bluuebunny/crossref_metadata_2025_split huggingface dataset:
Directed Growth and Electrical‐ Transport Properties of Carbon Nanotube Architectures on Indium Tin Oxide Films on Silicon‐Based Substrates
Authors: Agrawal S. , Frederick M. J. , Lupo F. , Victor P. , Nalamasu O. , Ramanath G. 
Published: October 2005

AbstractGrowing aligned carbon nanotubes (CNTs) on electrically conducting and/or optically transparent materials is potentially useful for accessing CNT properties through electrical and optical stimuli. Here, we report a new approach to growing aligned bundles of multiwalled CNTs on a porous back contact of optically transparent and electrically conducting indium tin oxide (ITO) films on silicon and silica substrates without the use of a predeposited catalyst. CNTs grow from a xylene/ferrocene mixture, which traverses through the pores in the thin ITO film, and decomposes on an interfacial silica layer formed via the reaction between ITO and the Si substrate. The CNTs inherit the topography of the silica substrate, enabling back‐contact formation for CNTs grown in any predetermined orientation. These features can be harnessed to form CNT contacts with other substrate materials which, upon reduction by Si, results in a conducting interfacial layer. The ITO‐contacted CNTs exhibit thermally activated ohmic behavior across a 100 ± 10 meV barrier at electric fields below ∼ 100 V cm–1 due to carrier transport through the outermost shells of the CNTs. At higher electric fields, we observe superlinear behavior due to carrier tunneling and transport through the inner graphene shells. Our findings open up new possibilities for integrating CNTs with Si‐based device technologies.
Energy Collection, Transport, and Trapping by a Supramolecular Organization of Dyes in Hexagonal Zeolite Nanocrystals
Authors: Minkowski C. , Pansu R. , Takano M. , Calzaferri G. 
Published: October 2005

AbstractThe incorporation of guest molecules into the cavities of molecular sieves leads to a large variety of highly interesting materials. Zeolite L—an aluminosilicate with one‐dimensional channels of open diameter 7.1 Å—is a very versatile material for building highly organized host–guest systems. We present materials where organic dye molecules have been incorporated into the channels of zeolite L by means of diffusion, to build artificial photonic antenna systems. The channel entrance can be plugged by adding closure molecules that then connect the guest molecules inside with materials or molecules outside of the zeolite channels, since they can act as extensions of the interior of the zeolite crystal. The photophysical processes taking place in such dye‐loaded zeolite L antennae can be studied either on single‐micrometer‐ or submicrometer‐sized crystals or on crystals dispersed in a solvent or coated as thin layers on a support. The energy‐transfer process occurring is of the Förster‐type, and its transfer rate can be tuned by separating the donor dyes and the acceptor dyes locally by varying amounts of spacer molecules. The distribution of the dye molecules and empty sites within a zeolite crystal has been modeled by means of a Monte Carlo simulation. The Förster energy migration and transfer steps are described as a random walk.
Hierarchical Pattern Formation in Thin Polymer Films Using an Electric Field and Vapor Sorption
Authors: Harkema S. , Steiner U. 
Published: October 2005

AbstractThe experimental observation of electric‐field‐induced instabilities of polymer films exposed to toluene vapors is reported. When using a laterally structured electrode, the pattern that forms in the polymer film is governed by the interplay of the intrinsic film instability and the periodicity of the electrode structure. By adjusting the applied voltage, it is possible to switch between two different pattern‐replication modes. A further important parameter is the aspect ratio of the structured electrode. For high ratios of polymer film thickness to capacitor‐plate spacing, structures with hierarchical length scales have been observed.
Ethylene‐Bridged Bissulfoximines in Copper‐Catalyzed Enantioselective Hetero‐Diels‐‐Alder Reactions
Authors: Bolm Carsten , Verrucci Marinella , Simic Oliver , Hackenberger Christian P. R. 
Published: October 2005

AbstractEthylene‐bridged bissulfoximines were applied as chiral ligands in copper‐catalyzed enantioselective hetero‐Diels–Alder reactions. After optimization of the reaction conditions, products with up to 99% ee were obtained.
Anionic Reactions of N‐(trans‐2,3‐Diphenylaziridin‐1‐yl)imines and Their Use as 1,1‐Dipoles in Anionic Cyclizations
Authors: Hwang Jung‐ll , Hong Young‐Taek , Kim Sunggak 
Published: October 2005

