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  • Inorganic Chemistry  (83,668)
  • Organic Chemistry  (68,947)
  • 1
    Keywords: Biochemistry ; Chemistry, Inorganic ; Cell Membranes ; Animal Biochemistry ; Inorganic Chemistry ; Membrane Biology ; Springer eBooks
    Description / Table of Contents: Membrane Transport Proteins and Receptors for Cadmium and Cadmium Complexes -- The Chemical Biology of Cadmium -- Interactions of Cadmium With Signaling Molecules -- Cell Organelles as Targets of Cadmium Toxicity -- Cadmium and its Impact on Genomic Stability
    Abstract: This book outlines the interaction of cadmium with the proteome and signalling molecules of mammalian cells. Chapters from expert contributors cover topics such as cadmium chemical biology, membrane receptors and transporters for cadmium and cadmium complexes, and targets of cadmium toxicity. Students and researchers working in bioinorganic chemistry will find this book an important account
    Pages: IX, 125 p. 13 illus., 9 illus. in color. : online resource.
    ISBN: 9783319896236
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  • 2
    Keywords: Life sciences ; Biotechnology ; Organic Chemistry ; Biochemistry ; Cell Biology ; Life sciences ; Cell Biology ; Biochemistry, general ; Biotechnology ; Organic Chemistry ; Springer eBooks
    Description / Table of Contents: 1. Trends in bioprobe research -- 2. Cell proliferation and differentiation -- 3. Epigenetics -- 4. Apoptosis and autophagy -- 5. Adaptive and innate immune Systems -- 6. Bioprobes at a glance
    Abstract: This new edition provides the most advanced research using bioprobes on the chemical control of 1) cell cycle and differentiation, 2) epigenetics, 3) apoptosis and autophagy, and 4) immune response. The “bioprobe”, first proposed in the first edition, has become an indispensable tool for chemical biology and has substantially assisted in the investigation of complex biochemical processes of cells. New areas of investigation such as stem cell research, epigenetic research, and autophagy research have rapidly advanced in the past 10 years. Including these new findings, this second edition supplies up-to-date information on the biochemical tools called bioprobes. Data on each bioprobe, such as chemical structure, origin, function, and references, are presented as one item in this volume. Readers will easily find useful information and will be able to determine the appropriate bioprobes to investigate cell functions. The information on bioprobes and their use in research makes this book a valuable source for researchers in diverse fields. Not only scientists in academia but also in the pharmaceutical industries will discover the most important information about small molecules useful for drug discovery
    Pages: VIII, 384 p. 173 illus., 10 illus. in color. : online resource.
    Edition: 2nd ed. 2017.
    ISBN: 9784431565291
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  • 3
    Keywords: Medicine ; Neurochemistry ; Organic Chemistry ; Radiology ; Biomedicine ; Neurochemistry ; Organic Chemistry ; Imaging / Radiology ; Springer eBooks
    Abstract: This book explores the revolutionary fMRI field from basic principles to state-of-the-art research. It covers a broad spectrum of topics, including the history of fMRI's development using endogenous MR blood contrast, neurovascular coupling, pulse sequences for fMRI, quantitative fMRI, genetic imaging using fMRI, multimodal neuroimaging, brain bioenergetics and function, and molecular-level fMRI. Comprehensive and intuitively structured, this book examines the physiological basis of fMRI, the basic principles of fMRI and its applications, and the latest advances of the technology. The final chapter discusses the field's future. fMRI: From Nuclear Spins to Brain Function is an ideal resource for clinicians and researchers in the fields of neuroscience, psychology, and MRI physics. This book also: ℗ʺ℗ ℗ ℗ ℗ ℗ ℗ ℗ ℗ Explores a wide range of topics, covering the physical basics, physiological bases, a selection of various applications, and cutting-edge advances in fMRI ℗ʺ℗ ℗ ℗ ℗ ℗ ℗ ℗ ℗ Engages the reader with a first-person account of the development and history of the fMRI field by the authors ℗ʺ℗ ℗ ℗ ℗ ℗ ℗ ℗ ℗ Discusses fMRI applications in a variety of contexts, including fMRI of the visual system, auditory cortex, and sensorimotor system as well as the history of fMRI's development using endogenous MR blood contrast, neurovascular coupling, pulse sequences for fMRI, and℗ quantitative fMRI ℗
    Pages: XVIII, 929 p. 235 illus., 179 illus. in color. : online resource.
    Edition: 1st ed. 2015.
    ISBN: 9781489975911
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  • 4
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    Cham : Springer International Publishing
    Keywords: Life sciences ; Medicine ; Chemistry, Organic ; Biochemistry ; Life sciences ; Protein Science ; Biomedicine general ; Organic Chemistry ; Springer eBooks
    Description / Table of Contents: Sequences -- Structures -- Systems
    Abstract: This book describes more than 60 web-accessible computational tools for protein analysis and is totally practical, with detailed explanations on how to use these tools and interpret their results and minimal mentions to their theoretical basis (only when that is required for making a better use of them). It covers a wide range of tools for dealing with different aspects of proteins, from their sequences, to their three-dimensional structures, and the biological networks they are immersed in. The selection of tools is based on the experience of the authors that lead a protein bioinformatics facility in a large research centre, with the additional constraint that the tools should be accessible through standard web browsers without requiring the local installation of specific software, command-line tools, etc. The web tools covered include those aimed to retrieve protein information, look for similar proteins, generate pair-wise and multiple sequence alignments of protein sequences, work with protein domains and motifs, study the phylogeny of a family of proteins, retrieve, manipulate and visualize protein three-dimensional structures, predict protein structural features as well as whole three-dimensional structures, extract biological information from protein structures, summarize large protein sets, study protein interaction and metabolic networks, etc. The book is associated to a dynamic web site that will reflect changes in the web addresses of the tools, updates of these, etc. It also contains QR codes that can be scanned with any device to direct its browser to the tool web site. This monograph will be most valuable for researchers in experimental labs without specific knowledge on bioinformatics or computing
    Pages: VIII, 106 p. 40 illus. in color. : online resource.
