- Preparation, characterization and catalytic properties of Pd-decorated carbon nanotubes possessing different linkers
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To investigate the relationship between the linker length and the catalytic activities of metal-decorated CNTs, three samples were prepared with different linker molecules, viz. NaSH, HSCH2CH2SH, and C 2H2N
- Kim, Ja Young,Park, Kyungho,Bae, Seung Yong,Kim, Gwui Cheol,Lee, Sunwoo,Choi, Hyun Chul
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- Fast synthesis of Ag-Pd@reduced graphene oxide bimetallic nanoparticles and their applications as carbon-carbon coupling catalysts
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Ultrafine Ag-Pd bimetallic nanoparticles homogeneously distributed on reduced graphene oxide (rGO) were prepared by redox reactions between Pd 2+, Ag+ and GO. This method is simple, and the use of rGO as a support facilitated the separation and reuse of the Ag-Pd@rGO catalyst. The Ag-Pd@rGO bimetallic nanoparticles were characterized by ultraviolet-visible spectroscopy, Raman spectroscopy, thermogravimetric analysis, X-ray diffraction analysis, and X-ray photoelectron spectroscopy. The microstructure of the Ag-Pd@rGO was investigated with scanning electron microscopy and transmission electron microscopy. The Ag-Pd@rGO catalyst exhibited high catalytic activities in the Suzuki-Miyaura carbon coupling reaction and the Sonogashira carbon coupling (SCC) reaction. These reactions used mild, efficient, ligand-free and heterogeneous conditions. Interestingly, the presence or absence of oxygen in the SCC catalytic system resulted in two different products, in which oxygen can be used as "switch" to control different products. the Partner Organisations 2014.
- Chen, Mingxi,Zhang, Zhe,Li, Lingzhi,Liu, Yu,Wang, Wei,Gao, Jianping
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- Functionalization of complexed N2O in bis(pentamethylcyclopentadienyl) systems of zirconium and titanium
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Methyl triflate reacts with the metastable azoxymetallacyclopentene complex Cp2Zr(N(O)NCPhCPh), generated in situ from nitrous oxide insertion into the Zr-C bond of Cp2Zr(η2-PhCCPh) at -78 °C, to afford the salt [Cp2Zr(N(O)N(Me)CPhCPh)][O3SCF 3] (1) in 48% isolated yield. A single-crystal X-ray structure of 1 features a planar azoxymetallacycle with methyl alkylation taking place only at the β-nitrogen position of the former Zr(N(O)NCPhCPh) scaffold. In addition to 1, the methoxy-triflato complex Cp2Zr(OMe)(O3SCF 3) (2) was also isolated from the reaction mixture in 26% yield and fully characterized, including its independent synthesis from the alkylation of Cp2Zr=O(NC5H5) with MeO3SCF 3. Complex 2 could also be observed, spectroscopically, from the thermolysis of 1 (80 °C, 2 days). In contrast to Cp2Zr(N(O) NPhCCPh), the more stable titanium N2O-inserted analogue, Cp 2Ti(N(O)NCPhCPh), reacts with MeO3SCF3 to afford a 1:1 mixture of regioisomeric salts, [Cp2Ti(N(O)N(Me)CPhCPh)] [O3SCF3] (3) and [Cp2Ti(N(OMe)NCPhCPh)][O 3SCF3] (4), in a combined 65% isolated yield. Single-crystal X-ray diffraction studies of a cocrystal of 3 and 4 show a 1:1 mixture of azoxymetallacyle salts resulting from methyl alkylation at both the β-nitrogen and the β-oxygen of the former Ti(N(O)NCPhCPh ring. As opposed to alkylation reactions, the one-electron reduction of Cp 2Ti(N(O)NCPhCPh) with KC8, followed by encapsulation with the cryptand 2,2,2-Kryptofix, resulted in the isolation of the discrete radical anion [K(2,2,2-Kryptofix)][Cp2Ti(N(O)NCPhCPh)] (5) in 68% yield. Complex 5 was studied by single-crystal X-ray diffraction, and its solution X-band EPR spectrum suggested a nonbonding σ-type wedge hybrid orbital on titanium, d(z2)/d(x2-y2), houses the unpaired electron, without perturbing the azoxymetallacycle core in Cp 2Ti(N(O)NCPhCPh). Theoretical studies of Ti and the Zr analogue are also presented and discussed.
- Mindiola, Daniel J.,Watson, Lori A.,Meyer, Karsten,Hillhouse, Gregory L.
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- Aromatic PCN pincer palladium complexes: forming and breaking C[sbnd]C bonds
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Through a salt metathesis reaction, (t?BuPCN)Pd-ONO2 (2) was prepared and used as a precursor for producing (t?BuPCN)Pd-OH (3) and (t?BuPCN)Pd-aryl acetylide complexes 4 (phenyl acetylide) and 5 (p-tolyl acetylide). The aryl acetylide complexes could also be prepared through another synthetic route: by condensation of 3 with the corresponding aryl acetylene. The reactivity of complexes 3 and 4 toward carbon dioxide was studied and it was found that both reactions give the hydrogen carbonate complex (6). The low reactivity of the Pd-acetylide bond was further confirmed by the fact that the propiolate complex undergoes decarboxylation to give 4. PCN palladium complexes are good catalysts for the decarboxylative cross coupling reactions between acetylene carboxylic acids and aryl halides. The yield of the cross coupling product was improved by adding a catalytic amount of CuI.
- Mousa, Abdelrazek H.,Fleckhaus, André,Kondrashov, Mikhail,Wendt, Ola F.
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- A Mo(VI) Alkylidyne complex with polyhedral oligomeric silsesquioxane ligands: Homogeneous analogue of a silica-supported alkyne metathesis catalyst
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A highly active alkyne metathesis catalyst is realized by replacing the amide ligands of a molybdenum(VI) trisamide alkylidyne complex with silanol groups from incompletely condensed POSS (polyhedral oligomeric silsesquioxane) ligands. This catalyst serves as an effective homogeneous mimic of an amorphous silica-supported catalyst. Reactivities of various catalytic mixtures are reported along with an X-ray structure of the aniline-coordinated amidodisiloxymolybdenum(VI) alkylidyne complex. Copyright
- Hyeon, Mo Cho,Weissman, Haim,Wilson, Scott R.,Moore, Jeffrey S.
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- Photoreduction of 1,1-diphenyl-2-haloethenes by metal hydrides
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The nature of the photochemical carbon - halogen bond cleavage in the presence of sodium borohydride or lithium aluminium hydride as reducing agents was studied when a halogen atom is bonded to the sp2 hybridized carbon atom, which is a part of a vinyl system. Irradiation of 1,1-diphenyl-2-bromoethene, or 1,1-diphenyl-2-chloroethene, in the presence of the metal hydrides resulted in an increased formation of the photoreduced product 1,1-diphenylethene in comparison to reactions run in their absence. Conversion of the starting compound and the products distribution depended on the halogen atom bonded, the reducing agent, and the solvent used.
- Zupancic, Natasa,Sket, Boris
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- Synthesis and characterization of copper(I) compounds incorporating pyrazole-derived ligands: A study on carbon-carbon coupling reaction
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A series of copper(I) compounds manifesting with the pyrazole mediated precursor, ArN[CH2(C3H3N2)]2 (Ar = 2,6-diisopropylphenyl) (LN3), were synthesized conveniently and treatment of the derivatives with small organic molecules like pyrazine and triphenylphosphine were analyzed. Reacting one and two equivalents of LN3 with [Cu(CH3CN)4]PF6 in CH3CN at room temperature afforded [Cu(LN3)(CH3CN)2]PF6 (1) and [Cu(LN3)2]PF6 (2), respectively in high yield. Similarly, while reacting one equivalent of LN3 and CuI in acetonitrile for 12 h, produced a white solid, [Cu(LN3)]I (3). Furthermore, by adding one or two equivalents of PPh3 into compound 1, using methylene chloride as solvent rendered [Cu(LN3)(PPh3)]PF6 (4) and [Cu(LN3)(PPh3)2]PF6 (5), respectively, in satisfactory yield. In addition, compound {[Cu(LN3)(C4H4N2)]2(PF6)2}n (6) was generated as one-dimensional polymer by treating compound 1 and pyrazine in THF at room temperature. All the Cu(I)-derivatives were characterized by 1H and 13C NMR spectroscopy and the molecular structures (1, 4, and 6) were determined by single crystal X-ray diffraction. Additionally, the catalytic reactions of Sonogashira type C-C coupling were discussed using compounds 2, 3, 5, and 6 as catalysts.
