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  • 1
    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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  • 2
    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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  • 3
    Unknown
    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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  • 4
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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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  • 5
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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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  • 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
    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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  • 8
    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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  • 9
    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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  • 10
    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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  • 11
    Keywords: Chemistry ; Chemistry, Organic ; Chemistry ; Organic Chemistry ; Springer eBooks
    Pages: : digital
    ISBN: 9781441972705
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  • 12
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 289-293 
    ISSN: 0899-0042
    Keywords: chirality ; time reversal symmetry ; asymmetric synthesis ; enantiomerism ; isomerism ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: If a molecule is identified not only by its static spatial constructions, but also by the motions at the sub-molecular level, application of time reversal symmetry operation to a certain molecule could lead to another distinguishable from the original in the sense of sub-molecular motions, a phenomenon now defined as time reversal isomerism. Assessment of the consideration of certain enantiomers as distinguishable time reversal isomers is suggested in order to evoke a comprehensive interpretation of a likely correlation between the two types of isomerisms. The conceptual basis of a connection between absolute asymmetric synthesis under the influence of external fields and the intrinsic time reversal symmetry violation at the molecular level is also established to encourage new experimental investigations on this theme. Chirality 10:289-293, 1998. © 1998 Wiley-Liss, Inc.
    Additional Material: 4 Ill.
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  • 13
    ISSN: 0899-0042
    Keywords: enantiospecific assay ; rat ; dog ; human ; enantiomer disposition ; HIV protease inhibitor ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: PNU-103017, 4-Cyano-N-(3-(cyclopropyl(5,6,7,8,9,10-hexahydro-4-hydroxy-2-oxo-2H-cycloocta(b) pyran-3-yl)methyl)phenyl)-benzenesulfonamide, is a selective HIV aspartyl protease inhibitor under evaluation as a potential oral treatment of Acquired Immunodeficiency Diseases. PNU-103017 is a racemic mixture of two enantiomers, designated PNU-103264 (R-) and PNU-103265 (S-). Stereoselective pharmacokinetics of the two enantiomers of PNU-103017 were observed in the dog, rat, and human after single and multiple dose administration of the racemate and were apparently species-dependent. Mean enantiomeric ratios of plasma concentrations (R-/S-) at each time point were greater than 1 in the dog, ranging from 1.22 to 3.06, but less than 1 in the rat and in the human, ranging from 0.44 to 0.80 and 0.23 to 0.73, respectively. A trend towards increased or decreased (farther from 1:1, R-/S-) enantiomeric ratio of plasma concentrations with time after each administration was also observed. The enantiomeric ratio remained unchanged after multiple dose administration in the rat, dog, and human although enzyme induction and increased plasma clearance were observed for both enantiomers. Chirality 10:210-216, 1998. © 1998 Wiley-Liss, Inc.
    Additional Material: 6 Ill.
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  • 14
    ISSN: 0899-0042
    Keywords: chiroptical properties ; Cotton effect ; atropisomerism ; quantum-mechanical calculation ; AM1 ; CNDO/S ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Rotational strengths calculated on the basis of quantum-mechanically obtained minimum energy geometries were used to determine the absolute configurations of axially chiral 3-aryl-4(3H)-quinazolinones from the sign of the observed Cotton effects (CEs). For the spectral data, CNDO/S calculations were used; for the geometries, ab initio (RHF/6-31G) and semiempirical (AM1) theories were used. Oscillator and rotational strengths of all excited states down to 200 nm were compared to experimental absorption and circular dichroism (CD) data. It was found that the sign of the 1Lb Cotton effects obtained for the enantiomers of methaqualone and derivatives of 3-aryl-2-alkylthio-4(3H)-quinazolinones can be correlated unambiguously with the absolute configuration. Furthermore, the sign of the Cotton effect of the π-π* transition of the thiocarbonyl chromophore of 3-aryl-2-mercapto-4(3H)-quinazolinones is suitable for a successful stereochemical correlation. Chirality 10:253-261, 1998. © 1998 Wiley-Liss, Inc.
    Additional Material: 9 Ill.
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  • 15
    ISSN: 0899-0042
    Keywords: chiral HPLC ; cellulose carbamates ; enantiomeric resolution ; warfarin ; flurbiprofen ; lorazepam ; oxazepam ; pindolol ; tertatolol ; nicardipine ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Four cellulose mixed 10-undecenoate/carbamate derivatives, simultaneously bearing 10-undecenoyl and variously substituted phenylaminocarbonyl groups, were chemically bonded on allylsilica gel. The study of the effect of these substitutions on the performance of the resulting chiral supports, and a comparison with the recently described 10-undecenoate/3,5-dimethylphenylcarbamate derivative, are presented. In this study heptane/2-propanol or heptane/chloroform mixtures were used as mobile phases. Chirality 10:283-288, 1998. © 1998 Wiley-Liss, Inc.
