bluuebunny/crossref_metadata_2025_split huggingface dataset:
Olefin‐Assisted Iron‐Catalyzed Alkylation of Aryl Chlorides
Authors: Gülak Samet , Gieshoff Tim N. , Jacobi von Wangelin Axel 
Published: August 2013

AbstractA selective and operationally simple iron‐catalyzed cross‐coupling of aryl chlorides with alkylmagnesium halides has been developed. The reaction tolerates various functional groups and exhibits high chemoselectivity even in the presence of aryl bromides. Mechanistic studies indicate the essential role of the olefin substituent for substrate activation. Competing polymerization and reduction are effectively suppressed.magnified image
Copper‐Catalyzed Intermolecular Oxidative Cyclization of Halo‐ alkynes: Synthesis of 2‐Halo‐substituted Imidazo[1,2‐a]pyridines, Imidazo[1,2‐a]pyrazines and Imidazo[1,2‐a]pyrimidines
Authors: Gao Yang , Yin Meizhou , Wu Wanqing , Huang Huawen , Jiang Huanfeng 
Published: August 2013

AbstractAn efficient copper‐catalyzed method for the synthesis of 2‐haloimidazopyridines with aminopyridines and haloalkynes using molecular oxygen as oxidant in a one‐pot manner has been developed. In this process, the reaction appears to be very general and suitable for the construction of a variety of 2‐halo‐substituted imidazopyridines, imidazopyrazines and imidazopyrimidines. The intermolecular oxidative diamination of haloalkynes was achieved for the first time. Importantly, the mild reaction conditions and the efficient conversion of the alkyl‐substituted haloalkynes are great improvements over the existing methods. Moreover, the resultant 2‐haloimidazo[1,2‐a]pyridines could be efficiently converted to other functionalized imidazopyridine products via substitution, coupling reactions and other transformations, which further indicates potential applications of this method in synthetic and pharmaceutical chemistry.magnified image
Copper‐Catalyzed Aerobic Oxidative Carbocyclization– Ketonization Cascade: Selective Synthesis of Quinolinones
Authors: Xie Peng , Wang Zhi‐Qiang , Deng Guo‐Bo , Song Ren‐Jie , Xia Jia‐Dong , Hu Ming , Li Jin‐Heng 
Published: August 2013

AbstractA new thematic extension method is described for the carbocyclization of α‐C(sp3)H bonds of amides with alkynes followed by ketonization of the alkynes that utilizes the inexpensive copper(II) acetoacetonate [Cu(acac)2] as catalyst under an oxygen atmosphere to synthesize quinolinones. It is noteworthy that the oxygen atom of the newly formed carbonyl group is from atmospheric molecular oxygen.magnified image
Chemo‐, Regio‐ and Stereoselective Tricyclohexylphosphine‐Catalyzed [3+2] Cycloaddition of Enynes with [60]Fullerene Initiated by 1,4‐Michael Addition: Synthesis of Cyclopenteno[60]fullerenes and their Electrochemical Properties
Authors: Tseng Po‐Yen , Chuang Shih‐Ching 
Published: August 2013

AbstractHerein we demonstrate a tricyclohexylphosphine‐catalyzed cycloaddition of (E)‐ or (Z)‐alkyl 5‐substituted phenylpent‐2‐en‐4‐ynoates with [60]fullerene to give cyclopentenofullerenes in good to excellent yields, through initial chemo‐ and regioselective 1,4‐addition of phosphines at the β‐carbon of the enyne substrates. The nucleophilic addition pattern of P(cHx)3 is found to be different from that of Gilman or Grignard reagents toward the studied enynes. The resulting cyclopentenofullerenes, characterized with spectrometric methods and single crystal X‐ray diffraction analysis, exhibit comparable or higher LUMO energy levels than a typical n‐type material, [6,6]‐phenyl‐C61‐butyric acid methyl ester (PCBM).magnified image
Combining Visible Light Catalysis and Transition Metal Catalysis for the Alkylation of Secondary Amines
Authors: Gao Xue‐Wang , Meng Qing‐Yuan , Xiang Ming , Chen Bin , Feng Ke , Tung Chen‐Ho , Wu Li‐Zhu 
Published: August 2013