- Li, Chen-Yi,Lien, Yu-Ling,Vinayagam, Jayaramann,Datta, Amitabha,Hu, Ting-Chia,Lin, Chia-Her,Huang, Jui-Hsien
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- Selective synthesis of Cu2O nanocrystals as shape-dependent catalysts for oxidative arylation of phenylacetylene
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Shape-dependent nanocatalysis: Monodisperse cubic, rhombic dodecahedral, and octadecahedral Cu2O nanocrystals (NCs) were selectively synthesized. Cu2O octadecahedra exhibited the best activity upon recycling, though etched on nanoframes, in the ligand-free oxidative arylation of phenylacetylene. Rhombic dodecahedra had moderate activity and optimal stability, whereas cubes suffered significant loss of activity during recycling. Copyright
- Li, Lingling,Nan, Caiyun,Peng, Qing,Li, Yadong
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- EFFICIENT COPPER-CATALYZED OXIDATION OF DIHYDRAZONES OF α-DIKETONES TO DISUBSTITUTED ACETYLENES
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Dihydrazones of α-diketones were oxidized by using Cu2Cl2/O2/pyridine system in dichloromethane at room temp to give disubstituted acetylenes.Although the dihydrazones were found to be oxidized with four equivalents of Cu(II) salt without oxygen, efficien
- Tsuji, Jiro,Kezuka, Hiroaki,Toshida, Yomishi,Takayanagi, Hiroshi,Yamamoto, Keiji
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- Intermolecular σ-Bond Cross-Exchange Reaction between Cyclopropenones and (Benzo)silacyclobutanes: Straightforward Access towards Sila(benzo)cycloheptenones
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Described herein is the first intermolecular σ-bond exchange reaction between the C?C bond of cyclopropenones and C?Si bond of (benzo)silacyclobutanes and it proceeds smoothly by treatment with either 1 mol % of a palladium or 2 mol % of a nickel catalyst. This reaction constitutes an unprecedented route for the synthesis of various sila(benzo)suberones. And it is also the first example of a σ-bond exchange reaction involving cyclopropenones.
- Zhao, Wen-Tao,Gao, Fang,Zhao, Dongbing
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- Efficient room-temperature alkyne metathesis with well-defined imidazolin-2-iminato tungsten alkylidyne complexes
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(Chemical Equation Presented) It's a game of give and take: Following the successful design strategy for high-oxidation-state alkene metathesis catalysts of the Schrock type, one of the most active homogeneous catalyst systems for alkyne metathesis has been developed. The activity of the tungsten alkylidyne complex (see picture) stems from the use of a strong electron-donating imidazolin-2-iminato ligand together with electron-withdrawing fluorinated alkoxides.
- Beer, Stephan,Hrib, Cristian G.,Jones, Peter G.,Brandhorst, Kai,Grunenberg, Joerg,Tamm, Matthias
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- One-Pot Multicomponent Tandem Reactions and Polymerizations for Step-Economic Synthesis of Structure-Controlled Pyrimidine Derivatives and Poly(pyrimidine)s
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The development of new polymerization methodologies for the construction of π-conjugated polymers with unique electronic and photophysical properties is of great importance. Multicomponent tandem polymerizations (MCTPs), featured with high synthetic efficiency and convenience, have proved their potential in the synthesis of polymers with π-conjugated structures. Herein, a new multicomponent tandem reaction of alkyne, guanidine hydrochloride, DMSO, and O2 was reported through the combination of four sequential Glaser coupling-nucleophilic addition-heterocyclization-oxidation reactions in a one-pot procedure. The corresponding MCTP of diyne, guanidine hydrochloride, DMSO, and O2 was also developed in the presence of CuCl, N,N,N′,N′-tetramethylethylenediamine, and Cs2CO3 to afford conjugated poly(pyrimidine) with well-defined structure, high yield of 87%, and high molecular weight of 25300 g/mol. A mechanistic study of the reaction and a kinetic study of the polymerization were conducted, enabling facile modulation of polymer mainchain structure from rigid conjugated backbone to flexible nonconjugated backbone by simply tuning the atmosphere of the MCTP from air to nitrogen. The poly(pyrimidine)s enjoy outstanding thermal stability and good solubility, whose hydrophobicity and photophysical property are influenced by their subtle structural difference. This MCTP directly converts monomers with simple structure to complex heterocycle-containing products in a step-economic manner and constructs new functional substituted pyrimidine rings embedded in the polymer main chain, providing a compact approach for the efficient and convenient synthesis of structurally controllable poly(heterocycle)s and the construction of polymer materials with potential high-tech applications.
- Tian, Wen,Hu, Rongrong,Tang, Ben Zhong
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- 1,3-Diphosphapropenes for novel chemistry of metal complexes
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2-Methyl-3,3-diphenyl-1-(2,4,6-tri-t-butylphenyl)-1,3-diphosphapropene was obtained as a chelate ligand for palladium(II) and platinum(II) complexes. Sulfurization of 2-methyl-1,3-diphosphapropene mainly gave 3-thioxo-1,3- diphosphapropene which bears a PC-PS skeleton and was used as a ligand of transition-metal complexes. A doubly-sulfurized product of the 1,3-diphosphapropene, 1,3-dithioxo-1,3-diphosphapropene, was isolated and characterized. The palladium(II) complexes containing the ligated 1,3-diphosphapropenes were used for catalytic reactions such as cross-couplings and direct conversion of allyl alcohol to allylaniline.
- Ito, Shigekazu,Liang, Hongze,Yoshifuji, Masaaki
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- Uranium versus Thorium: Synthesis and Reactivity of [η5-1,2,4-(Me3C)3C5H2]2U[η2-C2Ph2]
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The synthesis, electronic structure, and reactivity of a uranium metallacyclopropene were comprehensively studied. Addition of diphenylacetylene (PhC≡CPh) to the uranium phosphinidene metallocene [η5-1,2,4-(Me3C)3C5H2]2U=P-2,4,6-tBu3C6H2 (1) yields the stable uranium metallacyclopropene, [η5-1,2,4-(Me3C)3C5H2]2U[η2-C2Ph2] (2). Based on density functional theory (DFT) results the 5f orbital contributions to the bonding within the metallacyclopropene U-(η2-C=C) moiety increases significantly compared to the related ThIV compound [η5-1,2,4-(Me3C)3C5H2]2Th[η2-C2Ph2], which also results in more covalent bonds between the [η5-1,2,4-(Me3C)3C5H2]2U2+ and [η2-C2Ph2]2? fragments. Although the thorium and uranium complexes are structurally closely related, different reaction patterns are therefore observed. For example, 2 reacts as a masked synthon for the low-valent uranium(II) metallocene [η5-1,2,4-(Me3C)3C5H2]2UII when reacted with Ph2E2 (E=S, Se), alkynes and a variety of hetero-unsaturated molecules such as imines, ketazine, bipy, nitriles, organic azides, and azo derivatives. In contrast, five-membered metallaheterocycles are accessible when 2 is treated with isothiocyanate, aldehydes, and ketones.
- Wang, Deqiang,Ding, Wanjian,Hou, Guohua,Zi, Guofu,Walter, Marc D.
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- Pd-Cu2O and Ag-Cu2O hybrid concave nanomaterials for an effective synergistic catalyst
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Palladium and silver salts were combined with Cu2O octadecahedra in concave heterostructures. The formation of concave faces involved selective oxidative etching of Cu2O on the {100} faces and in situ growth of Pd/Ag on different sites. The structures showed superior catalytic activities to both single domains and their mixtures in a model Sonogashira-type organic reaction. Copyright
- Li, Lingling,Chen, Xiaobin,Wu, Yuen,Wang, Dingsheng,Peng, Qing,Zhou, Gang,Li, Yadong
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- Catalytic Addition of Aromatic C-H Bonds to Acetylenes
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The reaction of α-tetralone with various internal acetylenes can be catalyzed by Ru(H)2(CO)(PPh3)3 and gives 1 : 1 addition products.Symmetrically substituted dialkyl- and diarylacetylenes gave an E/Z mixtures of 1 : 1 coupling products in good yields. 1-
- Kakiuchi, Fumitoshi,Yamamoto, Yoshimi,Chatani, Naoto,Murai, Shinji
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- The standard molar enthalpy of formation of 2,3-diphenylcycloprop-2-en-1-one
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The standard molar enthalpies of combustion and sublimation for 2,3-diphenylcycloprop-2-en-1-one (C15H10O) at 298.15 K have been redetermined.The experimental values: ΔfH0m(C15H10O, cr) = (198.03 +/- 1.96) kJ*mol-1 and ΔgcrH0m(C15H10O) = (119.7 +/- 8) kJ*mol-1 yield a value for ΔfH0m(C15H10O, g) = (317.7 +/- 8.2) kJ*mol-1.If one assumes a ring strain in cycloprop-2-en-1-one of 280 kJ*mol-1, then the resonance stabilization in the three-membered ring is 88 kJ*mol-1.This indicates substantial ground-state aromatic stabilization in this molecule.
- Steele, William V.,Gammon, Bruce E.,Smith, Norris K.,Chickos, James S.,Greenberg, Arthur,Liebman, Joel F.
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- Monitoring Reactions on Solid Phases with Raman Spectroscopy
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The benefits of Raman spectroscopy were shown for the on-bead monitoring of diverse reactions. Raman spectroscopy was used for the development of new procedures on established linker systems, the real-time observation of several reactions on solid phases and the estimation of the reaction time for a new cleavage strategy. Selected conversions on solid phases, such as the on-bead conversion of functional groups and the attachment of novel building blocks, were demonstrated. Raman spectra were obtained after isolation and purification of the solid supports, but they were also measured directly in the reaction vessels. Even the detection of Raman-active functional groups in swollen polymer resins and in reaction mixtures was demonstrated, and allows real-time observation of the progress of diverse reactions on solid supports.
- Protasova, Irina,Hei?ler, Stefan,Jung, Nicole,Br?se, Stefan
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- New application of the transient grating method to a photochemical reaction: The enthalpy, reaction volume change, and partial molar volume measurements
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A new application of the time-resolved transient grating method for measuring the enthalpy and reaction volume changes in a photochemical reaction is described in detail. From the temporal profile of the signal, these quantities can be determined independently in one particular solvent at a temperature and a pressure. The advantages of this method become clear by a comparison with the previously used photothermal methods, such as the thermal lens and photoacoustic methods. The partial molar volumes of carbon monoxide as well as the reaction volume changes of the photodissociation of diphenylcyclopropenone in several alkanes and aqueous solution are measured, and its solvent dependence is discussed in terms of the isothermal compressibility of the matrix.
