bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Molecular Necklace: Threading β‐Cyclodextrins onto Polymers Derived from Bile Acids
Authors: Jia Yong‐Guang , Malveau Cedric , Mezour Mohamed A. , Perepichka Dmitrii F. , Zhu X. X. 
Published: August 2016

AbstractA molecular necklace of polypseudorotaxanes was prepared by threading β‐cyclodextrins (β‐CD) onto biodegradable and thermoresponsive polyurethanes derived from bile acids. These polyurethanes were synthesized via a simple step condensation of bile acid‐based dicarbonate with poly(ethylene glycol)‐diamine. The β‐CD rings slide onto the poly(ethylene glycol) segments and selectively recognize the bile acid units of the polyurethane chains, whereas the poly(ethylene glycol) segments remain crystalline with a lower crystallinity. This bio‐compound‐derived molecular necklace can be visualized by scanning tunneling microscopy. The polypseudorotaxanes show thermosensitivity in water and the phase transition temperature may be fine‐tuned by varying the molar ratios of β‐CD to the bile acid units. Such an interesting necklace model of polypseudorotaxane constructed from natural compounds may lead to the further exploration of their applications, such as as an enzyme model, due to their biological nature.
5‐Formylcytosine Could Be a Semipermanent Base in Specific Genome Sites
Authors: Su Meng , Kirchner Angie , Stazzoni Samuele , Müller Markus , Wagner Mirko , Schröder Arne , Carell Thomas 
Published: August 2016

Abstract5‐Formyl‐2′‐deoxycytosine (fdC) is a recently discovered epigenetic base in the genome of stem cells, with yet unknown functions. Sequencing data show that the base is enriched in CpG islands of promoters and hence likely involved in the regulation of transcription during cellular differentiation. fdC is known to be recognized and excised by the enzyme thymine‐DNA‐glycosylase (Tdg). As such, fdC is believed to function as an intermediate during active demethylation. In order to understand the function of the new epigenetic base fdC, it is important to analyze its formation and removal at defined genomic sites. Here, we report a new method that combines sequence‐specific chemical derivatization of fdC with droplet digital PCR that enables such analysis. We show initial data, indicating that the repair protein Tdg removes only 50 % of the fdCs at a given genomic site, arguing that fdC is a semipermanent base.
Asymmetric Hydrogenation of Azaindoles: Chemo‐ and Enantioselective Reduction of Fused Aromatic Ring Systems Consisting of Two Heteroarenes
Authors: Makida Yusuke , Saita Masahiro , Kuramoto Takahiro , Ishizuka Kentaro , Kuwano Ryoichi 
Published: August 2016

AbstractHigh enantioselectivity was achieved for the hydrogenation of azaindoles by using the chiral catalyst, which was prepared from [Ru(η3‐methallyl)2(cod)] and a trans‐chelating bis(phosphine) ligand (PhTRAP). The dearomative reaction exclusively occurred on the five‐membered ring, thus giving the corresponding azaindolines with up to 97:3 enantiomer ratio.
Wearable Thermocells Based on Gel Electrolytes for the Utilization of Body Heat
Authors: Yang Peihua , Liu Kang , Chen Qian , Mo Xiaobao , Zhou Yishu , Li Song , Feng Guang , Zhou Jun 
Published: August 2016

AbstractConverting body heat into electricity is a promising strategy for supplying power to wearable electronics. To avoid the limitations of traditional solid‐state thermoelectric materials, such as frangibility and complex fabrication processes, we fabricated two types of thermogalvanic gel electrolytes with positive and negative thermo‐electrochemical Seebeck coefficients, respectively, which correspond to the n‐type and p‐type elements of a conventional thermoelectric generator. Such gel electrolytes exhibit not only moderate thermoelectric performance but also good mechanical properties. Based on these electrolytes, a flexible and wearable thermocell was designed with an output voltage approaching 1 V by utilizing body heat. This work may offer a new train of thought for the development of self‐powered wearable systems by harvesting low‐grade body heat.
Ultrafast Click Chemistry with Fluorosydnones
Authors: Liu Hui , Audisio Davide , Plougastel Lucie , Decuypere Elodie , Buisson David‐Alexandre , Koniev Oleksandr , Kolodych Sergii , Wagner Alain , Elhabiri Mourad , Krzyczmonik Anna , Forsback Sarita , Solin Olof , Gouverneur Véronique , Taran Frédéric 
Published: August 2016

