bluuebunny/crossref_metadata_2025_split huggingface dataset:
Chlorinated Biphenyls [MAK Value Documentation, 2013]
Authors: Hartwig A. ,   MAK Commission
Published: April 2016

Toxic Effects and Mode of ActionMechanism of ActionToxicokinetics and MetabolismAbsorption, distribution and eliminationMetabolismEffects in HumansSingle exposuresRepeated exposureLocal effects on skin and mucous membranesAllergenic effectsReproductive and developmental toxicityGenotoxicityCarcinogenicityAnimal Experiments and in vitro StudiesAcute toxicitySubacute, subchronic and chronic toxicityLocal effects on skin and mucous membranesAllergenic effectsReproductive and developmental toxicityGenotoxicityCarcinogenicityManifesto (MAK value/classification)
Gold‐Catalyzed Cyclizations of Alkynyl Silyl Enol Ethers: An Easy Access to Bicyclo[3.2.1]octanone Derivatives
Authors: Carrër Amandine , Péan Christophe , Perron‐Sierra Françoise , Mirguet Olivier , Michelet Véronique 
Published: April 2016

AbstractThe efficient gold‐catalyzed cyclization reactions of alkynyl silyl enol ethers were successfully applied to the preparation of bicyclo[3.2.1]octanone derivatives. Accordingly, after optimization of the gold catalytic system, several bicyclic α,β‐unsaturated keto adducts were synthesized in good to excellent yields. The process followed a major 5‐exo cyclization via an anti addition of the silyl enol ether to the π‐activated intermediate, which was demonstrated by a deuterium incorporation experiment. A 6‐endo cyclization process was observed for a silyl enol ether bearing an electron‐donating aromatic group.magnified image
Efficient Modular Synthesis of Isomeric Mono‐ and Bispyridyl[2.2]paracyclophanes by Palladium‐Catalyzed Cross‐ Coupling Reactions
Authors: Braun Carolin , Spuling Eduard , Heine Niklas B. , Cakici Murat , Nieger Martin , Bräse Stefan 
Published: April 2016

AbstractPyridyl‐substituted [2.2]paracyclophanes build a multifunctional structural motif that is useful in material chemistry, catalysis and for luminescent structures. Nonetheless, there is still a lack of general methods for the synthesis of these structures tolerating easily accessible bromides as well as different isomeric pyridyl groups. Hence the coupling of functionalized [2.2]paracyclophanes with various substituted and functionalized pyridyl derivatives was achieved using Stille, Suzuki and Kumada coupling conditions. Hereby the Stille coupling of a [2.2]paracyclophane is presented as a versatile reaction for the formation of heteromeric [2.2]paracyclophane‐containing biaryl structures.magnified image
Gold Functionalized Platinum M12L24‐Nanospheres and Their Application in Cyclization Reactions
Authors: Leenders Stefan H. A. M. , Dürr Maximillian , Ivanović‐Burmazović Ivana , Reek Joost N. H. 
Published: April 2016

AbstractNanospheres can be formed by combining 24 bispyridinyl building blocks with a palladium or platinum precursor. These spheres can be functionalized on the inside with a gold(I) chloride complex leading to a high local concentration of gold(I) complexes. The high local concentration makes the neutral gold species an active catalyst. Furthermore, the platinum‐gold spheres can be post‐modified with a silver(I) salt to form cationic gold(I) catalysts. The platinum assemblies are demonstrated to be stable in the presence of various substrates and as a result several cyclization reactions have been carried out using these new spheres as catalysts. Higher conversions in a [4+2] cycloaddition are observed for the sphere catalyst compared to the mono‐nuclear analogues. Also the cyclization of 1,6‐enynes can be facilitated by the confined gold catalyst and high activity is observed in the activation of allenes. For the lactonization of alkynoic acids, a different selectivity is observed compared to a standard gold(I) complex, demonstrating that the high local concentration due to a confined space can induce other selectivity in catalysis.magnified image
Gold‐Catalyzed Imination/Mannich Reaction Cascades of 3‐En‐1‐ynamides with Anilines and Aldehydes to Enable 1,5‐Nitrogen Functionalizations
Authors: Singh RahulKumar Rajmani , Liu Rai‐Shung 
Published: April 2016