    ISBN: 9783319127279
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  • 5
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    Cham : Springer International Publishing
    Keywords: Medicine ; Chemistry, Organic ; Life sciences ; Biomedicine ; Biomedicine general ; Life Sciences, general ; Organic Chemistry ; Springer eBooks
    Description / Table of Contents: Alkanes, Composition, Constitution and Configuration -- Functional Groups -- Electronic Structure of Organic Molecules -- Alkenes and Alkynes -- Substitutions on Saturated Carbon Atom -- Nucleophilic Additions -- Stereochemistry, Symmetry and Molecular Chirality -- Derivatives of Carboxylic Acids -- Electrophilic Substitutions -- Cycloadditions -- Organic Natural Products
    Abstract: This work provides an overview of the basics of organic chemistry for non-chemists. As such, this book should be very useful for university students of biology, molecular biology, ecology, medicine, agriculture, forestry, and other specialties where the knowledge of organic chemistry plays the important role but is not a core discipline. The book should also be of interest to non-professionals, and it may serve as a manual or repetitorium to high school teachers. ℗ The text is divided into eleven chapters on the basis of the systematization of fundamental organic reaction types, and classes of organic compounds. The first chapters comprise fundamental aspects of structural theory, reaction mechanisms, electronic structure, some basic spectroscopy, and properties of main groups of organic compounds. At the end of the book, the largest chapter contains the elements of the organic chemistry of natural products. Comparison of the reactions in the laboratory with the analogous molecular transformations in living cells will enable the reader to better understand the basic principles of biochemistry
    Pages: XIII, 179 p. 331 illus., 51 illus. in color. : online resource.
    ISBN: 9783319076058
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  • 6
    Keywords: Medicine ; Spectroscopy ; Biotechnology ; Chemistry, Organic ; Chemistry, Physical organic ; Biochemistry ; Biomedicine ; Biomedicine general ; Spectroscopy/Spectrometry ; Biotechnology ; Physical Chemistry ; Organic Chemistry ; Biochemistry, general ; Springer eBooks
    Description / Table of Contents: The basis of Nuclear Magnetic Resonance Spectroscopy -- Spectroscopic parameters in Nuclear Magnetic Resonance -- Basic NMR experiments -- Biomolecular NMR
    Abstract: This book intends to be an easy and concise introduction to the field of nuclear magnetic resonance or NMR, which has revolutionized life sciences in the last twenty years. A significant part of the progress observed in scientific areas like Chemistry, Biology or Medicine can be ascribed to the development experienced by NMR in recent times. Many of the books currently available on NMR deal with the theoretical basis and some of its main applications, but they generally demand a strong background in Physics and Mathematics for a full understanding. This book is aimed to a wide scientific audience, trying to introduce NMR by making all possible effort to remove, without losing any formality and rigor, most of the theoretical jargon that is present in other NMR books. Furthermore, illustrations are provided that show all the basic concepts using a naive vector formalism, or using a simplified approach to the particular NMR-technique described. The intention has been to show simply the foundations and main concepts of NMR, rather than seeking thorough mathematical expressions
    Pages: XII, 115 p. 36 ill. : digital.
    ISBN: 9789400769762
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  • 7
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    Dordrecht : Springer
    Keywords: Medicine ; Spectroscopy ; Chemistry, Organic ; Chemistry, Physical organic ; Chemistry ; Biomedicine ; Biomedicine general ; Organic Chemistry ; Physical Chemistry ; Spectroscopy/Spectrometry ; Organometallic chemistry ; Electrochemistry ; Springer eBooks
    Description / Table of Contents: Molecular structures -- An overview of synthetic methods for preparation of nitrosoaromatic compounds -- Molecular properties and spectroscopy -- Organometallic compounds -- Bilological systems
    Abstract: This volume will present the reader with an update on the scientific research on organic chemistry of nitroso compounds that was performed in the last two decades. The overview will include the original synthetic applications of nitroso compounds, but will also cover the discovery of novel physico-chemical phenomena and their potential future uses. The properties that form the basis for this technological potential originate from the intriguing property of C-nitroso molecules to form dimers through the formation of a relatively weak nitrogen-nitrogen double bond. The equilibrium between the different monomeric and dimeric forms, which appears under controlled environmental parameters, opened new areas of research in organic chemistry.The novel paradigm presented in this volume includes insight into the original problem of organic reactivity and synthesis, but also sheds light on the solid-state reaction mechanisms. A number of fascinating photochemical, electrochemical, supramolecular, and biological properties, as well as advanced techniques in spectroscopy, now enables us to use these compounds as molecular models for studying a number of general chemical concepts.℗
    Pages: : digital.
