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https://www.readbyqxmd.com/read/28429945/copper-catalyzed-oxidative-cyclization-of-2-amino-azaarenes-with-lignin-models-synthesis-of-3-phenoxy-imidazo-heterocycles
#1
Jian Zhang, Xiunan Lu, Tingyan Li, Shanlu Wang, Guofu Zhong
A catalytic oxidative cyclization of 2-aminopyridines or 2-aminobenzothiazole with 2-phenoxyacetophenones (a kind of lignin platform compounds) was developed, efficiently providing valuable 3-phenoxy imidazo[1,2-a]pyridines or 3-phenoxy benzo[d]imidazo[2,1-b]thiazoles. The reaction was realized under oxygen by simply using inexpensive CuI as the catalyst.
April 21, 2017: Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28425134/record-broken-a-copper-peroxide-complex-with-enhanced-stability-and-faster-hydroxylation-catalysis
#2
Sonja Herres-Pawlis, Patricia Liebhäuser, Kristina Keisers, Alexander Hoffmann, Thomas Schnappinger, Isabella Sommer, Anne Thoma, Claudia Wilfer, Roland Schoch, Kai Stührenberg, Matthias Bauer, Maximilian Dürr, Ivana Ivanovic-Burmazovic
Tyrosinase model systems pinpoint pathways to translate nature´s synthetic abilities into useful synthetic catalysts. Mostly, they use N-donor ligands which mimic the histidine residues coordinating the two copper centres. Copper complexes with bis(pyrazolyl)methanes with pyridinyl or imidazolyl moieties are already reported as excellent tyrosinase models. Substitution of the pyridinyl donor results now in the new ligand HC(3 tBuPz)2(4 CO2MePy) which stabilises a room-temperature stable -2:2-peroxide dicopper(II) species upon oxygenation...
April 19, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28422333/assembling-porphyrins-into-extended-network-structures-employing-aromatic-dicarboxylates-synthesis-metal-exchange-and-heterogeneous-catalytic-studies
#3
Srinivasan Natarajan, Gargi Dutta, Ajay Kumar Jana
Three new metal-organic porphyrinic framework compounds of zinc and 5,10,15,20-tetrakis(4-pyridyl)porphyrin(TPyP) have been synthesized under solvothermal conditions. The compounds [Zn5(C40H24N8)(C8H4O4)2(NO3)6(DMA)2](DMA)3(H2O)8, 1; [Zn3(C40H24N8)(C8H4O4)2(DMF)](DMF)5(H2O)12, 2; and [Zn3(C40H24N8)(C12H6O4)2(DMA)2](H2O)7, 3 have two- (1) and three- dimensionally (2 and 3) extended structures. All the three structures contain porphyrinic unit connected through the carboxylate linkers. The nitrates binds the metal centers and not hydrogen bonded...
April 19, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28421770/selective-synthesis-of-e-and-z-allyl-nitriles-via-decarboxylative-reactions-of-alkynyl-carboxylic-acids-with-azobis-alkylcarbonitriles
#4
Francis Mariaraj Irudayanathan, Sunwoo Lee
Allyl nitriles were synthesized from the reactions of arylpropiolic acids with azobis(alkylcarbonitriles) (AIBN or ACCN). In the presence of Cu(OAc)2 as a catalyst and pyridine as the solvent, the (E)-stereoisomer was formed as the major product. This transformation shows good tolerance toward alkoxy, halogen, alcohol, amine, ester, and ketone functional groups. When the reaction was conducted with the sterically bulky amine, ethyldiisopropylamine, in the absence of a copper catalyst, the corresponding (Z)-stereoisomers were formed preferentially...
April 19, 2017: Organic Letters
https://www.readbyqxmd.com/read/28421756/reactions-of-copper-and-silver-cations-with-carbon-dioxide-an-infrared-photodissociation-spectroscopic-and-theoretical-study
#5
Zhi Zhao, Xiangtao Kong, Dong Yang, Qinqin Yuan, Hua Xie, Hongjun Fan, Jijun Zhao, Ling Jiang
The reaction of copper and silver cations with carbon dioxide was studied by mass-selected infrared photodissociation spectroscopy. Quantum chemical calculations were performed on these products, which aided the experimental assignments of the infrared spectra and helped to elucidate the geometrical and electronic structures. The Cu(+) and Ag(+) cations bind to an oxygen atom of CO2 in an end-on configuration via a charge-quadrupole electrostatic interaction in the [M(CO2)n](+) complexes. The formation of oxide-carbonyl and carbonyl-carbonate structures is not favored for the interaction of CO2 with Cu(+) and Ag(+)...