AbstractBy combining the visible‐light catalyst, Ru(bpy)3Cl2, and transition metal salts, Cu(OTf)2, we are able to functionalize secondary amines to form Csp3Csp3 bonds with β‐keto esters efficiently by an aerobic oxidative coupling reaction under visible light irradiation at ambient conditions.magnified image
Palladium‐Catalyzed Direct Alkoxycarbonylation of Aromatic CH Bonds via Selective CC Cleavage of α‐Keto Esters
Authors: Zhou Wei , Li Pinhua , Zhang Yicheng , Wang Lei 
Published: August 2013

AbstractA novel palladium‐catalyzed direct alkoxycarbonylation of 2‐arylpyridines, 2‐arylquinolines, benzo[h]quinolines, 2‐phenylpyrimidines, N‐pyrimidine pyrroles and N‐pyrimidine indoles via aromatic CH bond activation and selective CC cleavage of α‐keto esters has been developed. The method has the advantages of wide functional group tolerance, high selectivity, broad range of substrates and good yields.magnified image
Efficient Construction of CN Double Bonds via Acceptorless Dehydrogenative Coupling
Authors: Sun Xiang , Hu Yu , Nie Shao‐zhen , Yan Yun‐yun , Zhang Xue‐jing , Yan Ming 
Published: August 2013

AbstractThe efficient construction of CN double bonds has been achieved by the Ir‐catalyzed intramolecular acceptorless dehydrogenative cross‐coupling of tertiary amines and amides. An iridium/2‐hydroxypyridine complex was identified as the highly efficient catalyst. A number of quinazolinone derivatives was prepared in excellent yields. An iridium‐mediated CH activation mechanism is proposed. This finding provides an unprecedented strategy for the direct imidation of sp3 CH bonds.magnified image
Copper(I) Iodide‐Catalysed Aerobic Oxidative Synthesis of Imidazo[1,2‐a]pyridines from 2‐Aminopyridines and Methyl Ketones
Authors: Chandra Mohan Darapaneni , Reddy Donthiri Ramachandra , Nageswara Rao Sadu , Adimurthy Subbarayappa 
Published: August 2013

AbstractWe report here an operationally simple copper‐catalysed synthesis of imidazo[1,2‐a]pyridines through CH activation with oxidative linkage of two CN bonds under very mild conditions using molecular oxygen as a sole oxidant. The process allows the quick assembly of imidazo[1,2‐a]pyridines including the antiulcer drug zolimidine from inexpensive and readily available 2‐aminopyridines and methyl ketones with broad range of functional group tolerance.magnified image
Copper Acetoacetonate [Cu(acac)2]/BINAP‐Promoted Csp3N Bond Formation via Reductive Coupling of N‐Tosylhydrazones with Anilines
Authors: Aziz Jessy , Brion Jean‐Daniel , Hamze Abdallah , Alami Mouad 
Published: August 2013

AbstractWe report the the copper(II) acetoacetonate [Cu(acac)2]/BINAP‐catalyzed synthesis of arylamines from N‐tosylhydrazones and anilines. A fine tuning of the reaction conditions was required to accomplish the cross‐coupling successfully, including the ligands effect and the addition of small amounts of water. The characteristic feature of this protocol is its functional group compatibility and its chemoselectivity when various aminophenol derivatives were used. Taking into consideration the interest for this copper‐reductive coupling in which no stoichiometric metal hydride reagent is employed, this can be considered as an alternative to the conventional reductive amination.magnified image
Silver‐Catalyzed Decarboxylative Acylarylation of Acrylamides with α‐Oxocarboxylic Acids in Aqueous Media
Authors: Wang Hua , Guo Li‐Na , Duan Xin‐Hua 
Published: August 2013