    Additional Material: 4 Ill.
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  • 16
    ISSN: 0899-0042
    Keywords: atropisomeric polychlorinated biphenyls (PCBs) ; Chirasil-Dex ; rotational barrier ; stopped-flow multidimensional gas chromatographic technique ; on-line enantiomerization kinetics ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The rotational barriers ΔG
    Additional Material: 3 Ill.
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  • 17
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 325-337 
    ISSN: 0899-0042
    Keywords: diastereomeric salts ; molecular recognition ; hydrogen bonding ; thermal analysis ; crystallography ; solubility ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: (+)-(1S;2S)-Pseudoephedrine and racemic mandelic acid form three distinct diastereomeric salts from solutions in 95% ethanol. The least-soluble phase, a hemihydrate, contains the (2R)-mandelate. A salt phase of intermediate solubility is the unsolvated double salt, containing both the (2R)- and the (2S)-mandelate. The most-soluble salt phase contains the (2S)-mandelate. Mandelate configuration and order of solubility (based on the heats of fusion) is inverted from that found in the same system synthesized from chiral base and acid, and then crystallized from benzene solution. The (2R)-mandelate hemihydrate (-H2O at 349.5K, mp 391K), monoclinic, P21, a = 6.788(5), b = 29.415(35), c = 9.488(10)Å, β = 108.91(8)°, Z = 4 (2 ion-pairs/asymmetric unit). Intermediate double salt (2S)- and (2R)-mandelate, mp 377.6K, anorthic, P1, a = 7.758(4), b = 9.966(5), c = 13.366(6)Å, α = 72.99(4), β = 79.98(4), γ = 70.51(4)°, Z = 1 (2 ion-pairs/asymmetric unit). The (2S)-mandelate (mp 386.2K), orthorhombic, P212121, a = 7.079(6), b = 13.443(10), c = 18.820(14)Å, Z = 4 is identical to a salt made from a combination of enantiomeric moieties from benzene solution. While differing from ephedrine mandelates in configuration at one center, solubilities of pseudoephedrine mandelates in 95% ethanol are much larger. A comparison of molecular structure (non-polar and H-bonding) regions of pseudoephedrine and ephedrine mandelates shows similarities and differences that are tentatively linked to crystal properties. This study reemphasizes the necessity for consistency in solvent use in resolution and in phase identification and comparison because the phases produced are frequently dependent upon the solvent. Chirality 10:325-337, 1998. © 1998 Wiley-Liss, Inc.
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  • 18
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 371-372 
    ISSN: 0899-0042
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: No abstract.
    Type of Medium: Electronic Resource
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  • 19
    ISSN: 0899-0042
    Keywords: (±)nicotine ; (±)nornicotine ; chiral separation ; enantiomers ; normal phase HPLC ; mobile phase additive ; cellulose-based chiral stationary phase ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: This paper describes the enantiorecognition of (±)nicotine and (±)nornicotine by high-performance liquid chromatography using two derivatized cellulose chiral stationary phases (CSPs) operated in the normal phase mode. It was found that different substituents linked to the cellulose backbone significantly influence the chiral selectivity of the derivatized CSP. The results showed that, in general, the tris(4-methylbenzoyl) cellulose CSP (Chiralcel OJ) surpasses tris(3,5-dimethylphenyl carbamoyl) cellulose CSP (Chiralcel OD). On the former column, the resolution (±)nicotine and (±)nornicotine enantiomers depended largely on mobile phase compositions. For the separation of the nicotine enantiomers, the addition of trifluoroacetic acid to a 95:5 hexane/alcohol mobile phase greatly improved the enantioresolution, probably due to enhanced hydrogen bonding interactions between the protonated analytes and the CSP. For (±)nornicotine separation, a reduction in the concentration of alcohol in the mobile phase was more effective than the addition of trifluoroacetic acid. Possible solute-mobile phase-stationary phase interactions are discussed to explain how different additives in the mobile phase and different substituents on the cellulose glucose units of the CSPs affect the separation of both pairs of enantiomers. Chirality 10:364-369, 1998. Published 1998 Wiley-Liss, Inc.This article is a US Government work and, as such, is in the public domain in the United States of America.
    Additional Material: 6 Ill.
