Angewandte Chemie International Edition

Cover image for Vol. 48 Issue 17

April 14, 2009

Volume 48, Issue 17

Pages 2993–3191

  1. Cover Picture

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Graphical Abstract
    5. News
    6. Author Profile
    7. Book Review
    8. Highlights
    9. Review
    10. Communications
    11. Preview
    1. Cover Picture: A Phosphorus Analogue of Bis(η4-cyclobutadiene)iron(0) (Angew. Chem. Int. Ed. 17/2009) (page 2993)

      Robert Wolf, J. Chris Slootweg, Andreas W. Ehlers, František Hartl, Bas de Bruin, Martin Lutz, Anthony L. Spek and Koop Lammertsma

      Version of Record online: 7 APR 2009 | DOI: 10.1002/anie.200990084

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      A rare phosphorus analogue of the elusive complex bis(η4-cyclobutadiene)iron(0) is reported by K. Lammertsma et al. in their Communication on page 3104 ff. The background of the cover picture shows John Montagu (1718–1792), 4th Earl of Sandwich and 1st Lord of the Admiralty, who certainly would not have dreamt that an important class of organometallic compounds, sandwich complexes, would bear his name one day. The synthesis of [Fe(P2C2tBu2)2] shows that sandwich complexes are still topical objects of research.

  2. Inside Cover

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Graphical Abstract
    5. News
    6. Author Profile
    7. Book Review
    8. Highlights
    9. Review
    10. Communications
    11. Preview
    1. Inside Cover: Synthesis and Biological Activity of Argiotoxin 636 and Analogues: Selective Antagonists for Ionotropic Glutamate Receptors (Angew. Chem. Int. Ed. 17/2009) (page 2994)

      Jared K. Nelson, Sidsel U. Frølund, Dennis B. Tikhonov, Anders S. Kristensen and Kristian Strømgaard

      Version of Record online: 7 APR 2009 | DOI: 10.1002/anie.200990085

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      Spiders of the genus Argiope, such as Argiope lobata, contain polyamine toxins that are potent but nonselective blockers of glutamate receptors. However, by very subtle modifications of the structure of native toxins, it is possible to obtain selectivity for subtypes of these receptors, as described by K. Strømgaard and co-workers in their Communication on page 3087 ff.

  3. Graphical Abstract

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Graphical Abstract
    5. News
    6. Author Profile
    7. Book Review
    8. Highlights
    9. Review
    10. Communications
    11. Preview
  4. News

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Graphical Abstract
    5. News
    6. Author Profile
    7. Book Review
    8. Highlights
    9. Review
    10. Communications
    11. Preview
  5. Author Profile

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Graphical Abstract
    5. News
    6. Author Profile
    7. Book Review
    8. Highlights
    9. Review
    10. Communications
    11. Preview
    1. Helmut Cölfen (page 3013)

      Version of Record online: 7 APR 2009 | DOI: 10.1002/anie.200900645

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      „The best advice I have ever been given is to never give up if it is worth it. My favorite subject at school was physics….“ This and more about Helmut Cölfen can be found on page 3013.

  6. Book Review

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Graphical Abstract
    5. News
    6. Author Profile
    7. Book Review
    8. Highlights
    9. Review
    10. Communications
    11. Preview
    1. Physical Biology.From Atoms to Medicine. Edited by Ahmed Zewail. (pages 3014–3016)

      Majed Chergui

      Version of Record online: 7 APR 2009 | DOI: 10.1002/anie.200900611

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      Imperial College Press, 2008. 584 pp., hardcover, $ 78.00.—ISBN 978-1848162006

  7. Highlights

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Graphical Abstract
    5. News
    6. Author Profile
    7. Book Review
    8. Highlights
    9. Review
    10. Communications
    11. Preview
    1. Nano- and Microstructures

      Zinc Oxide Nano- and Microfabrication from Coordination-Polymer Templates (pages 3018–3021)

      Xiaogang Liu

      Version of Record online: 26 FEB 2009 | DOI: 10.1002/anie.200805972

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      Hex nut: An emerging synthetic approach based on metal–organic coordination-polymer templates has been used to fabricate micro- and nanoscale crystals. By using a diverse range of molecular building blocks coupled with conventional synthetic techniques, it is possible to synthesize ZnO crystals with tailored sizes, shapes (such as hexagonal rings; see figure), and surface properties.