    ISBN: 9789400763371
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  • 8
    Keywords: Life sciences ; Chemistry, Inorganic ; Bioorganic chemistry ; Emerging infectious diseases ; RNA-ligand interactions ; Microbiology ; Life sciences ; Microbiology ; Protein-Ligand Interactions ; Inorganic Chemistry ; Bioorganic chemistry ; Infectious Diseases ; Springer eBooks
    Description / Table of Contents: A History of Iron Metabolism in the Mycobacteria -- Mycobacterial Iron Uptake Mechanisms -- Siderocalin Combats Mycobacterial Infections -- Design of Anti-TB Drugs Using the Iron Uptake Platform
    Abstract: Iron Acquisition by the Genus Mycobacterium summarizes the early evidence for the necessity of iron in mycobacteria and the discovery of the mycobacterial siderophores mycobactin, carboxymycobactin, and exochelin. The structural characterization of the mycobacterial siderophores is described. ℗ The genes so far identified as essential for iron acquisition and maintenance of an infection by pathogenic mycobacteria are discussed.℗ The potential role of siderocalin in iron gathering by M. tuberculosis is featured. Because new drugs for M. tuberculosis are needed, this brief also emphasizes the design of antibiotics that interfere with siderophore biosynthesis and the use of siderophore analogs and/or conjugates
    Pages: : digital.
    ISBN: 9783319003030
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  • 9
    Keywords: Life sciences ; Toxicology ; Chemistry, Organic ; Pharmacy ; Oceanography ; Biochemistry ; Aquatic biology ; Life sciences ; Biochemistry, general ; Organic Chemistry ; Freshwater & Marine Ecology ; Oceanography ; Pharmacology/Toxicology ; Pharmacy ; Springer eBooks
    ISBN: 9789048138340
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  • 10
    Keywords: Life sciences ; Chemistry, Organic ; Carbohydrates ; Biochemistry ; Proteomics ; Cytology ; Cell Membranes ; Life sciences ; Biochemistry, general ; Organic Chemistry ; Carbohydrate Chemistry ; Cell Biology ; Membrane Biology ; Proteomics ; Springer eBooks
    Pages: : digital.
    ISBN: 9781461433811
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  • 11
    Keywords: Chemistry ; Chemistry, Organic ; Chemistry ; Organic Chemistry ; Springer eBooks
    Pages: : digital
    ISBN: 9781441972705
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  • 12
    Keywords: Medicine ; Toxicology ; Pharmaceutical technology ; Chemistry, Organic ; Chemical engineering ; Biochemistry ; Biomedicine ; Pharmacology/Toxicology ; Pharmaceutical Sciences/Technology ; Organic Chemistry ; Medicinal Chemistry ; Medical Biochemistry ; Industrial Chemistry/Chemical Engineering ; Springer eBooks
    Pages: : digital
    ISBN: 9783034801256
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  • 13
    Keywords: Life sciences ; Chemistry, Organic ; Nucleic Acids ; Biochemistry ; Life sciences ; Nucleic Acid Chemistry ; Protein Science ; Organic Chemistry ; Springer eBooks
    Pages: : digital
    ISBN: 9783642169311
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  • 14
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    Dordrecht : Springer Science+Business Media B.V.
    Keywords: Medicine ; Chemistry, Inorganic ; Cytology ; Environmental toxicology ; Biomedicine ; Biomedicine general ; Cell Biology ; Oxidative Stress ; Apoptosis ; Ecotoxicology ; Inorganic Chemistry ; Springer eBooks
    Pages: : digital
    ISBN: 9789400704282
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  • 15
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 492-498 
    ISSN: 0899-0042
    Keywords: racemate ; enantiomer ; HPLC ; chiral stationary phase ; benzoylcellulose ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The advantages that can be gained from derivatization of various racemic aliphatic and aromatic alcohols prior to enantiomeric chromatographic separation have been systematically investigated for a series of benzoate derivatives. Three cellulose-based CSPs available in the pure polymeric form - tribenzoyl cellulose (TBC), meta-methylbenzoyl cellulose (MMBC), and para-methylbenzoyl cellulose (PMBC) - were selected and several benzoate derivatives varying in the nature and the position of the substituent on the benzoyl group were prepared and analysed. TBC clearly gives the broadest application range, and among the different benzoate esters the best selectivity was generally obtained with either the 4-methoxybenzoate or the 4-methylbenzoate derivatives. Based on these results, some empirical rules could be formulated for optimizing the enantiomeric separation of racemic alcohols, which make up one of the most important classes of chemical substances used as drugs and biocides, or as building blocks for their synthesis. An application of this approach to the preparative separation of the enantiomers of a drug intermediate is also shown. Chirality 10:492-498, 1998. © 1998 Wiley-Liss, Inc.
    Additional Material: 5 Ill.
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  • 16
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 507-512 
    ISSN: 0899-0042
    Keywords: chiroptical method ; drug analysis ; β-lactam antibiotics ; CD spectroscopy ; human fluids ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A study of the applicability of circular dichroism (CD) for the determination of drug levels in human serum is described and a new method for the quantitative determination of optically active absorbing drugs having Cotton effects at wavelengths above 250 nm in human serum and/or plasma is proposed. The principal advantages of this method are speed, economy, and simplicity, no derivatization or chromatographic separation steps being needed. The validity of the CD determination was confirmed by analysis of variance, β-lactam antibiotics being chosen as model drugs. In addition, the validation studies performed confirm the accuracy and precision of the proposed method. For β-lactam antibiotics lacking Cotton effects above 250 nm, an alternative method based on the extraction of the drug from serum is considered. Chirality 10:507-512, 1998. © 1998 Wiley-Liss, Inc.
    Additional Material: 5 Ill.
