bluuebunny/crossref_metadata_2025_split huggingface dataset:
Direct Nucleophilic Substitution Reaction of Cage B−H Bonds by Grignard Reagents: A Route to Regioselective B4‐Alkylation of o‐Carboranes
Authors: Tang Cen , Zhang Jiji , Xie Zuowei 
Published: May 2017

AbstractDirect nucleophilic substitution reaction of cage B−H bonds of o‐carboranes by Grignard reagents in the absence of any transition metals has been achieved for the first time, and leads to the regioselective synthesis of a series of 4‐alkyl‐1,2‐diaryl‐o‐carboranes in very high yields. The presence of two electron‐withdrawing aryl groups on the cage carbon atoms is crucial to realizing the reaction. The regioselectivity is controlled by both electronic and steric factors. This work represents a new strategy for the development of methods for carborane functionalization.
Deprotonation of a Seemingly Hydridic Diborane(6) To Build a B−B Bond
Authors: Kaese Thomas , Budy Hendrik , Bolte Michael , Lerner Hans‐Wolfram , Wagner Matthias 
Published: May 2017

AbstractDeprotonation of the doubly arylene‐bridged diborane(6) derivative 1H2 with (Me3Si)3CLi or (Me3Si)2NK gives the B−B σ‐bonded species M[1H] in essentially quantitative yields (THF, room temperature; M=Li, K, arylene=4,4′‐di‐tert‐butyl‐2,2′‐biphenylylene). With nBuLi as the base, the yield of Li[1H] drops to 20 % and the 1,1‐bis(9‐borafluorenyl)butane Li[2H] is formed as a side product (30 %). In addition to the 1,1‐butanediyl fragment, the two boron atoms of Li[2H] are linked by a μ‐H bridge. In the closely related molecule Li[3H], the corresponding μ‐H atom can be abstracted with (Me3Si)3CLi to afford the B−B‐bonded conjugated base Li2[3] (THF, 150 °C; 15 %). Li[1H] and Li[2H] were characterized by NMR spectroscopy and X‐ray crystallography.
A Structurally Characterized Fluoroalkyne
Authors: Hall Lewis M. , Tew David P. , Pridmore Natalie E. , Whitwood Adrian C. , Lynam Jason M. , Slattery John M. 
Published: May 2017

AbstractThe facile synthesis of a stable and isolable compound with a fluoroalkynyl group, M−C≡CF, is reported. Reaction of [Ru(C≡CH)(η5‐C5Me5)(dppe)] with an electrophilic fluorinating agent (NFSI) results in the formation of the fluorovinylidene complex [Ru(=C=CHF)(η5‐C5Me5)(dppe)][N(SO2Ph)2]. Subsequent deprotonation with LiN(SiMe3)2 affords the fluoroalkynyl complex [Ru(C≡CF)(η5‐C5Me5)(dppe)]. In marked contrast to the rare and highly reactive examples of fluoroalkynes that have been reported previously, this compound can be readily isolated and structurally characterized. This has allowed the structure and bonding in the CCF motif to be explored. Further electrophilic fluorination of this species yields the difluorovinylidene complex [Ru(C=CF2)(η5‐C5Me5)(dppe)][N(SO2Ph)2].
Morphologische Kontrolle von heteroleptischen cis‐ und trans‐Pd2L2L′2‐Käfigen
Authors: Bloch Witold M. , Holstein Julian J. , Hiller Wolf , Clever Guido H. 
Published: May 2017