AbstractA mild and efficient silver‐catalyzed acylarylation of activated alkenes with easily available α‐oxocarboxylic acids has been developed. The reactions provide a rapid access to a variety of functionalized oxindoles via a tandem decarboxylative radical cyclization strategy. This transformation proceeds well under mild reaction conditions and exhibits excellent functional group tolerance, affording the desired oxindoles in good to excellent yields.magnified image
Metal‐Free Oxidative Coupling: Xanthone Formation via Direct Annulation of 2‐Aryloxybenzaldehyde using Tetrabutylammonium Bromide as a Promoter in Aqueous Medium
Authors: Rao Honghua , Ma Xinyi , Liu Qianzi , Li Zhongfeng , Cao Shengli , Li Chao‐Jun 
Published: August 2013

AbstractA metal‐free intramolecular annulation of 2‐aryloxybenzaldehydes to xanthones is disclosed, which proceeds through the direct oxidative coupling of an aldehyde CH bond and aromatic CH bonds using tetrabutylammonium bromide (TBAB) as a promoter in aqueous medium. This strategy works smoothly in the presence of both electron‐donating and electron‐withdrawing groups, and displays good tolerance towards catalytically reactive substituents, thus promising further functionalizations of xanthone products.magnified image
Copper(I)‐Catalyzed Boron Addition Reactions of Alkynes with Diboron Reagents
Authors: Yun Jaesook 
Published: August 2013

AbstractThe development of catalytic Cu‐B additions to carbon–carbon unsaturated bonds (borylcupration) with high regio‐ and stereoselectivity has enabled facile and direct syntheses of alkenylboronic esters, which are versatile synthetic intermediates in organic synthesis. An increasing number of relevant reactions have been reported over the past several years, which can be categorized based on the electrophilic reagent that reacts with the common alkenylcopper intermediates that are generated in situ by Cu‐B addition to alkynes. In this Focus Review, recent advances in copper‐catalyzed boron addition reactions for the synthesis of alkenylboronic esters with diboron reagents are summarized.
Entwicklung struktureller Komplexität durch Selbstorganisation in flüssigkristallinen Systemen
Authors: Tschierske Carsten 
Published: August 2013

AbstractSeit der Entdeckung erster Flüssigkristalle vor 125 Jahren haben sich diese zu einem Wissenschaftsgebiet mit vielseitigen Facetten entwickelt. Dieser Aufsatz beleuchtet aktuelle Entwicklungen auf diesem Gebiet mit dem Schwerpunkt auf dem molekularen Design flüssigkristalliner Materialien und ihrer Selbstorganisation. Im Fokus stehen neue und ungewöhnliche Organisationsformen mit erhöhter Komplexität, wie zelluläre Strukturen, “mehrfarbige” Kompartimentierungen, komplexe periodische und quasiperiodische Anordnungen von sphärischen Aggregaten und Nanopartikeln, sowie resultierende Phänomene wie Ferroelektrizität und Symmetriebruch. Diese werden in Zusammenhang mit anderen geordneten Strukturen in selbstorganisierten Monoschichten, in Multiblock‐Copolymeren und periodischen Nanopartikel‐Arrays diskutiert. Als Maß der strukturellen Komplexität dienen die Größe der resultierenden periodischen Gitter, der Grad der Kompartimentierung des Raumes und die “logische Tiefe” der Überstrukturen.
Sulfoximine: Eine vernachlässigte Chance in der medizinischen Chemie
Authors: Lücking Ulrich 
Published: August 2013