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  • 17
    ISSN: 0899-0042
    Keywords: chiral HPLC ; quantitative substituent effect ; recognition mechanism ; fluorene derivative-chiral separation ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The chromatographic parameters for 12 structurally related compounds in the 4a-methyl-2,3,4,4a-tetrahydro-1H-fluorene and 4a-methyl-1,2,3,4,4a,9a-hexahydro-fluoren-9-one series are reported on CTA-I and Chiralcel OJ chiral stationary phases. Arrangement of the k' values according to configurationally related enantiomer series (Class I and Class II) and not according to the actual order of elution, allows the treatment of the data by linear correlation with structure and substituent effect. A detailed analysis of the capacity factor variation with respect to the structural changes shows clearly that the framework and substitution effects do not result in the same response on the two cellulose ester chiral stationary phases. More interestingly, it emerges that chiral discimination may be attributed to certain areas of the molecule, these areas being different in the interaction within CTA-I and Chiralcel OJ. Furthermore, our analysis points out the relevance of attempting to develop quantitative relationships for configurationally related series of enantiomers (in our case Class I and Class II), the main effort being devoted to the understanding of the capacity factor variation in each class rather than of the α values, which are derived entities. Chirality 10:522-527, 1998. © 1998 Wiley-Liss, Inc.
    Additional Material: 4 Ill.
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  • 18
    ISSN: 0899-0042
    Keywords: asymmetric hydrogenation ; non-coded amino acids ; enantioselectivity ; dipeptides ; diastereoselectivity ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The enantiomers of Propranolol, Pindolol, and Carazolol, well-known β-blockers, have been used to prepare cationic aminophosphine phosphinite rhodium complexes. Propraphos-Rh and Pindophos-Rh are very efficient catalysts in the asymmetric hydrogenation of N-Boc-protected unusual dehydroamino acid derivatives. Carazolol-Rh is less suitable in both activity and enantioselectivity. Under the same conditions, N-Boc-protected dehydrodipeptides are hydrogenated with diastereoselectivities between 70 and 90% de. Chirality 10:535-539, 1998. © 1998 Wiley-Liss, Inc.
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  • 19
    ISSN: 0899-0042
    Keywords: quinuclidine derivatives ; chromatographic separation ; borane complexes ; fractional crystallization ; resolution ; X-ray crystallography ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The four stereoisomers of the antimuscarinic 3-(2,3-dihydrobenzofuran-2-yl)quinuclidine have been prepared by a method involving chromatographic separation of the racemic diastereoisomers as borane complexes. The relative and absolute configurations of the stereoisomers were determined by X-ray crystallographic methods. The crystal structure of (2′R,3R)-3-(2,3-dihydrobenzofuran-2-yl)quinuclidine · HCl · H2O contains two independent molecules with different conformations of both the quinuclidine moiety and the dihydrofuran ring. Chirality 10:813-820, 1998. © 1998 Wiley-Liss, Inc.
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  • 20
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 1-2 
    ISSN: 0899-0042
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: No abstract.
    Additional Material: 1 Ill.
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  • 21
    ISSN: 0899-0042
    Keywords: α-hydroxy acids ; chiral stationary phases ; enantiomer resolution ; copper ternary complexes ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Direct separation of several α-hydroxy acid racemic mixtures was performed by the aid of ligand exchange chromatography using L-hydroxyproline chemically bound to silica stationary phase and aqueous solutions of copper (II) sulphate as a mobile phase. The elution order of the D- and L-enantiomers of α-hydroxy acids is interpreted in terms of a modified Davankov's rule. Several aspects of the Davankov's model of selectand-Cu(II)-selector ternary complexes are discussed based on the theoretical calculations within the quantum mechanical semiempirical and density functional theories. Chirality 10:821-830, 1998. © 1998 Wiley-Liss, Inc.
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  • 22
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 3-7 
    ISSN: 0899-0042
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: No abstract.
    Additional Material: 7 Ill.
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  • 23
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 8-13 
    ISSN: 0899-0042
    Keywords: stereochemistry ; ion channel proteins ; nAChR ; K+ channels ; subunit arrangement ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Studies of ion channel proteins present many special challenges, including the potential for novel stereochemical phenomena. Here we describe several examples in which modern studies of ion channels have involved or made use of stereochemistry. Chirality 10:8-13, 1998. © 1998 Wiley-Liss, Inc.
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  • 24
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 14-23 
    ISSN: 0899-0042
    Keywords: biological signalling ; ristocetin A ; cooperativity ; dimerization ; asymmetry ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The self-regulation of biological signalling receptors via homodimerization is discussed in relation to the symmetry changes occurring when these receptors bind their target ligand. The idea of positive and negative cooperativity between dimerization and ligand binding, mediated by changes in the symmetry of the system, as a source of signalling control is considered; and an analogy made with the homodimerization of a glycopeptide antibiotic, ristocetin A, which displays negative cooperativity. Finally, the regulation of the bacterial aspartate receptor and the human growth hormone receptor is discussed as a function of ligand-induced asymmetry. Chirality 10:14-23, 1998. © 1998 Wiley-Liss, Inc.
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  • 25
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 24-27 
    ISSN: 0899-0042
    Keywords: homochirality ; origins of chirality ; spontaneous resolution ; molecular evolution ; racemic state ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An evaluation of some common misconceptions of the racemic state in combination with an articulation of principles for the spontaneous generation and amplification of chirality leads to the conclusion that homochirality in nature is a stereochemical imperative. Chirality 10:24-27, 1998. © 1998 Wiley-Liss, Inc.