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  • 20
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 430-433 
    ISSN: 0899-0042
    Keywords: Whelk-O 1 ; chromatography ; HPLC ; enantiodifferentiation ; heterocycles ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In concert with a larger study of the processes by which chiral stationary phase CSP 1 differentiates between enantiomers, we have investigated the chromatographic separation of the enantiomers of a series of aryl-substituted heterocycles of systematically varied structure. A mechanistic picture of how these and similar resolutions occur is emerging. The mechanistic hypothesis described herein is of predictive value. Chirality 10:430-433, 1998. © 1998 Wiley-Liss, Inc.
    Additional Material: 4 Ill.
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  • 21
    ISSN: 0899-0042
    Keywords: chiral inversion ; ibuprofen ; ketoprofen ; flurbiprofen ; indoprofen ; suprofen ; fenoprofen ; metabolism of 2-arylpropionic acids ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The fungus Cordyceps militaris has been previously shown to be capable of inverting the chirality of 2-phenylpropionic acid from its (R)-enantiomer to its (S)-antipode. The structure of this compound is similar to the 2-arylpropionic acid non-steroidal anti-inflammatory drugs, which have also been reported to undergo a similar chiral inversion process in mammals and man. We report here an investigation into the substrate specificity of the enzyme system present in C. militaris using pure enantiomers and racemates of ibuprofen and ketoprofen and racemates of indoprofen, suprofen, flurbiprofen, and fenoprofen and the structurally related compounds 2-phenylbutyric acid and 2-phenoxypropionic acid as substrates, using optimised incubation conditions developed for the inversion of 2-phenylpropionic acid. The results demonstrated that C. militaris is capable of inverting the chirality of all the compounds investigated, which suggests that the active sites of the enzymes are very flexible with regard to the molecular dimensions of the substrate molecule and the spatial occupation of the groups surrounding the chiral centre. Metabolism of all the substrates was observed but the rate of metabolism varied extensively depending on the substrate. Achiral HPLC analysis was used to detect any potential metabolites and the results suggested that the site of the metabolism appeared to be at the aliphatic side groups only, with the aromatic ring being left intact in all cases. These results suggest that C. militaris could be a valuable tool in the investigation of the prospective metabolic fates of new 2-arylpropionic acids during their development. Chirality 10:528-534, 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. 555-555 
    ISSN: 0899-0042
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: No abstract.
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  • 23
    ISSN: 0899-0042
    Keywords: asymmetric hydrogenation ; aminophosphine phosphinites ; rhodium complexes ; dehydro aminophosphonic acids ; NMR ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Chiral α-aminophosphonic acid derivatives are efficiently synthesized by asymmetric hydrogenation of the prochiral N-acyl-α,β-dehydroaminophosphonates. PROPRAPHOS-Rh-catalysts from readily available (S)- and (R)-Propranolol proved to be suitable in the homogenous reaction affording an enantiomeric excess of 87-92% with high rate. The aminophosphonic acid derivatives and precursors were fully characterized by 1H, 13C, and 31P NMR spectroscopy. Chirality 10:564-572, 1998. © 1998 Wiley-Liss, Inc.
    Additional Material: 7 Ill.
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  • 24
    ISSN: 0899-0042
    Keywords: chiral separation ; chiral selector ; separation of enantiomers ; liquid chromatography ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A chiral stationary phase (CSP 1) prepared starting from (R)-4-hydroxyphenylglycine and then grafting (R)-N-butanoyl-4-allyloxyphenylglycine N-propyl amide to silica gel was found to be very effective in separating the enantiomers of N-(3,5-dinitrobenzoyl)-α-amino amides. From the chromatographic behaviors of the resolution of N-propyl amides, N,N-diethyl amides and ethyl esters of N-(3,5-dinitrobenzoyl)-α-amino acids and the resolution of various N-(substituted benzoyl)leucine N-propyl amides, the hydrogen bonding and the π-π donor-acceptor sites of the analyte for the interaction with the CSP have been proposed. Similarly, the hydrogen bonding donor and acceptor sites of the CSP for the interaction with the analyte have been proposed from the comparison of the chromatographic behaviors of the resolution of various N-(3,5-dinitrobenzoyl)-α-amino N-propyl amides on modified CSPs (CSP 7 containing trifluoroacetyl group instead of the butanoyl group of CSP 1 and CSP 8 containing N,N-diethyl group instead of the N-propyl group of CSP 1) with those on CSP 1. By correlating the interaction sites of the CSP and their complementary interaction sites of the analyte, a chiral recognition mechanism which utilizes the two hydrogen bonding interactions and the π-π donor-acceptor interaction between (R)-CSP 1 and more retained analytes, (S)-N-(3,5-dinitrobenzoyl)-α-amino amides, has been proposed. Chirality 10:592-599, 1998. © 1998 Wiley-Liss, Inc.