AbstractGold‐catalyzed imination/Mannich reaction cascades on readily available 3‐en‐1‐ynamides enable the diastereoselective synthesis of 1,5‐iminoamino compounds in a one‐pot operation. The reactions work well with diversified 3‐en‐1‐ynamides, aldehydes and anilines with good to excellent diastereoselectivities. Our control experiments indicate gold‐catalyzed aminations of 3‐en‐1‐ynamides to yield α‐imino allylgold intermediates that react subsequently with iminiums to implement the Mannich reactions stereoselectively. The reactions proceed with anti‐selectivity for those 3‐en‐1‐ynamides bearing acyclic alkenes whereas syn‐selectivity is seen for their cycloalkene‐based analogues. An open‐transition state can satisfactorily rationalize these observed stereoselectivities based on an antiperiplanar conformation.magnified image
Design and Synthesis of Alanine Triazole Ligands and Application in Promotion of Hydration, Allene Synthesis and Borrowing Hydrogen Reactions
Authors: Yang Yongchun , Qin Anni , Zhao Keyan , Wang Dawei , Shi Xiaodong 
Published: April 2016

AbstractA new type of alanine triazole (ATA) ligand was found to be an efficient partner for the stabilization of gold(III), thus rendering improved stability and high catalytic activities in allene synthesis and hydration reactions through the 3,3′‐arrangement of propargyl esters and propargyl alcohols. In addition to Au(I), ATA‐gold(III) was also proven to be an effective catalyst in promoting the formation of allenes with high yields. Furthermore, alanine triazole ruthenium has exhibited excellent potential as a means to catalyze borrowing hydrogen of alcohols and amines, ketones and alcohols.magnified image
Mild and Functional Group Tolerant Method for Tandem Palladium‐Catalyzed Carbocyclization–Coupling of ε‐Acetylenic β‐Ketoesters with Aryl Bromides and Chlorides
Authors: Chaładaj Wojciech , Domański Sylwester 
Published: April 2016

AbstractWe report a new protocol for the annulative difunctionalization of acetylenes via tandem carbocyclization–coupling of ε‐acetylenic β‐ketoesters with aryl and heteroaryl bromides and chlorides catalyzed by the palladium species derived from an air‐ and moisture‐stable palladacyclic precatalyst. In the tandem process, the palladium complex combines appropriate carbophilic Lewis acidity and redox activity to catalyze two mechanistically distinct reactions ‐ nucleophilic addition of the enolate to unactivated alkyne, followed by CC coupling.We found that a broad range of electronically varied aryl and heteroaryl bromides and chlorides underwent this reaction with various ε‐acetylenic β‐ketoesters, providing corresponding substituted vinylidenecyclopentanes in high yield with excellent functional group tolerance.magnified image
P450 BM3 Monooxygenase as an Efficient NAD(P)H‐Oxidase for Regeneration of Nicotinamide Cofactors in ADH‐Catalysed Preparative Scale Biotransformations
Authors: Holec Claudia , Neufeld Katharina , Pietruszka Jörg 
Published: April 2016

AbstractEnzymatic oxidations of primary and secondary alcohols catalysed by nicotinamide dependent alcohol dehydrogenases on the preparative scale require cofactor regeneration systems. Of critical value from an economic and ecological perspective is the application of NAD(P)H‐oxidases, which utilise molecular oxygen as a cost‐effective, atom‐efficient and environmentally benign oxidant to regenerate the cofactor NAD(P)+. Herein, the P450 BM3 monooxygenase from Bacillus megaterium is presented as an NAD(P)H‐oxidase for the successful regeneration of both NADP+ and NAD+ on the preparative scale. This enzyme was exemplarily applied for ADH‐catalysed oxidative kinetic resolutions of racemic secondary alcohols and the desymmetrisation of a meso‐diol leading to enantiomerically enriched secondary alcohols in both cases. Furthermore, the ADH‐catalysed oxidation of a primary alcohol targeting the corresponding aldehyde was performed. The obtained results significantly broaden the scope of feasible oxidative biotransformations, thereby increasing the number of synthetic reactions complying with key challenges of a modern and sustainable chemistry such as mild reaction conditions, environmentally benign solvents, and biodegradable non‐toxic catalysts.magnified image
Synthesis and Anti‐HIV Activity of 5′‐Homo‐2′,3′‐dideoxy‐2′,3′‐didehydro‐4′‐selenonucleosides (5′‐Homo‐4′‐Se‐d4 Ns)
Authors: Qu Shuhao , Kim Gyudong , Yu Jinha , Sahu Pramod K. , Choi Yoojin , Naik Siddhi D. , Jeong Lak Shin 
Published: April 2016