- Hara, Takashi,Hirota, Noboru,Terazima, Masahide
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- A water soluble, recyclable organostannatrane
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Synthesis of a water-soluble recyclable organostannatrane has been accomplished via a straightforward three-step synthesis. The organostannatrane exhibits excellent water-solubility (0.33 M) and can be recovered from aqueous solutions via removal of water in vacuo. The compound can be readily converted by standard transformations into reagents suitable for Stille cross-coupling reactions. The reagent can also be transformed into a reactive, water-soluble organotin hydride.
- Han, Xiaojun,Hartmann, Gregory A.,Brazzale, Antony,Gaston, Rick D.
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- Fast solute diffusivity in ionic liquids with silyl or siloxane groups studied by the transient grating method
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To achieve ionic liquids (ILs) that show fast solute diffusivity independent of viscosity domination, sixteen ILs containing Si or Si-O-Si groups (SiILs) were synthesized. Diffusion coefficients of three solute molecules with different molecular sizes, i.e., CO, diphenylacetylene, and diphenylcyclopropenone, were determined in SiILs using the transient grating method and the results were compared to other solvent system. SiILs showed distinguishably faster diffusivity for the smallest solute, CO, than conventional ILs at the same viscosity, particularly in the high viscosity region. Based on previous results and our estimation, three plausible factors exists that contribute to the faster solute diffusivity in SiILs, i.e., the flexibility of the Si or Si-O-Si group, decreased interaction between the cation and the solute, and increased free volume because of the bulky structure.
- Endo, Takatsugu,Nemugaki, Shinya,Matsushita, Yuki,Sakai, Yasuhiro,Ozaki, Hiroaki,Hiejima, Yusuke,Kimura, Yoshifumi,Takahashi, Kenji
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- Heck reactions of quinoline-derived nonaflates
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An efficient synthesis of a series of quinolyl-substituted ketones or ketone precursors via the Heck reaction of 6- or 8-quinolyl nonaflates with an appropriate selection of olefins is presented. These ketones are useful building blocks for the diastereoselective construction of azapolycycles via SmI 2-induced intramolecular cyclization of (het)aryl-substituted ketones. Georg Thieme Verlag Stuttgart.
- Aulenta, Francesca,Reissig, Hans-Ulrich
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- A new pathway for the preparation of diaryl acetylenes
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A simple method for the preparation of diaryl acetylenes in yields up to 61% from aryl bromides and 1-bromo-2-chloroethane using the palladium catalyst (dppb)Pd(OAc)2 under PTC conditions (solid KOH/18-crown-6) has been developed.
- Abele, Edgars,Abele, Ramona,Arsenyan, Pavel,Lukevics, Edmunds
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- Molecular and Silica-Supported Molybdenum Alkyne Metathesis Catalysts: Influence of Electronics and Dynamics on Activity Revealed by Kinetics, Solid-State NMR, and Chemical Shift Analysis
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Molybdenum-based molecular alkylidyne complexes of the type [MesC≡Mo{OC(CH3)3-x(CF3)x}3] (MoF0, x = 0; MoF3, x = 1; MoF6, x = 2; MoF9, x = 3; Mes = 2,4,6-trimethylphenyl) and their silica-supported analogues are prepared and characterized at the molecular level, in particular by solid-state NMR, and their alkyne metathesis catalytic activity is evaluated. The 13C NMR chemical shift of the alkylidyne carbon increases with increasing number of fluorine atoms on the alkoxide ligands for both molecular and supported catalysts but with more shielded values for the supported complexes. The activity of these catalysts increases in the order MoF0 3 6 before sharply decreasing for MoF9, with a similar effect for the supported systems (MoF0 ≈ MoF9 6 3). This is consistent with the different kinetic behavior (zeroth order in alkyne for MoF9 derivatives instead of first order for the others) and the isolation of stable metallacyclobutadiene intermediates of MoF9 for both molecular and supported species. Detailed solid-state NMR analysis of molecular and silica-supported metal alkylidyne catalysts coupled with DFT/ZORA calculations rationalize the NMR spectroscopic signatures and discernible activity trends at the frontier orbital level: (1) increasing the number of fluorine atoms lowers the energy of the π?(M≡C) orbital, explaining the more deshielded chemical shift values; it also leads to an increased electrophilicity and higher reactivity for catalysts up to MoF6, prior to a sharp decrease in reactivity for MoF9 due to the formation of stable metallacyclobutadiene intermediates; (2) the silica-supported catalysts are less active than their molecular analogues because they are less electrophilic and dynamic, as revealed by their 13C NMR chemical shift tensors.
- Estes, Deven P.,Gordon, Christopher P.,Fedorov, Alexey,Liao, Wei-Chih,Ehrhorn, Henrike,Bittner, Celine,Zier, Manuel Luca,Bockfeld, Dirk,Chan, Ka Wing,Eisenstein, Odile,Raynaud, Christophe,Tamm, Matthias,Copéret, Christophe
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- Well-Defined Scandacyclopropenes: Synthesis, Structure, and Reactivity
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Although transition metallacyclopropenes have been extensively explored for more than 40 years, their analogues of rare-earth metals have remained elusive. Herein, we report the synthesis of three isolable scandacyclopropenes, thus representing the first well-defined rare-earth metallacyclopropenes. Structural characterization and DFT calculations revealed a delocalized three-center two-electron (3c-2e) aromatic system. When scandacyclopropenes were treated with phenylacetylene or TMSN3, the scandium complex of bis-phenylacetylide or bis-azide was obtained, respectively. The reaction of scandacyclopropene with phenazine could provide the binuclear ring-opening scandium complex via 1,4-insertion of phenazine into one Sc-C bond and subsequent metathesis reaction. However, insertion of TMSNCO or N2O into one Sc-C bond of scandacyclopropenes gave a five- or six-membered scandacycle. In addition, scandacyclopropenes can serve as a two-electron reductive agent for PhSSPh and PhNNPh. These results show that scandacyclopropenes exhibit diversified and unique reactivity toward small molecules because of the strongly nucleophilic alkenediyl dianion and highly strained three-membered ring.
- Lv, Ze-Jie,Huang, Zhe,Shen, Jinghang,Zhang, Wen-Xiong,Xi, Zhenfeng
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- Heterobimetallic Pd/Mn and Pd/Co complexes as efficient and stereoselective catalysts for sequential Cu-free Sonogashira coupling–alkyne semi-hydrogenation reactions
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A series of heterobimetallic PdII/MII complexes (MII = Mn, Co) were synthesised and tested as precatalysts for sequential Sonogashira coupling–alkyne semi-hydrogenation reactions to form Z-aryl alkenes. The carbometalated heterobimetallic PdII/CoII complex CoPdL3′ demonstrated an apparent cooperative effect compared to the corresponding monometallic counterparts. This compound was identified as a potent single-molecule catalyst for the one-pot Cu-free Sonogashira coupling of aryl bromides with terminal alkynes followed by chemo- and stereoselective semi-hydrogenation of the alkyne intermediate using NH3·BH3 as a hydrogen source. Furthermore, different aromatic substrates have been tested to show the generality of the reaction for the synthesis of Z-alkenes, including biologically active combretastatin A-4. In addition, the homogeneous nature of the catalytically active species was demonstrated.
- Baweja, Saral,Clauss, Reike,Gelman, Dmitri,Hey-Hawkins, Evamarie
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supporting information
p. 1344 - 1356
(2022/02/03)
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- Mechanochemical Synthesis of Diarylethynes from Aryl Iodides and CaC 2
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A mechanochemical synthesis of diarylethynes from aryl iodides and calcium carbide as acetylene source is reported. The reaction is catalyzed by a palladium catalyst in the presence of copper salt, base, and ethanol as liquid assisting grinding (LAG) additive. Various aryl and heteroaryl iodides have been converted in up to excellent yields.
- Bolm, Carsten,Van Bonn, Pit
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supporting information
(2022/02/25)
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- Synthesis of N-Heterocyclic Carbine Silver(I) and Palladium(II) Complexes with Acylated Piperazine Linker and Catalytic Activity in Three Types of C—C Coupling Reactions
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Two bis-imidazolium salts LH2·Cl2 and LH2·(PF6)2 with acylated piperazine linker and two N-heterocyclic carbene (NHC) silver(I) and palladium(II) complexes [L2Ag2](PF6)2 (1) and [L2Pd2Cl4] (2) were prepared. The crystal structures of LH2·Cl2 and 1 were confirmed by X-ray analysis. In 1, one 26-membered macrometallocycle was generated through two silver(I) ions and two bidentate ligands L. The catalytic activity of 2 was investigated in Sonogashira, Heck-Mizoroki and Suzuki-Miyaura reactions. The results displayed that these C—C coupling reactions can be smoothly carried out under the catalysis of 2.
