordination sites at the palladium, while the fourth site is occupied by the monodentate triphenylphosphine ligand. The catalytic potential of all three complexes was explored in the carbonylative Suzuki coupling of aryl bromides and iodides with arylboronic acids to yield biaryl ketones, using CHCl3 as the source of carbonyl. The reported protocol is convenient and safe as it obviates the use of carbon monoxide (CO) balloons or pressured CO reactors which are otherwise needed for the carbonylation reactions. The methodology has been successfully applied to the synthesis of two antineoplastic drugs, namely, phenstatin and naphthylphenstatin, in good yields (81% and 85%, respectively). Under the optimized reaction conditions, complex 2 exhibited the best catalytic activity in the carbonylative Suzuki couplings. The reported catalysts have wide reaction scope with good functional group tolerance. All catalysts could be retrieved from the reaction after completion and recycled up to three times with insignificant loss in the catalytic activity.
- Layek, Samaresh,Agrahari, Bhumika,Ganguly, Rakesh,Das, Parthasarathi,Pathak, Devendra D.
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- Synthesis of biaryl ketones by arylation of Weinreb amides with functionalized Grignard reagents under thermodynamic controlvs.kinetic control ofN,N-Boc2-amides
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A highly efficient method for chemoselective synthesis of biaryl ketones by arylation of Weinreb amides (N-methoxy-N-methylamides) with functionalized Grignard reagents is reported. This protocol offers rapid entry to functionalized biaryl ketones after Mg/halide exchange with i-PrMgCl·LiCl under operationally-simple and practical reaction conditions. The scope of the method is highlighted in >40 examples, including bioactive compounds and pharmaceutical derivatives. Collectively, this transition-metal-free approach offers a major advantage over the recently established cross-coupling of amides by oxidative addition of N-C(O) bonds. Considering the utility of amide acylation reactions in modern synthesis, we expect that this method will be of broad interest.
- Li, Guangchen,Szostak, Michal
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supporting information
p. 3827 - 3831
(2020/06/03)
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- Silylcarboxylic Acids as Bifunctional Reagents: Application in Palladium-Catalyzed External-CO-Free Carbonylative Cross-Coupling Reactions
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A palladium-catalyzed external-CO-free carbonylative Hiyama-Denmark cross-coupling reaction is presented. The introduction of silylcarboxylic acids as bifunctional reagents (CO and nucleophile source) avoids the need for external gaseous CO and a silylarene coupling partner. The transformation features high functional group tolerance and it is successful with electron-rich, -neutral, and -poor aryl iodides. Stoichiometric studies and control experiments provide insight into the reaction mechanism and support the hypothesized dual role of silylcarboxylic acids. (Figure presented.).
- Li, Xiong,Xu, Jie,Li, Yue,Kramer, S?ren,Skrydstrup, Troels,Lian, Zhong
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p. 4078 - 4083
(2020/07/30)
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- Palladium-Catalyzed Amide N-C Hiyama Cross-Coupling: Synthesis of Ketones
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N-Acylglutarimides and arylsiloxanes reacted in the presence of Pd(OAc)2/PCy3, Et3N·3HF, and LiOAc to provide the corresponding arylketones in good yields. Aryl-, vinyl-, and alkyl-substituted N-acylglutarimides showed good activity in the coupling reactions of arylsiloxanes. The reaction had a broad substrate scope and showed good functional group tolerance. N-Benzoylsuccinimide and N-protected N-phenylbenzamides showed good activities in coupling reactions with phenylsiloxane. The employment of CuF2 as an activor afforded the decarbonylative products at 160 °C.
- Idris, Muhammad Aliyu,Lee, Sunwoo
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supporting information
p. 9190 - 9195
(2020/11/18)
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- Method for catalytically dehydrogenating and oxidizing aryl secondary alcohol into ketone
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The invention discloses a method for catalytically dehydrogenating and oxidizing aryl secondary alcohol into ketone. The method comprises the following steps: dissolving the aryl secondary alcohol inan organic solvent, and reacting at 40-120 DEG C in the presence of an acid catalyst and a cocatalyst to obtain substituted aryl ketone, wherein the acid is aryl sulfonic acid (ArSO3H), alkyl sulfonicacid (RSO3H) or boron trifluoride diethyl ether, and the cocatalyst is tertiary halogenated hydrocarbon or benzyl halogenated hydrocarbon. According to the method, a metal catalyst and an oxidizing agent are not used, the adopted catalyst is cheap and non-toxic and can tolerate water and air, the reaction condition is mild, and the method is simple to operate and high in atom economy, and can beused for large scale production.