AbstractInnovation ist häufig als der Schlüssel zur Wirkstoff‐Findung beschrieben worden. Doch in der täglichen Routine neigen Medizinalchemiker dazu, nur das Instrumentarium der funktionellen Gruppen und Strukturelemente zu verwenden, das sie bereits kennen und lieben. Das Blockbuster‐Krebsmedikament Velcade (Bortezomib) wurde beispielsweise von mehr als 50 Unternehmen abgelehnt, vermutlich wegen seiner ungewöhnlichen Boronsäuregruppe (“Only a moron would put boron in a drug!”). Auch im Entwicklungsprozess des pan‐CDK‐Inhibitors BAY 1000394 sorgte der unkonventionelle Vorschlag, eine Sulfoximingruppe in die Leitstruktur einzuführen, zunächst für Spott und Stirnrunzeln, da Sulfoximine selten in der medizinischen Chemie verwendet worden sind. Jedoch war es gerade die Sulfoximingruppe, die es schließlich ermöglichte, die fundamentalen Probleme des Projekts zu überwinden, und so zur Identifizierung des klinischen pan‐CDK‐Inhibitors BAY 1000394 führte. Der vorliegende Kurzaufsatz gibt einen Überblick über eine weithin vernachlässigte Chance in der medizinischen Chemie – die Sulfoximingruppe.
Sulfoximines: A Neglected Opportunity in Medicinal Chemistry
Authors: Lücking Ulrich 
Published: August 2013

AbstractInnovation has frequently been described as the key to drug discovery. However, in the daily routine, medicinal chemists often tend to stick to the functional groups and structural elements they know and love. Blockbuster cancer drug Velcade (bortezomib), for example, was rejected by more than 50 companies, supposedly because of its unusual boronic acid function (as often repeated: “only a moron would put boron in a drug!”). Similarly, in the discovery process of the pan‐CDK inhibitor BAY 1000394, the unconventional proposal to introduce a sulfoximine group into the lead series also led to sneers and raised eyebrows, since sulfoximines have seldom been used in medicinal chemistry. However, it was the introduction of the sulfoximine group that finally allowed the fundamental issues of the project to be overcome, culminating in the identification of the clinical sulfoximine pan‐CDK inhibitor BAY 1000394. This Minireview provides an overview of a widely neglected opportunity in medicinal chemistry—the sulfoximine group.
Vertically aligned carbon nanotube‐based composite: Elaboration and monitoring of the nanotubes alignment
Authors: Huard Mickael , Roussel Florent , Rouzière Stéphan , Patel Stéphanie , Pinault Mathieu , Mayne‐L'Hermite Martine , Launois Pascale 
Published: August 2013

ABSTRACTWe present the different elaboration steps of a composite formed of carbon nanotubes (CNT) carpet embedded in an epoxy polymer. Detailed characterization at each step of the elaboration process is performed. The good alignment of CNT in as‐grown carpets is kept all along the elaboration process of the composite, as it is measured at both macro and microscopic scales by X‐ray scattering. We also ensured by X‐ray fluorescence measurements that the iron‐based catalyst particles used for the synthesis were removed from the carpet after a high temperature post‐annealing treatment. These measurements give valuable information for further applications involving unidirectional nanotube composites and membranes, where CNT alignment is a key parameter. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 39730.
Reactive red 120 and NI(II) derived poly(2‐hydroxyethyl methacrylate) nanoparticles for urease adsorption
Authors: Türkcan Ceren , Uygun Deniz Aktaş , Akgöl Sinan , Denizli Adil 
Published: August 2013

ABSTRACTNon‐porous poly(2‐hydroxyethyl methacrylate) [p(HEMA)] nanoparticles were prepared by surfactant free emulsion polymerization. The p(HEMA) nanoparticles was about 200 nm diameter, spherical form, and non‐porous. Reactive Red 120 (RR 120) was covalently attached to the p(HEMA) nanoparticles and Ni(II) ions were incorporated to attach dye molecules. Urease was immobilized onto RR120‐Ni(II) attached p(HEMA) nanoparticles via adsorption. The maximum urease adsorption capacity of RR120‐Ni(II) attached p(HEMA) nanoparticles was 480.01 mg g−1 nanoparticles at pH 7.0 in phosphate buffer. It was observed that urease could be repeatedly adsorbed and desorbed without significant loss in adsorption amount. Km values were 21.50 and 34.06 mM for the free and adsorbed enzyme. The Vmax values were 4 U for the free enzyme and 3.3 U for the adsorbed enzyme. The optimum pH was 25 mM pH 7 phosphate buffer for free and adsorbed enzyme. The optimum temperature was determined at 35°C and 55°C for the free and adsorbed enzyme, respectively. These findings show considerable promise for this material as an adsorption matrix in biotechnological applications. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 39757.
Properties and phase segregation of crosslinked PCL‐based polyurethanes
Authors: Güney Aysun , Hasirci Nesrin 
Published: August 2013