AbstractDie kontrollierte integrative Selbstsortierung metallosupramolekularer Strukturen eröffnet Möglichkeiten, mehr Komplexität und Funktion in eine einzelne selbstassemblierte Struktur einzuführen. Wir klären hier die Beziehung zwischen der Geometrie von drei Ligandkomponenten und der Morphologie von drei selbstsortierten heteroleptischen [Pd2L2L′2]4+‐Käfigen auf. So ergibt die Pd‐vermittelte Assemblierung von zwei doppelt‐einzähnigen Pyridyl‐Liganden mit einem nativen Bisswinkel von 75° und 120° einen cis‐[Pd2L2L′2]4+‐Käfig, wohingegen die gleiche Reaktion von zwei Liganden mit Bisswinkeln von 75° und 60° den letzteren Liganden in eine anti‐Konformation zwingt. Dies führt zu einem heteroleptischen trans‐[Pd2(anti‐L)2L′2]4+‐Käfig mit der Topologie einer “zweifach verbrückten Acht”. Jede der heteroleptischen Strukturen ist durch eine Käfig‐zu‐Käfig‐Umwandlung ihrer homoleptischen Vorstufen zugänglich. Die Morphologie der [Pd2L2L′2]‐Käfige kann durch selektiven Ligandenaustausch gezielt gesteuert werden.
A Membrane‐Free Neutral pH Formate Fuel Cell Enabled by a Selective Nickel Sulfide Oxygen Reduction Catalyst
Authors: Yan Bing , Concannon Nolan M. , Milshtein Jarrod D. , Brushett Fikile R. , Surendranath Yogesh 
Published: May 2017

AbstractPolymer electrolyte membranes employed in contemporary fuel cells severely limit device design and restrict catalyst choice, but are essential for preventing short‐circuiting reactions at unselective anode and cathode catalysts. Herein, we report that nickel sulfide Ni3S2 is a highly selective catalyst for the oxygen reduction reaction in the presence of 1.0 m formate. We combine this selective cathode with a carbon‐supported palladium (Pd/C) anode to establish a membrane‐free, room‐temperature formate fuel cell that operates under benign neutral pH conditions. Proof‐of‐concept cells display open circuit voltages of approximately 0.7 V and peak power values greater than 1 mW cm−2, significantly outperforming the identical device employing an unselective platinum (Pt) cathode. The work establishes the power of selective catalysis to enable versatile membrane‐free fuel cells.
Selektive, narzisstische Selbstsortierung bei der Synthese von metallorganischen Strukturen mit Poly‐NHC‐Liganden
Authors: Sinha Narayan , Tan Tristan T. Y. , Peris Eduardo , Hahn F. Ekkehardt 
Published: May 2017

AbstractNarzisstische Selbstsortierung wurde bei der Eintopfsynthese von drei metallorganischen molekularen Zylindern des Typs [M3{L‐(NHC)3}2](PF6)3 (M=Ag+, Au+; L=Benzol, Triphenylamin oder 1,3,5‐Triphenylbenzol) ausgehend von L‐(NHC)3 und Silber(I)‐ oder Gold(I)‐Ionen beobachtet. Die molekularen Zylinder enthalten stets nur einen Typ der Tris‐NHC‐Liganden, ohne dass Heteroligand‐Verbindungen zu detektieren sind. Die Transmetallierung der Tris‐NHC‐Liganden von Ag+ auf Au+ in einer Eintopfreaktion verläuft unter Erhaltung der supramolekularen Strukturen. Selbstsortierung wurde auch bei der Eintopfreaktion von Benzol‐verbrückten Tris‐ und Tetrakis‐NHC‐Liganden mit Ag2O beobachtet. Die vorliegende Studie überträgt erstmals narzisstische Selbstsortierung von Metall‐Ligand‐Wechselwirkungen in Werner‐Komplexen auf metallorganische Derivate.
Gold‐Catalyzed Cadiot–Chodkiewicz‐type Cross‐Coupling of Terminal Alkynes with Alkynyl Hypervalent Iodine Reagents: Highly Selective Synthesis of Unsymmetrical 1,3‐Diynes
Authors: Li Xiangdong , Xie Xin , Sun Ning , Liu Yuanhong 
Published: May 2017

AbstractA new and efficient method for the synthesis of unsymmetrical 1,3‐butadiynes by gold‐catalyzed C(sp)–C(sp) cross‐coupling of terminal alkynes with alkynyl hypervalent iodine(III) reagents has been developed. The reaction features high selectivity and efficiency, mild reaction conditions, wide substrate scope, and functional‐group compatibility, and is a highly attractive complement to existing methods. Mechanistic studies reveal that formation of a phenanthrolinyl‐ligated gold(I) complex is crucial for the efficiency and selectivity of the target transformation.
Synthesis of Aldehydes by Organocatalytic Formylation Reactions of Boronic Acids with Glyoxylic Acid
Authors: Huang He , Yu Chenguang , Li Xiangmin , Zhang Yongqiang , Zhang Yueteng , Chen Xiaobei , Mariano Patrick S. , Xie Hexin , Wang Wei 
Published: May 2017

