bluuebunny/crossref_metadata_2025_split huggingface dataset:
Optically Active Tetra‐tert‐butyl‐P5‐deltacyclene Epimers: Preparation, Spectroscopy, Dynamic Equilibriums, H/D Exchange, and Transition‐Metal Complex Chemistry
Authors: Rohwer Lars , Höhn Christine , Autschbach Jochen , Bauer Walter , Heinemann Frank W. , Huguet Torrell Sergi , Keller Irene , Shubina Tatyana E. , Steffen Jacob , Zenneck Ulrich 
Published: March 2014

AbstractOn the basis of isolated diastereomeric triorganylstannyl‐P5‐deltacyclenes 7′ and 7′′, almost pure enantiomers of their destannylation products 8′ and 8′′ are now available. These stereochemically inert cage chiral species contain a configurationally labile P1H1 group that defines two epimers 8 a and 8 b of each of the enantiomers, which are connected by a rapid equilibrium. Mirror‐symmetric circular dichroism (CD) spectra of the enantiomeric cages are compatible with the identification of epimers. A simulation of the CD spectrum of the major epimer 8′a relates the cage chirality of the system to the observed chiroptical effects. Both cage epimers and two of the phosphorus cage atoms are active as ligands with respect to [M(CO)5] fragments of Cr, Mo, and W. Four almost isoenergetic regio‐ and stereoisomers of the resulting mononuclear complexes are formed for these metals, but only one of the isomers per metal crystallized in the case of the racemic series of the complexes. The enantiopure versions of cages and cage complexes, however, did not crystallize at all, a well‐known phenomenon for chiral compounds. CD spectra of the optically active complex isomer mixtures are close to identical with the CD spectra of the related free cages and point again to the chiral cages as the dominant source of the CD effects of the complexes. [(Benzene)RuCl2] complexes of the cage ligand 8 behave totally differently. Only a single species 12=[(benzene)RuCl2⋅8 b] is formed in almost quantitative yield and the minor epimer 8 b plays the role of the ligand exclusively. The reaction works as well for the separated enantiomeric cage versions to yield the highly enriched enantiomers 12′ and 12′′ separately. An efficient kinetic resolution process was identified as the main reason for this finding. It is based on a high stereo‐ and regiochemical flexibility of the PC cage ligand that is capable of adjusting to the specific requirements of a suitable transition‐metal complex fragment. Such ligand flexibility is regularly observed in metalloenzymes, but is a very rare case in classical and organometallic complex chemistry.
Charge‐Transfer Complex Formation in Gelation: The Role of Solvent Molecules with Different Electron‐Donating Capacities
Authors: Basak Shibaji , Bhattacharya Sumantra , Datta Ayan , Banerjee Arindam 
Published: March 2014

AbstractA naphthalenediimide (NDI)‐based synthetic peptide molecule forms gels in a particular solvent mixture (chloroform/aromatic hydrocarbon, 4:1) through charge‐transfer (CT) complex formation; this is evident from the corresponding absorbance and fluorescence spectra at room temperature. Various aromatic hydrocarbon based solvents, including benzene, toluene, xylene (ortho, meta and para) and mesitylene, have been used for the formation of the CT complex. The role of different solvent molecules with varying electron‐donation capacities in the formation of CT complexes has been established through spectroscopic and computational studies.
Efficient Atropodiastereoselective Access to 5,5′‐Bis‐1,2,3‐triazoles: Studies on 1‐Glucosylated 5‐Halogeno 1,2,3‐Triazoles and Their 5‐Substituted Derivatives as Glycogen Phosphorylase Inhibitors
Authors: Goyard David , Chajistamatiou Aikaterini S. , Sotiropoulou Anastasia I. , Chrysina Evangelia D. , Praly Jean‐Pierre , Vidal Sébastien 
Published: March 2014

