bluuebunny/crossref_metadata_2025_split huggingface dataset:
Solid acids and their use as environmentally friendly catalysts in organic synthesis
Authors: Wilson Karen , Clark James H. 
Published: October 2007

Abstract
Tightening environmental legislation is driving the fine and speciality chemicals industries to consider alternative processes that avoid the use of conventional mineral acids. The use of heterogeneous catalysts in these processes would vastly simplify catalyst removal, minimizing the amount of waste formed. However, diffusion limitation of liquids within porous solids dictates that effective solid acids for liquid-phase reactions require the use of mesoporous materials &lt;20_100Å. Recent developments in materials chemistry has led to the discovery of a family of ordered mesoporous silicas which opens up new possibilities for preparing solid-acid catalysts for liquid-phase reactions. This review concentrates on recent developments in the synthesis of new mesoporous solid acids for liquid-phase organic synthesis.
Environment-friendly organic synthesis. The photochemical approach
Authors: Albini Angelo , Fagnoni Maurizio , Mella Mariella 
Published: October 2007

Abstract
Photochemical reactions are expected to have an increasing role in organic synthesis with the drive towards environment-friendly reactions. Some examples illustrating the scope and versatility of radical alkylation of electrophilic alkenes via photoinduced electron transfer are presented. A few applications in special fields are mentioned.
Frontiers in green chemistry utilizing carbon dioxide for polymer synthesis and applications
Authors: Young Jennifer L. , DeSimone Joseph M. 
Published: October 2007

Abstract
In the last ten years, there has been incredible growth in research involving the use of carbon dioxide as an environmentally benign solvent. This article will highlight polymer synthesis, characterization, and applications in CO2 and place this research in the context of both green chemistry and the latest developments in CO2 technology.
Quantum chemistry in the 21st century (Special topic article)
Authors: Barden Christopher J. , Schaefer Henry F. 
Published: October 2007

Abstract
Quantum chemistry is the field in which solutions to the Schrödinger equation are used to predict the properties of molecules and solve chemical problems. This paper considers possible future research directions in light of the discipline's past successes. After decades of incremental development—accompanied by a healthy dose of skepticism from the experimental community—the ready availability of fast computers has ushered in a "golden age" of quantum chemistry. In this new era of acceptance, theoretical predictions often precede experiment in small molecule chemistry, and quantum chemical methods play an ever greater role in biochemical and other larger systems. Quantum chemists increasingly divide their efforts along three fronts: high-level (spectroscopic) accuracy for small molecules, characterized by such techniques as Brueckner methods, r12 formalisms, and multireference calculations; parameterization- or extrapolation-based intermediate-level schemes (such as Gaussian-N theory) for medium molecules; and lower-level (chemical) accuracy for large molecules, characterized by density functional theory and linear scaling techniques. These tools, and quantum chemistry as a whole, are examined here from a historical perspective and with a view toward their future applications.
Guidelines for terms related to chemical speciation and fractionation of elements. Definitions, structural aspects, and methodological approaches (IUPAC Recommendations 2000)
Authors: Templeton Douglas M. , Ariese Freek , Cornelis Rita , Danielsson Lars-Göran , Muntau Herbert , van Leeuwen Herman P. , Lobinski Ryszard 
Published: October 2007

Abstract
This paper presents definitions of concepts related to speciation of elements, more particularly speciation analysis and chemical species. Fractionation is distinguished from speciation analysis, and a general outline of fractionation procedures is given. We propose a categorization of species according to isotopic composition of the element, its oxidation and electronic states, and its complex and molecular structure. Examples are given of methodological approaches used for speciation analysis. A synopsis of the methodology of dynamic speciation analysis is also presented.
Internet and other sources of methods for the assessment of workplace air quality (Technical report)
Authors: Brown R. H. 
Published: October 2007

Abstract
Methods for assessing occupational exposure to toxic chemicals have been developed semi-independently by a number of standards organizations and regulatory authorities in Europe and beyond. Few of these have been systematically reviewed against Comité Europeán de Normalisation (CEN) criteria for accuracy and reliability. Some of these methods have been complied into indexes, either in hard copy or on the Internet, but existing indices are incomplete. There is a clear need for the harmonization and validation of these methods and for a full compendium of available methods and their validation status, while avoiding duplication of essentially equivalent procedures. Many of the methods are accessible on the Internet, so that in such instances the compendium need not contain full details of the methods themselves but can provide links to the pertinent web sites.
New developments in radical chemistry. Applications to total synthesis and asymmetric processes
Authors: Aïssa Christophe , Delouvrié Bénédicte , Dhimane Anne-Lise , Fensterbank Louis , Malacria Max 
Published: October 2007