AbstractOn the hypothesis that one carbon homologation of 4′‐selenonucleosides might relieve the steric repulsion between cellular kinases and bulky selenium, 5′‐homo‐4′‐Se‐d4Ns, 3 a–e, as anti‐HIV agents were designed and synthesized stereoselectively from d‐gulonic γ‐lactone, with the conversion of 2′,3′‐diol into the olefin as the key step. The anti‐HIV activity of all synthesized compounds, 5′‐homo‐4′‐Se‐d4Ns, was toxicity‐dependent, unlike normal 4′‐Se‐d4Ns, which were inactive against HIV‐1. This result indicates that 5′‐homo‐4′‐Se‐d4Ns might be phosphorylated by cellular kinases as per the hypothesis.
Biosensitive Kontrastmittel für die Magnetresonanztomographie – was wir mit ihnen wirklich tun können
Authors: Angelovski Goran 
Published: April 2016

AbstractBiosensitive MRT‐Kontrastmittel sind sehr vielversprechend, lassen sich doch mit ihnen wichtige physiologische und pathologische Prozesse nichtinvasiv überwachen. Sie sind in der Lage, durch Veränderungen in ihrer Mikroumgebung das MRT‐Signal abzuwandeln, sodass sich Funktionen in lebenden Organismen in Echtzeit verfolgen lassen. Die Chemie bietet uns diverse Lösungen für die Konstruktion solcher Kontrastmittel an, die auf eine große Zahl spezifischer Ziele reagieren. Der Weg zur Nutzung dieser Biomarker in den gewünschten funktionellen MRT‐Studien erfordert jedoch eine Berücksichtigung mehrerer wissenschaftlicher, technischer und praktischer Aspekte über unterschiedliche Forschungsdisziplinen hinweg. Dieser Kurzaufsatz bietet einen Überblick über die entscheidenden Schritte bei der Planung und Ausführung solcher multidisziplinären Projekte, die darauf zielen, unser Wissen über die grundlegenden biologischen Prozesse zu vertiefen.
Enantioselective Synthesis of Cyclobutylboronates via a Copper‐Catalyzed Desymmetrization Approach
Authors: Guisán‐Ceinos Manuel , Parra Alejandro , Martín‐Heras Víctor , Tortosa Mariola 
Published: April 2016

AbstractThe first catalytic enantioselective synthesis of cyclobutylboronates, by using a chiral copper(I) complex, is reported. A broad variety of cyclobutanes have been prepared with consistently high levels of diastereo‐ and enantiocontrol. Moreover, this method constitutes the first report of an enantioselective desymmetrization of meso‐cyclobutenes to prepare chiral cyclobutanes.
Coupling of the Decarboxylation of 2‐Cyano‐2‐phenylpropanoic Acid to Large‐Amplitude Motions: A Convenient Fuel for an Acid–Base‐Operated Molecular Switch
Authors: Berrocal José Augusto , Biagini Chiara , Mandolini Luigi , Di Stefano Stefano 
Published: April 2016

AbstractThe decarboxylation of 2‐cyano‐2‐phenylpropanoic acid is fast and quantitative when carried out in the presence of 1 molar equivalent of a [2]catenane composed of two identical macrocycles incorporating a 1,10‐phenanthroline unit in their backbone. When decarboxylation is over, all of the catenane molecules have experienced large‐amplitude motions from neutral to protonated catenane, and back again to the neutral form, so that they are ready to perform another cycle. This study provides the first example of the cyclic operation of a molecular switch at the sole expenses of the energy supplied by the substrate undergoing chemical transformation, without recourse to additional stimuli.
The influence of bus service satisfaction on university students' mode choice
Authors: Shaaban Khaled , Kim Inhi 
Published: April 2016