AbstractWhereas copper‐catalyzed azide–alkyne cycloaddition (CuAAC) between acetylated β‐D‐glucosyl azide and alkyl or phenyl acetylenes led to the corresponding 4‐substituted 1‐glucosyl‐1,2,3‐triazoles in good yields, use of similar conditions but with 2 equiv CuI or CuBr led to the 5‐halogeno analogues (>71 %). In contrast, with 2 equiv CuCl and either propargyl acetate or phenyl acetylene, the major products (>56 %) displayed two 5,5′‐linked triazole rings resulting from homocoupling of the 1‐glucosyl‐4‐substituted 1,2,3‐triazoles. The 4‐phenyl substituted compounds (acetylated, O‐unprotected) and the acetylated 4‐acetoxymethyl derivative existed in solution as a single form (d.r.>95:5), as shown by NMR spectroscopic analysis. The two 4‐phenyl substituted structures were unambiguously identified for the first time by X‐ray diffraction analysis, as atropisomers with aR stereochemistry. This represents one of the first efficient and highly atropodiastereoselective approaches to glucose‐based bis‐triazoles as single atropisomers. The products were purified by standard silica gel chromatography. Through Sonogashira or Suzuki cross‐couplings, the 1‐glucosyl‐5‐halogeno‐1,2,3‐triazoles were efficiently converted into a library of 1,2,3‐triazoles of the 1‐glucosyl‐5‐substituted (alkynyl, aryl) type. Attempts to achieve Heck coupling to methyl acrylate failed, but a stable palladium‐associated triazole was isolated and analyzed by 1H NMR and MS. O‐Unprotected derivatives were tested as inhibitors of glycogen phosphorylase. The modest inhibition activities measured showed that 4,5‐disubstituted 1‐glucosyl‐1,2,3‐triazoles bind weakly to the enzyme. This suggests that such ligands do not fit the catalytic site or any other binding site of the enzyme.
High‐Concentration Graphene Dispersions with Minimal Stabilizer: A Scaffold for Enzyme Immobilization for Glucose Oxidation
Authors: Sun Zhenyu , Vivekananthan Jeevanthi , Guschin Dmitrii A. , Huang Xing , Kuznetsov Volodymyr , Ebbinghaus Petra , Sarfraz Adnan , Muhler Martin , Schuhmann Wolfgang 
Published: March 2014

AbstractModified acrylate polymers are able to effectively exfoliate and stabilize pristine graphene nanosheets in aqueous media. Starting with pre‐exfoliated graphite greatly promotes the exfoliation level. The graphene concentration is significantly increased up to 11 mg mL−1 by vacuum evaporation of the solvent from the dispersions under ambient temperature. TEM shows that 75 % of the flakes have fewer than five layers with about 18 % of the flakes consisting of monolayers. Importantly, a successive centrifugation and redispersion strategy is developed to enable the formation of dispersions with exceptionally high graphene‐to‐stabilizer ratio. Characterization by high‐resolution transmission electron microscopy, X‐ray photoelectron spectroscopy, X‐ray diffraction, and Raman spectroscopy shows the flakes to be of high quality with very low levels of defects. These dispersions can act as a scaffold for the immobilization of enzymes applied, for example, in glucose oxidation. The electrochemical current density was significantly enhanced to be approximately six times higher than an electrode in the absence of graphene, thus showing potential applications in enzymatic biofuel cells.
Spin‐State Ordering on One Sub‐lattice of a Mononuclear Iron(III) Spin Crossover Complex Exhibiting LIESST and TIESST
Authors: Murnaghan Kevin D. , Carbonera Chiara , Toupet Loic , Griffin Michael , Dîrtu Marinela M. , Desplanches Cédric , Garcia Yann , Collet Eric , Létard Jean‐François , Morgan Grace G. 
Published: March 2014