AbstractReported herein is a conceptually novel organocatalytic strategy for the formylation of boronic acids. New reactivity is engineered into the α‐amino‐acid‐forming Petasis reaction occurring between aryl boronic acids, amines, and glyoxylic acids to prepare aldehydes. The operational simplicity of the process and its ability to generate structurally diverse and valued aryl, heteroaryl, and α,β‐unsaturated aldehydes containing a wide array of functional groups, demonstrates the practical utility of the new synthetic strategy.
From Extended Nanofluidics to an Autonomous Solar‐Light‐Driven Micro Fuel‐Cell Device
Authors: Pihosh Yuriy , Uemura Jin , Turkevych Ivan , Mawatari Kazuma , Kazoe Yutaka , Smirnova Adelina , Kitamori Takehiko 
Published: May 2017

AbstractAutonomous micro/nano mechanical, chemical, and biomedical sensors require persistent power sources scaled to their size. Realization of autonomous micro‐power sources is a challenging task, as it requires combination of wireless energy supply, conversion, storage, and delivery to the sensor. Herein, we realized a solar‐light‐driven power source that consists of a micro fuel cell (μFC) and a photocatalytic micro fuel generator (μFG) integrated on a single microfluidic chip. The μFG produces hydrogen by photocatalytic water splitting under solar light. The hydrogen fuel is then consumed by the μFC to generate electricity. Importantly, the by‐product water returns back to the photocatalytic μFG via recirculation loop without losses. Both devices rely on novel phenomena in extended‐nano‐fluidic channels that ensure ultra‐fast proton transport. As a proof of concept, we demonstrate that μFG/μFC source achieves remarkable energy density of ca. 17.2 mWh cm−2 at room temperature.
Biocatalytic Friedel–Crafts Acylation and Fries Reaction
Authors: Schmidt Nina G. , Pavkov‐Keller Tea , Richter Nina , Wiltschi Birgit , Gruber Karl , Kroutil Wolfgang 
Published: May 2017

AbstractThe Friedel–Crafts acylation is commonly used for the synthesis of aryl ketones, and a biocatalytic version, which may benefit from the chemo‐ and regioselectivity of enzymes, has not yet been introduced. Described here is a bacterial acyltransferase which can catalyze Friedel–Crafts C‐acylation of phenolic substrates in buffer without the need of CoA‐activated reagents. Conversions reach up to >99 %, and various C‐ or O‐acyl donors, such as DAPG or isopropenyl acetate, are accepted by this enzyme. Furthermore the enzyme enables a Fries rearrangement‐like reaction of resorcinol derivatives. These findings open an avenue for the development of alternative and selective C−C bond formation methods.
A Modular Flow Design for the meta‐Selective C−H Arylation of Anilines
Authors: Gemoets Hannes P. L. , Laudadio Gabriele , Verstraete Kirsten , Hessel Volker , Noël Timothy 
Published: May 2017

AbstractDescribed herein is an effective and practical modular flow design for the meta‐selective C−H arylation of anilines. The design consists of four continuous‐flow modules (i.e., diaryliodonium salt synthesis, meta‐selective C−H arylation, inline copper extraction, and aniline deprotection) which can be operated either individually or consecutively to provide direct access to meta‐arylated anilines. With a total residence time of 1 hour, the desired product could be obtained in high yield and excellent purity without the need for column chromatography, and the residual copper content meets the standards for parenterally administered pharmaceutical substances.
Absolute Minimal Sampling of Homonuclear 2D NMR TOCSY Spectra for High‐Throughput Applications of Complex Mixtures
Authors: Hansen Alexandar L. , Li Dawei , Wang Cheng , Brüschweiler Rafael 
Published: May 2017