- Liu, Qingxiang,Zhang, Xiantao,Zhao, Zhixiang,Li, Xinying,Zhang, Wei
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supporting information
p. 605 - 613
(2021/02/01)
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- Co3O4 nanoparticles embedded in triple-shelled graphitic carbon nitride (Co3O4/TSCN): a new sustainable and high-performance hierarchical catalyst for the Pd/Cu-free Sonogashira–Hagihara cross-coupling reaction
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Inspired by the synthesis of triple-shelled periodic mesoporous organosilica hollow spheres, a straightforward and controllable approach for the preparation of Co3O4 NPs embedded in triple-shelled graphitic carbon nitride has been es
- Ghodsinia, Sara S. E.,Akhlaghinia, Batool,Jahanshahi, Roya
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p. 3217 - 3244
(2021/05/17)
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- Introduction of a Recyclable Basic Ionic Solvent with Bis-(NHC) Ligand Property and The Possibility of Immobilization on Magnetite for Ligand- and Base-Free Pd-Catalyzed Heck, Suzuki and Sonogashira Cross-Coupling Reactions in Water
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A new versatile and recyclable NHC ligand precursor has been developed with ligand, base, and solvent functionalities for the efficient Pd-catalyzed Heck, Suzuki and Sonogashira cross-coupling reactions under mild conditions. Furthermore, NHC ligand precursor was immobilized on magnetite and its catalytic activity was also evaluated towards the coupling reactions as a heterogeneous catalyst. The NHC ligand precursor was prepared with imidazolium functionalization of TCT followed by a simple ion exchange by hydroxide ions. However, the results revealed an excellent catalytic activity for the both homogeneous and heterogeneous catalytic systems. 1.52?g.cm?3 and 1194 cP was obtained for the density and viscosity of the NHC ligand precursor respectively. On the other hand, the heterogeneous type could be readily recovered from the reaction mixture and reused for several times while preserving its properties. Heterogeneous nature of the magnetic catalyst was studied by hot filtration, mercury poisoning, and three-phase tests. High to excellent yields were obtained for all entries for the both homogeneous and heterogeneous catalysts, which reflects the high consistency of the catalyst. Graphic Abstract: [Figure not available: see fulltext.]
- Min, Qingwang,Miao, Penghua,Chu, Deyu,Liu, Jinghan,Qi, Meijuan,Kazemnejadi, Milad
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p. 3030 - 3047
(2021/02/16)
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- Bis(NHC)-Pd-catalyzed one-pot competitive C-C*C-C, C-C*C-O, C-C*C-N, and C-O*C-N cross-coupling reactions on an aryl di-halide catalyzed by a homogenous basic ionic liquid (TAIm[OH]) under base-free, ligand-free, and solvent-free conditions
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Bis(NHC)-Pd-catalyzed competitive asymmetrical C-C*C-C, C-C*C-O, C-C*C-N, and O-C*C-N cross-coupling reactions were performedviathe one-pot strategy in the presence of a new ionic liquid, which played the roles of solvent, base, and ligand simultaneously. The ionic liquid was prepared based on a methyl imidazolium moiety with hydroxyl counter anionsviaa Hofmann elimination on a 1,3,5-triazine framework (TAIm[OH]). Pd ions could be efficiently coordinated through the bis(NHC)-ligand moiety in the ionic liquid. Based on differences in the competitive kinetics of C-C cross-coupling reactions (Heck, Suzuki, and Sonogashira) with C-N and C-O cross-coupling reactions, and also differences in the kinetics of aryl halides, the coupling reactions could be selectively performed with a low amount of by-products. The competitive cross-coupling reactions were thus performed with high selectivity under mild reaction conditions.
- Zhu, Yanfang,Xu, Guiyang,Kazemnejadi, Milad
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p. 11662 - 11671
(2021/07/11)
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- A Waste-Minimized Approach to Cassar-Heck Reaction Based on POLITAG-Pd0 Heterogeneous Catalyst and Recoverable Acetonitrile Azeotrope
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Three different Pd0-based heterogeneous catalysts were developed and tested in the Cassar–Heck reaction (i. e., copper-free Sonogashira reaction) aiming at the definition of a waste minimized protocol. The cross-linked polymeric supports used in this investigation were designed to be adequate for different reaction media and were decorated with different pincer-type ionic ligands having the role of stabilizing the formation and dimension of palladium nanoparticles. Among the ionic tags tested, bis-imidazolium showed the best performances in terms of efficiency and durability of the metal catalytic system. Eventually, aqueous acetonitrile azeotrope was selected as the reaction medium as it allowed the best catalytic efficiency combined with easy recovery and reuse. Finally, the synergy between the selected catalyst and reaction medium allowed to obtain highly satisfactory isolated yields of a variety of substrates while using a low amount of metal catalyst. The high performance of the designed POLymeric Ionic TAG (POLITAG)-Pd0, along with its good selectivity achieved in a copper-free process, also led to a simplified purification procedure allowing the minimization of the waste generated as also proven by the very low E-factor values (1.4–5) associated.
- Valentini, Federica,Ferlin, Francesco,Tomarelli, Elena,Mahmoudi, Hamed,Bagherzadeh, Mojtaba,Calamante, Massimo,Vaccaro, Luigi
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p. 3359 - 3366
(2021/07/28)
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- Si-Gly-CD-PdNPs as a hybrid heterogeneous catalyst for environmentally friendly continuous flow Sonogashira cross-coupling
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We have reported a waste-minimized protocol for the Sonogashira cross-coupling exploiting the safe use of a CPME/water azeotropic mixture and the utilization of a heterogeneous hybrid palladium catalyst supported onto a silica/β-cyclodextrin matrix in con
- Cravotto, Giancarlo,Ferlin, Francesco,Martina, Katia,Menzio, Janet,Sciosci, Daniele,Vaccaro, Luigi,Valentini, Federica
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supporting information
p. 7210 - 7218
(2021/09/28)
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- Lipids as versatile solvents for chemical synthesis
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Development of safe, renewable, cheap and versatile solvents is a longstanding challenge in chemistry. We show here that vegetable oils and related systems can become prominent solvents for organic synthesis. Suzuki-Miyaura, Hiyama, Stille, Sonogashira and Heck cross-couplings proceed with quantitative yields in a range of vegetable oils, fish oil, butter and waxes used as solvents. Appropriate methodologies for high-throughput screening and sustainable isolation techniques applicable for vegetable oils and related lipids are presented.
- Bayer, Annette,Gevorgyan, Ashot,Hopmann, Kathrin H.
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supporting information
p. 7219 - 7227
(2021/09/28)
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- Aerobic Cu and amine free Sonogashira and Stille couplings of aryl bromides/chlorides with a magnetically recoverable Fe3O4@SiO2 immobilized Pd(II)-thioether containing NHC
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Two value added C–C cross coupling reactions; Sonogashira and Stille couplings were achieved at milder conditions in the catalytic presence of a magnetically recoverable heterogeneous catalyst Fe3O4@SiO2@NHC^SPh-Pd(II). The catalyst was earlier reported for Suzuki-Miyaura reaction, and as an extension of its catalytic efficiency, the Stille and Sonogashira cross coupling reactions under aerobic condition has been explored in present report. The Sonogashira coupling of aryl bromides and terminal alkynes produced an excellent yield (~96% at 0.25 mol% Pd) of the desired coupling product under copper and amines free conditions. Moreover, an excellent Stille coupling of readily available and more latent aryl chlorides and trialkylstannane was obtained (yields up to 95% at 0.25 mol% Pd) in absence of toxic fluorides additives. The broad substrate scope of the catalyst for both the coupling reactions and the magnetically recoverable feature of catalyst make this reaction highly desirable for industrial applications of present heterogeneous catalysis.
- Khandaka, Himanshu,Sharma, Kamal Nayan,Joshi, Raj Kumar
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supporting information
(2021/02/20)
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- Versatile and an efficient Sonogashira coupling reaction catalyzed with modified Pd-functionalized TMU-16 as a novel and reusable nanocatalyst
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This research paper, reports the preparation of palladium impregnated [Zn2(BDC)2(4-bpdh)]3DMF (Pd@TMU-16) with a simple liquid impregnation-reduction method as a novel and efficient catalyst with the high catalytic performance for co
- Alinezhad, Heshmatollah,Ghasemi, Shahram,Kiani, Ameneh
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- Pd supported on clicked cellulose-modified magnetite-graphene oxide nanocomposite for C-C coupling reactions in deep eutectic solvent
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Cellulose-modified magnetite-graphene oxide nanocomposite was prepared via click reaction and utilized for immobilization of palladium (Pd) nanoparticles without using additional reducing agent. The abundant OH groups of cellulose provided the uniform dispersion and high stability of Pd nanoparticles, while magnetite-graphene oxide as a supporting material offered high specific surface area and easy magnetic separation. The as-prepared nanocomposite served as a heterogeneous catalyst for the Heck and Sonogashira coupling reactions in various hydrophilic and hydrophobic deep eutectic solvents (DESs) as sustainable and environmentally benign reaction media. Among the fifteen DESs evaluated for coupling reactions, the hydrophilic DES composed of dimethyl ammonium chloride and glycerol exhibited the best results. Due to the low miscibility of catalyst and DES in organic solvents, the separated aqueous phase containing both of the catalyst and DES can be readily recovered by evaporating water and retrieved eight times with negligible loss of catalytic performance.
- Karimi, Sabah,Masteri-Farahani, Majid,Niakan, Mahsa,Shekaari, Hemayat
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- Simple and efficient diaryl alkyne synthesis method
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The embodiment of the invention discloses a simple and efficient diaryl alkyne synthesis method. The method comprises the steps of by taking arylmethylbenzotriazole and aromatic aldehyde as raw materials, carrying out addition and double-beta-elimination reaction under the action of bis (trimethylsilyl) amino salt MN (SiMe3) 2 to synthesize diaryl alkyne by a one-pot method. The raw materials and chemical reagents used in the method are easy to obtain, the reaction conditions are mild, the operation is simple, the substrate universality is good, the product yield is high, and the method is a simple and efficient diaryl alkyne synthesis method.
