Angewandte Chemie International Edition in English

Cover image for Vol. 31 Issue 7

July 1992

Volume 31, Issue 7

Pages 805–930

Currently known as: Angewandte Chemie International Edition

    1. Cover Picture (Angew. Chem. Int. Ed. Engl. 7/1992)

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199208051

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      The cover picture shows a ball-and-stick model of a conformation of the cyclic decapeptide antamanide superimposed on a two-dimensional exclusive NMR correlation spectrum (E. COSY), with which the structure and dynamics of the molecule can be studied. From an analysis of the cross-peak multiplet structure, the puckering motion of the four proline rings (that is, the interconversion of the envelope conformations) could be particularly clearly deduced: two of these proline rings are rigid, whereas the other two are fluxional. The puckering motion has also been simulated with molecular dynamics. This investigation shows once more how useful NMR spectoscopy can be for structural elucidation, and underlines the high performance that can now be achieved. Other applications, as well as an account of the development of this extremely important technique, were described by R. R. Ernst in his Nobel lecture. The transcript appears on p. 805 ff.

    2. Graphical Abstract (Angew. Chem. Int. Ed. Engl. 7/1992)

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199208052

  1. Reviews

    1. Top of page
    2. Reviews
    3. Highlights
    4. Correspondences
    5. Communications
    6. Book Reviews
    1. Nuclear Magnetic Resonance Fourier Transform Spectroscopy (Nobel Lecture) (pages 805–823)

      Prof. Dr. Richard R. Ernst

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199208053

      The development of NMR spectroscopy into a multifaceted tool for chemists, biochemists, and medical doctors is certainly due in part to the research of Richard R. Ernst, who received the Nobel Prize in Chemistry last year. In his Nobel lecture he describes the evolution of the field from the first Fourier transform NMR spectra to two-, three-, and four-dimensional experiments. With spectra of the cyclopeptide antamanide he illustrates how information on constitution, configuration, and conformation may be obtained with various NMR techniques.

    2. Ion Channels for Communication Between and Within Cells (Nobel Lecture) (pages 824–829)

      Prof. Dr. Erwin Neher

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199208241

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      A new era in cell biology has been heralded by the prize-winning research of Erwin Neher and Bert Sakmann. These laureates measured the picoampere currents through individual ion channels (see A, below; ACh = acetylcholine). The breakthrough in suppressing the background noise was achieved by applying a slight suction to the pipette used for the current measurement. This improved the crucial pipette-to-membrane seal by two orders of magnitude. In B, below, such a “patch pipette” is shown on the end-plate membrane of denervated frog muscle fiber. Today the patch-clamp technique is used routinely with other methods such as DNA recombination or fluorimetric techniques, for example, to study the synaptic transfer in its molecular detail.

    3. Elementary Steps in Synaptic Transmission Revealed by Currents through Single Ion Channels (Nobel Lecture) (pages 830–841)

      Prof. Dr. Bert Sakmann

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199208301

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      A new era in cell biology has been heralded by the prize-winning research of Erwin Neher and Bert Sakmann. These laureates measured the picoampere currents through individual ion channels (see A, below; ACh = acetylcholine). The breakthrough in suppressing the background noise was achieved by applying a slight suction to the pipette used for the current measurement. This improved the crucial pipette-to-membrane seal by two orders of magnitude. In B, below, such a “patch pipette” is shown on the end-plate membrane of denervated frog muscle fiber. Today the patch-clamp technique is used routinely with other methods such as DNA recombination or fluorimetric techniques, for example, to study the synaptic transfer in its molecular detail.

    4. Soft Matter (Nobel Lecture) (pages 842–845)

      Prof. Pierre-Gilles de Gennes

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199208421

      Polymers, tensides, liquid crystals, and colloids have always stood at the forefront of Pierre-Gilles de Gennes's interests. He obtained the Nobel Prize for Physics in 1991, and his Nobel lecture is a “sentimental journey in the wonderland of soft matter”, which is what he calls complex fluids. In his contribution, de Gennes laid more emphasis on the description of experiments than on theory. Thus he devotes one section to the techniques for making “Janus grains” from hollow glass particles; these grains are microparticles with a polar and an apolar side and have interesting properties for potential applications.