AbstractModern applications of 2D NMR spectroscopy to diagnostic screening, metabolomics, quality control, and other high‐throughput applications are often limited by the time‐consuming sampling requirements along the indirect time domain t1. 2D total correlation spectroscopy (TOCSY) provides unique spin connectivity information for the analysis of a large number of compounds in complex mixtures, but standard methods typically require >100 t1 increments for an accurate spectral reconstruction, rendering these experiments ineffective for high‐throughput applications. For a complex metabolite mixture it is demonstrated that absolute minimal sampling (AMS), based on direct fitting of resonance frequencies and amplitudes in the time domain, yields an accurate spectral reconstruction of TOCSY spectra using as few as 16 t1 points. This permits the rapid collection of homonuclear 2D NMR experiments at high resolution with measurement times that previously were only the realm of 1D experiments.
Phenotypic Identification of a Novel Autophagy Inhibitor Chemotype Targeting Lipid Kinase VPS34
Authors: Robke Lucas , Laraia Luca , Carnero Corrales Marjorie A. , Konstantinidis Georgios , Muroi Makoto , Richters André , Winzker Michael , Engbring Tobias , Tomassi Stefano , Watanabe Nobumoto , Osada Hiroyuki , Rauh Daniel , Waldmann Herbert , Wu Yao‐Wen , Engel Julian 
Published: May 2017

AbstractAutophagy is a critical regulator of cellular homeostasis and metabolism. Interference with this process is considered a new approach for the treatment of disease, in particular cancer and neurological disorders. Therefore, novel small‐molecule autophagy modulators are in high demand. We describe the discovery of autophinib, a potent autophagy inhibitor with a novel chemotype. Autophinib was identified by means of a phenotypic assay monitoring the formation of autophagy‐induced puncta, indicating accumulation of the lipidated cytosolic protein LC3 on the autophagosomal membrane. Target identification and validation revealed that autophinib inhibits autophagy induced by starvation or rapamycin by targeting the lipid kinase VPS34.
Frozen Acrylamide Gels as Dynamic Nuclear Polarization Matrices
Authors: Viger‐Gravel Jasmine , Berruyer Pierrick , Gajan David , Basset Jean‐Marie , Lesage Anne , Tordo Paul , Ouari Olivier , Emsley Lyndon 
Published: May 2017

AbstractAqueous acrylamide gels can be used to provide dynamic nuclear polarization (DNP) NMR signal enhancements of around 200 at 9.4 T and 100 K. The enhancements are shown to increase with crosslinker concentration and low concentrations of the AMUPol biradical. This DNP matrix can be used in situations where conventional incipient wetness methods fail, such as to obtain DNP surface enhanced NMR spectra from inorganic nanoparticles. In particular, we obtain113Cd spectra from CdTe‐COOH NPs in minutes. The spectra clearly indicate a highly disordered cadmium‐rich surface.
Modified Tetrathiafulvalene as an Organic Conductor for Improving Performances of Li−O2 Batteries
Authors: Zhang Jinqiang , Sun Bing , Zhao Yufei , Kretschmer Katja , Wang Guoxiu 
Published: May 2017

AbstractLarge over‐potentials owing to the sluggish kinetics of battery reactions have always been the drawbacks of Li−O2 batteries, which lead to short cycle life. Although redox mediators have been intensively investigated to overcome this issue, side‐reactions are generally induced by the solvated nature of redox mediators. Herein, we report an alternative method to achieve more efficient utilization of tetrathiafulvalene (TTF) in Li−O2 batteries. By coordinating TTF+ with LiCl during charging, an organic conductor TTF+Clx− precipitate covers Li2O2 to provide an additional electron‐transfer pathway on the surface, which can significantly reduce the charge over‐potential, improve the energy efficiency of Li−O2 batteries, and eliminate side‐reactions between the lithium metal anode and TTF+. When a porous graphene electrode is used, the Li−O2 battery combined with TTF and LiCl shows an outstanding performance and prolonged cycle life.
Rhodium‐Catalyzed Enantioselective Radical Addition of CX4 Reagents to Olefins
Authors: Chen Bo , Fang Cheng , Liu Peng , Ready Joseph M. 
Published: May 2017