April 21, 2017: Journal of Physical Chemistry. A
https://www.readbyqxmd.com/read/28419580/liquid-liquid-interfacial-synthesis-of-click-nanosheet
#6
Amalia Rapakousiou, Ryo Shiotsuki, Ryota Sakamoto, Ryota Matsuoka, Ukyo Nakajima, Tigmansu Pal, Rintaro Shimada, Md Amran Hossain, Hiroyasu Masunaga, Satoshi Horike, Yasutaka Kitagawa, Sono Sasaki, Kenichi Kato, Takeaki Ozawa, Didier Astruc, Hiroshi Nishihara
A liquid/liquid interfacial synthesis is employed for the first time to synthesize a covalent two-dimensional polymer nanosheet. Copper-catalyzed azide-alkyne cycloaddition (CuAAC) between three-way terminal alkyne and azide at a water/dichloromethane interface generates a 1,2,3-triazole-linked nanosheet. The resultant nanosheet with a flat and smooth texture has a maximum domain size of 20 μm and minimum thickness of 5.3 nm. The starting monomers in the organic phase and the copper catalyst in the aqueous phase can meet together only at the liquid/liquid interface as a two-dimensional reaction space, which allows them to form the two-dimensional polymer...
April 18, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28407352/copper-catalyzed-aminothiolation-of-1-3-dienes-via-a-dihydrothiazine-intermediate
#7
Christopher E Sleet, Uttam K Tambar
Heteroatom-containing organic molecules are of particular interest to medicinal chemists and materials scientists. A strategy to reach these architectures via direct difunctionalization of abundant 1,3-dienes is especially attractive. Herein, we describe the development of a regio- and diastereoselective 1,4-aminothiolation of 1,3-dienes with a sulfur diimide reagent, a copper catalyst, and alkyl Grignard reagents. This unique protocol provides remote nitrogen and sulfur functionalities with high levels of stereocontrol...
April 13, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28406296/light-mediated-atom-transfer-radical-polymerization-of-semi-fluorinated-meth-acrylates-facile-access-to-functional-materials
#8
Emre H Discekici, Athina Anastasaki, Revital Kaminker, Johannes Willenbacher, Nghia P Truong, Carolin Fleischmann, Bernd Oschmann, David J Lunn, Javier Read de Alaniz, Thomas P Davis, Christopher M Bates, Craig J Hawker
A highly efficient photomediated atom transfer radical polymerization protocol is reported for semi-fluorinated acrylates and methacrylates. Use of the commercially available solvent, 2-trifluoromethyl-2-propanol, optimally balances monomer, polymer, and catalyst solubility while eliminating transesterification as a detrimental side reaction. In the presence of UV irradiation and ppm concentrations of copper(II) bromide and Me6-TREN (TREN = tris(2-aminoethyl amine)), semi-fluorinated monomers with side chains containing between three and 21 fluorine atoms readily polymerize under controlled conditions...
April 13, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28403614/synthesis-of-enantiomerically-pure-8s-9s-10r-6z-trihydroxyoctadec-6-enoic-acid
#9
Jogula Srinivas, Yoichi Namito, Ryosuke Matsubara, Masahiko Hayashi
We have accomplished the asymmetric synthesis of (8S,9S,10R,6Z)-trihydroxyoctadec-6-enoic acid in optically pure form, and determined the absolute configuration of the natural product based on stereodetermined chiral building block 7, which was prepared by the catalytic enantioselective allylic oxidation of 4,5-epoxycyclohex-1-ene using an S-configurated N,N-bidentate ligand-copper catalyst.
April 13, 2017: Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28402669/n-trifluoromethylation-of-nitrosoarenes-with-sodium-triflinate
#10
Angela van der Werf, Matic Hribersek, Nicklas Selander
A highly efficient N-trifluoromethylation of nitrosoarenes is reported. The inexpensive and convenient Langlois reagent (sodium triflinate) is employed as a CF3-radical source in combination with a copper catalyst and an oxidant. N-Trifluoromethylated hydroxylamines are obtained in high yields within 1 h at room temperature. The addition of hydroquinone was found to be instrumental to prevent the formation of side products. The method is high-yielding, is scalable, and displays a high functional group tolerance...
