Angewandte Chemie International Edition in English

Cover image for Vol. 35 Issue 22

December 1996

Volume 35, Issue 22

Pages 2551–2683

Currently known as: Angewandte Chemie International Edition

    1. Cover Picture (Angew. Chem. Int. Ed. Engl. 22/1996)

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199625491

      Thumbnail image of graphical abstract

      The cover picture shows the first completely conjugated, tubelike hydrocarbon that is constructed by conventional chemical synthesis—a type of “picotube”. It is synthesized in one step from tetradehydrodianthracene by photochemically induced metathesis reaction, which makes use of the strain energy as driving force. The highly symmetrical compound is characterized by exceptional stability. Ring-expanding metathesis—a new method for the construction of tubelike molecules—in conjunction with cyclization–dehydrogenation might point the way to interesting tube- and belt-shaped systems. The picture was generated by S. Kammermeier with the program POV-Ray on a Silicon Graphics Workstation. R. Herges et al. report on the synthesis and structure of the picotubes on p. 2669 ff.

  1. Reviews

    1. Top of page
    2. Reviews
    3. Highlights
    4. Communications
    5. Book Reviews
    1. Enantioselective Protonation of Enolates and Enols (pages 2566–2587)

      Dr. Charles Fehr

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199625661

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      The preferential transfer of a proton to one enantiotopic face of an enolate or enol derivative from a chiral proton donor HX* or from an achiral proton source in the presence of a chiral ligand is becoming increasingly important as a synthetic method. By judicious choice of reagents, both ketones and carboxylic acid derivatives can be obtained in almost enantiomerically pure form (see schematic overview below).

    2. What Can We Learn from Molecular Recognition in Protein–Ligand Complexes for the Design of New Drugs? (pages 2588–2614)

      Dr. Hans-Joachim Böhm and Prof. Dr. Gerhard Klebe

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199625881

      It's a great deal, but we still require additional information—that is the answer to the question in the title. How the knowledge of the three-dimensional structures of protein–ligand complexes and small organic molecules can be exploited for the development of computational tools for predicting binding affinities, molecular conformations, and binding modes is described herein. Evidence is also presented that care is needed—particularly for considerations based purely on structural arguments—since interactions such as hydrogen bonds and lipophilic contacts can lead to unexpected orientations of ligands in a protein pocket.

  2. Highlights

    1. Top of page
    2. Reviews
    3. Highlights
    4. Communications
    5. Book Reviews
    1. Defluorination of Perfluoroalkanes and Chlorofluorocarbons (pages 2615–2617)

      Dr. Graham C. Saunders

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199626151

      Electron transfer from a reducing agent to a fluorocarbon leads to cleavage of the strong and supposedly inert C[BOND]F bond. This process can be used to defluorinate perfluoroalkanes to produce perfluoroarenes or -alkenes catalytically under mild conditions. The transfer of two electrons from alkali metal oxalates to chlorofluoro-carbons leads to complete degradation at relatively low temperatures [Eq. (a)].

      • equation image
    2. Ylidic Four-Membered Rings with Four π-Electrons—Another Exciting Chapter in Phosphorus Chemistry (pages 2618–2621)

      Prof. Dr. Lothar Weber

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199626181

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      In contrast to the antiaromatic and nonelusive mono- and oligophosphetes featuring only two-coordinate phosphorus atoms, unsaturated, four-membered phosphorus heterocycles with at least one η5, σ4-phosphorus atom such as triphosphete 1, which was prepared by Karsch et al., are surprisingly stable compounds. These systems can undergo ring expansion to give five-membered heterocycles such as 2 (according to Bertrand et al.), react to form complexes, or undergo addition and substitution reactions.

  3. Communications

    1. Top of page
    2. Reviews
    3. Highlights
    4. Communications
    5. Book Reviews
    1. Biomimetic Growth and Self-Assembly of Fluorapatite Aggregates by Diffusion into Denatured Collagen Matrices (pages 2624–2626)

      Prof. Dr. Rüdiger Kniep and Dipl.-Ing. Susanne Busch

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199626241

      Thumbnail image of graphical abstract

      Elongated, hexagonal-prismatic seed crystals are the starting point for the hierarchical growth of anisotropic spherical aggregates of fluorapatite in gelatin matrices. Discrete dumbbell-shaped aggregates (scanning electron microscope image shown on the right) are formed by self-similar, branched, needlelike upgrowths at both ends of the seeds. With successive generations, these aggregates close to give pheres with diameters of up to 400 μm. The system makes it possible to monitor the development of antibiotic information pattern into the macroscopic range.