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  • 26
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 28-34 
    ISSN: 0899-0042
    Keywords: collagen ; nuclear magnetic resonance (NMR) ; nuclear Overhauser effect (NOE) ; stereospecific assignment ; triple-helix ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An improved model-based method for the stereospecific assignment of prochiral centers in collagen-like triple-helical molecules is introduced. Using the concepts of reporter atoms and of ensemble NOEs, the proposed methodology extracts the stereochemical information contained in the chiral elements of triple-helices and transfers it to prochiral centers with nondegenerate proton resonances. The improved approach has been successfully validated using -(Gly-Pro-Hyp)n- triple-helices for which the stereospecific assignment was previously obtained with established techniques. We have applied our stereochemical characterization to novel peptoid containing triple-helices for which existing methods of stereospecific assignment can not be used for all the prochiral centers. In our approach, several different NOE measurements are employed to make a given stereospecific assignment. The multiple NOE comparisons allow internal cross checks, which reduce the chance of erroneous assignments caused by experimental artifacts including spin diffusion and bias from anisotropic rotational motions. In addition, the multiple NOE comparisons are useful in overcoming problems associated with resonance overlap often encountered in the 1H-NMR spectra of collagen-like molecules. Our stereochemical analysis is anticipated to improve the precision and accuracy of the characterization of collagen-like triple-helices through a better correlation of structures with their 1H-NMR spectra. Chirality 10:28-34, 1998. © 1998 Wiley-Liss, Inc.
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  • 27
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 35-40 
    ISSN: 0899-0042
    Keywords: de novo design ; self-assembly ; metalloproteins ; diastereoselection ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The stereochemical consequences of the metal-ion assisted self-assembly of parallel three-helix peptide bundles are investigated. Chiral induction in the self-assembly of systems containing extensive protein secondary structure is compared with the racemic synthesis of short metallopeptides. Isolation and characterization of the individual stereoisomers of an exchange-inert metalloprotein provide structural insights into analogous exchange-labile systems. Chirality 10:35-40, 1998. © 1998 Wiley-Liss,Inc.
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  • 28
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 195-209 
    ISSN: 0899-0042
    Keywords: molecular imprinting ; molecular recognition ; chirality ; chromatography ; catalysis ; biosensor ; immunoassay ; antibody mimic ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Molecular imprinting is a technique for the fabrication of biomimetic polymeric recognition sites or “plastic antibodies/receptors” which is attracting rapidly increasing interest. By this technology, recognition matrices can be prepared which possess high substrate selectivity and specificity. In the development of this technology, several applications have been foreseen in which imprinted materials may be exchanged for natural recognition elements. Thus, molecularly imprinted polymers have been used as antibody/receptor binding mimics in immunoassay-type analyses, as enzyme mimics in catalytic applications and as recognition matrices in biosensors. The best developed application area for imprinted materials, though, has been as stationary phases for chromatography, in general, and chiral chromatography, in particular. This review seeks to highlight some of the more intriguing advantages of the technique as well as pointing out some of the difficulties encountered. The prospects for future development will also be considered. Chirality 10:195-209, 1998. © 1998 Wiley-Liss, Inc.
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  • 29
    ISSN: 0899-0042
    Keywords: amylose ; 3,5-dimethylphenyl-carbamate ; polysaccharide phase ; tert-butyl 2-tert-butyl-4-methoxy-2,5-dihydro-1,3-imidazole-1-carboxylate; amino acid ester synthesis ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The preparative separation of the enantiomers of the title compound, a versatile chiral building block for the synthesis of unnatural amino acid esters, by high performance liquid chromatography on a chiral stationary phase (CSP), is reported for the first time. The CSP consists of amylose-(3,5-dimethylphenyl-carbamate), which has been coated onto the surface of macroporous aminopropyl-functionalized silica gel. The effect of mobile phase composition and the amount of amylose derivative on the silica gel has been thoroughly investigated. Using 2-propanol as organic modifier in hexane as mobile phase, on a semi-preparative column (200 mm × 40 mm ID, containing 192 g of stationary phase) about 200 mg of the racemate was separated per injection. Running the equipment under automatic conditions with repetitive injection mode allowed for the separation of 30 g per day. Both enantiomers were obtained with enantiopurities >99.75:0.25. Chirality 10:217-222, 1998. © 1998 Wiley-Liss, Inc.
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  • 30
    ISSN: 0899-0042
    Keywords: thalidomide enantiomers ; in vitro kinetics ; blood distribution ; human serum albumin ; chiral inversion ; plasma protein binding ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The aim of this investigation was to elucidate the distribution and reactions of the enantiomers of thalidomide at their main site of biotransformation in vivo, i.e., in human blood. Plasma protein binding, erythrocyte: plasma distribution, and the kinetics of chiral inversion and degradation in buffer, plasma, and solutions of human serum albumin (HSA) were studied by means of a stereospecific HPLC assay. The enantiomers of thalidomide were not extensively bound to blood or plasma components. The geometric mean plasma protein binding was 55% and 66%, respectively, for (+)-(R)- and (-)-(S)-thalidomide. The corresponding geometric mean blood:plasma concentration ratios were 0.86 and 0.95 (at a haematocrit of 0.37) and erythrocyte:plasma distributions were 0.58 and 0.87. The rates of inversion and hydrolysis of the enantiomers increased with pH over the range 7.0-7.5. HSA, and to a lesser extent human plasma, catalysed the chiral inversion, but not the degradation, of (+)-(R)- and (-)-(S)-thalidomide. The addition of capric acid or preincubation of HSA with acetylsalicylic acid or physostigmine impaired the catalysis to varying extents. Correction for distribution in blood enhances previously observed differences between the pharmacokinetics of the enantiomers in vivo. The findings also support the notion that chiral inversion in vivo takes place mainly in the circulation and in albumin-rich extravascular spaces while hydrolysis occurs more uniformly in the body. In addition, the chiral inversion and hydrolysis of thalidomide apparently occur by several different mechanisms. Chirality 10:223-228, 1998. © 1998 Wiley-Liss, Inc.