  2. Highlights

    1. Top of page
    2. Reviews
    3. Highlights
    4. Correspondences
    5. Communications
    6. Book Reviews
    1. Cyclodextrins, Off-the-Shelf Components for the Construction of Mechanically Interlocked Molecular Systems (pages 846–848)

      Prof. J. Fraser Stoddart

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199208461

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      Titillating games of “molecular artists” or serious attempts at the production of new, functionalized materials? This question arises in the evaluation of several recent articles by Kaifer et al., Wenz et al., Harada et al., and Macartney et al. on the threading of cyclodextrins on “thin” molecules. If these “threads” are short, [2] rotaxanes result; if they are polymers, polyrotaxanes are the products. One thing remains certain: cyclodextrins will continue to inspire imaginative projects.

    2. Protein Engineering: Modified Hemoglobin as a Blood Substitute (pages 848–849)

      Dr. Timm-H. Jessen and Dr. Rolf Hilgenfeld

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199208481

      Does the race for an efficient and safe blood substitute have a front-runner? Since hemoglobin plays a crucial role in the transport of oxygen in the human body, most of the research into blood substitutes concentrates on this protein. However, because even hemoglobin in one's own body can induce extreme immune reactions, its administration is not without danger. Nagai et al. have now succeeded in modifying this protein by genetic engineering, and several of the problems so far encountered—decomposition of hemoglobin into dimers, prohibitively high oxygen affinity—have been solved. The experiments on rats and dogs with regard to the suitability of solutions of this modified hemoglobin as a blood substitute have been successful.

  3. Correspondences

    1. Top of page
    2. Reviews
    3. Highlights
    4. Correspondences
    5. Communications
    6. Book Reviews
    1. A Safe Synthesis of Diphosphazenium Salts (page 850)

      Dipl.-Chem. Reinhard Link and Priv.-Doz. Dr. Reinhard Schwesinger

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199208501

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      Nitromethane, a potential hazard in the synthesis of the phosphazenium ion 1, is no longer the recommended solvent. The preparation first described in this journal in 1991 has been modified for safety's sake.

  4. Communications

    1. Top of page
    2. Reviews
    3. Highlights
    4. Correspondences
    5. Communications
    6. Book Reviews
    1. Reaction of Heterodinuclear μ-Ethynediyl Complexes Containing Palladium and Platinum: Multiple and Successive Insertion of Isocyanides (pages 851–852)

      Dipl.-Chem. Kiyotaka Onitsuka, Dr. Takashi Joh and Prof. Dr. Shigetoshi Takahashi

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199208511

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      The living polymerization of aryl isocyanides has been achieved with the PdPt–ethynediyl complexes 1. The molecular weight distribution is very narrow for the polymers 2 (n̄ = 10) and 3 (n̄ = 100), and the same end groups as in complex 1 ensure the living nature of the polymerization. If the ratio of isocyanide to 1 is restricted to 2:1, a double-insertion product can be isolated. R = Et, nBu; Ar = Ph, 4-NO2C6H4 inter alia.

    2. Three-Dimensional Structure of an Unsymmetrical Proton–Electron Transfer System Containing a Disulfide Bond: The Bis(4-hydroxy-phenyl)disulfide-Benzoquinone Complex (pages 852–854)

      Kenichi Sugiura, Dr. Jiro Toyoda, Dr. Hiroshi Okamoto, Kaoru Okaniwa, Prof. Dr. Tadaoki Mitani, Dr. Atsushi Kawamoto, Prof. Dr. Jiro Tanaka and Prof. Dr. Kazuhiro Nakasuji

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199208521

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      Three factors determine the three-dimensional crystal structure of the charge-transfer complex of bis(4-hydroxyphenyl)disulfide and 1,4-benzoquinone: the charge-transfer interaction between the components, the hydrogen bonds, and the twist of the phenyl rings about the S[BOND]S bond of the disulfide unit. The ribbon-shaped structures depicted on the right result, which line up along the c axis.