- -
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Paragraph 0026; 0041-0042
(2021/04/14)
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- Catalytic Alkyne and Diyne Metathesis with Mixed Fluoroalkoxy-Siloxy Molybdenum Alkylidyne Complexes
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The reaction of the molybdenum alkylidyne complex [MesC≡Mo{OC(CF3)3}3] (MoF9, Mes = 2,4,6-trimethylphenyl) with the potassium siloxides KOSi(OtBu)3and KOSi(OtBu)2(OMes) furnished the mixed fluoroalkoxy-siloxy alkylidyne complexes [MesC≡Mo{OC(CF3)3}2{OSi(OtBu)3}] (MoSiF9) and [MesC≡Mo{OC(CF3)3}2{OSi(OtBu)2(OMes)}] (MoSi*F9). A treatment ofMoF9MoSiF9, andMoSi*F9with an excess of 3-hexyne (EtC≡CEt) afforded labile metallacyclobutadiene (MCBD) complexes with a (C3Et3)Mo core, which are in equilibrium with the corresponding propylidyne (EtC≡Mo) complexes in solution. Thermodynamic parameters for these [2 + 2]-cycloaddition/cycloreversion reactions were determined by van’t Hoff plots, revealing that the nature of the ancillary siloxide ligand exerts a significant effect on the MCBD stability. An X-ray diffraction analysis of MoSi*F9-MCBDprovided one of the first accurate crystal structures of a molybdenacyclobutadiene. MoF9MoSiF9, andMoSi*F9proved active catalysts for the metathesis of internal alkynes and diynes, withMoSi*F9showing unprecendented selectivity in the conversion of sterically encumbered 1,3-pentadiynes into symmetrical 1,3,5-triynes and 2-butyne.
- Bockfeld, Dirk,Colombel-Rouen, Sophie,Ehrhorn, Henrike,Mauduit, Marc,Tamm, Matthias,Trolez, Yann,Zier, Manuel L.
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supporting information
(2021/07/17)
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- Impact of Ligands and Metals on the Formation of Metallacyclic Intermediates and a Nontraditional Mechanism for Group VI Alkyne Metathesis Catalysts
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The intermediacy of metallacyclobutadienes as part of a [2 + 2]/retro-[2 + 2] cycloaddition-based mechanism is a well-established paradigm in alkyne metathesis with alternative species viewed as off-cycle decomposition products that interfere with efficient product formation. Recent work has shown that the exclusive intermediate isolated from a siloxide podand-supported molybdenum-based catalyst was not the expected metallacyclobutadiene but instead a dynamic metallatetrahedrane. Despite their paucity in the chemical literature, theoretical work has shown these species to be thermodynamically more stable as well as having modest barriers for cycloaddition. Consequentially, we report the synthesis of a library of group VI alkylidynes as well as the roles metal identity, ligand flexibility, secondary coordination sphere, and substrate identity all have on isolable intermediates. Furthermore, we report the disparities in catalyst competency as a function of ligand sterics and metal choice. Dispersion-corrected DFT calculations are used to shed light on the mechanism and role of ligand and metal on the intermediacy of metallacyclobutadiene and metallatetrahedrane as well as their implications to alkyne metathesis.
- Thompson, Richard R.,Rotella, Madeline E.,Zhou, Xin,Fronczek, Frank R.,Gutierrez, Osvaldo,Lee, Semin
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supporting information
p. 9026 - 9039
(2021/06/30)
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- Pd nanoparticles loaded on modified chitosan-Unye bentonite microcapsules: A reusable nanocatalyst for Sonogashira coupling reaction
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This work investigates the preparation of a catalytic complex of palladium nanoparticles supported on novel Schiff base modified chitosan-Unye bentonite microcapsules (Pd NPs@CS-UN). The complex has been characterized by FT-IR, EDS, XRD, TEM, HRTEM, Raman
- Shafiei, Nasrin,Nasrollahzadeh, Mahmoud,Baran, Talat,Baran, Nuray Y?lmaz,Shokouhimehr, Mohammadreza
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- Facile synthesis of Pd nanoparticles supported on a novel Schiff base modified chitosan-kaolin: Antibacterial and catalytic activities in Sonogashira coupling reaction
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The present work studies the Sonogashira coupling reaction (SCR) between aryl halides and acetylenes under aerobic conditions using the catalytic complex of Pd nanoparticles (NPs) supported on a novel Schiff base modified chitosan-kaolin (Pd NPs@CS-Kao) in ethanol solvent. The prepared catalyst was characterized by TEM, SEM, FT-IR, XRD, EDS, XPS, elemental mapping, and Raman analyses. The products were formed in high yields. At the end of the reaction, Pd NPs@CS-Kao can be filtered and reused for five consecutive cycles. The advantages of this catalytic process include simple methodology, high yields, and easy work-up. In addition, Pd NPs@CS-Kao exhibited effective antibacterial performance against E. coli gram-negative bacteria.
- Nasrollahzadeh, Mahmoud,Shafiei, Nasrin,Baran, Talat,Pakzad, Khatereh,Tahsili, Mohammad Reza,Baran, Nuray Y?lmaz,Shokouhimehr, Mohammadreza
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- Immobilized Pd on a NHC-functionalized metal-organic FrameworkMIL-101(Cr): An efficient heterogeneous catalyst in the heck and copper-free Sonogashira coupling reactions
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A heterogeneous palladium catalyst system based on immobilization of palladium moieties on a N-heterocyclic carbene (NHC) modified metal organic framework (MOF) was developed for the Heck and copper-free Sonogashira coupling reactions. In order to prepare this catalyst system, first, MIL-101(Cr) was functionalized with NHC moieties through a post synthetic modification (PSM) approach, and then Pd metal was stabilized on the prepered MIL-101(Cr)-NHC substrate. This material was characterized using various microscopic and spectroscopic techniques and then was used as an efficient heterogeneous Pd catalyst system in the Heck and copper-free Sonogashira reactions. Results of the heterogeneity tests showed that the Pd-NHC-MIL-101(Cr) catalyst can efficiently catalyzed these coupling reactions heterogeneously and no remarkable changes observed in the morphology and structure of MIL-101(Cr) template during the reaction progress. Also, existence of palladium nanoparticles immobilized on the MOF structure affirmed by the TEM and XPS analysis confirmed the oxidation state of Pd. A variety of alkene and alkyne derivatives were synthesized in good to excellent yields using this heterogeneous Pd catalyst system under normal conditions. More importantly Pd-NHC-MIL-101(Cr) catalyst was simply recovered from the reaction medium without remarkable decreasing in its catalytic activities after five times of reusability. The ICP analysis showed the very low Pd and Cr metals leaching, representing high stability and applicability of this catalyst in Pd coupling reactions.
- Niknam, Esmaeil,Panahi, Farhad,Khalafi-Nezhad, Ali
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supporting information
(2021/01/12)
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- Highly Reactive Cationic Molybdenum Alkylidyne N-Heterocyclic Carbene Catalysts for Alkyne Metathesis
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The tetracoordinated cationic molybdenum alkylidyne N-heterocyclic carbene (NHC) complexes [Mo(CC6H4-p-OMe)(IMes)(OCMe(CF3)2)2][BPh4] (Mo5) and [Mo(CC6H4-p-OMe)(IMes)(OCMe(CF3)2)2][B(ArF)4] (Mo6, IMes = 1,3-dimesitylimidazol-2-ylidene)) were synthesized from the pentacoordinated progenitor Mo(CC6H4-p-OMe)(IMes)(OCMe(CF3)2)2(OTf) (Mo4). Complexes Mo4-Mo6 were evaluated for their ability to catalyze the self-metathesis of several internal alkynes. The presence of a triflate group facilitates formation of a cationic species while preformation of the cationic molybdenum center in molybdenum alkylidyne NHC complexes indeed results in a strong increase in catalyst productivity and activity, also in the presence of functional groups, compared to previously reported neutral congeners. The most striking feature of this class of tetracoordinate cationic complexes is the excellent catalytic activity in the alkyne metathesis of non-protic substrates, thereby supporting our previously published proposal of a tetracoordinate cationic active species in alkyne metathesis formed from the neutral, pentacoordinate molybdenum alkylidyne NHC progenitors. Catalyst productivity, expressed as turnover number, reached 20 000 in the self-metathesis of 1-phenyl-1-propyne (S1) using Mo(CC6H4-p-OMe)(1,3-dimesitylimidazol-2-ylidene)(OCMe(CF3)2)2[B(ArF)4] (Mo6) and 5-(benzyloxy)-2-pentyne (S2) at catalyst loadings as low as 0.005 mol %.
- Groos, Jonas,Hauser, Philipp M.,Koy, Maximilian,Frey, Wolfgang,Buchmeiser, Michael R.