    2. Prototypical Reagent for the Synthesis of Substituted Hydrazines (pages 2626–2627)

      Dr. Uno Mäeorg, Dr. Leif Grehn and Dr. Ulf Ragnarsson

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199626261

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      “Almost all possibilities have been exhausted”, stated H. Wieland in 1913 in the preface to his monograph Die Hydrazine with regard to the synthesis of N,N′-substituted hydrazines. Even today suitable reagents and methods are lacking for the preparation of these compounds, which are important as precursors of pharmaceuticals, agrochemicals, and dyestuffs. The readily available, protected hydrazine 1 is a new reagent that may fill this gap.

    3. Catalytic Antibodies as Probes of Evolution: Modeling of a Primordial Glycosidase (pages 2628–2630)

      Doron Shabat, Dr. Subhash C. Sinha, Dr. Jean-Louis Reymond and Prof. Ehud Keinan

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199626281

      Thumbnail image of graphical abstract

      The hydrolysis of unactivated cyclic ketals such as 1 can be catalyzed by antibodies raised against the transition state analog 2. This transformation is closely related to the cleavage of the glycosidic bond. The observed catalysis is triggered more by electrostatic complementarity to the transition state than by shape complementarity.

    4. Synthesis and Structure of CoB2P3O12(OH)·C2H10N2: The First Metal Borophosphate with an Open Framework Structure (pages 2630–2632)

      Prof. Slavi C. Sevov

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199626301

      Thumbnail image of graphical abstract

      Channels measuring roughly 5.2 × 7.6 Å (O[BOND]O distances) are found in the first microporous borophosphate (a section of the structure is shown on the right). Ethylenediamine serves as a template in the hydrothermal synthesis. The framework is constructed from BO4 and PO4 tetrahedra and CoO6 octahedra, and organic dications occupy the channels.

    5. Synthesis and Properties of PNA/DNA Chimeras (pages 2632–2635)

      Dr. Eugen Uhlmann, Dr. David W. Will, Dr. Gerhard Breipohl, Dietrich Langner and Dr. Antonina Ryte

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199626321

      Thumbnail image of graphical abstract

      Unambiguous binding to complementary DNA and RNA, stability toward 3′-exonucleases, and a similar uptake by cells as DNA oligomers characterize the PNA/DNA chimeras of type 1 described here. These chimeric oligomers are accessible in an automated synthesis sequence.

    6. Phosphonic Ester Nucleic Acids (PHONAs): Oligonucleotide Analogues with an Achiral Phosphonic Acid Ester Backbone (pages 2636–2638)

      Dr. Anusch Peyman, Dr. Eugen Uhlmann, Konrad Wagner, Sascha Augustin, Dr. Gerhard Breipohl, Dr. David W. Will, Dr. Andrea Schäfer and Dr. Holger Wallmeier

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199626361

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      The water-solubility of PHONAs and their ability to bind complementary DNA make them interesting potential therapeutics. The nucleobases are attached to an achiral, charged backbone through a methylenecarbonyl linker, as in the case of PNAs (see below). PHONAs are synthesized in solution by block condensation.

    7. Are the Most Stable Fused Heterobicycles the Most Aromatic? (pages 2638–2641)

      Dr. Govindan Subramanian, Prof. Paul von Ragué Schleyer and Dr. Haijun Jiao

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199626381

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      The authors' answer to the question in the title is: No, the most stable positional isomers of the isoelectronic heteroatom analogues (1 and 2) of the pentalene dianion are not the most aromatic. Their arguments are based on the geometric and magnetic criteria (computed magnetic susceptibilities and anisotropies, 1H NMR chemical shifts and nucleus-independent chemical shifts).

    8. Liquid-Crystalline, Substituted Octakis-(dimethylsiloxy)octasilsesquioxanes: Oligomeric Supermolecular Materials with Defined Topology (pages 2641–2643)

      Dr. Georg H. Mehl and Prof. John W. Goodby

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199626411

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      Cuboid silsesquioxanes with appropriate side chains (see below; n = 4, 6, 11) provide a means of structuring soft matter with inorganic cores. These compounds combine material characteristics of polymer and low molecular mass liquid crystals.

    9. Oligo-THF Peptides: Synthesis, Membrane Insertion, and Studies of Ion Channel Activity (pages 2643–2646)

      Dr. Holger Wagner, Dr. Klaus Harms, Prof. Dr. Ulrich Koert, Dr. Sabine Meder and Prof. Dr. Günther Boheim

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199626431

      Thumbnail image of graphical abstract

      Membrane-modifying and conductance-inducing, decapeptide 1 marks a new class of compounds, the oligo(tetrahydrofuranyl) peptides, which form artifical ion channels and can potentially contribute to a better understanding of the function and structure of their naturally occurring counterparts.