    2. Fluorescent Probes for H2O2

      Lighting up H2O2: The Molecule that Is a “Necessary Evil” in the Cell (pages 3022–3024)

      Wei Zhao

      Version of Record online: 22 JAN 2009 | DOI: 10.1002/anie.200805651

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      A cunning plan: In the multifunctional fluorescent probe MitoPY1 the phosphonium head group (red) targets mitochondria and the boronate group (green) responds to hydrogen peroxide. MitoPY1 reacts selectively with mitochondrial H2O2 in living cells, and an increase in fluorescence is triggered by the conversion of MitoPY1 into MitoPY1ox (yellow).

    3. Carbene Analogues

      Ligand-Stabilized Chalcogen Dications (pages 3025–3027)

      Tristram Chivers and Jari Konu

      Version of Record online: 4 FEB 2009 | DOI: 10.1002/anie.200806010

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      Chalcogen-transfer reagents? The bonding in the dicationic rings C2N2E2+ (see picture) differs from that in N-heterocyclic carbenes and their isovalent p-block analogues in accommodating a lone pair of electrons with π symmetry, as well as σ symmetry, on the chalcogen center. The labile electrophilic chalcogenium dications (E2+) are potentially versatile chalcogen-transfer reagents in reactions with a variety of inorganic and organic substrates.

  8. Review

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Graphical Abstract
    5. News
    6. Author Profile
    7. Book Review
    8. Highlights
    9. Review
    10. Communications
    11. Preview
    1. Medicinal Chemistry

      Alzheimer's Disease: From Pathology to Therapeutic Approaches (pages 3030–3059)

      Roland Jakob-Roetne and Helmut Jacobsen

      Version of Record online: 28 MAR 2009 | DOI: 10.1002/anie.200802808

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      Mind how you go: The current strategies for the development of therapies for Alzheimer's disease are very diverse. Particular attention is given to the search for inhibitors (see picture for two examples) of the proteolytic enzyme β- and γ-secretase, which inhibits the cleavage of the amyloid precursor proteins into amyloid β peptides, from which the disease-defining deposits of plaque in the brains of Alzheimer's patients originates.

  9. Communications

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Graphical Abstract
    5. News
    6. Author Profile
    7. Book Review
    8. Highlights
    9. Review
    10. Communications
    11. Preview
    1. Self-Assembled Monolayers

      Formation of Patches on 3D SAMs Driven by Thiols with Immiscible Chains Observed by ESR Spectroscopy (pages 3060–3064)

      Cristina Gentilini, Paola Franchi, Elisabetta Mileo, Stefano Polizzi, Marco Lucarini and Lucia Pasquato

      Version of Record online: 29 JAN 2009 | DOI: 10.1002/anie.200805321

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      Beyond stripes: The extreme lipophobicity of perfluorinated chains attached to amphiphilic thiolates triggers the formation of “stars” (or patches) surrounded by amphiphilic alkylthiolates in three-dimensional self-assembled monolayers. This strategy led to the first example of a water-soluble multicompartment monolayer wrapped around a gold core.

    2. Conformational Analysis

      The Fluorine-Iminium Ion Gauche Effect: Proof of Principle and Application to Asymmetric Organocatalysis (pages 3065–3068)

      Christof Sparr, W. Bernd Schweizer, Hans Martin Senn and Ryan Gilmour

      Version of Record online: 25 MAR 2009 | DOI: 10.1002/anie.200900405

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      Thegaucheeffect that is induced upon reversible formation of an iminium ion (see structure: green F, blue N) provides a powerful method for the preorganization of transient intermediates that are central to secondary amine catalyzed processes. This phenomenon has been exploited in the design of a novel organocatalyst and is showcased in the stereoselective epoxidation of α,β-unsaturated aldehydes.