    3. Structures of Two Highly Reactive Intermediates upon LiAlH4 Reduction in the Solid State and in Solution: [(Me3Si)2NAlH3Li · 2Et2O]2 and [(Me3Si)2N]2AlH2Li · 2Et2O (pages 854–855)

      Dipl.-Chem. Andreas Heine and Dr. Dietmar Stalke

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199208541

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      A central kite-shaped AlH2Li ring in which the Li atom bridges the two hydride ligands bound to the Al atom is found in an intermediate of the reaction of HN(SiMe3)2 with LiAlH4. The bond angles show that compound 1 is relatively strained. Nevertheless, 1 does not dissociate in solution; in the 7Li NMR spectrum at low temperature a 1JLi, H coupling is observed.

      • equation image
    4. Total Synthesis of the Carbohydrate Fragments of Esperamicin A1 (pages 855–857)

      Prof. Dr. K. C. Nicolaou and David Clark

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199208551

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      In optically active form the two carbohydrate fragments of the enediyne anti-cancer antibiotic esperamicin A (1) were obtained. Both were also equipped with protecting groups suitable for a total synthesis of the natural product.

    5. A New Strategy for Solid-Phase Synthesis of O-Glycopeptides (pages 857–859)

      Dipl.-Chem. Tim Bielfeldt, Dipl.-Chem. Stefan Peters, Dr. Morten Meldal, Prof. Dr. Klaus Bock and Prof. Dr. Hans Paulsen

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199208571

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      By direct glycoside synthesis, activated glycosyl amino acids are accessible. They can be utilized in the solid-phase synthesis for the preparation of glycopeptides with 2-azido-2-deoxy-D-galactose residues. The transformation into the acetamido derivatives and the subsequent deblocking occur on the polymeric support. This method is quite powerful, as the synthesis of the pentaglycosidated octapeptide shown below proves.

    6. Deuterium-Induced Phase Transition of an Organic Metal—An Unusual Isotope Effect (pages 859–862)

      Prof. Dr. Siegfried Hünig, Dipl.-Chem. Klaus Sinzger, Martina Jopp, Dagmar Bauer, Dipl.-Phys. Werner Bietsch, Dr. Jost Ulrich von Schütz and Prof. Dr. Hans Christoph Wolf

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199208591

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      A phase transition in which the conductivity drops by a factor of 106–108 within 2–3 K is triggered by the replacement of R1,R3 = CH3 in the radical anion salts 1 by R1 = CH3, R3 = CD3 and R1,R3 = CD3. This extreme change is in sharp contrast with the known minimal variations caused by secondary deuterium isotope effects.

    7. Doubly Bridged Prismane and Dewar Benzene Intermediates in an Unusual Photochemical Rearrangement of Tricyclic Phthalic Esters (pages 862–864)

      Prof. Dr. Rolf Gleiter and Dipl.-Chem. Björn Treptow

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199208621

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      Because of the double tethering of two neighboring centers in the dimethyl phthalate 1, intermediates in the photolysis to the isomeric terephthalates 2—doubly bridged prismane 3 and Dewar benzene 4—could be detected by NMR and UV spectroscopy.

    8. Template-Controlled Organization of a Fluoride Surface—An Analogue of a Crown Ether in the Reaction of [{(η5-C5Me5)TiF3}2] with Sodium Fluoride (pages 864–866)

      Prof. Dr. Herbert W. Roesky, Dipl.-Chem. Mansoreh Sotoodeh and Dr. Mathias Noltemeyer

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199208641

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      One sodium counterion in 1 can be selectively exchanged for PPhmath image, since the Na ions are distinguishable: complexation of one Na+ ion by two [(Cp*TiF3)2F] fragments occurs through a “fluoride surface”. The anion in 1 thus belongs to a new class of host–guest complexes, since in molecular recognition studies so far the receptor surfaces of host molecules were almost exclusively formed from O, S, N, and/or P atoms. Cp* = η5-C5Me5.

