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Angewandte Chemie

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https://www.readbyqxmd.com/read/29160961/a-metal-organic-framework-with-exceptional-activity-for-c-h-bond-amination
#1
Le Wang, Douglas W Agnew, Xiao Yu, Joshua S Figueroa, Seth Mason Cohen
The development of catalysts capable of fast, robust C-H bond amination under mild conditions is an unrealized goal despite substantial progress in the field of C-H activation in recent years. Here we describe a Mn-based metal-organic framework (CPF-5) that promotes the direct amination of C-H bonds with exceptional activity. CPF-5 is capable of functionalizing C-H bonds in an intermolecular fashion with unrivaled catalytic stability producing an unrivaled >105 turnovers.
November 21, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/29160951/exploiting-the-strong-hydrogen-bond-donor-properties-of-the-borinic-acid-functionality-for-fluoride-anion-recognition
#2
Chang-Hong Chen, Francois Pierre Gabbai
Borinic acids have typically not been considered as hydrogen bond donor groups in molecular recognition. Here, we describe a bifunctional borane / borinic acid derivative (2) in which the two functionalities are connected by a 1,8-biphenylenediyl backbone. Anion binding studies reveal that 2 readily binds a fluoride anion via formation of a unique B-F···H-O-B hydrogen bond. This hydrogen bond is characterized by a short H-F distance of 1.79(3) Å and a large coupling constant 1JHF of 57.2 Hz. The magnitude of this interaction, which has also been investigated computationally, augments the fluoride anion binding properties of 2, making it compatible with aqueous environments...
November 21, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/29160950/superconductivity-in-a-cu-ii-based-coordination-polymer-with-perfect-kagom%C3%A3-structure
#3
Xing Huang, Shuai Zhang, Liyao Liu, Lei Yu, Genfu Chen, Wei Xu, Daoben Zhu
Highly crystalline material of Copper (II) benzenehexathiolate coordination polymer (Cu-BHT) has been prepared. Its two dimensional kagomè structure has been confirmed by powder x-ray diffraction (PXRD), high-resolution transmission electron microscope (HRTEM) and high-resolution scanning transmission electron microscope (STEM). The as-prepared sample exhibits bulk superconductivity at ~ 0.25 K which is confirmed by the zero resistivity, AC magnetic susceptibility and specific heat measurements. Another diamagnetic transition at ~ 3K suggests that there is a second superconducting phase which may be associated to the single layer or few-layer of Cu-BHT...
November 21, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/29160936/liquid-photonic-crystals-for-mesopore-detection
#4
Biting Zhu, Qianqian Fu, Ke Chen, Jianping Ge
Nitrogen adsorption-desorption for mesopore characterization requires the using of expensive instrument, time-consuming process and consumption of liquid nitrogen. Here, a new method was developed to measure the pore parameters through mixing of mesoporous substance with supersaturated SiO2 colloidal solution at different temperatures, followed by quick measurement of reflection changes of the precipitated liquid photonic crystals. Pore volumes and diameters of mesoporous silica were measured according to the positive correlation between unit mass reflection change (Δλ/m) and pore volume (V), and the negative correlation between average absorption temperature (T) and pore diameter (D)...
November 21, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/29160932/on-the-use-of-polyelectrolytes-and-polymediators-in-organic-electrosynthesis
#5
Benjamin Schille, Niels Ole Giltzau, Robert Francke
Although organic electrosynthesis is generally considered to be a green method, the necessity for excess amounts of supporting electrolyte constitutes a severe drawback. Furthermore, the employment of redox mediators represents an additional separation problem. In this context, we have explored the applicability of soluble polyelectrolytes and polymediators using the TEMPO-mediated transformation of alcohols to carbonyl compounds as test reaction. Catalyst benchmarking based on CV studies indicates that the redox-active polymer can compete with molecularly defined TEMPO species...
