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https://www.readbyqxmd.com/read/28319299/manganese-catalyzed-n-formylation-of-amines-by-methanol-liberating-h2-a-catalytic-and-mechanistic-study
#1
Subrata Chakraborty, Urs Gellrich, Yael Diskin-Posner, Gregory Leitus, Liat Avram, David Milstein
The first example of a base metal (manganese) catalyzed acceptorless dehydrogenative coupling of methanol and amines to form formamides is reported herein. The novel pincer complex (iPr-PN(H) P)Mn(H)(CO)2 catalyzes the reaction under mild conditions in the absence of any additives, bases, or hydrogen acceptors. Mechanistic insight based on the observation of an intermediate and DFT calculations is also provided.
March 20, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28304407/uv-light-promoted-c-h-bond-activation-of-benzene-and-fluorobenzenes-by-an-iridium-i-pincer-complex
#2
Simone A Hauser, Jack Emerson-King, Scott Habershon, Adrian B Chaplin
Iridium(i) carbonyl complex [Ir(2,6-(P(t)Bu2CH2)2C6H3)(CO)] undergoes reversible C-H bond activation of benzene and a series of fluorobenzenes on UV irradiation. Exclusive ortho-selectivity is observed in reactions of fluorobenzene and 1,2-difluorobenzene.
March 17, 2017: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/28304030/hydroboration-of-co2-catalyzed-by-bis-phosphinite-pincer-ligated-nickel-thiolate-complexes
#3
Ting Liu, Wenjuan Meng, Qiang-Qiang Ma, Jie Zhang, Huizhen Li, Shujun Li, Qianyi Zhao, Xuenian Chen
We report the hydroboration of CO2 with catecholborane catalyzed by a series of bis(phosphinite) pincer ligated nickel thiolate complexes. Turnover frequencies (TOFs) up to 2400 h(-1) were achieved at room temperature under an atmospheric pressure of CO2. This represents the highest TOF value known to date for the reduction of CO2 to the methoxide level under mild conditions.
March 17, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/28276677/a-readily-accessible-chiral-nnn-pincer-ligand-with-a-pyrrole-backbone-and-its-ni-ii-chemistry-syntheses-structural-chemistry-and-bond-activations
#4
Jan Wenz, Alexander Kochan, Hubert Wadepohl, Lutz H Gade
A new class of chiral C2-symmetric N-donor pincer ligands, 2,5-bis(2-oxazolinyldimethylmethyl)pyrroles (PdmBox)H, was synthesized starting from the readily available ethyl 2,2-dimethyl-3-oxobutanoate (1). The synthesis of the ligand backbone was achieved by oxidative enole coupling with CuC12 followed by Paal-Knorr-type pyrrole synthesis. The corresponding protioligands ((R)PdmBox)H (R = iPr: 5a; Ph: 5b) were obtained by condensation with amino alcohols and subsequent zinc-catalyzed cyclization. Reaction of the lithiated ligands with [NiCl2(dme)] yielded the corresponding square-planar nickel(II) complexes [((R)PdmBox)NiCl] (6a/b)...
March 9, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28273108/structure-based-mutational-analysis-of-icat-residues-mediating-negative-regulation-of-%C3%AE-catenin-co-transcriptional-activity
#5
Mélanie J Domingues, Juan Martinez-Sanz, Laura Papon, Lionel Larue, Liliane Mouawad, Jacky Bonaventure
ICAT (Inhibitor of β-CAtenin and TCF) is a small acidic protein that negatively regulates β-catenin co-transcriptional activity by competing with TCF/LEF factors in their binding to β-catenin superhelical core. In melanoma cells, ICAT competes with LEF1 to negatively regulate the M-MITF and NEDD9 target genes. The structure of ICAT consists of two domains: the 3-helix bundle N-terminal domain binds to β-catenin Armadillo (Arm) repeats 10-12 and the C-terminal tail binds to Arm repeats 5-9. To elucidate the structural mechanisms governing ICAT/β-catenin interactions in melanoma cells, three ICAT residues Y15, K19 and V22 in the N-terminal domain, contacting hydrophobic β-catenin residue F660, were mutated and interaction was assessed by immunoprecipitation...