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Paragraph 0028; 0045-0048
(2019/12/02)
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- Polymer-incarcerated palladium-catalyzed facile: In situ carbonylation for the synthesis of aryl aldehydes and diaryl ketones using CO surrogates under ambient conditions
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In this existing work, an efficient polymer-supported palladium catalyst, a furfurylamine-functionalized Merrifield complex of palladium [Pd@(Merf-FA)], was synthesized and characterized, showing excellent catalytic activity towards in situ carbonylation reactions using carbon monoxide surrogates like formic acid and chloroform. Herein, we examined the catalytic activity of the Pd@(Merf-FA) catalyst for the formylation of aryl iodides and carbonylative Suzuki-Miyaura coupling reactions. The Pd@(Merf-FA) catalyst was systematically characterized by several techniques like HRTEM, elemental mapping, PXRD, TGA-DTA, FESEM, UV-vis, EDAX, CHN and AAS analysis. The catalyst is highly recyclable, able to be recycled up to six times without showing any significant decrease in catalytic activity. The [Pd@(Merf-FA)] catalyst proved to be more efficient compared to the corresponding homogeneous palladium catalyst. In addition, the leaching experiment of the synthesized catalyst was studied, which showed that negligible leaching of metal occurred from the polymeric support.
- Dey, Tusar Kanto,Basu, Priyanka,Riyajuddin, Sk,Ghosh, Aniruddha,Ghosh, Kaushik,Manirul Islam, Sk
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p. 9802 - 9814
(2019/07/04)
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- Hydroxyl-functionalized triazolylidene-based PEPPSI complexes: Metallacycle formation effect on the Suzuki coupling reaction
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We report the preparation and full characterization of a series of hydroxyl functionalized 1,2,3-triazolylidene-based PEPPSI complexes 2a-c and their catalytic application in the Suzuki cross coupling reaction of aryl chlorides/amides with boronic acids. Under basic reaction conditions, complexes 2a-c show a notable increase in their catalytic efficiency compared with two ether-wingtip functionalized PEPPSI analogues (3 and 4) and a commercially available NHC-Pd complex (5). The catalytic results suggest that deprotonation of the hydroxyl group in complexes 2a-c plays an important role in the overall process. Deprotonation of the alcohol moiety of complexes 2a-b with sodium tert-butoxide allows for the isolation of metallacycles 6a-b, which are proposed as the active species of cross coupling reactions.
- Rendón-Nava, David,álvarez-Hernández, Alejandro,Rheingold, Arnold L.,Suárez-Castillo, Oscar R.,Mendoza-Espinosa, Daniel
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supporting information
p. 3214 - 3222
(2019/03/13)
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- A convenient and practical heterogeneous palladium-catalyzed carbonylative Suzuki coupling of aryl iodides with formic acid as carbon monoxide source
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A practical heterogeneous palladium-catalyzed carbonylative Suzuki coupling of aryl iodides with arylboronic acids under carbon monoxide gas-free conditions has been developed using a bidentate phosphino-functionalized magnetic nanoparticle-immobilized palladium(II) complex as catalyst. Formic acid was utilized as the carbon monoxide source with dicyclohexylcarbodiimide as the activator, and a wide variety of biaryl ketones were generated in moderate to high yields. The new heterogeneous palladium catalyst can be prepared via a simple procedure and can easily be separated from a reaction mixture by simply applying an external magnet and recycled up to 10 times without any loss of activity.
- You, Shengyong,Yan, Chenyu,Zhang, Rongli,Cai, Mingzhong
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- 2-Methyltetrahydrofuran (2-MeTHF): A Green Solvent for Pd?NHC-Catalyzed Amide and Ester Suzuki-Miyaura Cross-Coupling by N?C/O?C Cleavage
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The palladium-NHC-catalyzed (NHC=N-heterocyclic carbene) Suzuki-Miyaura cross-coupling of amides and esters via highly chemoselective N?C(O) and O?C(O) cleavage with aryl boronic acids using green, sustainable and eco-friendly 2-methyltetrahydrofuran (2-MeTHF) is reported. A variety of amides and aryl esters were coupled with aryl boronic acids in high to excellent yields. This method employs commercially-available, air- and moisture-stable Pd(II) ?NHC precatalysts. Crucially, the use of 2-MeTHF leads to the highest TON reported to date in amide N?C(O) bond cross-coupling. This operationally-simple protocol was utilized in the synthesis a bioactive ketone intermediate, emphasizing the potential of 2-MeTHF as a green solvent in unconventional amide bond disconnection. Given the tremendous importance of amide bond cross-coupling strategies and the drive to maintain full sustainability in cross-coupling processes, we expect that the synthetic method will be of broad interest.