    9. Synthesis of Isocyanate-Substituted Allenes and 1,3-Butadienes by [3,3] Sigmatropic Rearrangements (pages 866–868)

      Doz. Dr. Klaus Banert and Dipl.-Chem. Stefan Groth

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199208661

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      In the transformation of thiatriazole 1 to allenyl isocyanate (3), a [3,3] sigmatropic cyanate [RIGHTWARDS ARROW] isocyanate rearrangement (of 2) was followed for the first time by NMR spectroscopy. Not only alkyl derivatives of 3 but also compounds 4 and 5 can be synthesized by analogous reactions. In this process thiatriazoles, which are prepared from alcohols in one step, are employed.

    10. Material Properties and Purity of C60 (pages 868–870)

      Dipl.-Chem. Harald Werner, Daniela Bublak, Dipl.-Chem. Ulrich Göbel, Dipl.-Chem. Bettina Henschke, Dr. Wolfgang Bensch and Prof. Dr. Robert Schlögl

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199208681

      The fullerenes can be described as molecular analogues of activated charcoal with a large inner surface. Accordingly, in the solid state, C60 adsorbs organic molecules and oxygen from the air. The conditions of the production, purification, and storage therefore dictate the electronic and dynamic properties of the van der Waals crystals. Obtaining fullerene samples with defined and reproducible properties is more difficult than previously thought.

    11. Enantioselective Synthesis of the Antidepressant Rolipram by Michael Addition to a Nitroolefin (pages 870–872)

      Prof. Dr. Johann Mulzer, Dr. Ralf Zuhse and Dr. Ralph Schmiechen

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199208701

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      In only four steps both enantiomers of the antidepressant Rolipram 3 can be made. The key step in the highly enantioselective synthesis is the Michael addition of nitroolefin 1 to the Evans enolate 2. M = Na, Bn = benzyl.

    12. The Benzene Ring as Dienophile in an Intramolecular [4 + 2] Cycloaddition: Degenerate Rearrangement of 7,8-Benzobicyclo[4.2.2]deca-2,4,7,9-tetraene (pages 872–874)

      Prof. Dr. Wolfram Grimme, Dr. Thomas Grommes, Prof. Dr. Wolfgang R. Roth and Rolf Breuckmann

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199208721

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      A Gibbs free energy of activation of 41.1 kcal mol−1 at 35°C has been determined for the rate-determining step 3 [RIGHTWARDS ARROW] 2 of the rearrangement 3 [RIGHTWARDS ARROW] 1 (R = Me). This value is about 20 kcal mol−1 higher than that for the rearrangement of the parent compound, bicyclo[4.2.2]decatetraene. At 230°C, 1 and 3 are in dynamic equilibrium; an intermolecular [4 + 2] cycloaddition has been postulated in which participation of a π bond of the benzene ring leads to compound 2 as intermediate.

    13. Photoselective Processes in Cyclooctasulfur Layers: Desorption versus Polymerization (pages 874–876)

      Jens Geyer, Heinrich Stülpnagel and Priv. Doz. Dr. Klaus Rademann

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199208741

      Since the desorption rate depends on the light intensity, a purely thermal desorption mechanism for a thin sulfur film at λ = 225 nm can be rejected. Nonthermal desorption of adsorbed cyclooctasulfur was hitherto unknown. By contrast, at λ = 328 and 382 nm only a small amount of light-induced desorption was detected. Instead, polymerization of sulfur was observed at these wavelengths to significantly larger extent than at λ = 255 nm.

    14. A Structurally Distorted Ligand in an Electron-Deficient Dizirconocene Cation: Unusual 1,2- and 1,1-Dimetallioalkenes (pages 876–878)

      Dr. Andrew D. Horton and Dr. A. Guy Orpen

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199208761

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      The selective formation of the catalytically inert complexes 1 and 2 from the potential catalyst system “[Cp2ZrMe]+”/[Cp2ZrMe2] and RC[TRIPLE BOND]CH shows how sensitive the catalytic oligomerization of alkynes is to changes in the steric bulk of the substituents at the alkyne and at the Cp ligand of the catalyst (the sterically more crowded [(C5Me5)2ZrMe]+ does catalyze this oligomerization). On account of the electron deficiency at the Zr centers, the MeCCtBu ligand in 1 is strongly distorted, and the alkynyl ligand is more strongly bound to the Zr atom that shows an agostic interaction with the methyl group; in contrast the alkenylidene ligand in 2 bridges symmetrically.