November 21, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/29160920/cobalt-catalyzed-electrophilic-amination-of-aryl-and-heteroaryl-zinc-pivalates-with-n-hydroxylamine-benzoates
#6
Yi-Hung Chen, Simon Graßl, Paul Knochel
Aryl- and heteroaryl-zinc pivalates are aminated with O-benzoylhydroxylamines at 25 °C within 2-4 h in the presence of 2-5% CoCl2*2LiCl furnishing the corresponding tertiary arylated or heteroarylated amines in good yields. This electrophilic amination provides also an access to diarylamines and aryl(heteroaryl)amines. A new tuberculosis drug candidate (Q203) was prepared in 6 steps and 56% overall yield using this cobalt-catalyzed amination as the key step.
November 21, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/29160029/dose-dependencies-and-biocompatibility-of-renal-clearable-gold-nanoparticles
#7
Jie Zheng, Jing Xu, Mengxiao Yu, Chuanqi Peng, Phoebe Carter, Jia Tian, Xuhui Ning, Qinhan Zhou, Qiu Tu, Greg Zhang, Anthony Dao, Xingya Jiang, Payal Kapur, Jer-Tsong Hsieh, Xudong Zhao, Pengyu Liu
While dose dependencies in pharmacokinetics and clearance are often observed in clinically used small molecules, very few studies have been dedicated to the understandings of potential dose-dependent in vivo transport of nanomedicines. Here we report that the pharmacokinetics and clearance of renal clearable gold nanoparticles (GS-AuNPs) are strongly dose-dependent once injection doses are above 15 mg/kg: high dose expedited the renal excretion and shortened the blood retention. As a result, the no-observed-adverse-effect-level (NOAEL) of GS-AuNPs was >1000 mg/kg in CD-1 mice...
November 20, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/29159912/nickel-0-catalyzed-hydroarylation-of-styrenes-and-1-3-dienes-with-organoborons
#8
Qi-Lin Zhou, Li-Jun Xiao, Lei Cheng, Wei-Min Feng, Mao-Lin Li, Jian-Hua Xie
The Ni-catalyzed hydroarylation of styrenes and 1,3-dienes with organoborons has been developed. The reaction offers a highly selective approach to the diarylalkanes and allylarenes under redox-neutral condition. In this hydroarylation reaction, a new strategy that uses easily available proton of methanol to generate active catalyst species Ni-H was developed. The Ni-catalyzed hydroarylation, combining with a Ir-catalyzed C-H borylation, affords a very efficient and straightforward access to retinoic acid receptor agonist...
November 20, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/29155468/gram-scale-synthesis-of-the-sparteine-surrogate-and-sparteine
#9
James D Firth, Steven J Canipa, Peter O'Brien, Leigh Ferris
An 8-step, gram-scale synthesis of the (-)-sparteine surrogate (22% yield, with just 3 chromatographic purifications) and a 10-step, gram-scale synthesis of (-)-sparteine (31% yield) are reported. Both syntheses proceed with complete diastereocontrol and allow access to either antipode. Since the syntheses do not rely on natural product extraction, our work addresses long-term supply issues relating to these widely used chiral ligands.
November 20, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/29155465/catalytic-dibenzocyclooctene-synthesis-via-cobalt-iii-carbene-radical-and-ortho-quinodimethane-intermediates
#10
Colet Te Grotenhuis, Naudin van den Heuvel, Jarl Ivar van der Vlugt, Bas de Bruin
Metalloradical activation of N-tosyl hydrazones 1 (o-benzallyl-aryl-tosylhydrazones), using [Co(TPP)] as a catalyst (TPP = tetraphenylporphyrin), allows controlled exploitation of single-electron reactivity of the redox non-innocent carbene intermediate. This method offers a novel route to prepare 8-membered rings, using base metal catalysis to construct a series of unique dibenzocyclooctenes via selective CcarbeneCaryl cyclization, producing the desired 8 membered ring products in good to excellent yields...
November 20, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/29155462/iron-ii-catalyzed-direct-synthesis-of-nh-sulfoximines-from-sulfoxides
#11
Hao Yu, Zhen Li, Carsten Bolm
Free NH-sulfoximines have directly been prepared from sulfoxides by iron catalysis applying a readily available, shelf-stable hydroxylamine triflic acid salt. No additional oxidant is needed, and the substrate scope is wide including a range of heterocyclic compounds.