AbstractWe describe the synthetically useful enantioselective addition of Br−CX3 (X=Cl or Br) to terminal olefins to introduce a trihalomethyl group and generate optically active secondary bromides. Computational and experimental evidence supports an asymmetric atom‐transfer radical addition (ATRA) mechanism in which the stereodetermining step involves outer‐sphere bromine abstraction from a [(bisphosphine)RhIIBrCl] complex by a benzylic radical intermediate. This mechanism appears unprecedented in asymmetric catalysis.
Eight‐Electron Silver and Mixed Gold/Silver Nanoclusters Stabilized by Selenium Donor Ligands
Authors: Chang Wan‐Ting , Lee Po‐Yi , Liao Jian‐Hong , Chakrahari Kiran Kumarvarma , Kahlal Samia , Liu Yu‐Chiao , Chiang Ming‐Hsi , Saillard Jean‐Yves , Liu C. W. 
Published: May 2017

AbstractThe first atomically and structurally precise silver‐nanoclusters stabilized by Se‐donor ligands, [Ag20{Se2P(OiPr)2}12] (3) and [Ag21{Se2P(OEt)2}12]+(4), were isolated by ligand replacement reaction of [Ag20{S2P(OiPr)2}12] (1) and [Ag21{S2P(OiPr)2}12]+ (2), respectively. Furthermore, doping reactions of 4 with Au(PPh3)Cl resulted in the formation of [AuAg20{Se2P(OEt)2}12]+ (5). Structures of 3, 4, and 5 were determined by single‐crystal X‐ray diffraction. The anatomy of cluster 3 with an Ag20 core having C3 symmetry is very similar to that of its dithiophosphate analogue 1. Clusters 4 and 5 exhibit an Ag21 and Au@Ag20 core of Oh symmetry composed of eight silver capping atoms in a cubic arrangement and encapsulating an Ag13 and Au@Ag12 centered icosahedron, respectively. Both ligand exchange and heteroatom doping result in significant changes in optical and emissive properties for chalcogen‐passivated silver nanoparticles, which have been theoretically confirmed as 8‐electron superatoms.
Antivitamin B12 Inhibition of the Human B12‐Processing Enzyme CblC: Crystal Structure of an Inactive Ternary Complex with Glutathione as the Cosubstrate
Authors: Ruetz Markus , Shanmuganathan Aranganathan , Gherasim Carmen , Karasik Agnes , Salchner Robert , Kieninger Christoph , Wurst Klaus , Banerjee Ruma , Koutmos Markos , Kräutler Bernhard 
Published: May 2017

AbstractB12 antivitamins are important and robust tools for investigating the biological roles of vitamin B12. Here, the potential antivitamin B12 2,4‐difluorophenylethynylcobalamin (F2PhEtyCbl) was prepared, and its 3D structure was studied in solution and in the crystal. Chemically inert F2PhEtyCbl resisted thermolysis of its Co−C bond at 100 °C, was stable in bright daylight, and also remained intact upon prolonged storage in aqueous solution at room temperature. It binds to the human B12‐processing enzyme CblC with high affinity (KD=130 nm) in the presence of the cosubstrate glutathione (GSH). F2PhEtyCbl withstood tailoring by CblC, and it also stabilized the ternary complex with GSH. The crystal structure of this inactivated assembly provides first insight into the binding interactions between an antivitamin B12 and CblC, as well as into the organization of GSH and a base‐off cobalamin in the active site of this enzyme.
Observation of CH⋅⋅⋅π Interactions between Methyl and Carbonyl Groups in Proteins
Authors: Perras Frédéric A. , Marion Dominique , Boisbouvier Jérôme , Bryce David L. , Plevin Michael J. 
Published: May 2017

AbstractProtein structure and function is dependent on myriad noncovalent interactions. Direct detection and characterization of these weak interactions in large biomolecules, such as proteins, is experimentally challenging. Herein, we report the first observation and measurement of long‐range “through‐space” scalar couplings between methyl and backbone carbonyl groups in proteins. These J couplings are indicative of the presence of noncovalent C−H⋅⋅⋅π hydrogen‐bond‐like interactions involving the amide π network. Experimentally detected scalar couplings were corroborated by a natural bond orbital analysis, which revealed the orbital nature of the interaction and the origins of the through‐space J couplings. The experimental observation of this type of CH⋅⋅⋅π interaction adds a new dimension to the study of protein structure, function, and dynamics by NMR spectroscopy.
High‐Fidelity, Narcissistic Self‐Sorting in the Synthesis of Organometallic Assemblies from Poly‐NHC Ligands
Authors: Sinha Narayan , Tan Tristan T. Y. , Peris Eduardo , Hahn F. Ekkehardt 
Published: May 2017