ABSTRACTPolyurethane (PU) films were prepared from different types of poly(ε‐caprolactone) glycols and hexamethylene diisocyanate without using any other ingredients such as solvent, catalyst, or chain extender. Polymers were stabilized by crosslinking formed as allophanate and/or biuret linkages during the curing process. The effects of different components on the product properties such as chemical structure, microphase segregation, mechanical strength, thermo‐mechanical, thermal properties, and surface hydrophilicities were investigated by FTIR‐ATR, atomic force microscope, mechanical tester, dynamic mechanical analyses, thermogravimetric analyzer, differential scanning calorimetry, and contact angle measurements. Phase separation of hard and soft segments significantly varied depending on the type and molecular weight of diol and triol. Films containing urethane‐urea bonds displayed the maximum phase separation and the highest mechanical strength. Polyols having higher molecular weight increased hydrophilicity while urea bonds caused a reverse effect resulted by bidentate hydrogen bonds. Results showed PUs with various properties can be synthesized via environmentally friendly process without using any solvent or catalyst. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 39758.
A redox‐mediator‐doped gel polymer electrolyte applied in quasi‐solid‐state supercapacitors
Authors: Yu Fuda , Huang Miaoliang , Wu Jihuai , Qiu Zhaoyuan , Fan Leqing , Lin Jianming , Lin Yibing 
Published: August 2013

ABSTRACTMethylene blue (MB) redox mediator was introduced into polyvinyl alcohol/polyvinyl pyrrolidone (PVA/PVP) blend host to prepare a gel polymer electrolyte (PVA‐PVP‐H2SO4‐MB) for a quasi‐solid‐state supercapacitor. The electrochemical properties of the supercapacitor with the prepared gel polymer electrolyte were evaluated by cyclic voltammetry, galvanostatic charge–discharge, electrochemical impedance spectroscopy, and self‐discharge measurements. With the addition of MB mediator, the ionic conductivity of gel polymer electrolyte increased by 56% up to 36.3 mS·cm−1, and the series resistance reduced, because of the more efficient ionic conduction and higher charge transfer rate, respectively. The electrode specific capacitance of the supercapacitor with PVA‐PVP‐H2SO4‐MB electrolyte is 328 F·g−1, increasing by 164% compared to that of MB‐undoped system at the same current density of 1 A·g−1. Meanwhile, the energy density of the supercapacitor increases from 3.2 to 10.3 Wh·kg−1. The quasi‐solid‐state supercapacitor showed excellent cyclability over 2000 charge/discharge cycles. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 39784.
Designing oligomeric ethylene terephtalate building blocks by chemical recycling of polyethylene terephtalate
Authors: Geyer Björn , Röhner Stefan , Lorenz Günter , Kandelbauer Andreas 
Published: August 2013