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p. 1178 - 1184
(2021/05/06)
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- NiFe2O4@SiO2@ZrO2/SO42-/Cu/Co nanoparticles: A novel, efficient, magnetically recyclable and bimetallic catalyst for Pd-free Suzuki, Heck and C-N cross-coupling reactions in aqueous media
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The novel heterogeneous bimetallic nanoparticles of Cu-Co were synthesized based on magnetic nanoparticles, and the magnetic nanocatalyst was characterized by XRD, FE-SEM, EDX mapping, BET, TEM, HRTEM, FTIR, TGA, and VSM. This catalyst was successfully applied as a recyclable magnetically catalyst in Heck, Suzuki, and C-N cross-coupling reactions with various aryl halides (iodides, bromides, and chlorides as challengeable substrates), with olefins, phenylboronic acid, and amines, respectively. We considered the rise of synergetic effects from the different Lewis acid and Br?nsted acid sites present in the catalyst. The catalyst was synthesized with cheap, available materials and a simple synthesis method. The catalyst can be separated easily using an external magnet. It was recycled for more than ten runs without a sensible loss of its catalytic activity, and no significant leaching of the Cu and Co quantity was observed. The significant benefits of the method are high-level generality, simple operation, and there are no heavy metals and toxic solvents. This is a quick, easy, efficacious and environmentally friendly protocol, and no by-products are formed in the reaction. These features make it an appropriate practical alternative protocol. In comparison with recent works, the other advantage of this catalyst is the synthesis of a wide variety of C-C and C-N bond derivatives (more than 40 derivatives). The other significant advantage is the low temperature of the reaction and the use of the least possible amount of the catalyst (0.003 g). The efficiency was good to excellent and the catalyst selectivity has been high. We aspire that our study inspires more interest to design novel catalysts based on using low-cost metal ions (such as cobalt and copper) in the cross-coupling reactions. This journal is
- Alavi G., Seyyedeh Ameneh,Nasseri, Mohammad Ali,Kazemnejadi, Milad,Allahresani, Ali,Hussainzadeh, Mahdi
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p. 7741 - 7757
(2021/05/13)
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- Palladium-Catalyzed Cascade Dearomative Spirocyclization and C?H Annulation of Aromatic Halides with Alkynes
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Described herein is a palladium-catalyzed intermolecular dearomative annulation of aryl halides with alkynes, which provides a rapid approach to a class of structurally unique spiroembedded polycyclic aromatic compounds. The cascade process is accomplished by a sequential alkyne migratory insertion, Heck-type dearomatization, and C-H bond annulation. Further optoelectronic study indicated this fused spirocyclic scaffold could be a potential host material for OLEDs, as exemplified by a fabricated red PhOLED device with a maximum external quantum efficiency of 23.0%.
- Liao, Xingrong,Zhou, Fulin,Bin, Zhengyang,Yang, Yudong,You, Jingsong
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supporting information
p. 5203 - 5207
(2021/07/19)
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- Xantphos-coordinated palladium dithiolates: Highly efficient catalyst for decarboxylative Sonogashira reaction into corresponding alkynes
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This work reports Xantphos-coordinated palladium dithiolate complexes as catalysts for decarboxylative Sonogashira coupling reaction of phenyl propiolic acid and 2-butynoic acid with various iodoarenes. These palladium aryl dithiolate complexes were synthesized and characterized by 1H and 31P nuclear magnetic resonance (NMR) spectroscopy, melting point, and elemental analysis (CHNS). Synthetic utility for the reported protocol is explored for the effect of various functional groups on the yield of corresponding heteroaryl alkynes. The current protocol showed excellent catalytic activity towards decarboxylative alkynylation reaction with high turn-over number (TON) up to 105 and turn-over frequency (TOF) up to 104 h?1. The catalyst could be recycled up to six recycles without losing its catalytic activity. The in situ generation of palladium nanoparticles (PdNPs) was observed after the third recycle, and the amount was significant after the sixth recycle, which were confirmed and characterized by powder X-ray diffraction (XRD), scanning electron microscope (SEM), and energy-dispersive X-ray (EDX) analysis and high-resolution transmission electron microscopy (HR-TEM). The catalytic activity of the reaction is attributed to the formation of PdNPs.
- Lokolkar, Manjunath S.,Mane, Pravin A.,Dey, Sandip,Bhanage, Bhalchandra M.
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- Copper(0) nanoparticle catalyzed Z-Selective Transfer Semihydrogenation of Internal Alkynes
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The use of copper(0) nanoparticles in the transfer semihydrogenation of alkynes has been investigated as a lead-free alternative to Lindlar catalysts. A stereo-selective methodology for the hydrogenation of internal alkynes to the corresponding (Z)-alkenes in high isolated yields (86% average) has been developed. This green and sustainable transfer hydrogenation protocol relies on non-noble copper nanoparticles for reduction of both electron-rich and electron-deficient, aliphatic-substituted and aromatic- substituted internal alkynes. Polyols, such as ethylene glycol and glycerol, have been proven to act as hydrogen sources, and excellent stereo- and chemoselectivity have been observed. Enabling technologies, such as microwave and ultrasound irradiation are shown to enhance heat and mass transfer, whether used alone or in combination, resulting in a decrease in reaction time from hours to minutes. (Figure presented.).
- Moran, Maria Jesus,Martina, Katia,Bieliunas, Vidmantas,Baricco, Francesca,Tagliapietra, Silvia,Berlier, Gloria,De Borggraeve, Wim M.,Cravotto, Giancarlo
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supporting information
p. 2850 - 2860
(2021/05/06)
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- Rh(iii)-Catalyzed olefination to build diverse oxazole derivatives from functional alkynes
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A novel Rh(iii)-catalyzed olefination reaction of oxazoles to generate diverse oxazole skeleton derivatives has been realized by directly using oxazole as the directing group. The reaction could tolerate many functional groups, affording complex oxazole derivatives with long chain alkenyls in moderate to good yields, which might find applications in the construction of diverse compounds.
- He, Yuan,Zheng, Ting,Huang, Yin-Hui,Dong, Lin
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supporting information
p. 4937 - 4942
(2021/06/16)
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- Synthesis of Diarylethynes from Aryldiazonium Salts by Using Calcium Carbide as an Alkyne Source in a Deep Eutectic Solvent
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An efficient method for the synthesis of diarylethynes from aryldiazonium salts by using calcium carbide as an alkyne source at room temperature in a deep eutectic solvent is described. The salient features of this protocol are an inexpensive and easy-to-handle alkyne source, a nonvolatile and recyclable solvent, mild conditions, and a simple workup procedure.
- Ma, Xiaolong,Li, Zheng
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supporting information
p. 631 - 635
(2020/12/28)
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- Palladium-Catalyzed C-C Bond Activation of Cyclopropenone: Modular Access to Trisubstituted α,β-Unsaturated Esters and Amides
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Strain-driven palladium/N-heterocyclic carbene-catalyzed C-C bond activation of diphenylcyclopropenone (DPC) has been explored for one-step access to trisubstituted α,β-unsaturated esters and amides. The designed transformation works under mild conditions providing exclusively a single stereoisomer. Mechanistic studies support the oxidative addition of the C-C bond of cyclopropenone to in-situ-generated Pd(0) intermediate. We have proved that vinylic hydrogen in the product is coming from phenol/aniline through deuterium-labeling studies. Late-stage functionalization of bioactive molecules such as procaine, estrone, and hymecromone demonstrates the robustness of this protocol.
- Nanda, Tanmayee,Biswal, Pragati,Pati, Bedadyuti Vedvyas,Banjare, Shyam Kumar,Ravikumar, Ponneri Chandrababu
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supporting information
p. 2682 - 2695
(2021/02/01)
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- Facile one-pot synthesis of diarylacetylenes from arylaldehydes: Via an addition-double elimination process
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A practical one-pot protocol has been developed to synthesize diarylacetylenes from arylaldehydes by treatment with 1-(arylmethyl)benzotriazoles and LiN(SiMe3)2. The reaction proceeded through imine formation, Mannich-type addition and double elimination to deliver products in up to 99% yields with broad substrate scope. In addition, gram-scale synthesis of 1-bromo-4-(phenylethynyl)benzene has been demonstrated.
- Chen, Jianyang,Zhang, Xuan,Wu, Jiajun,Wang, Rui,Lei, Chunlin,An, Yanan
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supporting information
p. 4701 - 4705
(2021/06/11)
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- A Close-to-Aromatize Approach for the Late-Stage Functionalization through Ring Closing Metathesis
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An efficient approach for the synthesis of monosubstituted aromatic compounds relying on a ring-closing metathesis followed by spontaneous 1,2-elimination is presented. The efficiency for late-stage functionalization is highlighted in various solvents (up to 920 TON). This approach is compatible with strained cycles and other multiple bonds in the substrate.
- Lozhkin, Boris,Ward, Thomas R.
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- Fritsch-Buttenberg-Wiechell rearrangement of magnesium alkylidene carbenoids leading to the formation of alkynes
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A series of 1-heteroatom-substituted vinyl p-tolyl sulfoxides were prepared and treated with organometallic reagents to evaluate which combination of sulfoxides and organometallic reagents yielded alkynes the most efficiently. The use of 1-chlorovinyl p-tolyl sulfoxide and isopropylmagnesium chloride was optimal for this purpose. A variety of 1-chlorovinyl p-tolyl sulfoxides were prepared from carbonyl compounds and chloromethyl p-tolyl sulfoxide and were converted into alkynes via the sulfoxide/magnesium exchange reaction and subsequent Fritsch-Buttenberg-Wiechell (FBW) rearrangement of the resulting magnesium alkylidene carbenoids. The mechanism of the FBW rearrangement of magnesium alkylidene carbenoids was studied by using13C-labeled sulfoxides and by using DFT calculations.
- Ando, Akane,Imafuji, Aki,Kimura, Tsutomu,Sekiguchi, Koto
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p. 1352 - 1359
(2021/06/06)
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- Decarbonylative Sonogashira Cross-Coupling of Carboxylic Acids
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Decarbonylative Sonogashira cross-coupling of carboxylic acids by palladium catalysis is presented. The carboxylic acid is activated in situ by the formation of a mixed anhydride and further decarbonylates using the Pd(OAc)2/Xantphos system to provide an aryl-Pd intermediate, which is intercepted by alkynes to access the traditional Pd(0)/(II) cycle using carboxylic acids as ubiquitous and orthogonal electrophilic cross-coupling partners. The methodology efficiently constructs new C(sp2)-C(sp) bonds and can be applied to the derivatization of pharmaceuticals. Mechanistic studies give support to decarbonylation preceding transmetalation in this process.