November 20, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/29155461/nanoscale-trimetallic-metal-organic-frameworks-enable-efficient-oxygen-evolution-electrocatalysis
#12
Xiaoqing Huang
Metal-organic frameworks (MOFs) are a class of promising materials for diverse catalysis, but they are usually not directly employed for oxygen evolution electrocatalysis. Most reports focus on using MOFs as templates to in-situ create efficient electrocatalysts via annealing. Herein, we prepared a series of Fe/Ni/-based trimetallic MOFs (Fe/Ni/Co(Mn)-Material of Institute Lavoisier (MIL-53)) by solvothermal synthesis, which can be directly adopted as electrocatalysts. It was revealed that the Fe/Ni/Co(Mn)-MIL-53 exhibited volcano-type oxygen evolution reaction (OER) activity as a function of compositions...
November 20, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/29154498/ru-ii-catalyzed-synthesis-of-spiro-benzofuranones-via-decarbonylative-annulation-reaction
#13
Partha P P Kaishap, Gauri Duarah, Bipul Sarma, Dipak Chetia, Sanjib Gogoi
The first decarbonylative insertion of alkyne through C-H/C-C activation of six membered compounds is reported. This Ru-catalyzed reaction of 3-hydroxy-2-phenyl-chromones with alkynes works most efficiently in the presence of ligand PPh3 to provide spiro-indenebenzofuranones. Unlike the previously reported metal-catalyzed decarbonylative annulation reactions, in the present decarbonylative annulation reaction, the annulation occurs before extrusion of carbon monoxide.
November 20, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/29154413/isoindigo-3-4-difluorothiophene-polymer-acceptors-yield-all-polymer-bhj-solar-cells-with-7-efficiency
#14
Shengjian Liu, Yuliar Firdaus, Simil Thomas, Zhipeng Kan, Federico Cruciani, Sergei Lopatin, Jean-Luc M Bredas, Pierre M Beaujuge
Poly(isoindigo-alt-3,4-difluorothiophene) (PIID[2F]T) analogues used as "polymer acceptors" in bulk-heterojunction (BHJ) solar cells achieve >7% efficiency when used in conjunction with the polymer donor PBFTAZ (model system). Considering that most efficient polymer acceptor alternatives to fullerenes (e.g. PC61BM or its C71 derivative) are based on perylenediimide (PDI) or naphthalenediimide (NDI) motifs thus far, branched alkyl-substituted PIID[2F]T polymers are remarkably promising nonfullerene candidates for "all-polymer" BHJ solar cells...
November 20, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/29154403/paleo-inspired-systems-durability-sustainability-and-remarkable-properties
#15
Loïc Bertrand, Claire Gervais, Admir Masic, Luc Robbiola
We designate as paleo-inspiration, the process of mimicking properties of specific interest (mechanical, optical, structural, etc.) observed in ancient and historical systems. For instance, recovery in archaeology or paleontology identifies materials that are a posteriori extremely resilient to alteration. This is all the more enthusing that many ancient materials were synthesized in soft chemical ways, often using low energy resources, and sometimes rudimentary manufacturing equipment. In this review, we highlight ancient systems as a source of inspiration for innovative conception in the Anthropocene...
November 20, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/29152826/synthesis-and-reactivity-of-nickel-stabilised-%C3%A2%C2%B52-%C3%AE-2-%C3%AE-2-p2-as2-and-pas-units
#16
Gabriele Hierlmeier, Alexander Hinz, Robert Wolf, Jose Manuel Goicoechea
The reactivity of two paramagnetic nickel(I) compounds, CpNi(NHC) (where Cp = cyclopentadienyl; NHC = 1,3-bis(2,4,6-trimethylphenyl)-imidazol-2-ylidene (IMes) or 1,3-bis(2,6-diisopropylphenyl)-imidazol-2-ylidene (IPr)), towards [Na(dioxane)x][PnCO] (Pn = P, As) is described. These reactions afford symmetric bimetallic compounds (µ2:η2,η2-Pn2){Ni(NHC)(CO)}2. Several novel intermediates en route to such species are identified and characterised, including a compound containing the PCO- anion in an unprecedented µ2:η2,η2-binding mode...