2017: PloS One
https://www.readbyqxmd.com/read/28272869/a-pyridine-alkoxide-chelate-ligand-that-promotes-both-unusually-high-oxidation-states-and-water-oxidation-catalysis
#6
Thoe K Michaelos, Dimitar Y Shopov, Shashi Bhushan Sinha, Liam S Sharninghausen, Katherine J Fisher, Hannah M C Lant, Robert H Crabtree, Gary W Brudvig
Water-oxidation catalysis is a critical bottleneck in the direct generation of solar fuels by artificial photosynthesis. Catalytic oxidation of difficult substrates such as water requires harsh conditions, so the ligand must be designed both to stabilize high oxidation states of the metal center and to strenuously resist ligand degradation. Typical ligand choices either lack sufficient electron donor power or fail to stand up to the oxidizing conditions. Our research on Ir-based water-oxidation catalysts (WOCs) has led us to identify a ligand, 2-(2'-pyridyl)-2-propanoate or "pyalk", that fulfills these requirements...
March 8, 2017: Accounts of Chemical Research
https://www.readbyqxmd.com/read/28272613/bifunctional-colorimetric-chemosensing-of-fluoride-and-cyanide-ions-by-nickel-pocop-pincer-receptors
#7
María K Salomón-Flores, Iván J Bazany-Rodríguez, Diego Martínez-Otero, Marco A García-Eleno, Jorge J Guerra-García, David Morales-Morales, Alejandro Dorazco-González
Three Ni(ii)-POCOP pincer complexes [NiCl{C6H2-4-OH-2,6-(OPPh2)2}], 1; [NiCl{C6H2-4-OH-2,6-(OPtBu2)2}], 2 and [NiCl{C6H2-4-OH-2,6-(OPiPr2)2}], 3 were studied as bifunctional molecular sensors for inorganic anions and acetate. In CH3CN, fluoride generates a bathochromic shift with a colorimetric change for 1-3 with a simultaneous fluorescence turn on, this optical effect is based on deprotonation of the para-hydroxy group of the POCOP ligand. On the other hand, in a neutral aqueous solution of 80 vol% CH3CN, additions of cyanide produce a distinct change of color by forming very stable complexes with the nickel-based receptors 1-3 with log Ka in the range of 4...
March 8, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/28266851/phenanthridine-containing-pincer-like-amido-complexes-of-nickel-palladium-and-platinum
#8
Pavan Mandapati, Patrick K Giesbrecht, Rebecca L Davis, David E Herbert
Proligands based on bis(8-quinolinyl)amine (L1) were prepared containing one (L2) and two (L3) benzo-fused N-heterocyclic phenanthridinyl (3,4-benzoquinolinyl) units. Taken as a series, L1-L3 provides a ligand template for exploring systematic π-extension in the context of tridentate pincer-like amido complexes of group 10 metals (1-M, 2-M, and 3-M; M = Ni, Pd, Pt). Inclusion of phenanthridinyl units was enabled by development of a cross-coupling/condensation route to 6-unsubstituted, 4-substituted phenanthridines (4-Br, 4-NO2, 4-NH2) suitable for elaboration into the target ligand frameworks...
March 7, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28265626/metal-free-pincer-ligand-chemistry-polycationic-phosphonium-lewis-acids
#9
Kevin M Szkop, Douglas W Stephan
Oxidation of 2,6-bis(diphenylphosphine)methyl pyridine with MeO3SCF3, yields the dication [2,6-(CH2PMePh2)2C5H3N][CF3SO3]22, while subsequent treatment with two equivalents of [K(THF)n][B(C6F5)4] (n = 1.3-1.5) afforded [2,6-(CH2PMePh2)2C5H3N][B(C6F5)4]23. Analogous treatment using XeF2 afforded 2,6-(CH2PF2Ph2)2C5H3N 4, while subsequent fluoride abstractions afford the corresponding [BF4], [CF3SO3] and [B(C6F5)4] salts, 5-7, respectively. Compound 4 reacts with an excess of MeO3SCF3 to give [2,6-(CH2PF2Ph2)2C5H3N(CH3)][CF3SO3] 8 while subsequent reaction with [Et3Si·2C7H8][B(C6F5)4] gave the related tricationic species, 9...
March 21, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/28263198/novel-surgical-method-for-pincer-nail-treatment-partial-matricectomy-and-triple-flap-technique
#10
Berna Aksoy, Hasan Mete Aksoy
No abstract text is available yet for this article.