AbstractReaction of N‐(trans‐2,3‐diphenylaziridin‐1‐yl)imines with alkyllithiums and organocuprates afforded the desired addition products after consecutive fragmentations along with liberation of stilbene and nitrogen gas, while the reaction of N‐(2‐phenylaziridin‐1‐yl)imines under similar conditions gave an anomalous by‐product. Anionic cyclizations of N‐(trans‐2,3‐diphenylaziridin‐1‐yl)imines using unactivated alkenes and alkynes as acceptors proceeded smoothly, yielding cyclized products in good yields.
Substrate‐Controlled Palladium‐Catalyzed Allylic Alkylations of Chelated Enolates – Scope and Limitations
Authors: Lindner Thomas , Kazmaier Uli 
Published: October 2005

AbstractChelated enolates of amino acid derivatives were found to be excellent nucleophiles for stereoselective palladium‐catalyzed allylic alkylations via terminal π‐allyl complexes. Neither the olefin geometry (linear substrates) nor the configuration of secondary allylic substrates has an influence on the newly formed stereogenic centre of the amino acid. This is exclusively controlled by the protecting group on the chiral centre. Therefore, depending on the protecting group used, both diastereomeric amino acids can be obtained in a highly stereoselective fashion (up to 96% ds for 1,5 induction) from one allylic alcohol.
Diastereoselective Synthesis of Enantioenriched, Annulated Tetrahydrofurans by Simultaneous Formation of the O‐1C‐5 and the C‐5C‐4 Bonds
Authors: Ünaldi Seda , Özlügedik Mustafa , Fröhlich Roland , Hoppe Dieter 
Published: October 2005

AbstractEnantiomerically enriched 1‐[2‐(1‐hydroxyalkyl)cycloalkylidene]methyl N,N‐diisopropylcarbamates, which are easily available by an asymmetric homoaldol reaction, condense with aldehydes under the influence of boron trifluoride etherate to form cyclohexano‐ or cyclopentano‐annulated tetrahydrofuran‐3‐carboxaldehydes, bearing two quaternary carbon atoms and four adjacent stereogenic centers, with complete diastereoselectivity.
Stereoselective Synthesis of 3‐Alkylideneoxindoles using Tandem Indium‐Mediated Carbometallation and Palladium‐Catalyzed Cross‐Coupling Reactions
Authors: Yanada Reiko , Obika Shingo , Kobayashi Yusuke , Inokuma Tsubasa , Oyama Munetaka , Yanada Kazuo , Takemoto Yoshiji 
Published: October 2005

AbstractThe first efficient methods for the stereoselective synthesis of various (E)‐, (Z)‐, and disubstituted 3‐alkylideneoxindoles via radical cyclization reactions were investigated using tandem indium‐mediated carbometallation and palladium‐catalyzed cross‐coupling reactions. The proper combination of substrates and reaction conditions is important for good yields. The key step is the first stereoselective carboindation reaction using the strong coordination ability of an indium cation to the amide carbonyl oxygen. We applied this method to the synthesis of TMC‐95A precursor. A new N‐debenzylation method with N‐hydroxyphthalimide‐O2‐Co(OAc)2‐Mn(OAc)2 was also developed using a one‐electron oxidation procedure.
Mannich‐Type Reaction Using Alkenyl Trichloroacetates Catalyzed by Dibutyltin Dimethoxide
Authors: Yanagisawa Akira , Saito Hironao , Harada Masanori , Arai Takayoshi 
Published: October 2005

AbstractA novel Mannich‐type reaction of alkenyl trichloroacetates with aldimines has been realized by using dibutyltin dimethoxide as a catalyst, which is regenerated by addition of methanol. A three‐component coupling reaction of aldehydes, primary amines, and alkenyl trichloroacetates has been also efficiently achieved. These procedures can provide a variety of β‐amino ketones not only from aromatic aldehydes but also from α,β‐unsaturated aldehydes mainly with syn‐selectivity in high yields up to 99%.
Synthesis of New C2‐Symmetrical Bissulfonamide Ligands and Application in the Enantioselective Addition of Alkynylzinc to Aldehydes and Ketones
Authors: Ni Ming , Wang Rui , Han Zhi‐jian , Mao Bin , Da Chao‐shan , Liu Lei , Chen Chao 
Published: October 2005

AbstractNovel C2‐symmetrical bissulfonamide ligands were easily prepared in three simple steps and applied in the enantioselective addition of alkynylzinc reagents to aldehydes. Compound 7a was found to be an outstanding ligand for this reaction. When the catalyst loading, 4 mol % of 7a, was used, high enantioselectivity with an ee value up to 97% was achieved under very mild conditions. When the amount of ligand 7a was lowered to 2 mol %, excellent levels of enantiocontrol up to 95% ee were still achieved. So far the most economic catalyst system was developed for the addition of terminal alkynes to aromatic aldehydes in terms of ligand loading and enantioselectivity. Moreover, ligand 7a in combination with Ti(O‐i‐Pr)4 was found to be effective in promoting the addition reaction of an alkynylzinc reagent to unactivated simple ketones under very mild conditions. The corresponding chiral tertiary propargylic alcohols were obtained with enantiomeric excesses of up to 81%.
Iron(III)‐Catalyzed Tandem Sequential Methanol Oxidation/Aldol Coupling
Authors: Lecomte Vincent , Bolm Carsten 
Published: October 2005