April 12, 2017: Organic Letters
https://www.readbyqxmd.com/read/28402648/copper-catalyzed-cascade-transformation-of-homopropargyl-azides-into-trifluoromethylated-nitriles-via-c-c-cleavage
#11
Shuang Chen, Deng-Yuan Li, Liang-Liang Jiang, Kai Liu, Pei-Nian Liu
A cascade reaction of homopropargyl azides in the presence of a Cu catalyst was achieved, affording 3-(trifluoromethyl)but-3-enenitriles with good yields and excellent regioselectivity. This reaction appears to be the first direct conversion of homopropargyl azides into trifluoromethylated nitriles. Mechanistic studies indicate that the transformation proceeds by addition of a CF3 radical to the alkyne, C-C cleavage by 1,4-aryl radical migration, and nitrile formation. This protocol provides a novel strategy for transforming azides into nitriles via C-C cleavage derived from radical migration...
April 12, 2017: Organic Letters
https://www.readbyqxmd.com/read/28401993/synthesis-of-n-propargylsulfoximines-by-copper-catalyzed-a3-couplings
#12
Hanchao Cheng, Jian Wen, Carsten Bolm
An efficient synthesis of N-propargylsulfoximines was developed through a copper-catalyzed coupling of aldehydes, alkynes and NH-sulfoximines. The reaction requires no co-catalyst or ligand and shows a wide substrate scope with moderate to good yields.
April 12, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28399364/pd-catalyzed-aerobic-oxidative-biaryl-coupling-non-redox-cocatalysis-by-cu-otf-2-and-discovery-of-fe-otf-3-as-a-highly-effective-cocatalyst
#13
Dian Wang, Shannon S Stahl
Copper salts find widespread use in Pd-catalyzed oxidation reactions, and they are typically used as oxidants or redox-active cocatalysts. Here, we probe the origin of a dramatic acceleration effect of Cu(OTf)2 in the C-H/C-H aerobic oxidative coupling of o-xylene. NMR spectroscopic analysis of the Pd(II) catalyst in the presence of Cu(OTf)2, together with other experimental and DFT computational studies of the catalytic reaction, show that Cu(OTf)2 activates the Pd(II) catalyst for C-H activation via a non-redox pathway and has negligible impact on catalyst reoxidation...
April 18, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28393446/copper-mediated-late-stage-functionalization-of-heterocycle-containing-molecules
#14
Ming Shang, Ming-Ming Wang, Tyler G Saint-Denis, Ming-Hong Li, Hui-Xiong Dai, Jin-Quan Yu
One long-standing issue in directed C-H functionalization is that either nitrogen or sulfur atoms present in heterocyclic substrates may bind preferentially to a transition-metal catalyst rather than to the desired directing group. This competitive binding has largely hindered the application of C-H functionalization in late-stage heterocycle drug discovery. Reported here is the use of an oxazoline-based directing group capable of overriding the poisoning effect of a wide range of heterocycle substrates. The potential use of this directing group in pharmaceutical drug discovery is illustrated by diversification of Telmisartan (an antagonist for the angiotensin II receptor) through copper-mediated C-H amination, hydroxylation, thiolation, arylation, and trifluoromethylation...
April 10, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28387507/subtle-structural-changes-in-cu-ii-l-2mn-ii-complexes-to-induce-heterometallic-cooperative-catalytic-oxidase-activities-on-phenolic-substrates-h2l-salen-type-unsymmetrical-schiff-base
#15
Prithwish Mahapatra, Soumavo Ghosh, Sanjib Giri, Vinayak Rane, Ramakant Kadam, Michael G B Drew, Ashutosh Ghosh
A new Cu(II) complex of an asymmetrically dicondensed Schiff base (H2L = N-(2-hydroxyacetophenylidene)-N'-salicylidene-1,3-propanediamine) derived from 1,3-propanediamine, salicylaldehyde, and o-hydroxyacetophenone has been synthesized. Using this complex, [CuL] (1), as a metalloligand, two new trinuclear Cu-Mn complexes, [(CuL)2Mn(N3)(H2O)](ClO4)·H2O (2) and [(CuL)2Mn(NCS)2] (3), have been prepared. Single-crystal structural analyses reveal that complexes 2 and 3 both have the same bent trinuclear {(CuL)2Mn}(2+) structural unit in which two terminal bidentate square-planar (CuL) units are chelated to the central octahedral Mn(II) ion...