AbstractThe two‐step spin crossover in mononuclear iron(III) complex [Fe(salpm)2]ClO4⋅0.5 EtOH (1) is shown to be accompanied by a structural phase transition as concluded from 57Fe Mössbauer spectroscopy and single crystal X‐ray diffraction, with spin‐state ordering on just one of two sub‐lattices in the intermediate magnetic and structural phase. The complex also exhibits thermal‐ and light‐induced spin‐state trapping (TIESST and LIESST), and relaxation from the LIESST and TIESST excited states occurs via the broken symmetry intermediate phase. Two relaxation events are evident in both experiments, that is, two T(LIESST) and two T(TIESST) values are recorded. The change in symmetry which accompanies the TIESST effect was followed in real time using single crystal diffraction. After flash freezing at 15 K the crystal was warmed to 40 K at which temperature superstructure reflections were observed to appear and disappear within a 10 000 s time range. In the frame of the international year of crystallography, these results illustrate how X‐ray diffraction makes it possible to understand complex ordering phenomena.
ChemInform Abstract: Above‐Room‐Temperature Ferroelastic Phase Transition in a Perovskite‐Like Compound [N(CH3)4][Cd(N3)3].
Authors: Du Zi‐Yi , Zhao Ying‐Ping , Zhang Wei‐Xiong , Zhou Hao‐Long , He Chun‐Ting , Xue Wei , Wang Bao‐Ying , Chen Xiao‐Ming 
Published: March 2014

AbstractBlock‐shaped single crystals of the new title compound are synthesized by slow evaporation of the filtrate of an aqueous mixture of Cd(NO3)2, NaN3, and Me4NBr in the ratio of 1:12:6 (20 °C, 55% yield).
ChemInform Abstract: [ZnBi4]3‐ Pentagon in K6ZnBi5: Aromatic All‐Metal Heterocycle.
Authors: Qin Qian , Zhou Liujiang , Wang Yi , Sang Ruili , Xu Li 
Published: March 2014

AbstractThe new Zintl phase of title is synthesized from stoichiometric mixtures of the elements (Nb containers, 700 °C, 48 h) and characterized by powder XRD, magnetic measurements, and projector augmented wave band structure computations.
ChemInform Abstract: Carbon—Carbon Bond Formation via Benzoyl Umpolung Attained by Photoinduced Electron‐Transfer with Benzimidazolines.
Authors: Igarashi Tomohito , Tayama Eiji , Iwamoto Hajime , Hasegawa Eietsu 
Published: March 2014

AbstractIt is proposed that electron transfer from a benzimidazoline additive to photoexcited benzoyl compounds (I) generates carbanions which react with alkyl halides to give alkylated alcohols.
ChemInform Abstract: Synthesis and Structure of Large Difluoromethylene Containing Alicycles by Ring Closing Metathesis (RCM).
Authors: Skibinski Maciej , Urbina‐Blanco Cesar A. , Slawin Alexandra M. Z. , Nolan Steven P. , O'Hagan David 
Published: March 2014

AbstractThe ring closing metathesis is applied to long terminal olefins (I) containing bis(thianes) to afford exclusively the corresponding (E)‐olefins (II).
ChemInform Abstract: Anodic Fluorination of 4‐Methoxy‐1‐naphthol and 4‐Nitroanisole Using Et3N·5HF in Mixed Nonaqueous Solvent.
Authors: Saraswat A. , Sharma L. K. , Singh S. , Siddiqui I. R. , Singh R. K. P. 
Published: March 2014

AbstractThe title reaction proceeds in the presence of Et3N·5HF which serves as supporting electrolyte and as fluorine source.
ChemInform Abstract: Asymmetric Michael Addition of Ketones to Nitroolefins Catalyzed by a Novel Chiral Pyrrolidine‐Thiourea in the Ionic Liquid.
Authors: Lu Jun , Chen Wei‐Yi 
Published: March 2014

AbstractA new catalyst is developed for the asymmetric Michael addition of cyclohexanone and acetone to nitroolefins giving the corresponding nitroolefins with high enantioselectivities.
ChemInform Abstract: Synthesis of N‐Heterocyclic Carbene Silver and Palladium Complexes Bearing Bis(pyrazol‐1‐yl)methyl Moieties.
Authors: Li Qiang , Xie Yun‐Fu , Sun Bao‐Chuan , Yang Jun , Song Hai‐Bin , Tang Liang‐Fu 
Published: March 2014