- Liu, Chengwei,Szostak, Michal
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supporting information
p. 4726 - 4730
(2021/06/28)
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- α-Bromoacrylic Acids as C1 Insertion Units for Palladium-Catalyzed Decarboxylative Synthesis of Diverse Dibenzofulvenes
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Herein α-bromoacrylic acids have been employed as C1 insertion units to achieve the palladium-catalyzed [4 + 1] annulation of 2-iodobiphenyls, which provides an efficient platform for the construction of diverse dibenzofulvenes. This protocol enables the formation of double C(aryl)-C(vinyl) bonds via a C(vinyl)-Br bond cleavage and decarboxylation. It is particularly noteworthy that the method features a broad substrate scope, and various interesting frameworks, such as bridged ring, fused (hetero)aromatic ring, and divinylbenzene, can be successfully incorporated into the products.
- Zhang, Minghao,Deng, Wenbo,Sun, Mingjie,Zhou, Liwei,Deng, Guobo,Liang, Yun,Yang, Yuan
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supporting information
p. 5744 - 5749
(2021/08/18)
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- Highly efficient synthesis of 1,2-disubstituted acetylenes derivatives from the cross-coupling reactions of 1-bromoalkynes with organotitanium reagents
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A Highly efficient route for the synthesis of 1,2-disubstituted acetylene derivatives has been developed by nickel catalyzed cross-couplings of alkynyl halides with aryl titanium reagents under mild conditions. This has given corresponding cross-coupling products good to excellent isolated yields of up to 92 %. The aryls bearing electron-donating or electron-withdrawing groups in either alkynylhalides or aryltitanium substrates gave cross-coupling products good yields. This process was simple and easily performed, which provides an efficient method for the synthesis of 1,2-disubstituted acetylenes derivatives.
- Li, Qing-Han,Wu, Chuan
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supporting information
(2021/08/25)
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- Pd/GF-Phos-Catalyzed Asymmetric Three-Component Coupling Reaction to Access Chiral Diarylmethyl Alkynes
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Significant attention has been given in the past few years to the selective transformations of N-tosylhydrazones to various useful compounds. However, the development of enantioselective versions poses considerable challenges. Herein we report a Pd-catalyzed enantioselective three-component coupling of N-tosylhydrazone, aryl halide, and terminal alkyne under mild conditions utilizing a novel chiral sulfinamide phosphine ligand (GF-Phos), which provides a facile access to chiral diarylmethyl alkynes, which are useful synthons in organic synthesis as well as exist as the skeleton in many bioactive molecules. A pair of enantiomers of the product could be easily prepared using the same chiral ligand by simply changing the aryl substituents of the N-tosylhydrazone and aryl halide. The salient features of this reaction include the readily available starting materials, general substrate scope, high enantioselectivity, ease of scale-up, mild reaction conditions, and versatile transformations.
- Zhao, Guofeng,Wu, Yi,Wu, Hai-Hong,Yang, Junfeng,Zhang, Junliang
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supporting information
p. 17983 - 17988
(2021/11/16)
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- Ligand-Promoted Alkynylation of Aryl Ketones: A Practical Tool for Structural Diversity in Drugs and Natural Products
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Conversion of the numerous aryl ketones into aryl electrophiles via Ar-C(O) cleavage remains a challenging yet highly desirable transformation in Sonogashira-type coupling. Herein, we report a palladium-catalyzed ligand-promoted alkynylation of unstrained aryl ketones. The protocol allows the alkynylation to be carried out in a one-pot procedure with broad functional-group tolerance and substrate scope. The potential applications of this protocol in drug discovery and chemical biology are further demonstrated by late-stage diversification of a number of pharmaceuticals and natural products. More importantly, two different biologically important fragments derived from a pharmaceutical and natural product could be connected by the consecutive alkynylation of ketones. Distinct from aryl halides in conventional Sonogashira reactions, the protocol provides a practical tool for the 1,2-bifunctionalization of aryl ketone by merging ketone-directed ortho-C-H activation with ligand-promoted ipso-Ar-C(O) alkynylation.
- Xu, Hui,Ma, Biao,Fu, Zunyun,Li, Han-Yuan,Wang, Xing,Wang, Zhen-Yu,Li, Ling-Jun,Cheng, Tai-Jin,Zheng, Mingyue,Dai, Hui-Xiong
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p. 1758 - 1764
(2021/02/09)
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- The synthesis of β-enaminones using trialkylamines and a Pd/DNA catalyst
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A new one-pot procedure leading to β-enaminones has been developed. The elaborated methodology involves the cascade sequencing of carbonylative Sonogashira coupling of aryl iodide with a terminal alkyne and the oxidative dealkylation of tertiary amines. The efficient syntheses of β-enaminones were performed with a Pd/DNA catalyst, with NEt3, NPr3 and NBu3 used as amine sources. The catalyst was successfully recovered and used in several subsequent tests with the same results. The reaction mechanism, summarizing the activity of immobilized Pd NPs (palladium nanoparticles), was proposed.
- Mart,Trzeciak
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- A Palladium-Catalyzed Cascade C-C Activation of Cyclopropenone and Carbonylative Amination: Easy Access to Highly Functionalized Maleimide Derivatives
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We describe herein the first report on palladium-catalyzed C-C bond activation of cyclopropenone and concomitant carbonylative amination to produce maleimides. The interesting aspect of this reaction is that the sacrificial elimination of carbon monoxide from the substrate is efficiently recaptured by one of the intermediates in the catalytic cycle for the formation of maleimides. 18O isotopic studies confirmed that the source of carbon monoxide is from cyclopropenone.
- Nanda, Tanmayee,Ravikumar, P. C.
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supporting information
(2020/02/15)
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- Green synthesis of graphene oxide (GO)-anchored Pd/Cu bimetallic nanoparticles using: Ocimum sanctum as bio-reductant: An efficient heterogeneous catalyst for the Sonogashira cross-coupling reaction
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To explore the synergism between two metal centers we have synthesized graphene oxide (GO) supported Pd/Cu?GO, Pd?GO and Cu?GO nanoparticles through bio-reduction of Pd(NO3)2 and CuSO4·5H2O using Tulsi (Ocimum sanctum) leaf extract as the reducing and stabilizing agent. The graphene oxide (GO) was obtained by oxidation of graphite following a simplified Hummer's method. The as-prepared nanomaterials have been extensively characterized by FTIR, powder X-ray diffraction (PXRD), HRTEM, TEM-EDS, XPS, ICP-AES and BET surface area measurement techniques. The morphological study of Pd/Cu?GO revealed that crystalline bimetallic alloy type particles were dispersed on the GO layer. The activity of Pd?GO, Cu?GO and Pd/Cu?GO as catalysts for the Sonogashira cross-coupling reaction have been investigated and it was found that the Pd/Cu?GO nanostructure showed highly superior catalytic activity over its monometallic counterparts, substantiating the cooperative influence of the two metals. The inter-atom Pd/Cu transmetalation between surfaces was thought to be responsible for its synergistic activity. The catalyst showed higher selectivity towards coupling of aryl iodides with both aliphatic and aryl alkynes resulting in moderate to excellent isolated yield of the desired products (45-99%). The products have been characterized by GC-MS and 1H-NMR spectroscopic techniques and compared with authentic samples. The Pd/Cu?GO catalyst could be easily isolated from the reaction products and reused for up to at least ten successive runs effectively.
- Borah, Geetika,Gogoi, Pradip K.,Hussain, Farhaz Liaquat,Mech, Swapna Devi,Pahari, Pallab,Sultana, Samim
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p. 23108 - 23120
(2020/07/03)
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- Synthesis of a Cellulosic Pd(salen)-Type Catalytic Complex as a Green and Recyclable Catalyst for Cross-Coupling Reactions
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Abstract: A green recyclable cellulose-supported Pd(salen)-type catalyst was synthesized through sequential three steps: chlorination with thionyl chloride, modification by ethylenediamine, and the formation of Schiff base with salicylaldehyde to immobilize palladium chloride through multiple binding sites. This novel heterogeneous cellulosic Pd(salen)-type catalytic complex was fully characterized by FT-IR, SEM, TEM, XPS, ICP-AES and TG. The traditional cross-coupling chemistry, such as Suzuki, Heck, Sonogashira, Buchwald–Hartwig amination and etherification, was then investigated in the presence of the above cellulose-palladium nanoparticle. Studies have shown that the synthesized catalyst shows high activity and efficiency for all types of transformations, providing the corresponding carbon–carbon or carbon–heteroatom coupling products in a general and mild manner. Furthermore, the catalyst demonstrates high to excellent yields and is easily recycled by simple filtration for up to twelve cycles without any significant loss of catalytic activity. Graphic Abstract: [Figure not available: see fulltext.]