March 2, 2017: Dermatologic Surgery: Official Publication for American Society for Dermatologic Surgery [et Al.]
https://www.readbyqxmd.com/read/28263078/pharmacokinetics-metabolism-and-partial-biodistribution-of-pincer-therapeutic-nitazoxanide-in-mice-following-pulmonary-delivery-of-inhalable-particles
#11
Anuradha Gupta, Sachin L Tulsankar, Rabi S Bhatta, Amit Misra
Nitazoxanide (NTZ) induces autophagy in mammalian cells and also has mycobactericidal activity, displaying a two-pronged therapeutic effect, on the host as well as the pathogen. The pharmacokinetics and biodistribution of inhaled NTZ were investigated. Particles containing NTZ in a matrix of PLGA were prepared by spray drying. HPLC and LC-MS/MS methods were developed and validated. Particles were administered as inhalations to mice. Drug concentrations in plasma and tissues were estimated at different time points...
March 14, 2017: Molecular Pharmaceutics
https://www.readbyqxmd.com/read/28261725/hydrogen-autotransfer-and-related-dehydrogenative-coupling-reactions-using-a-rhenium-i-pincer-catalyst
#12
Patrick Piehl, Miguel Peña-López, Anna Frey, Helfried Neumann, Matthias Beller
A novel rhenium complex bearing a non-innocent PNP pincer ligand was prepared. This novel catalyst is active in hydrogen autotransfer reactions to form new C-C and C-N bonds. More specifically, valuable alkylations of ketones and sulfonamides with primary alcohols are herein presented. In addition, the first examples of rhenium-catalysed synthesis of pyrroles are described by dehydrogenative coupling of diols, amines and ketones.
March 18, 2017: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/28247451/cyclometalated-gold-iii-complexes-containing-n-heterocyclic-carbene-ligands-engage-multiple-anti-cancer-molecular-targets
#13
Sin Ki Fung, Taotao Zou, Bei Cao, Pui-Yan Lee, Yi Man Eva Fung, Di Hu, Chun-Nam Lok, Chi-Ming Che
Metal N-heterocyclic carbene (NHC) complexes are a promising class of anti-cancer agents displaying potent in vitro and in vivo activities. Taking a multi-faceted approach employing two clickable photoaffinity probes, herein we report the identification of multiple molecular targets for anti-cancer active pincer gold(III) NHC complexes. These complexes display potent and selective cytotoxicity against cultured cancer cells and in vivo anti-tumor activities in mice bearing xenografts of human cervical and lung cancers...
March 1, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28229494/cobalt-catalyzed-regioselective-borylation-of-arenes-n-heterocyclic-silylene-as-electron-donors-in-metal-mediated-activation-of-c%C3%AF-h-bonds
#14
Chunming Cui, Hailong Ren, Yu-Peng Zhou, Yun-Ping Bai, Matthias Driess
C-H Borylation of arenes has been a subject of great current interest because of its atom-economy and the wide applicability of borylated products in value-added synthesis. A new bis(silylene)cobalt(II) complex bearing a bis(N-heterocyclic silylene)-pyridine pincer ligand (SiNSi) has been synthesized and structurally characterized. It enabled the regioselective catalytic C-H borylation of pyridines, furans and fluorinated arenes. Notably, it exhibited the complementary regioselectivity for the borylation of fluorinated arenes compared to previously known catalytic systems, demonstrating that N-heterocyclic silylene donors have enormous potential in metal-catalyzed catalytic applications...
February 23, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28220919/phosphorescent-pt-ii-complexes-bearing-a-monoanionic-c-n-n-luminophore-and-tunable-ancillary-ligands
#15
Marian Hebenbrock, Linda Stegemann, Jutta Kösters, Nikos L Doltsinis, Jens Müller, Cristian A Strassert
A versatile design strategy is presented towards new monoanionic pincer luminophores, showing that cyclometallating C^N^N ligands can yield phosphorescent Pt(ii) complexes even if a neutral 1,2,3-triazole ring is inserted by click chemistry. The overall charge, intermolecular interactions and excited state properties can be manipulated and controlled by varying the nature of the ancillary ligand, and its effect on the structural and the triplet state characteristics can be thoroughly investigated and correlated by means of theory and spectroscopy...