    10. The Novel, [n-B20H18]2−-Induced Nucleophilic Ring Opening of Tetrahydrofuran by Alkoxide Anions (pages 2646–2649)

      Fangbiao Li, Dr. Kenneth Shelly, Dr. Robert R. Kane, Dr. Carolyn B. Knobler and Prof. M. Frederick Hawthorne

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199626461

      Thumbnail image of graphical abstract

      Completely unexpectedly, [ae-B20H170(CH2)4OR]2−1 is formed and not the expected [ae-B20H17OR]4− in the reaction of [n-B20H18]2− with alkoxides NaOR (R [DOUBLE BOND] methyl, isopentyl). The products result from the nucleophilic attack by an alkoxide ion on a THF solvent molecule that is associated with [n-B20H18]2−. The anhydrous oxidation of 1 in ethanol produced the [μ-B20H17O(CH2)4OR]2− ions (2), which can be hydrolyzed to produce the [μ-B20H17OH]2− anion.

    11. Towards Synthetic Adrenaline Receptors—Strong Binding of Amino Alcohols by Bisphosphonates (pages 2649–2651)

      Dr. Thomas Schrader

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199626491

      Thumbnail image of graphical abstract

      A new class of ammonium receptors binds especially strongly to biologically important amino alcohols such as glucosamine, norephedrine, and the β-blocker propranolol (Ka > 50 000 in DMSO). The mechanism of molecular recognition (see the model on the right obtained from force-field calculations) imitates that of the natural adrenergic receptor.

    12. K7HW5O19·10H2O—A Novel Isopolyoxotungstate(VI) (pages 2651–2653)

      Prof. Dr. Joachim Fuchs, Rosemarie Palm and Prof. Dr. Hans Hartl

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199626511

      Thumbnail image of graphical abstract

      The anion [HW5O19]7− (depicted on the right) could be an intermediate on the way to highly condensed polyoxotungstates(VI). The compound K7[HW5O19] · 10 H2O, which contains this anion, was obtained by fractional crystallization from an acidified K2WO4 solution.

    13. Dimeric Triaryltelluronium Arenetellurolates: New Metastable Tetramers of Diaryltellurium (pages 2653–2655)

      Dipl.-Chem. Jörg Jeske, Prof. Dr. Wolf-Walther du Mont and Prof. Dr. Peter G. Jones

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199626531

      Thumbnail image of graphical abstract

      A description as pairs of ion pairs best suits the telluronium tellurolates Rmath imageTeTeR2 (R1 [DOUBLE BOND] phenyl, R2 [DOUBLE BOND] 4-methylphenyl for 1a, R2 [DOUBLE BOND] 4-methoxy-phenyl for 1b) and the corresponding selenolates, whose existence in the solid state is connected with cooperative chalcogen–chalcogen interactions. The central Te4 ring of 1 a is shown on the right (phenyl substituents on Te1 and Te2 have been omitted for clarity).

    14. Coelenterands: A New Class of Metal-Encapsulating Ligands (pages 2655–2657)

      Chris M. Hartshorn and Dr. Peter J. Steel

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199626551

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      Half-sandwich coordination and tripodal chelation by one ligand is possible with the novel class of ligand, the coelenterands, described here. An example of a metal complex containing a coelenterand—the name is derived from the Greek words for hollow stomach—is shown on the right.

    15. Molecular Redox-Switches by Ligand Exchange (pages 2657–2660)

      Christophe Canevet, Dr. Jacqueline Libman and Prof. Abraham Shanzer

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199626571

      Thumbnail image of graphical abstract

      Simply by flipping up, suitable ligand units attached to the calix[4]arene -- iron(III) complex represented schematically on the right can bind the “soft” iron(II) ion generated on reduction (X = coordinating buffer molecules). The calixarene bears two sets of ion-binding groups: one for “hard” and one for “soft” metal ions. The metal complex switches between the two states during redox reactions, and this switching process can be followed in real time by UV/V is spectroscopy.

    16. Hexaaryltellurium, the First Neutral Compounds Comprising Hexaarylated Elements (pages 2660–2662)

      Dr. Mao Minoura, Takao Sagami, Prof. Dr. Kin-ya Akiba, Claudia Modrakowski, Allexander Sudau, Prof. Dr. Konrad Seppelt and Dr. Stephan Wallenhauer

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199626601

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      The highest possible oxidation state of +6 is displayed by the tellurium center in the hexaaryltellurium compounds 1 a and 1 b. Both are extremely thermally stable and, unlike other organotellurium compounds, not light-sensitive. X-ray crystallographic analyses of 1 revealed rare examples of approximate Th molecular symmetry.