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  • 25
    ISSN: 0899-0042
    Keywords: nucleophilic aromatic substitution ; optical resolution ; asymmetric synthesis ; diastereoselective reaction ; Grignard reaction ; atrolactic acid derivatives ; biaryl coupling reaction ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Novel 1-aryl-9H-fluoren-9-ols 1 were conveniently synthesized by using the ester-mediated nucleophilic aromatic substitution on 2,6-dimethoxybenzoate 2 by aryl Grignard reagents as the key step. Racemic 1-phenylfluorenol 1a was converted to the diastereomeric esters 8 of (S)-2′-methoxy-1,1′-binaphthyl-2-carboxylic acid, which were readily separable by silica-gel column chromatography. Reduction of the optically pure diastereomer (+)-8 with LiAlH4 accompanied an appreciable racemization to give (+)-1a of 89% ee, which provides the first isolation of an optically active fluorenol of defined enantiomeric purity. Intrinsic chiral induction abilities of the 9-fluorenols 1 were examined in the atrolactic acid synthesis from phenylglyoxylates 9 and methylmagnesium iodide with diastereoselectivity of up to 85% de and the binaphthyl coupling of 1-methoxy-2-naphthoates 11 with 2-methoxy-1-naphthylmagnesium bromide with up to 73% de. Chirality 10:619-626, 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. 693-698 
    ISSN: 0899-0042
    Keywords: Pseudomonas cepacia ; lipase PS ; transesterification ; kinetic resolution ; 2-substituted 3-hydroxy ester ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Kinetic resolution of 2-substituted 3-hydroxy esters was examined by lipase PS catalyzed transesterification using vinyl acetate as an acyl donor. Resolution of (±)-syn- and -anti-1a, -1e possessing a small methyl group at the C-3 position was accomplished enantioselectively. The outcome of the resolution seems to be related to the differences in size of the substituents at the stereocenter bearing a secondary hydroxy group. Chirality 10:693-698, 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. 699-704 
    ISSN: 0899-0042
    Keywords: ormeloxifene ; chiral separation ; sulfated cyclodextrin ; enantiomers ; capillary electrophoresis ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: (-)-Ormeloxifene, a drug candidate under development, was separated from (+)-ormeloxifene using capillary electrophoresis (CE) with sulfated β-cyclodextrin as chiral buffer additive. With conventional long-end injection the method showed high efficiency, since the theoretical plate number for (-)-ormeloxifene was over 1 million per m and the enantiomeric resolution was more than 100. However, the relatively long separation time of ∼22 min was a limiting factor. In order to reduce separation time, short-end injection experiments were carried out. By using the instrumental limits for capillary dimensions and field strength, the separation time was reduced to 〈40 sec. A further and significant reduction was achieved by applying extended short-end injection, which is a novel injection technique presented in this paper. With the extended short-end injection procedure, a plug of run buffer is injected after the sample has been injected, thus moving the sample closer to the detector and resulting in very short effective capillary lengths. Using the extended short-end injection technique, the separation was performed on 1.8 cm capillary (effective length) and the enantiomers were separated within 10 sec, which is a reduction of the original separation time by a factor of ∼155. Chirality 10:699-704, 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. iii 
    ISSN: 0899-0042
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: No abstract.
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  • 29
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 742-746 
    ISSN: 0899-0042
    Keywords: methamphetamine ; enantiomer ; serum albumin ; CD spectra ; association equilibrium ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The association equilibria for complex formation between serum albumin (bovine, rat) and the optical isomers of methamphetamine (MAMP) was determined using an ultrafiltration method. It was found that serum albumin/d-MAMP and serum albumin/l-MAMP complexes had distinctly different Scatchard plots with bovine and rat albumin. The binding parameters of each association equilibrium were estimated from the Scatchard plots by Rosenthal's graphic method. This distinguished two kinds of specific binding sites in terms of the association equilibrium between bovine serum albumin and d-MAMP, and one binding site for rat serum albumin and d-MAMP. One specific binding site was found between serum albumin and l-MAMP in both bovine and rat. Molar ellipticities, [θ], of peaks were decreased in the CD spectra of the complexes formed between bovine serum albumin and d-MAMP or l-MAMP when compared with the CD spectrum of bovine serum albumin alone. However, no difference in [θ] was found between the CD spectra of the enantiomers of MAMP in the measured wavelength range. The non-specific binding site was distinct from the specific binding site and resulting from altered tertiary structure of the albumin molecule. Chirality 10:742-746, 1998. © 1998 Wiley-Liss, Inc.