    15. The Crystal Structure of [(Pyrene•−){Na+[(C2H5)2O]}]: A Model for Stacked Radical Anion Salts (pages 878–879)

      Dipl.-Chem. Wolfgang Jost, Dipl.-Chem. Martin Adam, Priv.-Doz. Dr. Volker Enkelmann and Prof. Dr. Klaus Müllen

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199208781

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      A polymeric contact cation pair with a zigzag arrangement of the π electron system is revealed for the stacked structure of the title compound in the solid state (the diagram left depicts a “monomer”). Although this structure allows a comparison with electrically conducting radical cation salts, strong coulombic forces would impair charge transport.

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    16. P-Functionalization of the Tetraphosphacubane System (pages 879–882)

      Dipl.-Chem. Manfred Birkel, Dr. Joachim Schulz, Dipl.-Chem. Uwe Bergsträsser and Prof. Dr. Manfred Regitz

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199208791

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      The C4P4 skeleton is maintained when tetra-tert-butyltetraphosphacubane is successively functionalized at the phosphorus centers. Its reactions with nonacarbonyldiiron ([RIGHTWARDS ARROW] 1), tetrachloro-o-benzoquinone ([RIGHTWARDS ARROW] 2), selenium ([RIGHTWARDS ARROW] 3), and bis(trimethylsilyl)peroxide ([RIGHTWARDS ARROW] 4) can be taken as examples.

    17. Pronounced Conformational Changes in Sixfold Nitrogen-Functionalized Metacyclophanes: Syntheses and Crystal Structures of Two 1,10-Diaza[11]metacyclophanes (pages 882–884)

      Dr. J. Jens Wolff, Prof. Dr. Stephen F. Nelsen, Dr. Douglas R. Powell and Dr. Bernhard Nuber

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199208821

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      The propensity for bending in tris(donor)- and tris(acceptor)-substituted benzene derivatives can be used for a simple synthesis of metacyclophanes. Treatment of the dichlorobenzene derivative 1 with 1,9-nonanediamine affords the metacyclophane 2 in 67% yield. The benzene ring in 2 is frozen in the boat form. Reduction and acetylation transforms 2 into 3 in which the benzene ring is almost planar. R,R′ = [BOND](CH2)math image, X = Ac, n = 9.

    18. Dynamic Motion in [HFe(CO)4] Ions as Observed by Mössbauer Spectroscopy—Evidence for Hydride “Tunneling” (pages 884–886)

      Prof. Gary J. Long, Prof. Fernande Grandjean and Prof. Kenton H. Whitmire

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199208841

      The iron atom is moved by up to 0.34 Å from its original position in the anion [HFe(CO4)] when the temperature is increased. This is suggested by the results of Mössbauer spectroscopy at temperatures from 78 to 280 K on a series of ammonium salts with this anion. The displacement is induced by a movement of the ligands and is in accord with a rapid change of position (“tunneling”) of the hydrido ligands, which makes the four carbonyl ligands equivalent. The Gibbs free energy of activation for the tunneling, determined from the temperature dependence of the displacement of the iron atom, is 29.2 kJ mol−1 for the Et4N+ salt and only 9.7 kJ mol−1 for the Me4N+ salt.

    19. Molecular Modeling of the Class I Human Histocompatibility Molecule HLA-A2 Presenting an Allele-Specific Nonapeptide from Influenza Matrix Protein (pages 886–890)

      Dipl.-Chem. Norbert Zimmermann, Olaf Rötzschke, Kirsten Falk, Dr. Didier Rognan, Prof. Dr. Gerd Folkers, Priv.-Doz. Dr. Hans-Georg Rammensee and Prof. Dr. Günther Jung

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199208861

      The conformation is not α-helical, but extended when the antigenic peptide binds in the pocket of the human major histocompatibility complex (MHC) protein HLA-A2 of class I. This was established by molecular modeling studies and molecular dynamics simulations on a complex of HLA-A2 and one nonapeptide from the influenza matrix protein. The investigations are based on the structure of HLA-A2 determined by X-ray crystallography and the recently determined HLA-A2-specific peptide binding motif. The described model supports the present ideas about MHC-limited antigenic binding.