Abstract
This article reviews our contribution in the field of radical synthetic chemistry, focusing on cascades relying on the use of propargylic BMDMS ethers and asymmetric synthesis using enantiopure vinylsulfoxides.
Stereoselective C,C-bond formation. Cyclizations of biradicals
Authors: Giese Bernd , Barbosa Frédérique , Stähelin Christian , Sauer Stefan , Wettstein Philipp , Wyss Caroline 
Published: October 2007

Abstract
The formation of C,C-bonds via photolytically generated biradicals can occur with high stereoselectivity. If triplet biradicals are involved, chiral induction is highly likely. Syntheses that occur only via singlet biradicals have a good chance to show a memory effect of chirality.
Total synthesis of herboxidiene, a complex polyketide from Streptomyces species A7847
Authors: Banwell Martin , McLeod Malcolm , Premraj Rajaratnam , Simpson Gregory 
Published: October 2007

Abstract
A formal total synthesis of the polyketide herboxidiene (1) has been achieved by Horner-Wittig coupling of the side-chain fragment 12-epi-(2) with the tetrahydropyran-2-acetic acid derivative (3) followed by desilylation of the resulting triene (19) and hydroxyl-directed mono-epoxidation of the ensuing bis-homoallylic alcohol (20).
Synthetic studies toward pyranonaphthoquinone antibiotics
Authors: Brimble Margaret A. 
Published: October 2007

Abstract
A furofuran annulation/oxidative rearrangement strategy was used to construct the basic skeleton of the pyranonaphthoquinone family of antibiotics. This synthetic methodology has been applied to the synthesis of the spiroacetal-containing pyranonaphthoquinone antibiotic griseusin A, to an analog of the C-glycoside medermycin, and to a dimeric pyranonaphthoquinone.
Fluorous methods for synthesis and separation of organic molecules
Authors: Curran Dennis P. 
Published: October 2007

Abstract
Fluorous molecules partition out of an organic phase and into a fluorous (highly fluorinated) phase in a liquid-liquid extraction. New fluorous techniques allow simple yet substantive separations of organic reaction mixtures based on the presence or absence of a fluorous tag. Fluorous-tagged molecules can also be separated from nontagged molecules by solid phase extraction over fluorous reverse-phase silica gel. This technique is ideal for solution-phase parallel synthesis because it allows simple yet substantive separations of organic reaction mixtures.
Hypervalent siloxane derivatives. An alternative to Stille and Suzuki couplings
Authors: DeShong Philip , Handy Christopher J. , Mowery Molly E. 
Published: October 2007

Abstract
Siloxane methodology is extended to couplings with iodo- and bromoanilines, hindered arylbromides, and substituted siloxanes as substrates. Additionally, initial studies with 5-bromoindole and other heteroaromatics suggest that the siloxane-mediated cross coupling methodology will also be applicable in these systems.
Synthetic studies on the A83586C and bryostatin antitumor macrolides and the monamycin antibiotics
Authors: Hale K. J. , Hummersone M. G. , Cai J. , Manaviazar S. , Bhatia G. S. , Lennon J. A. , Frigerio M. , Delisser V. M. , Chumnongsaksarp A. , Jogiya N. , Lemaitre A. 
Published: October 2007

Abstract
After a brief summary of our asymmetric total syntheses of A83586C and 4-epi-A83586C, we will go on to describe some of our synthetic work on the monamycins, and our most recent total synthesis studies on the bryostatin antitumor macrolides.
Stereoselective and enantioselective synthesis of five-membered rings via conjugate additions of allylsulfone carbanions
Authors: Hassner Alfred , Ghera Eugene , Yechezkel Tamar , Kleiman Victoria , Balasubramanian Thiagarajan , Ostercamp Daryl 
Published: October 2007