    3. Chiral Imprinting

      Supramolecular Chiral Transcription and Recognition by Mesoporous Silica Prepared by Chiral Imprinting of a Helical Micelle (pages 3069–3072)

      Huibin Qiu, Yoshihisa Inoue and Shunai Che

      Version of Record online: 23 MAR 2009 | DOI: 10.1002/anie.200900303

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      Let′s twist again: The chirality of a helical propeller-like micelle has been memorized by functional groups on the mesopore surface of chiral mesoporous silicas. Such imprinted supramolecular chirality can be transcripted to poly(propiolic acid) sodium salt and tetraphenylporphine tetrasulfonic acid (see picture), and recognized by B-DNA.

    4. Ultrathin Luminescent Films

      Ordered Poly(p-phenylene)/Layered Double Hydroxide Ultrathin Films with Blue Luminescence by Layer-by-Layer Assembly (pages 3073–3076)

      Dongpeng Yan, Jun Lu, Min Wei, Jingbin Han, Jing Ma, Feng Li, David G. Evans and Xue Duan

      Version of Record online: 19 MAR 2009 | DOI: 10.1002/anie.200900178

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      Lavender layers: A poly(p-phenylene) anionic derivate and exfoliated Mg-Al layered double hydroxide monolayers were assembled into ultrathin films with well-defined blue fluorescence (see picture; the numbers indicate the number of bilayers), long-range order, and high photostability. These films work as multiple quantum-well structures for valence electrons.

    5. Single-Molecule Magnets

      Iron Polyoxometalate Single-Molecule Magnets (pages 3077–3081)

      Jean-Daniel Compain, Pierre Mialane, Anne Dolbecq, Israël Martyr Mbomekallé, Jérôme Marrot, Francis Sécheresse, Eric Rivière, Guillaume Rogez and Wolfgang Wernsdorfer

      Version of Record online: 25 MAR 2009 | DOI: 10.1002/anie.200900117

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      Iron sandwich on a tungstate bun: Two new polyoxotungstates with paramagnetic iron(III) heteroatoms (see structure, W blue, Fe yellow, O red) possess S=15/2 and S=5 ground states. Both compounds are single-molecule magnets, and the hexairon species shows large hysteresis (see picture) and quantum tunneling effects at low temperature. Electrochemical studies indicate that these species are stable in solution for a wide range of pH values.

    6. NMR Crystallography

      Crystal-Structure Determination of Powdered Paramagnetic Lanthanide Complexes by Proton NMR Spectroscopy (pages 3082–3086)

      Gwendal Kervern, Anthony D'Aléo, Loïc Toupet, Olivier Maury, Lyndon Emsley and Guido Pintacuda

      Version of Record online: 19 MAR 2009 | DOI: 10.1002/anie.200805302

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      Shifts for crystals: Solid-state NMR spectroscopy can be used for structure determination of microcrystalline paramagnetic solids at natural isotopic abundance. The protocol makes use of paramagnetic effects, measured on suitably recorded 1H NMR spectra, to define the conformation of a molecule in the lattice and the intermolecular packing in the solid phase. The method is illustrated with a family of lanthanide compounds (see picture).

    7. Biologically Active Compounds

      Synthesis and Biological Activity of Argiotoxin 636 and Analogues: Selective Antagonists for Ionotropic Glutamate Receptors (pages 3087–3091)

      Jared K. Nelson, Sidsel U. Frølund, Dennis B. Tikhonov, Anders S. Kristensen and Kristian Strømgaard

      Version of Record online: 16 JAN 2009 | DOI: 10.1002/anie.200805426

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      More discerning than the parent: Analogues of the polyamine toxin argiotoxin 636 (shown docked in the ion channel of an ionotropic glutamate (iGlu) receptor; N blue, O red) distinguish subtypes of iGlu receptors. Depending on which of the two internal amine groups is replaced with a methylene group, the analogue inhibits one or other of two receptor subtypes as potently as the natural compound, which itself inhibits both subtypes nonselectively.