AbstractHighly selective, narcissistic self‐sorting has been observed in the one‐pot synthesis of three organometallic molecular cylinders of type [M3{L‐(NHC)3}2](PF6)3 (M=Ag+, Au+; L=1,3,5‐benzene, triphenylamine, or 1,3,5‐triphenylbenzene) from L‐(NHC)3 and silver(I) or gold(I) ions. The molecular cylinders contain only one type of tris‐NHC ligand with no crossover products detectable. Transmetalation of the tris‐NHC ligands from Ag+ to Au+ in a one‐pot reaction with retention of the supramolecular structures is also demonstrated. High‐fidelity self‐sorting was also observed in the one‐pot reaction of benzene‐bridged tris‐NHC and tetrakis‐NHC ligands with Ag2O. This study for the first time extends narcissistic self‐sorting in metal–ligand interactions from Werner‐type complexes to organometallic derivatives.
Base‐Selective Five‐ versus Six‐Membered Ring Annulation in Palladium‐Catalyzed C–C Coupling Cascade Reactions: New Access to Electron‐Poor Polycyclic Aromatic Dicarboximides
Authors: Seifert Sabine , Schmidt David , Shoyama Kazutaka , Würthner Frank 
Published: May 2017

AbstractPalladium‐catalyzed base‐selective annulation of dibromonaphthalimide to different aryl boronate esters by combined Suzuki–Miyaura cross‐coupling and direct C−H arylation afforded a series of new five‐ and six‐membered ring annulated electron‐poor polycyclic aromatic hydrocarbons. Cesium carbonate (Cs2CO3) as auxiliary base in these C−C coupling cascade reactions led exclusively to six‐membered ring annulation, while the use of organic base diazabicycloundecene (DBU) afforded the corresponding five‐membered ring annulated products. This base‐dependent selective mode of annulation is attributed to different mechanistic pathways directed by the applied base. The selective annulation was revealed by single crystal X‐ray analysis of the respective five‐ and six‐membered ring annulated products. The optical and redox properties of the new polycyclic aromatic dicarboximides were characterized by UV/Vis absorption and fluorescence spectroscopy and cyclic voltammetry.
Rapid Production of High‐Purity Hydrogen Fuel through Microwave‐Promoted Deep Catalytic Dehydrogenation of Liquid Alkanes with Abundant Metals
Authors: Jie Xiangyu , Gonzalez‐Cortes Sergio , Xiao Tiancun , Wang Jiale , Yao Benzhen , Slocombe Daniel R. , Al‐Megren Hamid A. , Dilworth Jonathan R. , Thomas John M. , Edwards Peter P. 
Published: May 2017

AbstractHydrogen as an energy carrier promises a sustainable energy revolution. However, one of the greatest challenges for any future hydrogen economy is the necessity for large scale hydrogen production not involving concurrent CO2 production. The high intrinsic hydrogen content of liquid‐range alkane hydrocarbons (including diesel) offers a potential route to CO2‐free hydrogen production through their catalytic deep dehydrogenation. We report here a means of rapidly liberating high‐purity hydrogen by microwave‐promoted catalytic dehydrogenation of liquid alkanes using Fe and Ni particles supported on silicon carbide. A H2 production selectivity from all evolved gases of some 98 %, is achieved with less than a fraction of a percent of adventitious CO and CO2. The major co‐product is solid, elemental carbon.
A Designed Approach to Enantiodivergent Enamine Catalysis
Authors: Macharia Juliet , Wambua Victor , Hong Yun , Harris Lawrence , Hirschi Jennifer S. , Evans Gary B. , Vetticatt Mathew J. 
Published: May 2017

AbstractThe rational design and implementation of enantiodivergent enamine catalysis is reported. A simple secondary amine catalyst, 2‐methyl‐l‐proline, and its tetrabutylammonium salt function as an enantiodivergent catalyst pair delivering the enantiomers of α‐functionalized aldehyde products in excellent enantioselectivities. This novel concept of designed enantiodivergence is applied to the enantioselective α‐amination, aldol, and α‐aminoxylation/α‐hydroxyamination reactions of aldehydes.