Abstract
This lecture describes some of our studies of lithio derivatives of allyl sulfone carbanions which add α-regioselectively as well as anti diastereoselectively to Michael acceptor olefins. This can be ascribed to chelation in the Michael addition step. When the reaction leads to subsequent ring closure by using a bromoallyl sulfone, the latter acts as a methylenemethane synthon in a (3+2) Michael-initiated ring closure, affording highly functionalized cyclopentane derivatives. Such additions proceed with high stereoselectivity and with asymmetric induction leading to nonracemic substituted cyclopentanones. Additions of allyl sulfone carbanions also proceed stereoselectively to C=N systems containing a chiral auxiliary on N. These can be used in the synthesis of optically active five- and six-membered ring N-heterocycles. Furthermore, chiral groups on the allyl sulfone moiety can induce significant remote asymmetric induction, made possible by the presence of an aromatic π-system which promotes intramolecular chelation to the Li cation.
Ring constructions by the use of fluorine substituent as activator and controller
Authors: Ichikawa Junji 
Published: October 2007

Abstract
By using the properties of fluorine such as electronic effects and leaving-group ability, two types of ring-forming reactions have been achieved starting from fluoroolefins: (i) fluorinated vinyl ketones with a vinyl and/or an aryl group, which undergo fluorine-directed and/or -activated Nazarov, Friedel-Crafts, and tandem cyclizations in their combination to construct highly functionalized and fused ring systems and (ii) gem-difluoroolefins bearing a nucleophilic center on the carbon δ to the flourines undergo intramolecular substitution for the fluorine via "anti-Baldwin" 5-endo-trig closures leading to ring-fluorinated heterocycles. Throughout these reactions, fluorines function as an activator of the substrates and a controller over the reaction pathways.
Stereocontrolled asymmetric synthesis
Authors: Kim Yong Hae , Kim Sam Min , Park Doo Han , Youn So Won 
Published: October 2007

Abstract
Stereo differentiated asymmetric syntheses have been achieved by S-indoline derivations. Diels-Alder cycloadditions of S-indoline chiral acrylamides with cyclopentadiene proceed with high diastereofacial selectivity, giving either endo-R or endo-S products depending on Lewis acid and the structures of chiral dienophiles. Diastereo- and enantio-selective pinacol coupling reactions of chiral α-ketoamides mediated by samarium diiodide afforded extremely high diastereoselectivities. Enantiopure (S,S)- or (R,R)-2,3-dialkyltar-taric acid and derivatives can be synthesized for the first time depending on the structure of α-ketoamides.
Selective transformations mediated by main-group organometallics
Authors: Knochel Paul , Boudier Andreas , Bromm Lars O. , Hupe Eike , Varela Jesús A. , Rodriguez Alain , Koradin Christopher , Bunlaksananusorn Tanasri , Laaziri Hamid , Lhermitte Frédéric 
Published: October 2007

Abstract
Main-group organometallics are useful intermediates for the chemoselective and diastereoselective C-C bond formation. The boron-zinc exchange is a unique way for preparing chiral secondary alkylzinc reagents which are configurationally stable over a wide temperature scale. Coupled with the thermal rearrangement of tertiary organoboranes, a broad range of open-chain and cyclic polyfunctional molecules have been prepared. In addition, several examples of a diastereoselective remote C-H activation have been studied. The second part shows that the main-group metallic alkoxides such as t-BuOK can be used for the performance of catalytic reactions such as a new indole synthesis.
New nucleoside analogs, synthesis, and biological properties
Authors: Wanner M. J. , Deghati P. Y. F. , Rodenko B. , Koomen G. J. 
Published: October 2007

Abstract
In view of the importance of nucleoside analogs as enzyme inhibitors and adenosine receptor (ant)agonists, new adenosine analogs were prepared and their activities studied on adenosine deaminase in vitro and on A1, A2A, and A3 receptors. Particularly useful for the synthesis of new analogs were the applications of the Pd-catalyzed Buchwald reaction and a radical nitration reaction of purine- and 1-deazapurine nucleosides.
Reactions involving inorganic compounds
Authors: Krief Alain , Delmotte Cathy , Colaux-Castillo Catherine 
Published: October 2007

Abstract
Selenium chemistry became, over the last 30 years, particularly useful for synthetic organic chemistry [1]. Inorganic as well as organic selenium compounds allow transformation which otherwise cannot be done or require much more drastic conditions to proceed. We have over the last 25 years explored the reactivity of elemental selenium as well as its inorganic and organic derivatives. We report here our recent finding concerning (i) organic diselenols and -diselenolates and (ii) the role of selenoxides in the enantioselective dihydroxylation of C,C double bonds using catalytic amounts of osmium tetroxide.
Titanacyclopropanes as versatile intermediates for carbon-carbon bond formation in reactions with unsaturated compounds
Authors: Kulinkovich O. G. 
Published: October 2007