AbstractWe report the synthesis and reactivity of 4‐fluorosydnones, a unique class of mesoionic dipoles displaying exquisite reactivity towards both copper‐catalyzed and strain‐promoted cycloaddition reactions with alkynes. Synthetic access to these new mesoionic compounds was granted by electrophilic fluorination of σ‐sydnone PdII precursors in the presence of Selectfluor. Their reactions with terminal and cyclic alkynes were found to proceed very rapidly and selectively, affording 5‐fluoro‐1,4‐pyrazoles with bimolecular rate constants up to 104 m−1 s−1, surpassing those documented in the literature with cycloalkynes. Kinetic studies were carried out to unravel the mechanism of the reaction, and the value of 4‐fluorosydnones was further highlighted by successful radiolabeling with [18F]Selectfluor.
Synthesis and Characterization of [XeOXe]2+in the Adduct‐Cation Salt, [CH3CN‐ ‐ ‐XeOXe‐ ‐ ‐NCCH3][AsF6]2
Authors: De Backere John R. , Bortolus Mark R. , Schrobilgen Gary J. 
Published: August 2016

AbstractAcetonitrile and [FXeOXe‐ ‐ ‐FXeF][AsF6] react at −60 °C in anhydrous HF (aHF) to form the CH3CN adduct of the previously unknown [XeOXe]2+cation. The low‐temperature X‐ray structure of [CH3CN‐ ‐ ‐XeOXe‐ ‐ ‐NCCH3][AsF6]2exhibits a well‐isolated adduct‐cation that has among the shortest Xe−N distances obtained for an sp‐hybridized nitrogen base adducted to xenon. The Raman spectrum was fully assigned by comparison with the calculated vibrational frequencies and with the aid of18O‐enrichment studies. Natural bond orbital (NBO), atoms in molecules (AIM), electron localization function (ELF), and molecular electrostatic potential surface (MEPS) analyses show that the Xe−O bonds are semi‐ionic whereas the Xe−N bonds may be described as strong electrostatic (σ‐hole) interactions.
Synthesis, characterization, DNA interaction, apoptosis and molecular docking of Cu(II) and Mn(II) complexes with endo‐norbornene‐cis‐5,6‐dicarboxylic acid
Authors: Gao Enjun , Ding Yuqing , Sun Na , Zhang Shaozhong , Qiu Xue , Zhan Yang , Zhu Mingchang 
Published: August 2016

Two new novel complexes, [Cu4(Endc)4(phen)4]⋅7(H2O)⋅2(O) and [Mn2(Endc)2(phen)2(H2O)2]⋅(H2O) (phen =1,10‐phenanthroline, H2Endc = endo‐norbornene‐cis‐5,6‐dicarboxylic acid), were synthesized and structurally characterized using IR and 1H NMR spectroscopies, elemental analysis and single‐crystal X‐ray diffractometry. Their reactivity with calf thymus DNA and HeLa cell DNA was measured using UV absorption and fluorescence spectroscopies. The results indicated that these complexes can bind to DNA with different binding affinity. Gel electrophoresis assay demonstrated the ability of the complexes to cleave pBR322 plasmid DNA. Apoptotic study showed that the complexes exhibit significant cancer cell inhibitory rates. Eventually, the complexes can suitably dock with a special DNA (PDB ID: 1AIO).
Novel conjugated nanoporous alkynyl metalloporphyrin framework as effective catalyst for oxidation of toluene with molecular oxygen
Authors: Li Yongjin , Sun Baoshuai , Zhou Yuanrong , Yang Weijun 
Published: August 2016