    20. Detection of Subpicomole Levels of Compounds Containing Hydroxyl and Amino Groups with the Fluorogenic Reagent, 2-Naphthoylimidazole (pages 890–891)

      Norihiro Ikemoto, Lee-Chiang Lo and Prof. Koji Nakanishi

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199208901

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      Even one tenth of a picomole of a sugar can be detected, if it is transformed into the alditol and treated with 1 to yield the pernaphthoate. In this way a mixture of nine sugars and aminosugars could be well separated by HPLC. The pernaphthoates were detected by their intense fluorescence at 374 nm, thus proving that 1 is ideal for derivatizing natural products containing hydroxyl and amino groups for analytical purposes.

    21. Tetramethyl-Ortho-quinodimethane, First Member of a Family of Custom-Tailored Cheletropic Spin Traps for Nitric Oxide (pages 891–893)

      Dr. Hans-Gert Korth, Prof. Dr. Keith U. Ingold, Prof. Dr. Reiner Sustmann, Priv.-Doz. Dr. Herbert de Groot and Prof. Dr. Helmut Sies

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199208911

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      The ortho-quinodimethane 1 reacts quickly and efficiently as a diradical equivalent in a cheletropic reaction with the radical NO to form 2, which can be very easily observed through ESR spectroscopy. The detection by this technique of the formation of 2 from 1 and NO released by liver macrophages demonstrates that diradical equivalents of type 1 could be suitable for monitoring NO production under physiological conditions.

    22. Multidentate Macrocyclic Lewis Acids: Release of “[12] Mercuracarborand-4” from Its Iodide Complex and the Structure of Its Tetra(tetrahydrofuran) Dihydrate Complex (pages 893–896)

      Dr. Xiaoguang Yang, Dr. Stephen E. Johnson, Dr. Saeed I. Khan and Prof. Dr. M. Frederick Hawthorne

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199208931

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      One or two iodide ions can be bound by the Lewis-acidic host “[12] mercuracarborand-4” 1, as is shown by 199Hg NMR spectroscopic studies. The halogen-free macrocycle 1 is accessible from 1. I2Li2 and silver acetate, and could be structurally characterized as the tetrakis(tetrahydrofuran) complex.

    23. Synthesis, Structure, and Bonding of [CpCoW2(OCH2tBu)6], and Comments on the Combining Properties of CO and CpCo (pages 896–898)

      Prof. Malcom H. Chisholm, Dr. Victor J. Johnston, Dr. Odile Eisenstein and Dr. William E. Streib

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199208961

      A triangle comprising one cobalt and two tungsten atoms is the central unit of the title compound 1, which is accessible from [CpCo(C2H4)2] and [Wmath image(OCH2tBu)6(py)] (py = pyridine). The structure of 1 shows a striking resemblance to the structure of the CO complex 2, which can be traced to the isolobal analogy between CO and CpCo. Compounds of the type [W2(OR)6] should also be suitable for the synthesis of further heterometallic clusters.

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    24. Synthetic Chain-Substituted Phospholipids: Ion Transport Across Their Bilayer Membranes (pages 898–900)

      Prof. Fredric M. Menger and Patricia Aikens

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199208981

      The passage of ions through phospholipid vesicles is facilitated by building alkyl substituents into the lipid chains. The effect of the size, position, and number of substituents on the ion flux can be studied by monitoring the decrease in fluorescence of a pH-sensitive dye within the vesicles on lowering the pH of the surrounding water. Substituents in the middle of the chains were most efficient in altering the flux. Such studies are of interest for the development of systems for controlled drug release.

    25. The Pyrolysis of Tetranitromethane in the Gas Phase (pages 900–902)

      Prof. Dr. Hans Bock and Dr. László Zanathy

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199209001

      C(NO2)4, one of the methane derivatives with the largest oxygen content (>65 wt.%) and therefore not exactly hazard-free, decomposes in the gas phase at 10−5 mbar and 610 K exclusively into the gaseous products NO2, NO, CO2, and CO. Together with the known kinetics for a radical dissociation as the first step, the temperature-dependent photoelectronic spectra and comprehensive quantum chemical calculations enable a mechanism to be proposed that explains all experimental findings. Conversions on silver wool and charcoal, and the cothermolysis of dimethylamine and dimethylnitramine suggest possibilities for further investigations.