SummaryThe purpose of this study was to determine the relationship between bus service satisfaction and the transport mode of choice among university students in Qatar. The degree of bus service satisfaction was collected directly from questionnaire surveys, in which university students were asked questions in relation to their satisfaction with the bus service they used and their transport mode of choice. These questions were categorized into three factors according to confirmatory factor analysis: service at bus stops, service of busses, and service of drivers. Furthermore, the students were asked which mode of transport they used given the choice between public and private transport. This study presents a structural equation model to determine how much bus service satisfaction affects people's decisions about their transport mode. The results from the analysis showed that three key factors—namely, service at bus stops, service of busses, and service of bus drivers—were strongly correlated to the mode of choice. In particular, the bus stop was strongly associated with ease of use, shade, cleanliness, safety, and crowdedness level, while the bus itself influenced reliability, travel time, and frequency. Complying with traffic laws and the driver's attitude were also important contributors to the level of bus service satisfaction. Ultimately, this study will be beneficial for policy/decision‐makers. It will allow them to determine what needs to be accomplished to encourage people to use public transportation. Copyright © 2016 John Wiley & Sons, Ltd.
Improving the Specific Capacity and Cyclability of Sodium‐Ion Batteries by Engineering a Dual‐Carbon Phase‐Modified Amorphous and Mesoporous Iron Phosphide
Authors: Han Fei , Tan Clara Yi Jun , Gao Zhiqiang 
Published: April 2016

AbstractBased on the concept of the nanoconfinement reaction, a synthetic strategy is developed to construct carbon‐coated iron phosphide (FeP) with an amorphous and mesoporous framework anchored on carbon nanotubes (CNTs). The synthesis involves direct growth of FeOOH on the CNTs followed by silica coating, carbon coating, and subsequent treatments of low‐temperature phosphidation and silica removal procedures. During the synthesis, the silica layer is adopted to not only serve as a sacrificial internal spacer to increase the mesoporosity (311 m2 g−1 and 0.36 cm3 g−1) of the FeP framework, but also to provide a confined environment in guiding the structural evolution of the homogenous/conformal framework and topologically amorphous nature of FeP. When used as an anode material in sodium‐ion batteries (SIBs), the FeP‐based electrode shows a utilization rate of 78 % for the active material and a reversible capacity of 415 mAhg−1. Even at a higher current density of 500 mAg−1, a capacity retention rate of 90 % over 500 cycles is obtained with a capacity‐decay rate of only 0.02 % per cycle. The much improved performance of the FeP‐based electrode in SIBs clearly demonstrates the potential of FeP to be used as the anode material in SIBs when it is engineered in a nanoconfinement environment to overcome its structural constraints. In principle, this strategy can be adapted to engineer other transition‐metal phosphide‐based materials for energy‐storage applications.
Vitamin B12 Phosphate Conjugation and Its Effect on Binding to the Human B12‐Binding Proteins Intrinsic Factor and Haptocorrin
Authors: Ó Proinsias Keith , Ociepa Michał , Pluta Katarzyna , Chromiński Mikołaj , Nexo Ebba , Gryko Dorota 
Published: April 2016

AbstractThe binding of vitamin B12 derivatives to human B12 transporter proteins is strongly influenced by the type and site of modification of the cobalamin original structure. We have prepared the first cobalamin derivative modified at the phosphate moiety. The reaction conditions were fully optimized and its limitations examined. The resulting derivatives, particularly those bearing terminal alkyne and azide groups, were isolated and used in copper‐catalyzed alkyne–azide cycloaddition reactions (CuAAC). Their sensitivity towards light revealed their potential as photocleavable molecules. The binding abilities of selected derivatives were examined and compared with cyanocobalamin. The interaction of the alkylated derivatives with haptocorrin was less affected than the interaction with intrinsic factor. Furthermore, the configuration of the phosphate moiety was irrelevant to the binding process.
Ferrous Iron Binding Key to Mms6 Magnetite Biomineralisation: A Mechanistic Study to Understand Magnetite Formation Using pH Titration and NMR Spectroscopy
Authors: Rawlings Andrea E. , Bramble Jonathan P. , Hounslow Andrea M. , Williamson Michael P. , Monnington Amy E. , Cooke David J. , Staniland Sarah S. 
Published: April 2016