A porous alkynylporphyrin conjugated organic polymer (MnE‐TPP) was synthesized by Sonogashira coupling reaction with Mn(II) 5,10,15,20‐tetrakis(4′‐ethynylphenyl)porphyrin and Mn(II) 5,10,15,20‐tetrakis(4′‐bromophenyl)porphyrin as building blocks. The polymer was characterized using nitrogen adsorption–desorption isotherms, field‐emission scanning electron microscopy, high‐resolution transmission electron microscopy, Fourier transform infrared and UV–visible spectroscopies, X‐ray diffraction, thermogravimetry and inductively coupled plasma atomic emission spectrometry. The electrochemical behaviors of MnE‐TPP were investigated by cyclic voltammetry. MnE‐TPP was developed as a heterogeneous catalyst for the activation of molecular oxygen to oxidize toluene under mild conditions. The selectivity of total benzaldehyde and benzyl alcohol remained above 70.0% with a conversion of toluene up to 10.2%. The turnover number was as high as 13 653. Also, MnE‐TPP remained structurally stable and the toluene conversion rate hardly decreased after 5 h of reaction and five cycles of reuse.
Divergent Synthesis of Hydro‐γ‐Carbolines and Multisubstituted Indoles through Grob Fragmentation/Mannich Cyclization
Authors: Jiang Long , Yu Yuanyuan , Li Guang , Zu Liansuo 
Published: August 2016

AbstractA distinct strategy for the divergent synthesis of hydro‐γ‐carbolines and multisubstituted indoles is reported. The stereochemical outcomes and a control experiment indicate that the reactions likely proceed through Grob fragmentation/Mannich cyclization rather than a concerted aza‐pinacol rearrangement.
Photolysis of Carbonyl Diisocyanate: Generation of Isocyanatocarbonyl Nitrene and Diazomethanone
Authors: Liu Qifan , Li Hongmin , Wu Zhuang , Li Dingqing , Beckers Helmut , Rauhut Guntram , Zeng Xiaoqing 
Published: August 2016

AbstractThe stepwise decomposition of carbonyl diisocyanate, OC(NCO)2, has been studied by using IR spectroscopy in solid argon matrices at 16 K. Upon irradiation with an ArF laser (λ=193 nm), carbonyl diisocyanate split off CO and furnished a new carbonyl nitrene, OCNC(O)N, in its triplet ground state. Two conformers of the nitrene, syn and anti, that were derived from the two conformers of OC(NCO)2 (62 % syn–syn and 38 % syn–anti) were identified and characterized by combining IR spectroscopy and quantum chemical calculations. Subsequent irradiation with visible light (λ>395 nm) caused the Curtius rearrangement of the nitrene into OCNNCO. In addition to the expected decomposition products, N2 and CO, further photolysis of OCNNCO with the ArF laser yielded NOCN, through a diazomethanone (NNCO) intermediate. To further validate our proposed reaction mechanism, ArF‐laser photolysis of the closely related NNNNCO and cyclo‐N2CO in solid argon matrices were also studied. The observations of NOCN and in situ CO‐trapped product OCNNCO provided indirect evidence to support the initial generation of NNCO as a common intermediate during the laser photolysis of OCNNCO, NNNNCO, and cyclo‐N2CO.
Chemical Genetic Screen Identifies Natural Products that Modulate Centriole Number
Authors: Graciotti Michele , Fang Zhou , Johnsson Kai , Gönczy Pierre 
Published: August 2016

AbstractCentrioles are microtubule‐based organelles found in most eukaryotic cells and that are critical for the formation of cilia and flagella, as well as of centrosomes in animal cells. The number of centrioles must be strictly regulated in proliferating cells in order to ensure genome integrity upon cell division. Despite their importance, however, the mechanisms governing centriole assembly and number control remain incompletely understood, owing in part to a paucity of available small‐molecule compounds for dissection and alteration of the underlying processes. Here we have developed a chemical genetic approach to identify small‐molecule compounds capable of modulating centriole numbers in human cells. High‐throughput screening of ≈2600 natural compounds identified 14 candidate molecules that either diminish (ten compounds) or augment (four compounds) the number of centrioles per cell. We investigated the mechanisms of action of four of these compounds and discovered that two of them potentially reduce centriole number through effects on NF‐κB signalling. Moreover, we established that one further compound blocks cell cycle progression and probably indirectly causes an augmentation of centriole number. The last compound analysed induces, in addition to excess centrioles, exceptionally long primary cilia‐like structures. Overall, our analysis demonstrates that natural products constitute a rich source of tool compounds useful for unravelling and manipulating the mechanisms governing centriole assembly and number control.
A High‐Performance Base‐Metal Approach for the Oxidative Esterification of 5‐Hydroxymethylfurfural
Authors: Sun Yuxia , Ma Hong , Jia Xiuquan , Ma Jiping , Luo Yang , Gao Jin , Xu Jie 
Published: August 2016