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  • 31
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    Chirality 10 (1998), S. 246-252 
    ISSN: 0899-0042
    Keywords: sulfoxides ; chloroperoxidase ; asymmetric oxidation ; enantioselective ; episulfide ; gas chromatography ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Asymmetric sulfoxidation by means of a chloroperoxidase from Caldariomyces fumago and hydrogen peroxide as the oxygen source was studied for a series of sterically well-defined substrates. The stereochemistry of the sulfoxidation was the same for all substrates studied. While 2,3-dihydrobenzo[b]thiophene (1) is an excellent substrate (giving 99.5% yield and 99% e.e. of the (R)-sulfoxide), replacement of a methylene group by either a more sterically demanding group or a heteroatom caused a substantial decrease in reactivity or in reactivity as well as enantioselectivity. A further investigation of the lowered catalytic efficiency of chloroperoxidase with these substrates has been carried out in a series of competitive reactions. Thus, benzo[1,3]oxathiole (5) acted as a competitive inhibitor of the enzyme, whereas 1-thiochroman (2) and 1-thiochroman-4-one (3) were shown to be too sterically demanding to significantly compete for the active site. For the oxidation of 2, 3, and 5, it was found that in the low CPO concentration range the chemical yield after 60 min reaction time increased almost linearly with the amount of CPO used. The products from 2 and 3 could be obtained in over 80% yield with an e.e. exceeding 96%. Chloroperoxidase was also found to be an effective catalyst in the oxidation of labile episulfides, yielding the corresponding anti-sulfoxides quantitatively and giving 12% e.e. of (1R, 2R)-sulfoxide in the oxidation of propylene sulfide. Chirality 10:246-252, 1998. © 1998 Wiley-Liss, Inc.
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  • 32
    Electronic Resource
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    Chirality 10 (1998), S. 173-179 
    ISSN: 0899-0042
    Keywords: chirality at low and high resolution ; functional groups ; fuzzy density fragments ; continuum models ; fuzzy sets ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Mislow's Label Paradox and the chirality preserving or abandoning properties of deformation paths of polyhedral models are extended to simple representations of electron density continua of molecules. Chirality 10:173-179, 1998. © 1998 Wiley-Liss, Inc.
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  • 33
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    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 180-189 
    ISSN: 0899-0042
    Keywords: hypercoordinate silicon in naphthylsilanes ; X-ray structures ; NMR spectra ; reinterpretation ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Hexacoordinate silicon has been claimed to occur in bis(8-dimethylamino-naphth-1-yl)silanes on the basis of X-ray data and NMR spectra. Very much the same effects are shown by a bis(8-dimethylamino-naphth-1-yl)carbinol, pointing to essentially the same bonding in the Si and C compounds. Faced with the choice that either the carbon in the carbinol is hexacoordinate, too, or that the silicon in the silanes is, in fact, tetracovalent, we prefer the latter conclusion. Chirality 10:180-189, 1998. © 1998 Wiley-Liss, Inc.
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  • 34
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    Chirality 10 (1998), S. 190-193 
    ISSN: 0899-0042
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: No abstract.
    Additional Material: 11 Ill.
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  • 35
    ISSN: 0899-0042
    Keywords: porphyrin ; chiral ; oxidation ; mechanism ; enantioselective ; asymmetric catalysis ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Enantioselective catalytic epoxidation of olefins is an important problem from both practical and mechanistic points of view. The origins of chiral induction by asymmetric porphyrin and salen complexes were investigated by FT-NMR T1 relaxation techniques. A new chiral vaulted porphyrin (1) that carries (S)-binaphthyl-L-alanine straps across both faces of the porphyrin macrocycle was synthesized and characterized. (R)-styrene oxide was obtained in >90% ee in the initial stages of styrene epoxidation with F5PhIO catalyzed by 1-Fe(III)Cl. The transition state for olefin epoxidation with high-valent metal-oxo species was modeled by coordinating epoxides to paramagnetic copper complexes of the corresponding ligands. The epoxide enantiomer that better fit the chiral cavity of the catalyst, as revealed by T1 relaxation measurements, was also the major product of catalytic olefin epoxidation. These results are consistent with the “lock-and-key” mechanism of asymmetric catalysis by metalloporphyrins. The copper complex of a chiral salen ligand showed no differentiation in terms of T1 relaxation rates between the enantiomers of cis-β-methylstyrene oxide in contrast to the high enantioselectivity observed for catalytic epoxidation. Chirality 10:106-119, 1998. © 1998 Wiley-Liss,Inc.
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  • 36
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    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 147-153 
    ISSN: 0899-0042
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of the chiral 9,12-dimethyl-4-oxa[7]paracyclophane 3 was achieved by the dithia route with subsequent sulfone pyrolysis. The conformational flexibility of the oxamethylene bridge with local Cs symmetry is evident from low temperature NMR experiments. Experimentally, an activation enthalpy of 11.4 kcal/mol is found for this process, which is in good agreement with the rotational barrier derived from semiempirical AM1 calculations (10.2 kcal/mol). Ab initio Hartree-Fock geometry optimizations have been performed for 3 and the corresponding hydrocarbon 9,12-dimethyl[7]paracyclophane 4. The distance of the O-atom to the center of the benzene ring in the structure of 3 is only 2.784 Å, i.e., significantly closer than the analogous C4-benzene ring distance in the slightly more strained 4 (3.112 Å). The enantiomeric separation of (±3) has been achieved by HPLC and the circular dichroism (CD) spectrum is reported. Ab initio all-electron DFT/SCI calculations of the CD spectrum are in good agreement with the experimental data and reveal the importance of p(O-atom)→ π* charge-transfer type excited states at relative low energies (6.6 eV, 188 nm) responsible for an intense negative CD band. The benzene type π → π* states are energetically lowered by 0.4-0.8 eV due to the boat-type deformation of the benzene moiety. By comparison of theoretical and experimental CD data the absolute configuration of 3 is assigned as (-)-(S). Chirality 10:147-153, 1998. © 1998 Wiley-Liss, Inc.