Abstract
Dialkoxytitanacyclopropane intermediates [or titanium (II)-olefin complexes] generated in situ from ethylmagnesium bromide and titanium (IV) isopropoxide react with allylic alcohols and allylic ethers to afford SN2' allylic ethylation products. The reaction proceeds with high regioselectivity and with low to high trans-/cis-stereoselectivity. This observation and others suggest a reaction mechanism involving an EtMgBr-initiated formation of titanacyclopentane ate complex 10 from titanacyclopropane-olefin complex 7 as a key step. Based on this assumption, a modified mechanism of titanium-mediated cyclopropanation of esters with Grignard reagents is proposed.
Oxazoline-N-oxide mediated asymmetric cycloadditions. Recent progress in the stereo-selective syntheses of β-lactones and β-lactams
Authors: Dirat O. , Kouklovsky C. , Mauduit M. , Langlois Y. 
Published: October 2007

Abstract
Camphor-derived oxazoline-N-oxides are versatile dipoles in a new kind of asymmetric [2+3] cycloadditions. Recent applications of this methodology allowed the stereoselective syntheses of several b-lactones natural products such as 1233A and tetrahydrolipstatine. Two formal syntheses of b-lactams antibiotics, b-methyl thienamycin and carpetimycin A, have also been achieved using this type of cycloaddition.
Gary A. Molander
Authors: Molander Gary A. 
Published: October 2007

Abstract
Metallocene complexes of the Group 3 metals and lanthanides have been utilized for cyclization/silylation reactions of polyunsaturated organic substrates. Acyclic dienes, trienes, enynes, and dienynes can be selectively cyclized to provide five- and six-membered rings in high yields.
Anionic cyclization approach toward perhydroindoles. Total synthesis of montanine-type Amaryllidaceae alkaloids
Authors: Sha C.-K. , Huang S.-J. , Huang C.-M. , Hong A.-W. , Jeng T.-H. 
Published: October 2007

Abstract
Hexahydro-1H-indol-3-one can be used as a building block for alkaloid synthesis. Radical and anionic cyclization approaches toward this useful structure were developed. Approaches toward total synthesis of montanine-type Amaryllidaceae alkaloids using hexahydro-1H-indol-3-one as a key intermediate were studied.
Stereochemical support for Serratia endonuclease active-site geometry
Authors: Stec W. J. , Koziolkiewicz M. , Taira K. 
Published: October 2007

Abstract
Earlier observation that stereoregular All-Rp-PS-oligonucleotides in the presence of nonsequence-specific Serratia endonuclease undergo nucleolytic degradation, confronted with recently published results on the active-site architecture of this enzyme, strongly supports an involvement of 3'-bridging and pro-Sp-nonbridging oxygen atoms of scissile internucleotide bond in the interactions with hydrated magnesium ion anchored by Asn-119 residue of this endonuclease.
Synthetic study of ravidomycin, a hybrid natural product
Authors: Suzuki Keisuke 
Published: October 2007

Abstract
Strategies and tactics associated with the total synthesis of hybrid natural products are discussed. The target is ravidomycin (2), one of the gilvocarcin-class antitumor antibiotics with an aryl C-glycoside structure. The first total synthesis of 2, which was achieved along similar lines of that of gilvocarcin V (1), served for the determination of the relative as well as the absolute stereochemistry of 2. Also revealed was a limitation of the synthetic scheme so long as the amino sugar congener was concerned. A preliminary result is discussed on the [2+2+2] approach that relies on the ready availability of various benzocyclobutene derivatives via regioselective [2+2] cycloaddition of α-alkoxybenzynes and ketene silyl acetals.
Thermodynamics of structured fluids. Hard science for soft materials
Authors: Prausnitz John M. 
Published: October 2007