AbstractA series of N‐heterocyclic carbene catalysts are screened for the three‐component coupling reaction of aldehydes with piperidine and phenylacetylene to produce propargylamines.
ChemInform Abstract: ortho‐Selective Nucleophilic Addition of Amines to 3‐Borylbenzynes: Synthesis of Multisubstituted Anilines by the Triple Role of the Boryl Group.
Authors: Takagi Akira , Ikawa Takashi , Saito Kozumo , Masuda Shigeaki , Ito Toyohiro , Akai Shuji 
Published: March 2014

AbstractThe investigations reveal that the nucleophilic addition to benzynes, generated in situ from triflate (I), exhibits higher ortho‐selectivities than those of 3‐(trimethylsilyl)benzynes.
ChemInform Abstract: ipso‐Hydroxylation of Arylboronic Acids and Boronate Esters by Using Sodium Chlorite as an Oxidant in Water.
Authors: Gogoi Pranjal , Bezboruah Pranjal , Gogoi Junali , Boruah Romesh C. 
Published: March 2014

AbstractThis is a simple, catalyst‐free, and inexpensive procedure for the title reaction giving the products in high yields without a chromatographic purification.
ChemInform Abstract: An in situ Generated CuI/Metformin Complex as a Novel and Efficient Catalyst for C—N and C—O Cross‐Coupling Reactions.
Authors: Ghorbani‐Vaghei Ramin , Hemmati Saba , Veisi Hojat 
Published: March 2014

AbstractMetformin is a novel, polydentate nitrogen donor ligand that can be used for N/O‐arylation reactions along with air‐stable and inexpensive copper(I) iodide.
ChemInform Abstract: Ethyl 2,2‐Bis(4‐methylphenylsulfonamido)acetate to Aromatic α‐Amino Acids: Stable Substrates for Catalytic Arylation Reactions.
Authors: Marques Carolina S. , Burke Anthony J. 
Published: March 2014

AbstractTitle compound (I) is converted to a series of α‐amino acids (III) using two catalytic systems.
ChemInform Abstract: Iodine‐Catalyzed Selective Synthesis of 2‐Sulfanylphenols via Oxidative Aromatization of Cyclohexanones and Disulfides.
Authors: Ge Wenlei , Zhu Xun , Wei Yunyang 
Published: March 2014

AbstractBoth aryl and alkyl disulfides are employed as sulfanylation reagents to give the desired products in good yields under the optimized reaction conditions.
ChemInform Abstract: Chiral Bidiaziridines by a Two‐Step Domino Aziridination of meso‐α‐Diimines.
Authors: Aresu Emanuele , Carroccia Laura , Fioravanti Stefania , Gasbarri Simona , Pellacani Lucio , Sciubb Fabio 
Published: March 2014

AbstractThe stereochemical outcome of the aziridination reaction of meso‐α‐diimines is investigated.
ChemInform Abstract: Di‐ and Triheteroarylalkanes via Self‐Condensation and Intramolecular Friedel—Crafts Type Reaction of Heteroaryl Alcohols.
Authors: Dhiman Seema , Ramasastry S. S. V. 
Published: March 2014

AbstractA general method for the conversion of heteroaryl alcohols (I), (III), and (V) to di‐ and triheteroarylalkanes (II), (IV), (VI), and 1,3‐heteroarylpropenes (VIII) in the presence of highly reactive Yb(OTf)3 catalyst is reported.
ChemInform Abstract: Asymmetric Synthesis of β‐Substituted α‐Methylenebutyrolactones via TRIP‐Catalyzed Allylation: Mechanistic Studies and Application to the Synthesis of (S)‐(‐)‐Hydroxymatairesinol.
Authors: Fuchs Michael , Schober Markus , Orthaber Andreas , Faber Kurt 
Published: March 2014

AbstractTRIP‐Catalyzed allylation of aldehydes proceeds via in situ generated zinc(II)‐allylbutyrolactone species which is crucial for chiral induction.
ChemInform Abstract: Palladium‐Catalyzed Synthesis of 3‐Acylated Indoles Involving Oxidative Cross‐Coupling of Indoles with α‐Amino Carbonyl Compounds.
Authors: Tang Ri‐Yuan , Guo Xiao‐Kang , Xiang Jian‐Nan , Li Jin‐Heng 
Published: March 2014