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  • 30
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    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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  • 31
    ISSN: 0899-0042
    Keywords: cellulose ; regioselective derivatization ; chiral stationary phases ; liquid chromatography ; enantioseparation ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Various cellulose-2,3-bis-arylcarbamate-6-O-arylesters and cellulose-2,3-bis-arylester-6-O-arylcarbamates, designed to test the possible combined effects of the known tris-arylcarbamate and tris-arylester classes, were synthesized with high regioselectivity at O-C(6), and their use as CSPs in liquid chromatography for enantiomeric separations was investigated. The separations obtained with the synthesized CSPs were compared to the separations achieved on a self-packed reference column, consisting of cellulose-tris-(3,5-dimethylphenyl-carbamate) as CSP standard. Among the synthesized, regioselectively substituted cellulose derivatives, 2,3-bis-O-(3,5-dimethylphenylcarbamate)-6-O-benzoate-cellulose and 2,3-bis-O-(benzoate)-6-O-(3,5-dichlorophenylcarbamate)-cellulose gave the best CSPs for the separation of the test racemates. CSPs from regioselectively substituted cellulose derivatives seem to exhibit higher selectivities than cellulose-tris-(3,5-dimethylphenylcarbamate) for certain classes of racemic compounds. Chirality 10:294-306, 1998. © 1998 Wiley-Liss, Inc.
    Additional Material: 8 Ill.
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  • 32
    ISSN: 0899-0042
    Keywords: additive ; selectivity ; efficiency ; modifier ; subcritical fluid chromatography ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Subcritical fluid chromatography (SubFC) using a carbon dioxide-methanol mobile phase is used for the chiral resolution of IIb/IIIa receptor antagonist enantiomers. The chiral resolution of three analogs, each containing two chiral centers, is optimized using various mobile phase additives. The effects that acidic, basic, and neutral additives have on retention, efficiency, and resolution are examined. The additive that gives the best resolution was found to be dependent upon the functionality and charge of the chiral analyte. For charged analytes, additives that act as competing ions of the same charge as the chiral analyte dramatically improve efficiency and resolution. Resolution of neutral chiral analyte enantiomers is also greatly affected by the choice of mobile phase additive. Chirality 10:338-342, 1998. © 1998 Wiley-Liss, Inc.
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  • 33
    ISSN: 0899-0042
    Keywords: cyclic imides ; barbiturates ; piperidine-2,6-diones ; mephenytoin ; chiral recognition ; enantioselectivity ; vancomycin chiral stationary phase ; normal-phase mode ; reversed-phase mode ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Several cyclic imidic compounds (barbiturates, piperidine-2,6-diones, and mephenytoin) are enantiomerically resolved via high-performance liquid chromatography (HPLC) on a macrocyclic antibiotic covalently bonded to a silica gel support. The Chirobiotic V chiral stationary phase (CSP) column contains the antibiotic vancomycin as the chiral selector. The results of the analysis show that the substituents at the chiral carbon position of the racemic drugs affect chiral resolution. In addition, ring size may also play a role when considering the formation of analyte-CSP inclusion complexes. Contrary to the piperidine-2,6-diones, the chromatographic parameters for the barbiturates are much the same under normal- or reversed-phase conditions. The details of these results are discussed. Chirality 10:358-361, 1998. © 1998 Wiley-Liss, Inc.
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  • 34
    ISSN: 0899-0042
    Keywords: liquid crystals ; circular dichroism ; X-ray diffraction ; self-recognition ; salt ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The title compounds show a pronounced cation-directed ability to self-assemble in water and to gives columnar structures similar to four-stranded helices; for compound (5′→5′)-d(GpG), this leads to the formation of cholesteric and hexagonal liquid crystalline phases. Both phases are columnar and the cholesteric phase is left-handed. This behaviour is a further confirmation of the tendency of guanine derivatives to self-assemble to give stacked columnar structures whenever not impossible for structural reasons. The CD spectra of the aggregates in isotropic solutions are dominated by a negative exciton couplet centred around 250 nm associated to a left-handed columnar chirality. The shapes of the profiles, in the 220-300-nm region, for (5′→5′)-d(GpG) (in water or in saline solutions) and for (3′→3′)-d(GpG) (in KCl solution) are quasi-mirror images of those of poly(G) and (3′→5′)-d(GpG). The appearance of relatively intense CD signals around 280-300 nm in solution of (3′→3′)-d(GpG) in the presence of NaCl resembles that of (3′→5′)-d(GpG) in the presence of Rb+ or Na+. In the compounds investigated in this work, which present two equivalent ends, one observes the two CD features that have been associated, in the current literature, with the signature of four-stranded parallel and antiparallel structures: hence the origin of these CD bands cannot be found in the polarity of the strands. Self-assembly is favoured by the addition of extra salt and the stabilising effect of K+ is greater than that of Na+, in the case of (3′→3′)-d(GpG), an assembled species could be detected by CD only in the presence of extra salt. Chirality 10:734-741, 1998. © 1998 Wiley-Liss, Inc.