February 21, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/28220194/-diagnostic-ability-of-power-measurement-of-different-grip-forms-for-distal-median-nerve-lesion
#16
N Wachter, M Mentzel, G Krischak, C Häderer, J Gülke
BACKGROUND: Peripheral lesions of the median nerve cause characteristic changes of the grip function of the hand. For evaluating grip force changes, measurement by dynamometers (JAMAR dynamometer and pinch dynamometer) is of high relevance. In this study the ability of grip force measurements of different grip forms was evaluated to discriminate between a simulated median nerve lesion and healthy subjects. MATERIAL AND METHODS: In 21 healthy subjects, the grip force of power grip was measured by the JAMAR dynamometer at the second stage including measurement of force at the fingertips and the thenar by a sensor glove...
February 20, 2017: Der Unfallchirurg
https://www.readbyqxmd.com/read/28219714/relationship-between-physical-activity-and-hip-pain-in-persons-with-and-without-cam-or-pincer-morphology-a-population-based-case-control-study
#17
J A Kopec, J Cibere, L C Li, C Zhang, M Barber, H Qian, H Wong, G Steininger, H Prlic, J Simatovic, C Ratzlaff, E C Sayre, J Ye, B B Forster, J M Esdaile
OBJECTIVES: The purpose of the study was to determine if physical activity (PA) is a risk factor for persistent or recurrent hip pain in young and middle-aged persons with and without radiographic findings of cam or pincer morphology (CPM). METHODS: A population sample of persons aged 20-49 with (cases) and without (controls) hip pain in Metro Vancouver, Canada, was selected through random digit dialing (RDD). Self-reported PA was expressed as average energy expenditure (MET-hours) per year, over lifetime...
February 20, 2017: Osteoarthritis and Cartilage
https://www.readbyqxmd.com/read/28217325/crystal-structures-of-a-novel-nnn-pincer-ligand-and-its-dinuclear-titanium-iv-alkoxide-pincer-complex
#18
Jakub Pedziwiatr, Ion Ghiviriga, Khalil A Abboud, Adam S Veige
This report describes a synthetic protocols and the crystal structures involving a novel pincer-type H3[NNN] ligand, namely di-μ-bromido-μ-{2-(2,2-di-methylpropanimido-yl)-N-[2-(2,2-di-methyl-propanimido-yl)-4-methyl-phen-yl]-4-methylaniline}-bis-[(diethyl ether)lithium], [Li2Br2(C24H33N3)(C4H10O)2] (1) and a dinuclear metal complex, namely di-μ-bromido-2:3κ(4)Br:Br-bis-{2-(2,2-di-methylpropanimido-yl)-N-[2-(2,2-di-methyl-propanimido-yl)-4-methyl-phen-yl]-4-methylaniline}-1κ(3)N,N',N'';4κ(3)N,N',N''-tetra-μ-iso-propano-lato-1:2κ(4)O:O;3:4κ(4)O:O-diiso-propano-lato-1κO,4κO-2,3-dilithium-1,4-dititanium, [Li2Ti2Br2(C24H32N3)2(C3H7O)6] or {[NHNNH]Ti(O (i) Pr)3(LiBr)2}2 (2)...
February 1, 2017: Acta Crystallographica. Section E, Crystallographic Communications
https://www.readbyqxmd.com/read/28210727/mn-iv-and-mn-v-radical-species-supported-by-the-redox-non-innocent-bis-2-amino-3-5-di-tert-butylphenyl-amine-pincer-ligand
#19
Nicolas Leconte, Jules Moutet, Khrystyna Herasymchuk, Ryan M Clarke, Christian Philouze, Dominique Luneau, Tim Storr, Fabrice Thomas
The electron-rich pincer ligand 1 has been synthesized and chelated to manganese. The octahedral Mn(iv) bis(diiminosemiquinonate) and Mn(v) (diiminobenzoquinone) (diiminosemiquinonate) radicals were structurally characterized.
February 17, 2017: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/28156034/the-nickel-pincer-complex-in-lactate-racemase-is-an-electron-relay-and-sink-that-acts-through-proton-coupled-electron-transfer
#20
Binju Wang, Sason Shaik
QM/MM calculations reveal that the nickel pincer complex in lactate racemase functions as a reversible "single-center electrode" that accepts and donates back an electron. In this way, it catalyzes the isomerization process d-lactate⇌l-lactate through successive proton-coupled electron-transfer steps.
February 3, 2017: Angewandte Chemie
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