AbstractFormation of magnetite nanocrystals by magnetotactic bacteria is controlled by specific proteins which regulate the particles’ nucleation and growth. One such protein is Mms6. This small, amphiphilic protein can self‐assemble and bind ferric ions to aid in magnetite formation. To understand the role of Mms6 during in vitro iron oxide precipitation we have performed in situ pH titrations. We find Mms6 has little effect during ferric salt precipitation, but exerts greatest influence during the incorporation of ferrous ions and conversion of this salt to mixed‐valence iron minerals, suggesting Mms6 has a hitherto unrecorded ferrous iron interacting property which promotes the formation of magnetite in ferrous‐rich solutions. We show ferrous binding to the DEEVE motif within the C‐terminal region of Mms6 by NMR spectroscopy, and model these binding events using molecular simulations. We conclude that Mms6 functions as a magnetite nucleating protein under conditions where ferrous ions predominate.
Total Synthesis and Complete Stereostructure of a Marine Macrolide Glycoside, (−)‐Lyngbyaloside B
Authors: Fuwa Haruhiko , Yamagata Naoya , Okuaki Yuta , Ogata Yuya , Saito Asami , Sasaki Makoto 
Published: April 2016

AbstractWe have described in detail the total synthesis of both the proposed and correct structures of (−)‐lyngbyaloside B, which facilitated the elucidation of the complete stereostructure of this natural product. Our study began with the total synthesis of 13‐demethyllyngbyaloside B, in which an esterification/ring‐closing metathesis (RCM) strategy was successfully used for the efficient construction of the macrocycle. We also established reliable methods for the introduction of the conjugated diene side chain and the l‐rhamnose residue onto the macrocyclic framework. However, the esterification/RCM strategy proved ineffective for the parent natural product because of the difficulties in acylating the sterically encumbered C‐13 tertiary alcohol; macrolactionization of a seco‐acid was also extensively investigated under various conditions without success. We finally completed the total synthesis of the proposed structure of (−)‐lyngbyaloside B by means of a macrolactonization that involves an acyl ketene as the reactive species. However, the NMR spectroscopic data of our synthetic material did not match those of the authentic material, which indicated that the proposed structure must be re‐examined. Inspection of the NMR spectroscopic data of the natural product and molecular mechanics calculations led us to postulate that the configuration of the C‐10, C‐11, and C‐13 stereogenic centers had been incorrectly assigned in the proposed structure. Finally, our revised structure of (−)‐lyngbyaloside B was unambiguously verified through total synthesis.
Singly Bonded Monoadduct rather than Methanofullerene: Manipulating the Addition Pattern of Trimetallic Nitride Clusterfullerene through One Endohedral Metal Atom Substitution
Authors: Wang Song , Huang Jing , Gao Congli , Jin Fei , Li Qunxiang , Xie Suyuan , Yang Shangfeng 
Published: April 2016

AbstractBingel–Hirsch reactions of trimetallic nitride clusterfullerenes (NCFs) generally yield methanofullerene (cyclopropane) adducts instead of singly bonded derivatives, which have been reported for monometallofullerenes. Herein, we report the synthesis and characterization of the Bingel–Hirsch derivative of a mixed metal nitride clusterfullerene (MMNCF) TiY2N@Ih‐C80. Surprisingly, in contrast to the reported Bingel–Hirsch cyclopropane adducts of the analogous NCF Y3N@Ih‐C80, the Bingel–Hirsch derivative of TiY2N@Ih‐C80 is the first singly bonded monoadduct (labeled as TiY2N@C80‐Mono) to be reported, which was determined unambiguously by single‐crystal X‐ray crystallography. Besides, the reactivity of TiY2N@Ih‐C80 was found to be significantly improved relative to that of Y3N@Ih‐C80. Upon substituting one endohedral yttrium (Y) atom of Y3N@Ih‐C80 with titanium (Ti), the Bingel–Hirsch derivative changes from the cyclopropane to the singly bonded monoadduct, revealing that not only the reactivity but also the addition pattern of NCFs can be manipulated simultaneously through one endohedral metal atom substitution.
ChemInform Abstract: THE POTASSIUM FLUORIDE‐BORIC ACID SYSTEM. HYDROGEN BONDING IN KF.H3BO3
Authors: EMSLEY J. , GOLD V. , LUCAS J. , OVERILL R. 
Published: April 2016