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  • 37
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    Chirality 10 (1998), S. 747-753 
    ISSN: 0899-0042
    Keywords: pantoprazole ; proton pump inhibitor ; chiral inversion ; stereoselective pharmacokinetics ; rats ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: (±)-Pantoprazole ((±)-PAN), (±)-5-(difluoromethoxy)-2-[[(3.4-dimethoxy-2-pyridinyl)methyl]sulfinyl]-1H-benzimidazole is a chiral sulfoxide that is used clinically as a racemic mixture. The disposition kinetics of (+)-PAN and (-)-PAN given separately has been studied in rats. Serum levels of (+)- and (-)-PAN and its metabolites, pantoprazole sulfone (PAN-SO2), pantoprazole sulfide (PAN-S), 4′-O-demethyl pantoprazole sulfone (DMPAN-SO2), and 4′-O-demethyl pantoprazole sulfide (DMPAN-S) were measured by HPLC. Following single intravenous or oral administration, both enantiomers were rapidly absorbed and metabolized, resulting in similar serum concentrations, suggesting that the two enantiomers have approximately the same disposition kinetics. The major metabolite of both (+)- and (-)-PAN was PAN-SO2, while DMPAN-SO2 was also detected as a minor metabolite. Serum levels of PAN-S and DMPAN-S could not be quantified after intravenous or oral administration of either enantiomer.Significant chiral inversion occurred after intravenous and oral administration of (+)-PAN. The AUCs of (-)-PAN after intravenous and oral dosing of (+)-PAN were 36.3 and 28.1%, respectively of those of total [(+) + (-)] PAN. In contrast, the serum levels of (+)-PAN were below quantitation limits after intravenous or oral administration of (-)-PAN. Therefore, chiral inversion was observed only after administration of (+)-PAN, supporting the hypothesis that stereoselective inversion from (+)-PAN to (-)-PAN occurs in rats. Chirality 10:747-753, 1998. © 1998 Wiley-Liss, Inc.
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  • 38
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The acid dissociation constants (Ka) of a series of 3,4-diaryl-1H-1,2,4-triazole-5-thiones (1) were determined and were found to correlated linearly with Hammett substituent constants; log Ka = 1.06 σx - 11.01. Such a result indicates that 1 exists essentially in one tautomeric form namely the thione form. Reactions of 1 with hydrazonoyl chlorides 2 gave the thiohydrazides 5. Similiar reaction of 3-phenyl-1H(4H)- 1,2,4-triazole-5-thione 1g with 2a gave the thiohydrazide 5h which was converted into 1,3,5-triphenyl-1,2,4-triazolo[3,4-c]-1,2,4-triazole (9). The latter was also prepared from 3-phenyl-5-methylthio-4H-1,2,4-triazole (6) and 2a. The mechanism of the reaction of 1 with 2 is discussed.
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  • 39
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    New York, NY : Wiley-Blackwell
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Starting from 1,3-oxazoline 6 synthesis of ketene-O,N-acetals 2b, 2c is described via NBS bromination and HBr elimination.The N-sulfonyl-oxazolidines 10, 11 are synthesized by cyclization starting from aminoalcohol 7, 10d react with potassium t-butoxide to the oxazolidine 2d; 11d gives under the some conditions the ring opening product 12d, compound 10a is inert.
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  • 40
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 41
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    New York, NY : Wiley-Blackwell
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reactions of 1-O-trimethylsilyl-glycoses, 1-O-acylglycoses and glycosyl fluorides, respectively, with silylated alcohols (glycodesilylations) are summarized. Synthetic strategies toward oligosaccharides using glycodesilylations are discussed as well and some typical experimental procedures are given.
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  • 42
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Pentafluorophenyluronium salts and related coupling reagents for the solid-phase synthesis of peptides and glycopeptides have been developed and employed in the synthesis of a glycopeptide sequence from the cell adhesion molecule E-CAD 1.
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  • 43
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The bis(acetone) complex of tetramethyl rac-3,3,7,7-tetramethyl-trans-5-palladatricyclo[4.1.0.02,4]heptane-1,2,4,6-tetracarboxylate rac-1a was crystallized and investigated by X-ray structure analysis. Unlike in complexes with bidendate ligands in rac-1a · 2(acetone), only a small deviation from the square planar coordination of palladium was observed. Efforts to crystallize the analogous pyridine, acetonitrile and benzonitrile complexes failed; but the labile complexes rac-1a · 2([D5]pyridine) and rac-1a · 2([D3] acetonitrile) as well as rac-1a · 2([D6]acetone) could be characterized by 1H and 13C NMR spectra and a fast ligand exchange was proven by nmr. Then the ability of different 1,2-disubstituted cyclopropenes to form trans-5-pallada-tricyclo[4.1.0.02,4] heptanes 1 was investigated. Only the diesters 5c-e lead to PTHs, with a diester possessing sterically demanding substituents in 3-position of the cyclopropene and with other substituents in 1- respectively 2-position of the cyclopropene either the cyclopropene-formation or the PTH-formation failed.