AbstractIron(III)‐catalyzed methanol oxidations have been performed using hydrogen peroxide as oxidant. Formaldehyde is formed in situ and reacts subsequently with activated ketones to give α‐hydroxymethyl carbonyl compounds in good yields. As side reactions iron‐catalyzed α‐hydroxylations have been observed.
Enantioselective Mannich‐Type Reaction Catalyzed by a Chiral Brønsted Acid Derived from TADDOL
Authors: Akiyama Takahiko , Saitoh Youichi , Morita Hisashi , Fuchibe Kohei 
Published: October 2005

AbstractA novel cyclic dialkyl phosphate was synthesized starting from (+)‐diethyl tartrate. Its catalytic activity as a chiral Brønsted acid has been examined in the Mannich‐type reaction of a ketene silyl acetal with aldimines as a model reaction. The corresponding β‐amino acid esters were obtained with high enantioselectivity.
Imine Additions of Internal Alkynes for the Synthesis of Trisubstituted (E)‐Alkene and Cyclopropane Peptide Isosteres
Authors: Wipf Peter , Xiao Jingbo , Geib Steven J. 
Published: October 2005

AbstractDivergent multi‐component reactions (DMCR) involving CC bond formations can provide large increases in structural diversity and allow the rapid assembly of complex products from readily available starting materials. Cascade hydrozirconation‐Zr/Zn transmetalation‐imine addition of alkynes represents a versatile methodology for the synthesis of (E)‐alkene and cyclopropane dipeptide isosteres. Appropriate substitutions at the sp2‐carbon of (E)‐alkene peptide isosteres allow a range of Pd‐catalyzed cross‐coupling reactions, which can be used for the fine‐tuning of the conformational and electronic properties of the parent peptide bond mimic. CC bond formation by microwave‐accelerated Stille coupling of stannylalkenes represents a fast, convergent synthetic approach toward trisubstituted (E)‐alkene dipeptide isosteres.
A New Method for the Generation of Titanium(III) Complexes and its Application in Pinacol Coupling Reactions
Authors: Knoop Christoph Alexander , Studer Armido 
Published: October 2005

AbstractA new method for thein situgeneration of various Ti(III) complexes is presented. Cyclohexadienyl‐Ti(IV) derivatives, which are readily prepared from the corresponding lithiated cyclohexadienes, afford the corresponding Ti(III) complexes upon thermal CTi‐bond homolysis. The Ti(III) compounds generated using this novel method have successfully been used in the reductive dimerization of benzaldehyde. In particular, TiBr3, TiCp2Cl and Ti(O‐i‐Pr)3have been generatedviathis approach. Moreover, the method also offers an entry to new chiral Ti(III) complexes as documented by the preparation of Ti(III)CpTADDOLate.
Allylation of Aldehydes Promoted by the Cerium(III) Chloride Heptahydrate/Sodium Iodide System: the Dependence of Regio‐ and Stereocontrol on the Reaction Conditions
Authors: Bartoli G. , Giuliani A. , Marcantoni E. , Massaccesi M. , Melchiorre P. , Lanari S. , Sambri L. 
Published: October 2005

AbstractThe cerium(III) chloride heptahydrate/sodium iodide complex (CeCl3 ⋅ 7 H2O/NaI) acts as a useful promoter in the carbon‐carbon bond forming reaction by addition of allyltributylstannanes to aldehydes. The reaction of 2‐butenyltributylstannane shows that the regio‐ and the stereochemical outcomes depend on the reaction conditions. When the promoter is adsorbed on a solid support (aluminum oxide), a highly prevalent formation of the γ‐adduct is observed in solvent‐free conditions. Conversely, when the reaction is carried out in acetonitrile as the solvent, the α‐adduct largely prevails. In the last case, a complete stereocontrol is observed, the less stable (Z)‐isomer being obtained in high geometrical purity.
Rhodium‐Catalyzed Asymmetric Intramolecular Cyclopropanation of Substituted Allylic Cyanodiazoacetates
Authors: Lin Wei , Charette André B. 
Published: October 2005