- Sun, Peng,Yang, Jiaojiao,Chen, Chunxia,Xie, Kaijun,Peng, Jinsong
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p. 2900 - 2910
(2020/03/31)
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- Encapsulating palladium nanoparticles inside ethylenediamine functionalized and crosslinked chlorinated poly(vinyl chloride) nanofibers as an efficient and stable heterogeneous catalyst for coupling reactions
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Palladium chloride and chlorinated poly (vinyl chloride) (CPVC) mixture were prepared into homogeneous solution, followed by electrospinning to make uniform nanofibers with average diameter of ~460 nm. Then, these composite nanofibers were treated in ethy
- Du, Yijun,Qi, Chenze,Qin, Min,Shao, Linjun,Tao, Hongyu,Wang, Qingqing
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- Fast heck-cassar-sonogashira (hcs) reactions in green solvents
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The replacement of toxic solvents with greener alternatives in Heck-Cassar-Sonogashira (HCS) cross-couplings was investigated. The fine-tuning of the HCS protocol allowed to achieve complete conversions and high speed under mild conditions. N-Hydroxyethylpyrrolidone (HEP) gave the best results. Moreover, the methodology was successfully applied to the synthesis of an intermediate of the anticancer drug Erlotinib, demonstrating the versatility of the new green protocol.
- Cabri, W.,Corbisiero, D.,Daka, A.,Fantoni, T.,Ferrazzano, L.,Martelli, G.,Ricci, A.,Tolomelli, A.,Viola, A.
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supporting information
p. 3969 - 3973
(2020/06/08)
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- A Pd confined hierarchically conjugated covalent organic polymer for hydrogenation of nitroaromatics: Catalysis, kinetics, thermodynamics and mechanism
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Herein, we propose a fast and scalable synthesis of a triazine based hierarchically conjugated covalent organic polymer under solvent and additive free conditions through a single step process. The synthesized material CCTP (Cyanuric Chloride-Thiourea-Polymer) was thoroughly characterized by various physicochemical techniques. The CCTP exhibited regular sponginess and excellent chemical as well as thermal stability. The solvent and additive free approach for CCTP synthesis provides a sustainable alternative for classical solvothermal methods. The CCTP was immobilized with Pd (0) and subsequently a heterogeneous material Pd&at;CCTP was obtained, which was used as an efficient catalyst for the hydrogenation of nitroarenes. The rate constant and Ea were measured to be 2.08 × 10-2 s-1 and 15.67 kJ mol-1 respectively and thereafter other thermodynamic parameters like ΔH, ΔS and ΔG for the hydrogenation of p-nitrophenol were also calculated. The obtained results indicate that the catalytic hydrogenation of p-nitrophenol is a non-spontaneous and endothermic process. We have also investigated the effect of surfactants (NH4OH, FA, and N2) on the reaction performance, and consequently NH4OH and FA both slow down the reaction while N2 doesn't affect the reaction medium. Further, we calculated the rate constant for the hydrogenation of 2,4-dinitrophenol and 2,4,6-trinitrophenol. An array of nitroarenes were further reduced to extend the substrate scope at RT; high TOFs were observed. Besides, Pd&at;CCTP showed excellent reusability in hydrogenation reactions without evident performance falloff.
- Awasthi, Satish Kumar,Yadav, Deepika
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supporting information
p. 4295 - 4303
(2020/07/30)
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- Shuttling Catalyst: Facilitating C?C Bond Formation via Cross-Couplings with a Thermoresponsive Polymeric Ligand
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A poly(ethylene glycol) (PEG) linked ortho-MeO-phenyldicyclohexylphosphine (MeO-WePhos) ligand has been synthesized to promote Pd-catalyzed carbon-carbon bond formation by cross-couplings including Sonogashira, Heck, Hiyama and Stille reactions, providing corresponding (hetero)aryl substituted alkynes, alkenes and bi(hetero)aryls in good to excellent isolated yields with low Pd loadings. Facilitated by the lower critical solution temperature behaviour of the polymeric monophosphine ligand, the metal-complex could rapidly shuttle between organic and water phases as regulated by temperature, enabling highly efficient catalyst recycling via a simple phase separation. The chemical structure of ligand was determined by matrix-assisted laser desorption/ionization-time of flight mass spectrometry, nuclear magnetic resonance spectrometry and size-exclusion chromatography measurements. Notably, as demonstrated by the inductively coupled plasma-atomic emission spectrometry measurement, 98% Pd was kept in the water phase after 6 cycles of catalyst recycling experiments. Given the profound impact of transition-metal-catalyzed covalent bond formation and the increasing demand of sustainable chemistry, this work provides an alternative method to conduct cross-couplings with a polymeric shuttling catalyst.
- Wang, Erfei,Zhang, Jiawei,Zhong, Zhuoran,Chen, Kaixuan,Chen, Mao
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p. 419 - 423
(2020/01/08)
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- Utilizing a copper-free Sonogashira reaction in the synthesis of the leukotriene a4 hydrolase modulator batatasin IV
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Batatasin IV is a dihydrostilbenoid isolated from Chinese yams which was shown to have inhibitory activities against plant growth. Later studies showed that this compound may exhibit anti-inflammatory properties by inhibiting the epoxide hydrolase activity of the leukotriene A4 hydrolase enzyme. To access the dihydrostilbenoid skeleton, a copper-free SPhos-mediated Sonogashira reaction was conceived and the substrate scope was explored. Our results indicate that the reaction can tolerate the presence of free alcohols, aldehydes, nitro groups, and anilinyl groups. However, a substituent with an acidic phenol or carboxylic acid group gave significantly lower yields. Next, a total synthesis of batatasin IV was accomplished in 16% overall yield incorporating the reported copper-free Sonogashira reaction. Finally, we show that batatasin IV inhibits the hydrolysis of alanine p-nitroanilide by leukotriene A4 hydrolase with an IC50 of 91.4 μM.
- Petruncio, Greg,Girgis, Michael,Moummi, Sanae,Jayatilake, Meth,Lee, Kyung Hyeon,Paige, Mikell
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supporting information
(2020/10/27)
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- Palladium(II) phthalocyanines efficiently promote phosphine-free Sonogashira cross-coupling reaction at room temperature
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Herein we report that exceptionally simple and inexpensive Pd(II) complexes of phthalocyanines efficiently catalyze direct formation of diphenylacetylenes at ambient conditions with low loading of catalyst (0.5 mol%). Results of this study demonstrate that terminal alkynes reacted mildly with p-substituted aryl bromides at room temperature under Pd and Cu-cocatalysis to give the corresponding phenylacetylenes in yields up to 98%. Also we have examined this catalyst in Sonogashira cross-coupling with aryl chlorides and it was very effective and this reaction at room temperature that there is no examples in recent articles. This protocol represents the first use of palladium phthalocyanine as homogeneous catalyst in the Pd/Cu-promoted Sonogashira reaction. The palladium(II) phthalocyanine complex is significantly more active in Sonogashira cross-coupling between aryl halides and terminal alkynes as compared with traditional catalysts because of absence of palladium black formation through agglomeration of metal particles and deactivation of catalyst.
- Platonova, Yana B.,Tomilova, Larisa G.,Volov, Alexander N.
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p. 224 - 228
(2020/09/17)
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- Palladium(II) complexes containing sterically bulky O, N donor ligands: Synthesis, characterization and catalytic activity in the Suzuki-Miyaura and Sonogashira coupling reactions
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A new class of palladium(II)1-(arylazo)naphtholate complexes of the type [Pd(L1-4)2] containing sterically bulky O, N donor functionalized arylazo ligands has been synthesized. These palladium(II) complexes were characterized by elemental analysis and spectral (FT-IR, UV–Vis, 1H NMR and 13C NMR) studies. The molecular structure of the Palladium(II) complexes [Pd(L1)2] and [Pd(L2)2] were established by X-ray crystallography. These complexes were found to efficiently catalyze the Suzuki-Miyaura coupling of arylboronic acids and aryl halides, and the Sonogashira reaction of aryl halides and phenylacetylene in DMF and i-PrOH media to afford the corresponding C–C coupling products in high yields.
- Nandhini, Raja,Vijayan, Paranthaman,Venkatachalam, Galmari
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- Pd/Cu-free Heck and Sonogashira coupling reactions applying cobalt nanoparticles supported on multifunctional porous organic hybrid
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A new heterogeneous cobalt catalyst has been synthesized by immobilizing Co species onto a nitrogen-rich porous organic polymer (Co@imine-POP). The heterogeneous catalyst synthesized was efficient in Heck and Sonogashira cross-coupling reactions in green media under mild reaction conditions without inert air and phase transfer agents. This phosphine-, copper-, and palladium-free catalyst was stable under the reaction conditions and could be reused for at least eight successive runs without a discernible decrease in its catalytic activity.
- Hajipour, Abdol R.,Khorsandi, Zahra
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- A Pd NP-confined novel covalent organic polymer for catalytic applications
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A novel unsymmetrical covalent organic polymer, COP (1), was designed and characterized using several analytical and spectroscopic techniques. COP (1) was synthesized via the nucleophilic substitution reaction of 2,4,6-trichloro-1,3,5-triazine with p-amin
- Yadav, Deepika,Awasthi, Satish Kumar
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p. 1320 - 1325
(2020/02/04)
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- Synthesis of Phenanthrenes via Palladium-Catalyzed Three-Component Domino Reaction of Aryl Iodides, Internal Alkynes, and o-Bromobenzoic Acids
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A new palladium-catalyzed domino alkyne insertion/C-H activation/decarboxylation sequence has been developed, which provides an efficient approach for synthesizing a variety of functionalized phenanthrenes in moderate to good yields. The method shows broad substrate scope and good functional group tolerance by employing readily available materials, including aryl iodides, internal alkynes, and o-bromobenzoic acids, as three-component coupling partners.
- Deng, Guobo,Liang, Yun,Luo, Xiai,Yang, Xiumei,Yang, Yuan,Yang, Yuzhong,Zhou, Liwei
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p. 1223 - 1230
(2020/04/15)
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