AbstractExploring high‐performance base‐metal approaches for the sustainable production of chemicals from biomass is presently attracting immense interest and is truly important to promote their industrialized application. Herein, CoOx‐N/C and α‐MnO2 were combined as a base‐metal catalyst that can achieve high yields of furan‐2,5‐dimethylcarboxylate (FDMC, 95.6 %) for the catalytic oxidative esterification of 5‐hydroxymethylfurfural (HMF) without basic additive. The reaction proceeds through fast conversion of HMF to diformylfuran (DFF) with α‐MnO2 and subsequent transformation of DFF to FDMC by CoOx‐N/C. Quantitative X‐ray photoelectron spectroscopy (XPS) analysis and density functional theory (DFT) calculations indicated that the pyridinic‐N present in doped carbon could behave as a Lewis base to promote the abstraction of hydrogen for the oxidative esterification reaction. Consequently, CoOx‐N/C is a high performance catalyst for the synthesis of FDMC from DFF in a neutral medium.
Solvent‐Free Synthesis of c‐Axis Oriented ZSM‐5 Crystals with Enhanced Methanol to Gasoline Catalytic Activity
Authors: Liu Ziyu , Wu Dan , Ren Shu , Chen Xinqing , Qiu Minghuang , Wu Xian , Yang Chengguang , Zeng Gaofeng , Sun Yuhan 
Published: August 2016

AbstractZSM‐5 crystals with controllable c‐axis length were successfully synthesized through a one‐pot solvent‐free route, with urea as an additive. X‐ray diffraction patterns (XRD) show that the prepared samples exhibit high crystallinity. N2 adsorption–desorption isotherms and mercury intrusion porosimetry (MIP) analysis together with TEM observations indicate that micro‐, meso‐, and macropores exist in the obtained samples. Catalytic tests for the methanol to gasoline (MTG) conversion showed that the prepared c‐axis oriented hierarchical ZSM‐5, which allow fast mass transfer, exhibited both 100 % methanol conversion and far longer lifetime (900 h) than those of ZSM‐5 with conventional morphology (350 h) in the MTG reaction. The enhanced MTG performance by the c‐axis oriented zeolite under one‐pot solvent‐free synthesis is of great importance as it is easily scaled‐up for industrial applications.
Control Strategy and Comparison of Tuning Methods for Continuous Lactide Ring‐Opening Polymerization
Authors: Costa Liborio I. , Trommsdorff Ulla 
Published: August 2016

AbstractPolylactic acid is industrially produced by ring‐opening polymerization of lactide. This reaction is extremely sensitive to the level of monomer contaminants, thus posing some challenges for the operability of continuous processes. A control strategy was designed and the corresponding controller parameters were determined using gProms simulations by applying the Ziegler‐Nichols, Tyreus‐Luyben, and Cohen‐Coon methods. The simulation results show that the proposed strategy is effective in restoring the targeted process conditions after a sudden change in the level of contaminants, with the Cohen‐Coon controller providing the best results. Additionally, the simulations demonstrate that the use of automatic process control significantly reduces the pressure rise along the reactors after a feed disturbance, thus ensuring safer plant operation.
Stereoretentive Copper‐Catalyzed Directed Thioglycosylation of C(sp2)−H Bonds of Benzamides
Authors: Chabrier Amélie , Bruneau Alexandre , Benmahdjoub Sara , Benmerad Belkacem , Belaid Sabrina , Brion Jean‐Daniel , Alami Mouâd , Messaoudi Samir 
Published: August 2016

AbstractAn efficient thioglycosylation of C(sp2)−H bonds with thiosugars has been established for the first time. Using only Cu(OAc)2⋅H2O as a catalyst and Ag2CO3 as an additive in DMSO, the protocol proved to have broad scope, and a variety of complex thioglycosides have been prepared in good yields with exclusive β‐selectivity.
SuFEx Click: New Materials from SOxF and Silyl Ethers
Authors: Yatvin Jeremy , Brooks Karson , Locklin Jason 
Published: August 2016