- Lei, Peng,Ling, Yun,An, Jie,Nolan, Steven P.,Szostak, Michal
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p. 5654 - 5660
(2019/11/16)
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- Cercosporin-bioinspired selective photooxidation reactions under mild conditions
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The development of an efficient system for selective oxidation of organic compounds to generate more valuable compounds with molecular oxygen is a significant challenge in industrial chemistry. Bioinspired by the ability of naturally occurring perylenequinonoid pigments (PQPs) to generate reactive oxygen species (ROS) upon photoirradiation, here we report that cercosporin, one of the perylenequinonoid pigments, can function as a cost-effective and environmentally friendly photocatalyst for a wide range of selective oxidations, including benzylic C-H bonds to carbonyls, amines to aldehydes, and sulfides to sulfoxides. All of the representative reactions proceeded smoothly with high efficiency under mild conditions. Owing to the use of inexpensive metal-free visible light-driven photocatalyst produced from microbial fermentation with cheap glucose as the starting material and the ease of handling, we expect that this developed method will be particularly attractive for many more applications in synthetic transformation.
- Li, Jia,Bao, Wenhao,Tang, Zhaocheng,Guo, Baodang,Zhang, Shiwei,Liu, Haili,Huang, Shuping,Zhang, Yan,Rao, Yijian
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supporting information
p. 6073 - 6081
(2019/11/20)
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- Ligand-free Palladium-Catalyzed Carbonylative Suzuki Coupling of Aryl Iodides in Aqueous CH3CN with Sub-stoichiometric Amount of Mo(CO)6 as CO Source
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A new method for the synthesis of diaryl and heterodiaryl ketones has been established based on the palladium-catalyzed carbonylative Suzuki coupling approach with sub-stoichiometric Mo(CO)6 as CO source. Using 0.5 mol% of Pd(TFA)2 as catalyst, 0.5 equivalent of Mo(CO)6 as solid carbonyl reagent and 3 equivalent of K3PO4 as base, a wide range of functionalized (hetero)aryl iodides and (hetero)aryl boronic acids could smoothly proceed the carbonylative cross-coupling reaction in aqueous CH3CN at 50 °C, affording the corresponding ketones in good to excellent yields. The newly developed method was easy to operate under mild conditions with high efficiency. (Figure presented.).
- Sun, Nan,Sun, Qingxia,Zhao, Wei,Jin, Liqun,Hu, Baoxiang,Shen, Zhenlu,Hu, Xinquan
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p. 2117 - 2123
(2019/03/28)
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- Carbonylative Suzuki coupling and alkoxycarbonylation of aryl halides using palladium supported on phosphorus-doped porous organic polymer as an active and robust catalyst
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Developing highly active catalysts with the combined advantages of molecular and solid catalysis is considered as the “Holy Grail” in the area of catalysis research. Herein, a phosphorus-doped porous polymer-immobilized palladium was successfully developed as an efficient, robust, and recyclable catalyst for the carbonylative Suzuki coupling and alkoxycarbonylation reactions of aryl halides. Rather than just as an immobilizing molecular catalyst, palladium supported on phosphorus-doped porous organic polymer exhibits even better catalytic performances than that of its analogue homogeneous catalysts in both carbonylation reactions. Moreover, the catalyst can be easily separated and reused for at least 5 times without significant loss in reactivity. Importantly, the catalyst was highly stable under carbonylation reaction conditions, and no palladium nanoparticle was observed even after the 5th reuse.
- Wan, Yali,Song, Fangxiang,Ye, Tao,Li, Guangxing,Liu, Dingfu,Lei, Yizhu
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- Heterogeneous Suzuki-Miyaura coupling of heteroaryl ester: Via chemoselective C(acyl)-O bond activation
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A site-selective supported palladium nanoparticle catalyzed Suzuki-Miyaura cross-coupling reaction with heteroaryl esters and arylboronic acids as coupling partners was developed. This methodology provides a heterogeneous catalytic route for aryl ketone formation via C(acyl)-O bond activation of esters by successful suppression of the undesired decarbonylation phenomenon. The catalyst can be reused and shows high activity after eight cycles. The XPS analysis of the catalyst before and after the reaction suggested that the reaction might be performed via a Pd0/PdII catalytic cycle that began with Pd0.
- Ma, Hongpeng,Bai, Chaolumen,Bao, Yong-Sheng
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p. 17266 - 17272
(2019/06/24)
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