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  • 35
    ISSN: 0899-0042
    Keywords: 1,4-benzoxazine-2-carboxylic acids ; X-ray crystal structure determination ; 1-phenylethylamine ; 2-amino-1,4-benzoxazin-3-ones ; racemization ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Both enantiomers of 2-methyl-3-oxo-3,4-dihydro-2H-1,4-benzoxazine-2-carboxylic acid 2 and 2,4-dimethyl-3-oxo-3,4-dihydro-2H-1,4-benzoxazine-2-carboxylic acid 3 were prepared via resolution of the corresponding racemic carboxylic acids with (R)- and (S)-1-phenylethylamine, respectively. Absolute configuration of (-)-(R)-2-methyl-3-oxo-3,4-dihydro-2H-1,4-benzoxazine-2-carboxylic acid was determined by X-ray crystallography. Curtius rearrangement of acyl azides prepared from enantiomers of these heterocyclic carboxylic acids carried out in benzyl alcohol afforded enantiomers of the corresponding benzyl carbamates, which upon hydrogenolysis gave racemic 2-amino-2-methyl-3,4-dihydro-2H-1,4-benzoxazin-3-one 4 and 2-amino-2,4-dimethyl-3,4-dihydro-2H-1,4h-benzoxazin-3-one 5. Chirality 10:791-799, 1998. © 1998 Wiley-Liss, Inc.
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  • 36
    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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  • 37
    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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  • 38
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A Novel Synthetic Route to Open-Chained and Cyclic OligoetherketonesOligoetherketones of the structure 2a,b can be generated by repetitive insertion reactions of terminal biscarbenoids 4a,b, into the O—H bonds of diols like 5. The formation of the corresponding ring systems 7a and the involved carbene dimerization leading to 8b are processes which compete with the linear polyinsertion. A related one-component reaction can be performed with ω-hydroxy-1-diazo-2-alkanones (13a-c → 14a-c).
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  • 39
    Electronic Resource
    Electronic Resource
    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
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 2,3,4,5,6-Penta-O-acetyl-D-galactonic acid chloride (1a) and D-gluconic acid chloride (1b), respectively, react with alkyl acetoacetates and benzoylacetates 2, respectively, to yield derivatives 3 of diuloses with an alkoxycarbonyl group in the branch. Decarboalkoxylation of these compounds gives 1,3-didesoxy-nono-2,4-diuloses 4a,b and 2-deoxy-octo-1,3-diuloses 4c, respectively. Compound 4a and diazomethane react to furnish the corresponding methyl enol ether 5a and 5b.
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  • 42
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: N-Iodosuccinimide (NIS): an “Old” Reagent and “New” Applications
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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 reaction of bis(vinamidinium salts) (5a, 6) and amidinium-vinamidinium salts (7, 21) with primary amines was studied. Whereas the condensation of 6 and 7a with p-phenylenediamine and 4,4′ diaminostilbene gave rise to polymeric vinamidines (12, 18), 5a and 7b reacted with aromatic amines and diamines to give pyrrole and imidazole derivatives. The reaction of p-aminophenylacetic acid with DMF-POCl3 produced a new amidinium-vinamidinium salt (21) which could be converted into a donor-acceptor substituted diazaterphenyl derivative (22) displaying a strong solvatochromism. - The crystal structure analysis of the 2,2′-bis(vinamidinium salt) 5b revealed a 73° twist angle between the planes of the vinamidinium moieties.
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  • 44
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1,3-Diaza-2-azoniaallene salts R1-N=N+=N—R2 6 represent a new functional group. 1,3-Disubstituted triazenes 8 are oxidized with tert-butyl hypochlorite to stable open-chain N-chlorotriazenes R1—N=N—NCl—R2 9, which at low temperatures with Lewis acids afford the reactive intermediates 6. The salt 6a is stable below -50 °C and was characterized by spectroscopic and analytical data. Heterocumulenes 6 behave as positively charged 1,3-dipoles undergoing cycloadditions to many different multiple bonds to furnish 1,2,3-triazolium and tetrazolium salts, e.g. to both electron-rich and electron-deficient alkenes, alkynes, to one or both double bonds of 1,3-butadienes, to carbodiimides, and cyanamides (1,3-dipolar cycloaddition with inverse electron demand). With an allene, a butatriene and a pentatetraene the 4,5-dihydro-1H-1,2,3-triazolium salts 17-19 were obtained. The constitutions of four of the products were secured by X-ray structural analyses. 4,5-Dihydro-1H-1,2,3-triazolium salts 11 and 1H-1,2,3-triazolium salts 20 are aza analogues of Arduengo's and Wanzlick's nucleophilic carbenes.