    17. Inversion of Optically Active Dihydropyridines by Oxidation and Electroreduction (pages 2662–2664)

      Dr. Alexander Straub and Dr. Axel Goehrt

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199626621

      Thumbnail image of graphical abstract

      Stereoselective oxidation of optically active dihydropyridines with NOBF4 or MnO2 leads with either inversion or retention to axial chiral arylpyridines (see below), which can be converted by cathodic reduction into the corresponding dihydropyridines. This is the first report of the successful inversion of configuration or dihydropyridines.

    18. Cyclic [6]- and [8]Paraphenylacetylenes (pages 2664–2666)

      Dr. Takeshi Kawase, Hossein R. Darabi and Prof. Dr. Masaji Oda

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199626641

      Thumbnail image of graphical abstract

      The belt-shaped, conjugated molecules 1 and 2 were synthesized by bromination–dehydrobromination of the corresponding hexaene and octaene. The air-sensitive but isolable compounds show appreciable strain in the triple bonds and large Stokes shifts in the emission spectra.

    19. Designed Synthesis of [TiSe2]m[NbSe2]n Superlattices from Modulated Reactants (pages 2666–2669)

      Myungkeun Noh and Prof. David C. Johnson

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199626661

      Thumbnail image of graphical abstract

      Intergrown dichalcogenide layers with a predetermined modulation of composition can be prepared through controlled crystallization of reactants with superlattice structure. The resulting superlattice products (the picture shows the transition from one dichalcogenide component (black spheres) to the other (gray spheres)) are formed as polycrystalline thin films oriented with the dichalcogenide layers parallel to the substrate surface. We are thus a step closer to being able to tune physical and chemical properties through the design of superlattices.

    20. Ring-Expanding Metathesis of Tetradehydro-anthracene—Synthesis and Structure of a Tubelike, Fully Conjugated Hydrocarbon (pages 2669–2671)

      Dipl.-Chem. Stefan Kammermeier, Prof. Dr. Peter G. Jones and Prof. Dr. Rainer Herges

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199626691

      Thumbnail image of graphical abstract

      A tubelike, fully conjugated hydrocarbon, a kind of “picotube”, was prepared by ring-expanding metathesis (see below). This method may provide an approach for the chemical synthesis of a variety of other carbon tubes.

    21. Samarium Diiodide Mediated Coupling of Glycosyl Phosphates with Carbon Radical or Anion Acceptors—Synthesis of C-Glycosides (pages 2671–2674)

      Dr. Shang-Cheng Hung and Prof. Dr. Chi-Huey Wong

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199626711

      Thumbnail image of graphical abstract

      Carbohydrate mimetics for the study of carbohydrate recognition in biological systems can be C-glycosides, which can now be prepared by the SmI2-mediated coupling of glycosyl phosphates with carbon radical or carbon anion acceptors. The reaction proceeds by one-electron processes via the radical or the anion, respectively (see scheme on the right), and is complete within 15–30 min.

    22. Prodrugs of the Cytostatic CC-1065 That Can Be Activated in a Tumor-Selective Manner (pages 2674–2677)

      Prof. Dr. Lutz F. Tietze, Dr. Robert Hannemann, Dr. Wilm Buhr, Dr. Michael Lögers, Dipl.-Chem. Pia Menningen, Dipl.-Chem. Monika Lieb, Dr. Dorothea Starck, Dr. Thomas Grote, Angela Döring and Dr. Ingrid Schuberth

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199626741

      Thumbnail image of graphical abstract

      The O-glycosides 1 of the seco-CI derivative 2, which is the seco form of the simplified pharmacophoric group of the potent cytotoxic antibiotic CC-1065, show only very low toxicity. In tumor-selective cancer therapy they can be used in conjunction with conjugates of glycohydrolases and monoclonal antibodies that bind at tumor-associated antigens. The glycohydrolases cleave the prodrugs 1 and release the cytotoxic components 2.

    23. [(enH2)0.5][Zr2(PO4)2(HPO4)F]·H2O: A Unique Zirconium Fluoride Phosphate with a Cavity Structure (pages 2677–2678)

      Prof. Dr. Erhard Kemnitz, Dipl.-Chem. Martin Wloka, Dr. Sergej Trojanov and Dipl.-Chem. Anja Stiewe

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199626771

      Thumbnail image of graphical abstract

      Medium-sized channels pass through the structure of the first zinc fluoride phosphate (section of the structure is shown on the right). The framework is constructed from ZrO6 and ZrO5F octahedra and PO4 and PO3(OH) tetrahedra. Further cavity-containing compounds of this type should be accessible by variation of the amine used as a template.

  4. Book Reviews

    1. Top of page
    2. Reviews
    3. Highlights
    4. Communications
    5. Book Reviews
    1. Book Review: Asymmetric Synthesis. By G. Procter (pages 2680–2681)

      A. Stephen K. Hashmi

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199626802