ABSTRACTThe intelligent recycling of plastics waste is a major concern. Because of the widespread use of polyethylene terephtalate, considerable amounts of PET waste are generated that are ideally re‐introduced into the material cycle by generating second generation products without loss of materials performance. Chemical recycling methods are often expensive and entail environmentally hazardous by‐products. Established mechanical methods generally provide materials of reduced quality, leading to products of lower quality. These drawbacks can be avoided by the development of new recycling methods that provide materials of high quality in every step of the production cycle. In the present work, oligomeric ethylene terephthalate with defined degrees of polymerization and defined molecular weight is produced by melt‐mixing PET with different quantities of adipic acid as an alternative pathway of recycling PET with respect to conventional methods, offering ecofriendly and economical aspects. Additionally, block‐copolyesters of defined block length are designed from the oligomeric products. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 39786.
Multimethod Geophysical Survey at the Iron Age Iberian Site of El Molí d'Espígol (Tornabous, Lleida, Catalonia): Exploring Urban Mesh Patterns Using Geophysics
Authors: Sala Roger , Principal Jordi , Olmos Pau , Tamba Robert , Garcia Ekhine 
Published: August 2013

ABSTRACTThis paper presents the results of a multisystem survey using magnetometry and dual frequency ground‐penetrating radar (GPR) carried out at the Iron Age Iberian site of El Molí d'Espígol, Tornabous, Catalonia, dated from the seventh to third centuries bce. The surroundings of the current urban area were explored with magnetometry in order to describe possible features related to the settlement. In the non‐excavated part of the urban area was surveyed by GPR in order to describe the urban mesh. The interpretation of the data has allowed not only the identification of new areas of archaeological interest and priority action, but also the proposal of a new hypotheses on the evolution of the town planning and the defensive system of the site. Copyright © 2013 John Wiley & Sons, Ltd.
Estimation of convective precipitation mass from lightning data using a temporal sliding‐window for a series of thunderstorms in Southeastern Brazil
Authors: Garcia João V. C. , Stephany Stephan , d'Oliveira Augusto B. 
Published: August 2013

AbstractSome studies have proposed the estimation of convective rainfall from lightning observations by the computation of the rainfall–lightning ratio (RLR). However, as such ratio may depend on season, convective regime and other factors, known approaches failed to provide values of RLR with low variability. An accurate RLR would allow estimating rainfall from lightning data in areas that lack weather radar coverage. This work proposes a straightforward approach for the computation of RLR, based on a temporal sliding‐window and a fitting function. It was tested for thunderstorms observed in the Southeastern Brazil with good results.
Les mystères du point critique
Authors: Yvon Jacques 
Published: August 2013

AbstractCette introduction au programme de la conférence sur les phénomènes critiques propose une définition expérimentale de la région critique. Un rappel des résultats de l'étude thermostatique traditionnelle précède la présentation qualitative des singularités qui ont été mises en évidence ces dernières années, ce qui conduit à revoir, mais en partie seulement, les conceptions théoriques. Au cœur même de la région critique, des effets de type capillaire viennent troubler l'observation de milieux qui autrement présentent des phases homogènes. Les phénomènes dynamiques — écoulement, transfert de chaleur, diffusion des rayons X, de la lumière, des neutrons — révèlent de nouvelles singularités. Ces phénomènes suscitent un très vif intérêt. Les résultats en fonction de la température sont exprimés dans chaque cas à l'aide d'un repère qui est la “température critique”: il serait souhaitable que ce repère soit défini avec moins d'arbitraire qu'actuellement.
Tunnelling Processes at Highly Doped ZnO‐Electrodes in Aqueous Electrolytes Part II: Electron Exchange with the Valence Band
Authors: Pettinger B. , Schöppel H.‐R. , Yokoyama T. , Gerischer H. 
Published: August 2013

AbstractHighly doped ZnO‐electrodes show a blocking region of only about 3 V. Above this region anodic breakdown currents set in which rise steeply with increasing potentials. The currents are attributed to the generation of holes by field emission of valence electrons into the conduction band. The generation of holes is shown by surface reactions, like the oxidative lattice decomposition, or by the current multiplication in particular oxidation reactions of organic substances which are well known as being caused by holes. Another indication of hole generation is the light emission during anodic breakdown currents caused by recombination of holes with electrons.On the polar ZnO surfaces (〈0001〉 and 〈0001〉 surface) considerable differences are observed in the anodic currents and in the composition of reaction products.