AbstractA chiral rhodium catalyst, Rh2[4S‐(4′)‐FBNAZ]4, was synthesized and was shown to catalyze the intramolecular cyclopropanation of substituted allylic cyanodiazoacetates. Alkenes bearing an electron‐deficient substituent including carbonyl and halogens are converted into the corresponding cyclopropanes in high yields with both chiral and achiral rhodium catalysts. The cyclopropane derivatives were generated with an enantioselectivity of up to 91% ee. For the asymmetric intramolecular cyclopropanation, cis‐halogen‐substituted substrates afforded cyclopropanes with higher enantioselectivities than the corresponding trans diastereomers. However, only moderate enantioselectivities were observed with alkenes bearing electron‐donating groups such as alkyls. The cyclopropanation of 3‐substituted 2‐propenyl cyanodiazoacetates was strongly influenced by steric and electronic factors arising from substituents on the alkenes. For the first time, we demonstrated that the intramolecular reaction of gem‐dihaloallylic cyanodiazoacetate afforded highly functionalized gem‐dihalocyclopropanes. This reaction is an appealing alternative to the addition of dihalocarbenes to alkenes for the formation of gem‐dihalocyclopropanes.
Continuous Chemoselective Methylation of m‐Cresol and Phenol with Supercritical Methanol over Solid Acid and Base Metal Oxide Catalysts
Authors: Oku Tomoharu , Arita Yoshitaka , Ikariya Takao 
Published: October 2005

AbstractThe chemoselective methylation of m‐ cresol and phenol with supercritical methanol (scCH3OH) promoted by metal oxide catalysts (MgO, ZrO2, CsPSi and FeV/SiO2) was investigated in a continuous flow fixed bed reactor. The use of scCH3OH as a carrier medium led to a significant change in the product selectivity compared to that attained in the gas phase reaction, and caused a marked suppression of the degradation of CH3OH during the reaction, resulting in an improvement in the catalyst lifetime. The chemoselective outcome of the reaction was highly influenced by the acid‐base character on the solid catalysts examined under supercritical conditions.
Practical Synthesis of (E)‐α,β‐Unsaturated Esters from Aldehydes
Authors: List Benjamin , Doehring Arno , Fonseca Maria T. Hechavarria , Wobser Kathrin , van Thienen Hendrik , Torres Ramon Rios , Galilea Pedro Llamas 
Published: October 2005

AbstractBased on a modification of the Doebner–Knoevenagel reaction, a practical and highly efficient synthesis of α,β‐unsaturated esters with excellent regio‐ and stereoselectivity was developed. The reactions are catalyzed by 4‐dimethylaminopyridine in DMF at room temperature or below. Both aliphatic and aromatic aldehydes can readily be used in the process.
Catalytic Enantioselective Michael Reaction of 1,3‐Dicarbonyl Compounds via Formation of Chiral Palladium Enolate
Authors: Hamashima Yoshitaka , Hotta Daido , Umebayashi Natsuko , Tsuchiya Yasunori , Suzuki Takeyuki , Sodeoka Mikiko 
Published: October 2005

AbstractAn efficient catalytic enantioselective Michael reaction has been developed using chiral palladium complexes. Various substrates including β‐keto esters and 1,3‐diketones reacted with α,β‐unsaturated carbonyl compounds to give the corresponding Michael adducts in good yield with up to 99% ee, thereby affording chiral quaternary carbon centers. In these reactions, chiral palladium enolates were generated as key intermediates, which acted cooperatively with a strong protic acid to activate the Michael acceptors for promotion of the CC bond‐forming reaction.
A Modular Approach to α‐Arylated Carbonyl Compounds via Indium Tris(bistriflylamide)‐Catalyzed Regioselective Addition of β‐Ketoesters to 1,3‐Diynes
Authors: Nakamura Masaharu , Endo Kohei , Nakamura Eiichi 
Published: October 2005

AbstractA modular synthesis of α‐arylated carbonyl compounds has been achieved by the combination of an indium‐catalyzed regioselective addition of β‐keto esters to conjugated diynes and a palladium‐catalyzed benzannulation reaction. Indium tris(bistriflylamide), In(NTf2)3, was found to be an efficient catalyst for the first addition reaction of β‐keto esters to diynes. The reaction proceeds with perfect regioselectivity to give conjugated enynes in high yield. The second palladium‐catalyzed benzannulation proceeds in high to excellent yield and with high regioselectivity for a variety of diynes. This two‐step α‐arylation of carbonyl compounds thus proceeds in a catalytic manner without loss of elements in the starting materials. The reaction may be performed in a single pot without isolation of the product of the first step.
Enantioselective Addition of Organozinc Reagents to Aldehydes Catalyzed by 3,3′‐Bis(diphenylphosphinoyl)‐BINOL
Authors: Hatano Manabu , Miyamoto Takashi , Ishihara Kazuaki 
Published: October 2005