Abstract
At liquid-like densities, molecules of complex fluids can assume a variety of structures (or positions) in space; when the molecules contain many atoms as, for example, in polymers, that variety becomes very large. Further, when confined to a narrow space, it is possible to achieve structures that are not normally observed. Thanks to recent advances in statistical mechanics and molecular physics, and thanks to increasingly fast computers, it is now possible to calculate a fluid's structure, that is, the positions of molecules at equilibrium under given conditions. Calculation of fluid structure is useful because thermodynamic properties depend strongly on that structure, leading to possible applications for new materials. Three examples illustrate some recent developments; each example is presented only schematically (with a minimum of equations) to indicate the physical basis of the mathematical description. The first example considers the effect of branching on self-assembly (micellization) of copolymers (with possible long-range applications in medicine). The second and third examples consider the effect of confinement on fluid structure: first, crystallization in a narrow, confined space to produce a desired crystal structure (with possible applications for light-emitting diodes) and second, suppression of micellization of a diblock copolymer in a thin film (with possible application in lithography). Whenever possible, theoretical calculations are compared with experimental results.
Thermochemical studies of advanced nuclear fuels and materials
Authors: Yamawaki Michio , Inoue Tadashi , Ogawa Toru 
Published: October 2007

Abstract
Thermochemical analyses related with development of advanced nuclear fuels (i.e., metalic, nitride, and hydride fuels) with respect to the transmutation of transuranium elements and relevant pyrochemical reprocessing and fabrication processes, which have been carried out mainly in Japan, are summarized. In addition, application of atmosphere-controlled high-temperature mass spectrometry on solid-gas reactions, in particular on the prediction of gas-interacting behaviors of cesium and lithium on respective oxide ceramics, are delineated in relation to nuclear material-relevant researches.
Hydrocarbon oxidation high-temperature chemistry
Authors: Warnatz Jürgen 
Published: October 2007

Abstract
The exact knowledge of hydrocarbon oxidation kinetics is very important due to the fact that this process is involved in many technological processes: combustion in engines and furnaces, flame synthesis of materials, partial oxidation processes in chemical technology, catalytic combustion, and exhaust gas treatment, etc. An overview is given on the present state of the art with respect to kinetic data on gas-phase and (shortly) surface oxidation of hydrocarbons. Furthermore, some applications are described in the areas mentioned above. Examples for the importance of the gas-phase oxidation of hydrocarbons are ignition and combustion in engines and furnaces and partial oxidation processes in industrial chemical reactors. In many applications, both gas-phase and surface chemistry are taking place. Examples here are flame generation of diamonds and syngas generation.
Chemical kinetics at solid-solid interfaces
Authors: Schmalzried Hermann 
Published: October 2007

Abstract
The kinetics of solid-solid interfaces controls in part the course of heterogeneous reactions in the solid state, in particular in miniaturized systems. In this paper, the essential situations of interface kinetics in solids are defined, and the basic formal considerations are summarized. In addition to the role interfaces play as resistances for transport across them, they offer high diffusivity paths laterally and thus represent two-dimensional reaction media. Experimental examples will illustrate the kinetic phenomena at static and moving boundaries, including problems such as exchange fluxes, boundary-controlled solid-state reactions, interface morphology, nonlinear phenomena connected with interfaces, and reactions in and at boundaries, among others.
Localization and bandwidth of the 3d-orbitals in magnetic Ni and Co clusters
Authors: Morenzin J. , Kietzmann H. , Bechthold P. S. , Ganteför G. , Eberhardt W. 
Published: October 2007

Abstract
Photoelectron spectra of negatively charged Nin
- , Cun
-, and Con
- clusters are presented. The spectra of the Nin
- clusters contain information about the degree of localization of the 3d valence orbitals, which is strongly related to the magnetic properties. In the clusters with less than 7 atoms, the 3d orbitals seem to be almost totally localized. For Co13
- we find indications of a narrowing of the 3d-derived valence "bandwidth" corresponding to a presumed high symmetry and a high degree of degeneracy of the 3d electronic states.
Transport processes in metal halide gas discharge lamps
Authors: van Erk W. 
Published: October 2007

Abstract
An overview is given of transport reactions and corrosion phenomena in metal halide gas discharge lamps filled with a mixture of alkali halides with scandium or rare-earth iodides. The phenomena that are discussed are: (a) pressures of light-emitting species above the molten salt mixture, (b) interaction of the metal halides with the vessel wall, quartz glass as well as polycrystalline alumina, (c) transport processes along the vessel wall giving rise to wall corrosion, and (d) transport to and from the electrodes (i.e., electrode corrosion and wall blackening).