April 7, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28387405/supramolecular-chemistry-of-pillar-n-arenes-functionalised-by-a-copper-i-catalysed-alkyne-azide-cycloaddition-click-reaction
#16
T Kakuta, T Yamagishi, T Ogoshi
Since we discovered pillar[n]arenes in 2008, many chemists have developed a strong interest in pillar[n]arene chemistry because of the many advantages associated with these materials, including their facile and high yielding synthesis, versatile functionality, planar chirality and unique host-guest properties. In this feature article, we discuss recent advances in the field of supramolecular chemistry based on the use of pillar[n]arenes as substrates for copper(i)-catalysed alkyne-azide cycloaddition (CuAAC) "click" chemistry...
April 7, 2017: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/28378444/exchanging-alkyl-groups-through-unstrained-c-c-bond-cleavage-in-the-presence-of-a-copper-catalyst
#17
Masaru Wada, Yushi Noda, Takashi Nishikata
Although numerous reports exist on strained C-C bond cleavage reactions in aryl substitutions, the cleavage methodology for unstrained C-C bonds in alkylation reactions has not yet been established. We found that unstrained allylic C-C bonds can be cleaved using α-radicals to form C(sp(3) )-C(sp(3) ) bonds in the presence of a copper catalyst. In this reaction, the property of leaving and loading radicals is very important for radical fragmentations. In this paper, we investigated the effects of these properties in cleavage reactions for unstrained C-C bonds...
April 5, 2017: Chemistry, An Asian Journal
https://www.readbyqxmd.com/read/28378392/why-dna-is-a-more-effective-scaffold-than-rna-in-nucleic-acid-based-asymmetric-catalysis-supramolecular-control-of-cooperative-effects
#18
Jasmin J Marek, Ulrich Hennecke
Nucleic acids can form efficient hybrid catalysts for asymmetric catalysis upon binding of low-molecular-weight metal complexes. Up to now DNA has been the preferred nucleic acid component, while RNA was largely ignored. It is shown that despite RNA's successful use in ribozymes, RNA is less suited for use in hybrid catalysts for asymmetric catalysis. A common dimethyl bipyridine copper complex does not form highly active and enantioselective hybrid catalysts with RNA due to the absence of synergistic effects between the copper complex and dsRNA...
April 5, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28376946/stability-of-a-bifunctional-cu-based-core-zeolite-shell-catalyst-for-dimethyl-ether-synthesis-under-redox-conditions-studied-by-environmental-transmission-electron-microscopy-and-in-situ-x-ray-ptychography
#19
Sina Baier, Christian D Damsgaard, Michael Klumpp, Juliane Reinhardt, Thomas Sheppard, Zoltan Balogh, Takeshi Kasama, Federico Benzi, Jakob B Wagner, Wilhelm Schwieger, Christian G Schroer, Jan-Dierk Grunwaldt
When using bifunctional core@shell catalysts, the stability of both the shell and core-shell interface is crucial for catalytic applications. In the present study, we elucidate the stability of a CuO/ZnO/Al2O3@ZSM-5 core@shell material, used for one-stage synthesis of dimethyl ether from synthesis gas. The catalyst stability was studied in a hierarchical manner by complementary environmental transmission electron microscopy (ETEM), scanning electron microscopy (SEM) and in situ hard X-ray ptychography with a specially designed in situ cell...
April 5, 2017: Microscopy and Microanalysis
https://www.readbyqxmd.com/read/28374445/a-dendritic-nanostructured-copper-oxide-electrocatalyst-for-the-oxygen-evolution-reaction
#20
Tran Ngoc Huan, Gwenaëlle Rousse, Sandrine Zanna, Ivan T Lucas, Xiangzhen Xu, Nicolas Menguy, Victor Mougel, Marc Fontecave
To use water as the source of electrons for proton or CO2 reduction within electrocatalytic devices, catalysts are required for facilitating the proton-coupled multi-electron oxygen evolution reaction (OER, 2 H2 O→O2 +4 H(+) +4 e(-) ). These catalysts, ideally based on cheap and earth abundant metals, have to display high activity at low overpotential and good stability and selectivity. While numerous examples of Co, Mn, and Ni catalysts were recently reported for water oxidation, only few examples were reported using copper, despite promising efficiencies...
April 4, 2017: Angewandte Chemie
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