    8. Host–Guest Systems

      Biotin–Avidin as a Protease-Responsive Cap System for Controlled Guest Release from Colloidal Mesoporous Silica (pages 3092–3095)

      Axel Schlossbauer, Johann Kecht and Thomas Bein

      Version of Record online: 23 MAR 2009 | DOI: 10.1002/anie.200805818

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      Tell your guests when it's time to go: When avidin caps are attached to biotinylated colloidal mesoporous silica, the four subunits of the protein avidin can each bind to a biotin moiety attached to the surface (see picture). The resulting material is a promising candidate for the design of smart detergents or drug-delivery systems. The caps can be opened to release guest molecules by controlled enzymatic hydrolysis of the protein.

    9. Crystal Growth

      Solution-Based Direct Growth of Organic Crystals on an Active Channel Region for Printable Bottom-Contact Organic Field-Effect Transistors (pages 3096–3098)

      Jung-Pyo Hong and Seonghoon Lee

      Version of Record online: 23 MAR 2009 | DOI: 10.1002/anie.200805971

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      The growth and self-organization of organic crystals between a source (S) and drain (D) electrode by a method based on the use of a micropipette and isothermal evaporation of the solvent in a two-liquid system led to the formation of organic-crystal transistors (see polarized optical micrograph). The method is similar to ink-jet printing and should be suitable for the fabrication of low-cost and mass-producible printed electronic devices.

    10. DNA Structures

      Solution Structure of a Locked Nucleic Acid Modified Quadruplex: Introducing the V4 Folding Topology (pages 3099–3103)

      Jakob T. Nielsen, Khalil Arar and Michael Petersen

      Version of Record online: 23 MAR 2009 | DOI: 10.1002/anie.200806244

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      Sharp curves: The structure of a locked nucleic acid modified telomeric sequence from Oxytricha nova displays a remarkable folding topology, distinct from the native O. nova quadruplex. Each guanine stretch folds back in a V-shaped turn that puts the first and fourth guanines in the same tetrad, looping over a tetrad with a sharp turn in the DNA backbone, showing how subtle interplay between sequence and conformation defines the folding topology.

    11. Cyclobutadiene Ligands

      A Phosphorus Analogue of Bis(η4-cyclobutadiene)iron(0) (pages 3104–3107)

      Robert Wolf, J. Chris Slootweg, Andreas W. Ehlers, František Hartl, Bas de Bruin, Martin Lutz, Anthony L. Spek and Koop Lammertsma

      Version of Record online: 13 JAN 2009 | DOI: 10.1002/anie.200805193

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      P makes it possible: The convenient oxidative synthesis of the 16-electron organophosphorus iron sandwich complex [Fe(η4-P2C2tBu2)2] (see structure) suggests that the elusive all-carbon complex [Fe(η4-C4H4)2] is a viable synthetic target.

    12. Carbene Ligands

      η3-Diphosphavinylcarbene: A P2 Analogue of the Dötz Intermediate (pages 3108–3111)

      Halil Aktas, J. Chris Slootweg, Andreas W. Ehlers, Martin Lutz, Anthony L. Spek and Koop Lammertsma

      Version of Record online: 15 DEC 2008 | DOI: 10.1002/anie.200805037

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      Do the twist: The reaction of in situ generated phosphinidenes with phosphaalkynes is a facile route to the new metal-coordinated η3-diphosphavinylcarbene 1, which shows facile ligand-exchange reactions and undergoes an unprecedented rearrangement that involves phosphinidene complex 2 and η3-phosphaalkenylphosphinidene complex 3, the 1,3 isomer of 1.

    13. Homogeneous Catalysis

      Gold-Catalyzed Homogeneous Oxidative Cross-Coupling Reactions (pages 3112–3115)

      Guozhu Zhang, Yu Peng, Li Cui and Liming Zhang

      Version of Record online: 25 MAR 2009 | DOI: 10.1002/anie.200900585

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      Oxidizing gold? A gold(I)/gold(III) catalytic cycle is essential for the first oxidative cross-coupling reaction in gold catalysis. By using Selectfluor for gold(I) oxidation, this chemistry reveals the synthetic potential of incorporating gold(I)/gold(III) catalytic cycles into contemporary gold chemistry and promises a new area of gold research by merging powerful gold catalysis and oxidative metal-catalyzed cross-coupling reactions.