    26. Synthesis of C-Glycopeptides via Free Radical Addition of Glycosyl Bromides to Dehydroalanine Derivatives (pages 902–904)

      Prof. Dr. Horst Kessler, Dipl.-Chem. Valentin Wittmann, Dipl.-Chem. Matthias Köck and Dr. Matthias Kottenhahn

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199209021

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      In only one reaction step, nonnatural C-glycopeptides of type 1 can be obtained (see right, (S) form). This new class of molecules has remarkable properties; their high chemical stability recommends them as potential glycosidase inhibitors. The absolute configuration of the C-glycopeptides can be elucidated with NMR spectroscopy and molecular dynamics calculations. (R1,R2 = H, OAc, sugar; R3,R4 = protecting group.)

    27. A RhI-Centered Cage Compound with Selective Catalytic Properties (pages 905–907)

      Hein K. A. C. Coolen, Prof. Dr. Piet W. N. M. van Leeuwen and Prof. Dr. Roeland J. M. Nolte

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199209051

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      A concave structure to bind substrates as well as two phosphite sites to bind Rh1 are found in compound 1. The schematic drawing 2 shows the structure of the Rh1 cage compound with a bound 4-allylcatechol molecule, which is either isomerized to methylstyrene or hydrogenated to the propyl derivative.

    28. Scavenger Templates: Synthesis and Electrospray Mass Spectrometry of a Linear Porphyrin Octamer (pages 907–910)

      Sally Anderson, Dr. Harry L. Anderson and Dr. Jeremy K. M. Sanders

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199209071

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      To avoid mixtures that are difficult to separate in the synthesis of oligomeric compounds, scavenger templates are invaluable. The schematic reaction below depicts how the template (in black) hinders side reactions in the dimerization of 2 to 4 from a reaction mixture including 1 and 2—one has two reactive ends and the other only one—by rapidly cyclizing 1 to 3; in effect the template prevents the reaction of 1 with 2 and the dimerization of 1 (and subsequent reactions). The performance of the methodology is demonstrated for the synthesis of a porphyrin octamer.

    29. Stereocontrolled Construction of 6 · 5 · 6 and 5 · 5 · 6 Ring Systems by Radical Tandem Cyclization (pages 910–913)

      Dr. Uwe Albrecht, Dr. Rudolf Wartchow and Prof. H. M. R. Hoffmann

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199209101

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      A 6-endo-digonal cyclization not observed before in radical chemistry forms one part of the tandem cyclization of enynes like 1 to tricycles like 2. The stereochemical course of this reaction was analyzed in detail by, for instance, the use of starting materials with well-defined configurations and X-ray structural analysis of the products. Thus the formation of 2 from 1 requires a transition state in a boat configuration with pseudoaxial propargyl side chains.

    30. Novel Iron Carbonyl Telluride Clusters: Synthesis and Characterization of [Fe5Te4(CO)14]2− and [Fe8Te10(CO)20]2− (pages 913–915)

      Lisa C. Roof, William T. Pennington and Prof. Joseph W. Kolis

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199209131

      A simple route to large Fe[BOND]Te clusters seems to have been found by the authors in the redox reaction between [Fe(CO)5] and (Ph4P)2Te4. Depending on the molar ratio of the reactants either (Ph4P)2-1 or (Ph4P)2-2 is isolated. In addition, 1 can be converted into 2 by elemental Te. Especially noteworthy in 2 is the Te2math image ligand which links two hardly distorted Fe4Te4 cubanes.

      • equation image
    31. The Total Synthesis of (±)-Mitomycin K (pages 915–917)

      John W. Benbow, Gayle K. Schulte and Samuel J. Danishefsky

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199209151

      Thumbnail image of graphical abstract

      The use of (phenylthio)methyl azide to build the N-methylaziridine unit and a provocative rearrangement to an imidazoledithiocarboxyl group are the crucial steps in the total synthesis of (±)-mitomycin K (3) via 1 and 2. Mitomycins of type 3 promise to provide an interesting bioorganic chemistry because of the exocyclic double bond. X = H, Y = OH, R = SC(S)-imidazole.