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  • 44
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A variety of 6H-1,2-oxazines 10 could efficiently be prepared by hetero Diels-Alder reaction of α-nitroso alkenes 2 with 1-bromo-2-ethoxyethene (8) and consecutive elimination of HBr by DBU. Heterodienes 2 were generated in situ from α-halogen oximes 6. Primary cycloadducts 9 were isolated in singular cases, however, an attempt to substitute bromide in 9e by an azido group gave the desired compound 11 only as minor component together with elimination product 10e. 6H-1,2-oxazines 10 are valuable precursors for addition reactions which open new synthetic possibilities.
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  • 45
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of racemic and enantiomerical enriched axial chiral liquid crystalline compounds incorporating a trisubstituted allene unit is described. All compounds 16-28 display the smectic C-phase and mostly also a nematic mesophase. All investigated enantiomerically enriched compounds have a ferroelectrically switchable chiral smectic SC*-phase.
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  • 46
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 47
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: α-(Bromothiocyanatomethyl)benzylidenemalononitrile (1) reacts with the hydrazides 2a-c, cyanoacethoydrazide (2d,) cyanoacetamide (3a) and cyanoacetanilides 3b-d to afford pyrrolo[2,1-b]thiadiazolines 5a-c, pyrrolo[2,1-b]thia-diazolo[3,2-a]pyrimidine (8) and the pyridone derivatives 11a-d. Structures and conceivable mechanisms are discussed.
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  • 48
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    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 49
    Electronic Resource
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    New York, NY : Wiley-Blackwell
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 50
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Interactions in Crystals. 136. Protonated Dipyridylamine Salts with Different Anions: Monomeric Tetraphenylborate as well as Bis(trifluormethylsulfonate), Dimeric Squarate and Polymeric Chloride DihydrateDi(pyrid-2-yl)amine is monoprotonated by acetic, squaric as well as hydrochloric acid and diprotonated by trifluoromethylsulfonic acid. To explore the anion and hydrogen-bridge dependency of its salts, crystals of the monomeric tetraphenylborate, the dimeric squarate as well as the bis(trifluoromethylsulfonate) and the polymeric chloride hydrate have been grown and their structures determined: Separated by bulky tetraphenylborate anions, pyrid-2-yl(2′-pyridinium) amine cation contains an intramolecular hydrogen bridge N⊕H…N and is slightly folded. The squarate salt dimer exhibits additional bridges, N—H…O⊖ and O—H…O. The severely twisted di(2-pyridinium)amine dication is connected to its trifluormethylsulfonate counter anions by altogether three H-bridges, two N⊕H…O and one N—H…O. The chloride dihydrate crystallizes in layers of 16-membered rings, formed from three Cl anions and five water molecules. The diversity of the hydrogen-bridge dominated salt structures is discussed based on comparison with selected literature examples and on PM3 calculations.
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  • 51
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    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The relationship between structure and circular dichroism was studied for a series of cardenolides including some compounds with saturated lactone ring.
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  • 52
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 53
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 54
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    New York, NY : Wiley-Blackwell
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 55
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    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Sultones are readily prepared by intramolecular Diels-Alder reaction of vinylsulfonates in an often highly stereoselective fashion. Various methods for the synthetic elaboration of these heterocycles have been developed and applied to the total synthesis of biologically active natural products.
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  • 56
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Starting from 3-acylaminobenzo[b]furan-2(3H)-ones (2) 3-arylthio substituted derivatives (3) were prepared via novel N-acylimines (5). Compounds of type 3 and 5 were found to show visible chemiluminescence upon base-induced oxidation in the presence of an oxygen source. A mechanistic interpretation for this chemiluminescence reaction is proposed.
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  • 57
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Investigations on Adhesion of Pigment Printings by UV-Laser TreatmentInvestigations on the influence of UV-laser treatment of polyethyleneterephthalate and polyamide fibers and foils on the adhesion properties of pigment printings are presented. It could be shown that even irradiation with low energy densities and low number of pulses applied increases binder film adhesion very efficiently. Some interpretations of the laser action upon adhesion improvement related to surface modification are presented.
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  • 58
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1,3-Dithienium and 1,3-Dithiolenium Salts. IX. Reactions of 1,3-Dithiane-2-ylium Tetrafluoroborates with C-Nucleophiles1,3-Dithian-2-ylium tetrafluoroborates (1), which can be easily obtained by variable methods, react in good to excellent yields with variable C-nucleophiles to new geminal disubstituted 1,3-dithianes. The latter compounds are potential precursors of interesting synthetic building blocks. Reactions are described with 2-lithio-1,3-dithianes 2, sodium cyanide 4, sodium salts of the nitro alkanes 7 and CH-acids of the type of the 1,3-dicarbonyl compounds 9. The reduction of 3-oxo-2-(2-phenyl-1,3-dithian-2-yl)-ethoxybutanoat-following a diastereoselective pathway - leads to the Cram product 11. Further presented is the crystal structure of 2-phenyl-1,3-dithiane-2-ylium tetrafluoroborate (1b).
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  • 59
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 60
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Conventional organic molecules for applications in second-order non-linear optics are donor-acceptor substituted π systems that show only one intense charge-transfer (CT) transition. Thus, only a single element of the second-order polarizability tensor, β, is significant in these one-dimensional systems. The advantages and optimization strategies for two new classes of molecules with multiple CT transitions and two-dimensional second-order polarizability are reviewed. These are donor-acceptor substituted π systems that lack a dipole and have a molecular symmetry of C3 or higher, and dipolar molecules of symmetry C2v. A basic introduction to the field is also given.
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  • 61
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000