November 20, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/29152832/mono-and-bis-imidazolidinium-ethynyl-cations-and-the-reduction-of-the-latter-to-give-an-extended-bis-1-4-3-cumulene-p-carbo-quinoid-system
#17
Brain Barry, Graeme Soper, Juha Hurmalainen, Akseli Mansikkamäki, Katherine N Robertson, William L McClennan, Alex J Veinot, Tracey L Roemmele, Ulrike Werner-Zwanziger, René T Boeré, Heikki M Tuononen, Jason Clyburne, Jason Masuda
An extended π-system containing two [3]cumulene fragments separated by a p-carbo-quinoid and stabilized by two capping N-heterocyclic carbenes (NHCs) has been prepared. Mono- and bis-imidazolidinium ethynyl cations have also been synthesized from the reaction of an NHC with phenylethynyl bromide or 1,4-bis(bromoethynyl)benzene. Cyclic voltammetry coupled with synthetic and structural studies showed that the dication is readily reduced to a neutral, singlet bis-1,4-([3]cumulene)-p-carbo-quinoid due to the π-accepting properties of the capping NHCs...
November 19, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/29149539/dynamic-cross-exchange-in-halophosphonium-species-first-direct-observation-of-stereochemical-inversion-in-the-course-of-an-sn2-process
#18
Kirill Nikitin, Elizabeth V Jennings, Sulaiman Al Sulaimi, Yannick Ortin, Declan G Gilheany
The complex fluxional interconversions between, otherwise very similar, phosphonium bromides and chlorides R3PX+X- (R = Alk, Ar, X = Cl or Br) was studied by NMR techniques. Their energy barriers are typically ca. 11 kcal/mol but rise rapidly as bulky groups are attached to phosphorus, revealing the importance of steric factors. In contrast, electronic effects, as measured by Hammett analysis, are modest (rho 1.46) but still clearly indicate negative charge flow towards phosphorus in the transition state. Most significantly, detailed analysis of the exchange pathways unequivocally, and for the first time in any such process, shows that nucleophilic attack of the nucleophilic anion on the tetrahedral centre results in inversion of configuration...
November 17, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/29149518/control-of-n-heterocyclic-carbene-catalyzed-switchable-linear-and-cycloaddition-reactions-of-enals-asymmetric-synthesis-of-oxindole-%C3%AE-amino-acid-derivatives
#19
Dieter Enders, Xiang-Yu Chen, Jia-Wen Xiong, Qiang Liu, Sun Li, He Sheng, Carolina von Essen, Kari Rissanen
A strategy to control the switchable linear and cycloaddition reactions of enals through NHC catalyisis has been developed. The new scalable protocol leads to γ-amino acid esters bearing a tetrasubstituted stereocenter in good yields and high stereoselectivities via homo-Mannich reactions of enals and isatin-derived ketimines. By simply changing the N-ketimine substituent to an ortho-hydroxy phenyl group, the corresponding spirocyclic oxindolo-γ-lactams are obtained.
November 17, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/29149501/the-weakly-coordinating-tris-trichlorosilyl-silyl-anion
#20
Marian Olaru, Maxie F Hesse, Elena Rychagova, Sergey Ketkov, Stefan Mebs, Jens Beckmann
Closely following the procedure for the preparation of the base-stabilized dichlorosilylene complex NHCDipp∙SiCl2 by Roesky and Stalke et al. (Angew. Chem. Int. Ed. 2009, 48, 5683-5686), besides the reported by-product [NHCDipp-H+∙∙∙Cl-], few crystals of the salt [NHCDipp-H∙∙∙Cl∙∙∙H-NHCDipp]Si(SiCl3)3 were isolated and characterized by X-ray crystallography (NHCDipp = N,N-di(2,6-isopropylphenyl)-imidazo-2-ylidene). They feature the weakly-coordinating anion Si(SiCl3)3-, which was more rationally obtained in high yields upon deprotonation of conjugate Brønsted acid HSi(SiCl3)3 with NHCDipp or PMP (PMP = 1,2,2,6,6-pentamethylpiperidine)...
November 17, 2017: Angewandte Chemie
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