    14. Heterocycles

      Addition–Hydroamination Reactions of Propargyl Cyanamides: Rapid Access to Highly Substituted 2-Aminoimidazoles (pages 3116–3120)

      Robert L. Giles, John D. Sullivan, Andrew M. Steiner and Ryan E. Looper

      Version of Record online: 25 MAR 2009 | DOI: 10.1002/anie.200900160

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      A valuable pharmacophore, the 2-aminoimidazole moiety, can be accessed with a variety of substitution patterns through an addition–hydroamination–isomerization sequence (see scheme; R1,R4,R5=alkyl; R3=alkyl, aryl; R2=H, alkyl, aryl). The synthesis of the propargyl cyanamide precursors through a three-component coupling enables the preparation of this important heterocyclic core structure in just three steps.

    15. Cyclopropanation

      Efficient Construction of α-Spirocyclopropyl Lactones: Iridium–Salen-Catalyzed Asymmetric Cyclopropanation (pages 3121–3123)

      Masami Ichinose, Hidehiro Suematsu and Tsutomu Katsuki

      Version of Record online: 25 MAR 2009 | DOI: 10.1002/anie.200805527

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      Three- and seven-membered rings were constructed by the title reaction of terminal olefins with vinyldiazolactone as a carbene source, the seven-membered rings upon subsequent hydrolysis and Cope rearrangement when 1,3-dienes were used (see example). The α-spirocyclopropyl lactones were formed with high E (trans) selectivity and high enantioselectivity, and cyclopropanation occurred at the terminal double bond in 1,3-dienes with excellent regioselectivity.

    16. Materials Science

      Highly Proton-Conducting Self-Humidifying Microchannels Generated by Copolymer Brushes on a Scaffold (pages 3124–3128)

      Basit Yameen, Anke Kaltbeitzel, Andreas Langer, Frank Müller, Ulrich Gösele, Wolfgang Knoll and Omar Azzaroni

      Version of Record online: 28 JAN 2009 | DOI: 10.1002/anie.200805576

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      Filling in the gaps: Macroporous silicon membranes modified with sulfonated polymer brushes have been synthesized by pore-filling surface polymerization (see picture) to give proton-conducting channels with tailor-made, finely tuned physicochemical characteristics. These membranes display high conductivity values (ca. 10−2 S cm−1) regardless of the humidity, thus surpassing the performance of nafion.

    17. Hydrogen Bonding

      Closed and Open Clamlike Structures Formed by Hydrogen-Bonded Pairs of Cyclotricatechylene Anions that Contain Cationic “Meat” (pages 3129–3132)

      Brendan F. Abrahams, Nicholas J. FitzGerald, Timothy A. Hudson, Richard Robson and Tom Waters

      Version of Record online: 19 MAR 2009 | DOI: 10.1002/anie.200805789

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      Clamming up: The hexaphenolic compound cyclotricatechylene, which has a bowl-shaped cavity, forms clamlike pairs that encapsulate cations (see picture). Variable hydrogen bonding allows two linked cyclotricatechylene clamshells to be in a closed arrangement when smaller cations such Rb+ or Cs+ provide the clam meat, whereas larger cations such as NMe4+ and NEt4+ cause the clam to be partially opened.

    18. Heterogeneous Catalysis

      Selective Isomerization of Epoxides to Allylic Alcohols Catalyzed by TiO2-Supported Gold Nanoparticles (pages 3133–3136)

      Christos Raptis, Hermenegildo Garcia and Manolis Stratakis

      Version of Record online: 23 MAR 2009 | DOI: 10.1002/anie.200805838

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      ReacTiO2ns for rings: Gold nanoparticles supported on TiO2 are used as a novel heterogeneous catalyst for the isomerization of epoxides to allylic alcohols by a concerted mechanism (see scheme). The reaction proceeds in high yields and the product selectivity is often remarkable.