AbstractThe enantioselective addition of organozinc reagents to aromatic and aliphatic aldehydes 1 gives secondary alcohols 2 with excellent enantioselectivities in high yields through the catalytic use of (R)‐3,3′‐bis(diphenylphosphinoyl)‐BINOL (3) or (R)‐3,3′‐bis(diphenylthiophosphinoyl)‐BINOL (4) without Ti(IV) complexes. The coordination of the O or S atom of a (thio)phosphinoyl group bearing a BINOL backbone to organozinc reagents can efficiently increase the nucleophilicity of the organozinc reagents.
Factors governing the consumption of explicit knowledge
Authors: Desouza Kevin C. , Awazu Yukika , Wan Yun 
Published: October 2005

AbstractKnowledge management as a field continues to receive resounding interest from scholars. While we have made progress in many areas of knowledge management, we are yet to understand what factors contribute to employee usage of knowledge artifacts. A field study of 175 employees in a software engineering organization was conducted to understand factors that govern consumption of explicit knowledge. We assert that the decision to consume knowledge can be framed as a problem of risk evaluation. Specifically, there are two sources of risk a consumer must evaluate prior to knowledge consumption—risk from the knowledge producer and risk from the knowledge product. We find support for the factors of perceived complexity, perceived relative advantage, and perceived risk as they relate to intentions to consuming knowledge.
Hierarchical phylogenetics as a quantitative analytical framework for evolutionary developmental biology
Authors: Serb Jeanne M. , Oakley Todd H. 
Published: October 2005

AbstractPhylogenetics has inherent utility in evolutionary developmental biology (EDB) as it is an established methodology for estimating evolutionary relationships and for making comparisons between levels of biological organization. However, explicit phylogenetic methods generally have been limited to two levels of organization in EDB—the species and the gene. We demonstrate that phylogenetic methods can be applied broadly to other organizational levels, such as morphological structures or cell types, to identify evolutionary patterns. We present examples at and between different hierarchical levels of organization to address questions central to EDB. We argue that this application of “hierarchical phylogenetics” can be a unifying analytical approach to the field of EDB. BioEssays 27:1158–1166, 2005. © 2005 Wiley Periodicals, Inc.
Microbial experiments on adaptive landscapes
Authors: Colegrave Nick , Buckling Angus 
Published: October 2005

AbstractThe adaptive landscape is one of the most widely used metaphors in evolutionary biology. It is created by plotting fitness against phenotypes or genotypes in a given environment. The shape of the landscape is crucial in predicting the outcome of evolution: whether evolution will result in populations reaching predictable end points, or whether multiple evolutionary outcomes are more likely. In a more applied sense, the landscape will determine whether organisms will evolve to lose ‘costly’ resistance to antibiotics, herbicides or pesticides when the use of the control agent is stopped. Laboratory populations of microbes allow evolution to be observed in real time and, as such, provide key insights into the topology of adaptive landscapes. BioEssays 27:1167–1173, 2005. © 2005 Wiley Periodicals, Inc.
Did internal transport, rather than directed locomotion, favor the evolution of bilateral symmetry in animals?
Authors: Finnerty John R. 
Published: October 2005

AbstractThe standard explanation for the origin of bilateral symmetry is that it conferred an advantage over radial symmetry for directed locomotion. However, recent developmental and phylogenetic studies suggest that bilateral symmetry may have evolved in a sessile benthic animal, predating the origin of directed locomotion. An evolutionarily feasible alternative explanation is that bilateral symmetry evolved to improve the efficiency of internal circulation by affecting the compartmentalization of the gut and the location of major ciliary tracts. This functional design principle is illustrated best by the phylum Cnidaria where symmetry varies from radial to tetraradial, biradial and bilateral. In the Cnidaria, bilateral symmetry is manifest most strongly in the internal anatomy and the disposition of ciliary tracts. Furthermore, the bilaterally symmetrical Cnidaria are typically sessile and, in those bilaterally symmetrical cnidarians that undergo directed locomotion, the secondary body axis does not bear a consistent orientation to the direction of locomotion as it typically does in Bilateria. Within the Cnidaria, the hypothesized advantage of bilateral symmetry for internal circulation can be tested by experimental analysis and computer modeling of fluid mechanics. The developmental evolution of symmetry within the Cnidaria can be further explored through comparative gene expression studies among species whose symmetry varies. BioEssays 27:1174–1180, 2005. © 2005 Wiley Periodicals, Inc.