AbstractNew forms of click chemistry present new opportunities in materials science. Sulfur(VI) fluoride exchange (SuFEx) is a recently discovered click reaction between molecules containing SOxF groups and silyl ethers, two functionalities that are orthogonal to all other known click chemistries, that generates sulfate or sulfonate connections upon the addition of certain organobases or fluoride sources. SuFEx also has several important advantages over other click reactions in that it is insensitive to ambient oxygen and water, and its precursor materials, especially SOxF, are chemically, UV, and thermally inert. This Concept article focuses on the unique reactivity of SuFEx and its relation to building high molecular weight polymers and surface coatings, both of which make it a powerful new tool for materials science.
Structures of Highly Twisted Amides Relevant to Amide N−C Cross‐Coupling: Evidence for Ground‐State Amide Destabilization
Authors: Pace Vittorio , Holzer Wolfgang , Meng Guangrong , Shi Shicheng , Lalancette Roger , Szostak Roman , Szostak Michal 
Published: August 2016

AbstractHerein, we show that acyclic amides that have recently enabled a series of elusive transition‐metal‐catalyzed N−C activation/cross‐coupling reactions are highly twisted around the N−C(O) axis by a new destabilization mechanism of the amide bond. A unique effect of theN‐glutarimide substituent, leading to uniformly high twist (ca. 90°) irrespective of the steric effect at the carbon side of the amide bond has been found. This represents the first example of a twisted amide that does not bear significant steric hindrance at the α‐carbon atom. The15N NMR data show linear correlations between electron density at nitrogen and amide bond twist. This study strongly supports the concept of amide bond ground‐state twist as a blueprint for activation of amides toward N−C bond cleavage. The new mechanism offers considerable opportunities for organic synthesis and biological processes involving non‐planar amide bonds.
Influence of Polymer Electronics on Selective Dispersion of Single‐Walled Carbon Nanotubes
Authors: Fong Darryl , Bodnaryk William J. , Rice Nicole A. , Saem Sokunthearath , Moran‐Mirabal Jose M. , Adronov Alex 
Published: August 2016

AbstractInvited for the cover of this issue is the group of Alex Adronov at McMaster University. The image depicts a stylized view of a metallic carbon nanotube that is being pulled into solution, and is related to the findings that the electronic nature of a conjugated polymer has an impact on its selectivity for metallic versus semiconducting single‐walled carbon nanotubes, allowing their selective dissolution. Read the full text of the article at 10.1002/chem.201602722.
Selenide‐Catalyzed Stereoselective Construction of Tetrasubstituted Trifluoromethylthiolated Alkenes with Alkynes
Authors: Wu Jin‐Ji , Xu Jia , Zhao Xiaodan 
Published: August 2016

AbstractThe efficient regio‐ and stereoselective construction of tetrasubstituted alkenes is challenging and very important. For this purpose, we have developed an efficient approach to synthesize tetrasubstituted trifluoromethylthiolated alkenes from simple alkynes in excellent regio‐ and stereoselectivities by selenide‐catalyzed multicomponent coupling. Using this method, trifluoromethylthiolated alkenyl triflates and arenes were achieved. In particular, the triflates could be further converted into carbofunctionalized alkenes by palladium‐catalyzed cross‐coupling reactions. Our method provides a new pathway for the construction of trifluoromethylthiolated tricarboalkenes. This work presents the first example of selenide‐catalyzed trifluoromethylthiolation of alkynes and enables the challenging functionalizations of alkynes.
ChemInform Abstract: Intramolecular Energy Transfer Studies of a New Mixed Isopolymolybdate [Eu(dmso)8] [Eu(η2‐NO3)2(dmso)4 (α‐Mo8O26)0.5] [Mo6O19]: Synthesis, Characterization and Europium(III) Luminescence Properties.
Authors: Ben Khelifa Arbia , Chekir‐Mzali Jalila , Ezzayani Khaireddine , Freslon Stephane , Belkhiria Mouhamed Salah 
Published: August 2016