    19. Synthetic Methods

      A Different Approach to Enantioselective Organic Synthesis: Absolute Asymmetric Synthesis of Organometallic Reagents (pages 3137–3140)

      Anders Lennartson, Susanne Olsson, Jonas Sundberg and Mikael Håkansson

      Version of Record online: 25 MAR 2009 | DOI: 10.1002/anie.200806222

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      Voilà, optical activity: Both enantiomers of 1-chloroindene have been synthesized in high selectivity from solely achiral starting materials, and without using optically active catalysts (see scheme). These symmetry-breaking syntheses provide a proof-of-concept for a new approach to asymmetric synthesis. NCS=N-chlorosuccinimide.

    20. Dendrimer Models

      How Do Redox Groups Behave around a Rigid Molecular Platform? Hexa(ferrocenylethynyl)benzenes and Their “Electrostatic” Redox Chemistry (pages 3141–3145)

      Abdou K. Diallo, Jean-Claude Daran, François Varret, Jaime Ruiz and Didier Astruc

      Version of Record online: 25 MAR 2009 | DOI: 10.1002/anie.200900216

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      A new family of hexakis(ferrocenylethynyl)benzenes was synthesized by Negishi coupling from ethynylferrocenes and C6Br6 and can be reversibly oxidized to stable hexaferrocenium salts (see picture, ArF=[3,5-C6H3(CF3)2]). Their cyclic voltammograms show a single six-electron wave, three distinct two-electron waves, or a cascade of six single-electron waves, depending on the electrolyte counterion and number of methyl substituents on the ferrocenyl groups.

    21. Cross-Coupling

      Palladium-Catalyzed Oxidative Intermolecular Difunctionalization of Terminal Alkenes with Organostannanes and Molecular Oxygen (pages 3146–3149)

      Kaveri Balan Urkalan and Matthew S. Sigman

      Version of Record online: 23 MAR 2009 | DOI: 10.1002/anie.200900218

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      A cationic palladium complex catalyzes the title transformations, which are thought to proceed via a π-allyl or π-benzyl intermediate. The regioselectivity of the reaction (1,2- or 1,1-difunctionalization) depends on the type of terminal double bond (conjugated or nonconjugated) in the substrate (see scheme) and appears to be controlled by the relative rates of β-hydride elimination and transmetalation. DMA=dimethylacetamide, Tf=triflyl.

    22. Macrocycle Synthesis

      One-Pot Formation of Large Macrocycles with Modifiable Peripheries and Internal Cavities (pages 3150–3154)

      Joseph S. Ferguson, Kazuhiro Yamato, Rui Liu, Lan He, Xiao Cheng Zeng and Bing Gong

      Version of Record online: 25 MAR 2009 | DOI: 10.1002/anie.200900584

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      The shape of things to come: Aromatic oligohydrazide macrocycles with planar backbones enforced by three-center hydrogen bonds are formed in high yield from monomeric diacid chlorides and dihydrazides. Macrocycles consisting of six meta-linked pyridine and benzene residues have an internal cavity of about 10 Å diameter, while those with alternating meta- and para-linked benzene residues are larger and contain multiple convergent sites (see picture).

    23. Asymmetric Synthesis

      Complete Regio- and Stereoselectivity Control in the Halohydroxylation of Non-activated Allenes Mediated by a Remote Sulfinyl Group (pages 3155–3157)

      José Luis García Ruano, Vanesa Marcos and José Alemán

      Version of Record online: 25 MAR 2009 | DOI: 10.1002/anie.200900448

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      No hurdle is too high: The regioselectivity and stereoselectivity of the halohydroxylation of non-activated allenes are controlled by a remote sulfinyl group through anchimeric assistance (see scheme). The resulting halohydrines are excellent chiral targets for the preparation of optically pure propargylic alcohols and Baylis–Hillman-type products.