    32. Supramolecular Self-Assemblies of Two-Directional Cascade Molecules: Automorphogenesis (pages 917–919)

      Prof. George R. Newkome, Dr. Charles N. Moorefield, Dr. Gregory R. Baker, Dr. Rajani K. Behera, Gregory H. Escamillia and Dr. Mary J. Saunders

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199209171

      Thumbnail image of graphical abstract

      Cascade molecules (arborols, dendrimers) can form larger structures with defined shape by self-association. Such a “supramolecular automorphogenesis” takes place with the amphiphilic arborol 1, which gels in aqueous solutions, forming single- and multistranded aggregates. Helical structures were detected by electron microscopy.

    33. The Reaction of Unactivated Cobalt Powder with Iodophosphoranes. The Synthesis of [Co(PMe3)2I3] and the Isolation of the “Frozen Transition-State” Complex [(nBu3PI)2(μ-I)] [(nBu3PI)(μ-I)CoI3] (pages 919–921)

      Prof. Dr. Charles A. McAuliffe, Stephen M. Godfrey, Anthony G. Mackie and Dr. Robin G. Pritchard

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199209191

      The alkyl substituents at the iodophosphorane determine the nature of the product formed in reactions with cobalt powder. Whereas Co and Me3PI2 react to give the trigonal-bipyramidal cobalt(III) complex 1, the reaction between Co and nBu3PI2 halts at the very unusual cobalt(II) compound 2. The structure of 2, which corresponds to a possible transition state in the formation of 1, provides an insight into the mechanistic pathway for the reaction of metal powders with dihalogen phosphoranes.

      • equation image
    34. Synthesis and Structure of Al(Oar*)3 (Ar* = 2,6-tBu2-4-MeC6H2): The First Three-Coordinate Homoleptic Aluminum Aryloxide (pages 921–922)

      Matthew D. Healy and Prof. Dr. Andrew R. Barron

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199209211

      Thumbnail image of graphical abstract

      Can three bulky aryloxide substituents fit around a single aluminum center? That this is indeed possible is shown by the product Al(OAr*)31 (Ar* = 2,6-tBu2-4-MeC6H2) of the reaction of HOAr* with LiAlH4. The 27Al{1H}NMR spectrum and the X-ray structural analysis are in accord with a very electron-rich three-coordinate aluminum center.

    35. Efficient Synthesis of Nanoscale Macrocyclic Hydrocarbons (pages 922–924)

      Prof. Jeffrey S. Moore and Jinshan Zhang

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199209221

      Thumbnail image of graphical abstract

      In unusually high yields of 75 and 70% respectively, the macrocycles with six (1) and twelve arene units have been efficiently synthesized by cyclization of α-iodo-ω-ethynylphenyl-acetylene oligomers. The success is probably due to the preassembly of these difunctional building blocks. Molecular models indicate an inner diameter of 8.4 Å for 1 and 22 Å (!) for the larger macrocycle.

    36. Generalized Edshammar Polyhedra for the Description of a Family of Solid-State Structures (pages 924–927)

      Dr. Sven Lidin, Dr. Thomas Popp, Dr. Mehmet Somer and Prof. Dr. Hans Georg von Schnering

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199209241

      Thumbnail image of graphical abstract

      A new class of space-filling polyhedra does yeoman's service in the description of solid-state structures. In this method the atoms of the minority component are considered as quasi-isolated units located in the interstices of close-packed polyhedra consisting of atoms of the majority component. These polyhedra are in a certain sense fragments of a body-centered cubic packing of spheres. They are based on interpenetrating cubes. The sketch shows the polyhedron for three such cubes.

  5. Book Reviews

    1. Top of page
    2. Reviews
    3. Highlights
    4. Correspondences
    5. Communications
    6. Book Reviews
    1. Book Review: Maximum Entropy in Action. Edited by B. Buck and V. A. Macaulay (pages 928–929)

      Christian Griesinger

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199209281

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