AbstractAus ab initio‐LCAO‐MO‐SCF‐Berechnungen zu den wahrscheinlichsten Wechselwirkungen zwischen F‐ und H3BO3 geht hervor, daß das Ion [BF(OH)3]‐ das stabilste ist, jedoch relativ zum H‐Bindungssystem F‐...HOB(OH)2 nur um 33 kJ mol‐1.
ChemInform Abstract: MAGNETOCHEMICAL SERIES FOR LANTHANOID COMPOUNDS
Authors: URLAND W. 
Published: April 2016

AbstractDie Magnetochemie ermöglicht Aussagen zur chemischen Bindung in Lanthanoidverbindungen wie NT‐CsTmOz , Cs, KPrFÖ, CS2 LiTmIÖ oder auch CszNaYbFö.
ChemInform Abstract: STRUCTURES IN THE TIN DIFLUORIDE‐TRIFLUOROBORANE SYSTEM
Authors: BOENISCH J. + , BERGERHOFF G. 
Published: April 2016

AbstractIn MeCN als Lösungsmittel erhält man aus SnFz und BF3Me2O die Phasen (I)‐(IV) (NMR‐Spektren).
ChemInform Abstract: RESIDUAL STRESS IN SINGLY AND DOUBLY ION‐EXCHANGED GLASS
Authors: SHAISHA E. E. , COOPER A. R. 
Published: April 2016

AbstractDie aus photoelastischen Messungen an mit Unterstützung eines elektrischen Feldes ionenausgetauschten Kronglasröhren ermittelten Restspannungen sind nicht zeitabhängig, nehmen jedoch mit sinkender Austauschtemp.
ChemInform Abstract: EFFECT OF THE NATURE OF AN ALKALINE EARTH CATION ON THE EVOLUTION OF ELECTRICAL PROPERTIES OF FERRITES A2LAFE3O8+X (A = CALCIUM, STRONTIUM, BARIUM)
Authors: ABOU SEKINA M. , BONNET J.‐P. , GRENIER J.‐C. , ONILLON M. , POUCHARD M. , HAGENMULLER P. 
Published: April 2016

AbstractDie elektrische Leitfähigkeit (o) der Ferrite (die Proben werden aus den Oxiden bei 1350°C dargestellt und nach dem Tempern bei 700‐1350°C abgeschreckt) wird in Abhängigkeit von der Temperatur (‐l 50 ‐ +100°C) und (bei 1000°C) vom O2‐Partialdruck (l0′" ‐l at ) gemessen.
ChemInform Abstract: MAGNETIC PROPERTIES OF PHASES OF NA3M2(PO4)3 (M = TITANIUM, VANADIUM, CHROMIUM, IRON)
Authors: BELTRAN PORTER D. , OLAZCUAGA R. , DELMAS C. , CHERKAOUI F. , BROCHU R. , LE FLEM G. 
Published: April 2016

AbstractDie Titelverbindungen zeigen bei tiefen Temperaturen antiferromagnetisches Verhalten, eine schwache ferromagnetische Komponente weist allein Na3Fe2(PO4)3 auf (Suszeptibilitätsmessungen im Bereich 4.2‐300 K).
ChemInform Abstract: MECHANISM OF THE AZIDE‐BROMINE REACTION IN AQUEOUS MEDIUM
Authors: VIVEKANANDAM T. S. , SINGH U. C. , RAMACHANDRAN M. S. 
Published: April 2016

AbstractDie Geschwindigkeit der gasvolumetrisch verfolgten Reaktion A ist proportional [N5] und [Brz] und die Reaktion zeigt einen positiven Salzeffekt.
ChemInform Abstract: ON THE SYNTHESIS AND PROPERTIES OF HYDRAZINIUM(1+) FLUORIDE
Authors: GLAVIC P. , SLIVNIK J. 
Published: April 2016

AbstractHydrazinmonohydrogenfluorid (II) läßt sich durch Umsetzung von Hydrazinhydrat mit 50%iger Flußsäure und Vakuumverdampfung des Lösungsmittels bei niedrigen Temperaturen herstellen.