AbstractIt provides a new and efficient approach to a series of 3‐acylated indoles.
ChemInform Abstract: Organocatalyzed Synthesis of Isoxazolidin‐5‐ones: The Meldrum′s Acid Approach.
Authors: Postikova Svetlana , Tite Tony , Levacher Vincent , Briere Jean‐Francois 
Published: March 2014

AbstractMeldrum′s acid is a useful ketene equivalent in the reaction with nitrones to give isoxazolidin‐5‐ones, via a domino anionic formal [3 + 2] cycloaddition‐decarboxylation process.
ChemInform Abstract: Meglumine Promoted One‐Pot, Four‐Component Synthesis of Pyranopyrazole Derivatives.
Authors: Guo Rui‐Yun , An Zhi‐Min , Mo Li‐Ping , Yang Shu‐Tao , Liu Hong‐Xia , Wang Shu‐Xia , Zhang Zhan‐Hui 
Published: March 2014

AbstractThe synthesis of title compounds [(IV), (VI), (VIII), (X), and (XII)] is conveniently and green approached using meglumine as an efficient and inexpensive reusable catalyst.
ChemInform Abstract: One‐Pot Synthesis of Phenylseleno N‐Acetyl α‐Amino Acids: Supra‐Molecular Self‐Assembling in Organoselenium Compounds.
Authors: Prabhu C. Parashiva , Phadnis Prasad P. , Wadawale Amey , Priyadarsini K. Indira , Jain Vimal K. 
Published: March 2014

AbstractA convenient one‐pot two‐step procedure is developed for the synthesis of the title acids (IV).
ChemInform Abstract: Enantioselective Synthesis of 2‐Substituted‐tetrahydroisoquinolin‐1‐yl Glycine Derivatives via Oxidative Cross‐Dehydrogenative Coupling of Tertiary Amines and Chiral Nickel(II) Glycinate.
Authors: Zhou Shengbin , Wang Jiang , Lin Daizong , Zhao Fei , Liu Hong 
Published: March 2014

AbstractIt provides a new, easy, and highly stereoselective approach to a number of tetrahydroisoquinolinyl glycine derivatives.
ChemInform Abstract: Regio‐ and Stereochemical Controlled Koenigs—Knorr‐Type Monoglycosylation of Secondary Hydroxy Groups in Carbohydrates Utilizing the High Site Recognition Ability of Organotin Catalysts.
Authors: Muramatsu Wataru , Yoshimatsu Hirofumi 
Published: March 2014

AbstractA Sn‐catalyzed one‐pot process for the monoglycosylation of secondary OH‐groups in carbohydrate is described.
ChemInform Abstract: Single Molecule Methods for the Study of Catalysis: From Enzymes to Heterogeneous Catalysts
Authors: Janssen Kris P. F. , De Cremer Gert , Neely Robert K. , Kubarev Alexey V. , Van Loon Jordi , Martens Johan A. , De Vos Dirk E. , Roeffaers Maarten B. J. , Hofkens Johan 
Published: March 2014

AbstractReview: 55 refs.
Substitutional Doping of Carbon Nanotubes with Heteroatoms and Their Chemical Applications
Authors: Zhang Yexin , Zhang Jian , Su Dang Sheng 
Published: March 2014

AbstractThe electronic properties of carbon nanotubes (CNTs) can be tuned by substitutional doping with heteroatoms (mainly B and N) to expand the applications of CNTs. Based on the comprehensive understanding of the substitutional doping of CNTs, it should be possible to deliberately design doped CNTs for specific purposes. Thus, relevant experimental and theoretical works are reviewed herein in an attempt to correlate the synthetic methods, electronic properties, and applications of heteroatom‐doped CNTs. The distribution and arrangement of heteroatoms in the graphitic lattice of CNTs can be modulated through the choice of synthetic conditions, which would further lead to different electronic properties of CNTs for their chemical applications.
Indium(0)‐Mediated C–S/O Cross‐Coupling Approach Towards the Regioselective Alkylation of α‐Enolic Esters/Dithioesters: A Mechanistic Insight
Authors: Chowdhury Sushobhan , Chanda Tanmoy , Gupta Ashutosh , Koley Suvajit , Ramulu B. Janaki , Jones Raymond C. F. , Singh Maya Shankar 
Published: March 2014