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  • 45
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Stable Tetraazafulvalenes - Syntheses and ChemistryThe syntheses, properties and reactions are described for 1,3,6,7-tetrakis[arylamino]-1,4,5,8-tetraazafulvalenes and their vinylogous derivatives. First, the acylation of form- as well as acetamidine with bis-imidoylchlorides derived from oxalic acid 6 formed reactive cyclic intermediates which dimerized to tetraazafulvalenes 12 or bisvinylogous tetraazafulvalenes 14. Based on, a further synthesis was found using a cycloacylation reaction of amidines with imidoylchlorides 6 followed by prototropic migration of α-hydrogen. Thus, the vinylogous compound 15 and the phenylogous derivatives 16, 17 could be isolated in moderate up to good yields. Besides amidines, other derivatives of carboxylic acids as amides or thioamides could be transformed into corresponding tetraazafulvalenes 18-20. Due to their vicinal amino groups, alkylation and acylation reactions were studied. For example, the reaction with orthoformates yielded the ring fused products 24a,b which may be starting material for carbenes just as the cyclization product with thiophosgene 27. Treatment of tetraazafulvalenes with anhydrous iron-II salts or molybdenum hexacarbonyl yielded the deeply colored metal diazadiene complexes 33 and 34. Finally, reduction using metallic lithium and subsequent alkylation constitutes a convenient synthetic entry to heterocyclic analogues of stilbene 37.
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  • 46
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Benzyl cation inititiated intramolecular cyclization reactions with conjugated C—C double bonds were performed providing rac. endo-exo isomers of 1-azabicyclo[3.2.1]octenes (2 and 3). Formation of the endo isomer 2 is favoured. Compounds 2 possess dopamine uptake inhibitory effect with an additional selective MAO-B enzyme inhibitory potential. The remarkable in vitro effects do not correspond to in vivo antidepressant activity.
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  • 47
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 48
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 49
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Monofunctionalized Dendrons of Different Generations - as Reagents for the Introduction of Dendritic SubstituentsIn recent years dendrimers become more and more important not only in organic chemistry. They represent a new class of molecules with unique characteristic features. But dendrimers represent not only designed molecular architecture. They stand for a new concept in chemistry. They can be used to alter the properties of already existing molecular skeletons or they can be used to transfer new properties to a classical functional unit. This means that functionalized dendrimers and dendrons (dendritic building blocks) can be regarded as reagents for the preparation of new compounds with dendritic properties. In this article the synthesis and the practical use of appropriate dendritic reagents is explained. Furthermore we introduce the new technical terms „{n} dendryl-“ for dendritic substituents of n generations and „dendriagent“ which stands for dendritic reagents. Moreover we give a short outlook on future developments.
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  • 50
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Several new push-pull azobenzene dyes were synthesized by diazonium salt coupling of electron-poor anilines with N,N-dialkylanilines. Their dipole moments and first-order hyperpolarizabilities were evaluated respectively from the concentration dependence of the dielectric constant of solutions in apolar solvents and by the electric-field-induced-second-harmonic-generation (EFISH) technique. Investigation of the influence of both nature and steric hindrance of the electron-withdrawing group allowed to highlight a significant deviation from linearity in the relationship between dipole moments and first-order hyperpolarizabilities. This effect was particularly noticeable when multiple electron withdrawing groups pointing in different directions were present on the same phenyl ring.
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  • 51
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ten N-alkylated lupininium derivatives 5-8 were prepared as potential enantioselective phase transfer catalysts. Compounds 5a-d, 6a-d contain four asymmetric centers (including one in the side chain) with known configuration resting on an X-ray structure. Preliminary PT catalytic experiments in several reactions gave high chemical yields but relatively disappointing enantioselectivities.
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  • 52
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The cis or trans-glycidic esters 1 or 7 give ring transformations with hydrazines affording optically active 4-hydroxypyrazolidin-3-ones 3 and 4 or 6 or 9 and 10, respectively, in different regioselectivities. 4-Hydroxypyrazolidin-3-ones 3 and 9 can serve as precursors for enantiomerically pure β-amino-α-hydroxycarboxylic acid amides 5 and 11 by hydrogenation in the presence of Raney-Ni.