AbstractThe title compound is obtained from DMSO solutions of [Bu4N][Mo6O19] and Eu(NO3)3 (333 K, 2 h, 75% yield).
ChemInform Abstract: A Gold(I)‐Catalyzed Substituent‐Controlled Cycloisomerization of Propargyl Vinylethers to Multi‐Substituted Furofuran and Furopyran Derivatives.
Authors: Liu Yongxiang , Jin Shengfei , Wang Yanshi , Cui Shanshan , Peng Xiaoshi , Niu Yuanyuan , Du Chuan , Cheng Maosheng 
Published: August 2016

AbstractCompounds (IIIa), (IIIc), (IIIe), (Va), (Vc), (VIa), (VII), (VIIIa), and (IX) show antifungal activity.
ChemInform Abstract: Palladium‐Catalyzed Arylation of β‐Methylene C(sp3)—H Bonds at Room Temperature: Desymmetrization of Simple Cycloalkyl Carboxylic Acids.
Authors: Nack W. A. , Wang B. , Wu X. , Jiao R. , He G. , Chen G. 
Published: August 2016

AbstractIn most cases, the β methylene C—H bonds of cycloalkylcarboxamides of varied ring size are monoarylated giving products with excellent cis‐diastereoselectivity whereby, diarylated products are also observed as by‐products.
ChemInform Abstract: Rhodium(II)‐Catalyzed Isomerization of Cyclopropenylmethyl Esters into (Acyloxymethylene)cyclopropanes.
Authors: Archambeau Alexis , Nguyen Dinh‐Vu , Meyer Christophe , Cossy Janine 
Published: August 2016

AbstractIn the presence of a rhodium(II) catalyst, 3,3‐disubstituted cyclopropenylmethyl esters that possess an electron‐rich or neutral aromatic group undergo isomerization into (acyloxymethylene)cyclopropanes.
ChemInform Abstract: Direct Conversion of Internal Alkynes into α‐Iodoenones: One‐Step Collaborative Iodination and Oxidation.
Authors: Wang Youliang , Genoux Alexandre , Ghorai Subir , Chen Hongyi , Todd Robert , Zhang Liming 
Published: August 2016

Abstract2,6‐Dichloropyridine N‐oxide as oxidant and NIS as iodination agent in stoichiometric amounts promote the title reaction regioselectively in high yields with preferred formation of Z isomers.
ChemInform Abstract: Highly Efficient and Regioselective Synthesis of Spirooxindolo Pyrrolizidines by Reaction of Isatin, Proline and Acrylonitrile/Methyl Acrylate in Water.
Authors: Tiwari Keshri Nath , Pandurang Taur Prakash , Pant Suyash , Kumar Rahul 
Published: August 2016

AbstractThe 1,3‐dipolar cycloaddition reaction of azomethine ylides generated in situ by isatin and L‐proline to acrylonitrile and methyl acrylate in water affords a series of spirooxindolo pyrrolizidines in good yields.
ChemInform Abstract: Ultrasound Assisted One‐Pot Synthesis of Benzo‐Fused Indole‐4,9‐dinones from 1,4‐Naphthoquinone and α‐Aminoacetals.
Authors: Luu Quang H. , Guerra Jorge D. , Castaneda Cecilio M. , Martinez Manuel A. , Saunders Jong , Garcia Benjamin A. , Gonzales Brenda V. , Aidunuthula Anushritha R. , Mito Shizue 
Published: August 2016

AbstractThe synthesis of benzo[f]indole‐4,9‐diones in one‐pot from 1,4‐naphthoquinone and α‐aminoacetals is reported.
ChemInform Abstract: Synthesis of 1,3‐Disubstituted Imidazo[1,5‐a]pyridines from Amino Acids via Catalytic Decarboxylative Intramolecular Cyclization.
Authors: Wang Huiqiao , Xu Wentao , Xin Lilan , Liu Wenmin , Wang Zhiqiang , Xu Kun 
Published: August 2016

Abstract2‐Aryloylpyridines or quinolines efficiently react with aryl or alkyl substituted α‐amino acids, thus offering not only a novel approach to 1,3‐diaryl substituted imidazo[1,5‐a]pyridines, but also to 3‐alkyl‐1‐aryl substituted derivatives which are difficult to access by previously developed methods.