AbstractWe have reported an indium(0)‐mediated C–S/O cross‐coupling approach that leads to the highly regioselective alkylation of α‐enolic acetate/dithioacetate systems. This hetero cross‐coupling reaction does not require additional co‐catalyst or promoter, and the in situ generated organoindium species promotes the reaction by acting as the coupling partner of the α‐enolic acetate/dithioacetate substrates. The excellent selectivity for C‐, S‐, or O‐alkylation is solely dependent on the nucleophilic behavior of α‐enolic acetate/dithioacetate systems. These results were further supported by DFT calculations of the relative electronic energies of the substrates and products as well as the activation barriers of the respective transformations.
Lewis‐Acid‐Catalyzed Benzylic Reactions of 2‐Methylazaarenes with Aldehydes
Authors: Mao Dan , Hong Gang , Wu Shengying , Liu Xin , Yu Jianjun , Wang Limin 
Published: March 2014

AbstractLewis‐acid‐catalyzed benzylic reactions of 2‐methylazaarenes with aldehydes have been investigated. Series of azaarene derivatives were afforded by this reaction. 2‐(Pyridin‐2‐yl)ethanols with common substituents were formed through the LiNTf2‐promoted aldol reaction for the first time. 2‐Alkenylpyridines, exclusively in the form of the E isomers, were synthesized in the presence of LiNTf2 cooperated with H2NTf. In the presence of La(Pfb)3 as catalysis, 2‐alkenylquinolines were obtained in high yields through the reactions between 2‐methylquinolines and aldehydes under air.
Titanocene(III) Chloride Mediated Stereoselective Synthesis of Trisubstituted Tetrahydrofurans and a Spirolactone by Tandem Radical Reactions
Authors: Mukherjee Shirshendu , Roy Rajdip , Chandra Roy Subhas 
Published: March 2014

AbstractThe titanocene(III) chloride (Cp2TiCl) mediated stereoselective synthesis of highly substituted tetrahydrofurans has been achieved by a reaction that proceeds through a tandem radical cyclization reaction between a Baylis–Hillman adduct and an activated bromo/iodo compound. The reaction of an epoxide with the Baylis–Hillman adduct furnished a spirolactone through a radical cyclization followed by an in situ lactonization. Cp2TiCl was prepared in situ from commercially available Cp2TiCl2and zinc dust in tetrahydrofuran.
Prediction of site factors by a non‐parametric approach
Authors: Peruš Iztok , Fajfar Peter 
Published: March 2014

SUMMARYThe problem addressed in this paper is the estimation of the (de)amplification of ground motion at soil sites (compared to rock sites) as a function of the intensity of the ground motion. A non‐parametric empirical approach, called the Conditional Average Estimator (CAE) method, has been used, which is different from all existing approaches. Site factors (SFs) for sites characterized with Vs30 between 180 and 360 m/s were predicted for the peak ground acceleration (PGA) and the spectral accelerations by using a combined database of recorded ground motions. Based on the results of the study, site factors for PGA and selected spectral accelerations are proposed, separately for weaker and stronger ground motions. Comparisons are made with the SFs used in two standards (Eurocode 8 and ASCE 7‐10) and with SFs proposed in the literature, including four Next Generation Attenuation (NGA) ground‐motion prediction equations. The study reveals that (i) SFs depend strongly on the ground‐motion intensity. In the case of stronger ground motions, they decrease with increasing acceleration. (ii) The SFs predicted in this study agree reasonably well with the existing SFs in the case of weak ground motion. For higher intensities of ground motion, they are generally smaller than the existing ones. Copyright © 2014 John Wiley & Sons, Ltd.