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  • 53
    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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  • 54
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A series of new 3,1′-bridged 2-[2′-(4″-dialkylaminophenyl)ethenyl]-4,6-diarylpyrylium perchlorates (3), 2-[2′-(4″-dialkylaminophenyl)ethenyl]-7-diethylamino-1-benzopyrylium perchlorates 5-8, 2-[4′-(4″-dialkylaminophenyl)butadien-1′,3″-yl]-, and 2-[2′-(7″-diethylaminocoumar-3″-yl)ethenyl]-7-diethylamino-1-benzopyrylium perchlorates 10-12 were synthesized and characterized by means of elemental analysis, m.p., Vis/NIR, and 1H NMR spectra. Semiempirical MO calculations were performed to elucidate the essential features of the chromophores. The size of the bridging ring strongly affects the geometry of the chromophores which, in turn, determines the extent of charge transfer of the longest wavelength electronic transition. Increasing deviation from planarity causes the polymethine-like chromophore to become more polyene-like.
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  • 55
    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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  • 56
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new synthesis of the title crown via isoxazolo crown ether 7 and macrocyclic bis-β-eneaminoketone 10 is described. 7 can be synthesized in 14% yield by a non-template double-[3+2] cycloaddition of dinitrileoxide 5 prepared in situ from dinitropolyether 19 by dehydration with Ph-NCO and alkyne 6. The compounds 16, 17 and 18 are synthesized by the same synthetic strategy. Comparable IR and 1H NMR spectroscopic data of macrocyclic and non-cyclic compounds show, that macrocyclic conformation stabilizing effects can be ruled out. The structures of the macrocycles 1, 7, 10 and that of the Hg(II)-complex 25, synthesized by reaction of 1 with Hg(OAc)2 were established by single-crystal X-ray structure analyses. Both inter- and intramolecular hydrogen bonds are observed for the macrocyclic bis-β-eneaminoketone 10, whereas only intramolecular hydrogen bonds are formed by 1.In the Hg(II)-complex of 1 the mercury is bonded to two methylene groups. C—Hg—C is almost linear [177(1)°], the mean Hg—C distance amounts to 215(1) pm. In addition to the Hg—C bonds, each Hg makes a short contact to a carbonyl oxygen in a neighbouring molecule in the plane perpendicular to the C—Hg—C axis [Hg(1)—O(1) = 279(1) pm, Hg(2)—O(5) = 284(1) pm].
    Additional Material: 4 Ill.
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    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis and stereochemical characteristics of pyrrolidino-, isoquinolino- and indolo-enaminones 2-11 are reported. The inhibition of cyclooxygenase was determined in a bovine thrombocyte intact cell assay and that of 5-lipoxygenase using intact bovine polymorphonuclear leucocytes. Except compound 2c′ which is a well-balanced dual inhibitor of both enzymes, all other enaminone derivatives are weak inhibitors of both cyclooxygenase and 5-lipoxygenase. Structure-activity relationships of the enaminones in relation to known anti-inflammatory drugs are discussed.
    Additional Material: 1 Ill.
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  • 58
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new synthesis of sodium cyanodithioformate 1 and the disodium salt of cis-1,2-dicyanoethylene-1,2-dithiol 2 is reported. The key step involves a nucleophilic thiolation with elemental sulfur starting from a substituted acetonitrile 4. This method may serve as a cyanide- and carbondisulfide-free alternative in the preparation of the title compounds.
    Additional Material: 1 Tab.
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  • 59
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 60
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The 2(3)-formyl-glycals 2, 4, 6 react with hydrazine hydrate to furnish the C-(1H-pyrazol-3-yl)alditoles 7, 8, 9. Treatment of 2, 4, 6 with cyanoacetamide provides the 2(3)-(2-aminocarbonyl-2-cyano-vinyl)-1,5(2,6)-anhydro-2(3)-deoxy-hex-enitols 10, 13, 15, which are converted into the polyhydroxyalkyl 2-amino-nicotinamides 11, 14, 16 and pyridinecarbonitriles 12, respectively.
    Additional Material: 1 Ill.
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  • 61
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Annulated Aminocyclopropane-endo-carbonitriles 11a,b are reductively decyanated by sodium in liquid ammonia with complete retention of configuration. An additionally existing chlorine atom in the starting materials 12a,c-e, thereby, is simulataneously replaced by hydrogen. The preparative advantage of this method is demonstrated by the selective access to 6α-H-isomers 13b and 13e as members of the ensemble of bicyclo[3.1.0]hexanediyl-dimorpholine diastereomers. A strong buckled bicyclohexane unit is present in 3α,6αisomer 13e as indicated by 1H NMR spectroscopy and X-ray structural analysis.
    Additional Material: 1 Ill.
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