    24. Iron Nitrido Complexes

      Formation of Ammonia from an Iron Nitrido Complex (pages 3158–3160)

      Jeremiah J. Scepaniak, Jessica A. Young, Ranko P. Bontchev and Jeremy M. Smith

      Version of Record online: 25 MAR 2009 | DOI: 10.1002/anie.200900381

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      Radical ideas: Reaction of the iron(IV) nitrido complex [PhB(MesIm)3Fe[TRIPLE BOND]N] (see picture, Mes=2,4,6-Me3C6H2) with TEMPO-H (1-hydroxy-2,2,6,6-tetramethylpiperidine) results in high yields of ammonia and quantitative formation of [PhB(MesIm)3Fe(tempo)]. The mechanism likely involves hydrogen-atom transfer from TEMPO-H to the nitrido complex. Similar reaction with the triphenylmethyl radical yields [PhB(MesIm)3Fe[TRIPLE BOND]N[BOND]CPh3].

    25. Coordination Complexes

      Structure and Reactivity of a Unique Y-Shaped Tricoordinate Bis(silyl)platinum(II)–NHC Complex (pages 3161–3164)

      Guillaume Berthon-Gelloz, Bas de Bruin, Bernard Tinant and István E. Markó

      Version of Record online: 25 MAR 2009 | DOI: 10.1002/anie.200900435

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      Y not? A unique, three-coordinate Y-shaped bis(silyl)platinum(II) complex was isolated and characterized (see structure; C light gray, N blue, Si pink, Pt dark gray). DFT studies on a model system shed light on the nature of this unusual coordination mode for platinum(II).

    26. Carbohydrates

      Stereodivergent De Novo Synthesis of Branched Amino Sugars by Lewis Acid Promoted Rearrangement of 1,2-Oxazines (pages 3165–3169)

      Fabian Pfrengle, Dieter Lentz and Hans-Ulrich Reißig

      Version of Record online: 25 MAR 2009 | DOI: 10.1002/anie.200805724

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      Well concealed: 1,2-oxazines such as 1 rearrange under Lewis acidic conditions to bicyclic products of type 2, which can be incorporated into oligosaccharides as protected amino sugar equivalents. Subsequent reductive steps provide unusual oligosaccharides 3 having C2-branched 4-amino sugar units. Most of the reactions proceed with excellent stereocontrol and allow the synthesis of a collection of stereoisomers.

    27. Silylene Complexes

      The Striking Stabilization of Ni06-Arene) Complexes by an Ylide-Like Silylene Ligand (pages 3170–3173)

      Antje Meltzer, Carsten Präsang, Carsten Milsmann and Matthias Driess

      Version of Record online: 25 MAR 2009 | DOI: 10.1002/anie.200900290

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      The right mix does the trick: Elusive {Ni06-arene)} moieties can be dramatically stabilized by the N-heterocyclic silylene ligand 1, which has a zwitterionic mesomeric structure. The σ, π-acid–base synergism between nickel and 1 explains the unexpectedly high stability of the new silylene complexes 2, which enables arene exchange studies at a Ni0 center. Addition of B(C6F5)3 to 2 affords the zwitterionic silylene complex 3 (see scheme, R=2,6-iPr2C6H3).

    28. Glycopeptides

      Sulfated and Non-Sulfated Glycopeptide Recognition Domains of P-Selectin Glycoprotein Ligand 1 and their Binding to P- and E-Selectin (pages 3174–3178)

      Katharina Baumann, Danuta Kowalczyk, Tobias Gutjahr, Markus Pieczyk, Claire Jones, Martin K. Wild, Dietmar Vestweber and Horst Kunz

      Version of Record online: 25 MAR 2009 | DOI: 10.1002/anie.200805999

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      Total synthesis through block glycosylation and selective chemical O-sulfation of tyrosine residues yielded the glycopeptide recognition domain A (X=SO3) of the P-selectin glycoprotein ligand 1, in which the terminal sialic acid of the complex hexasaccharide side chain was replaced by (S)-cyclohexyl lactic acid. In binding assays the O-sulfated structure A showed high affinity towards P-selectin, the non-sulfated towards E-selectin.

    29. Self-Assembly

      Protecting-Group-Controlled Surface Chemistry—Organization and Heat-Induced Coupling of 4,4′-Di(tert-butoxycarbonylamino)biphenyl on Metal Surfaces (pages 3179–3183)

      Serpil Boz, Meike Stöhr, Umut Soydaner and Marcel Mayor

      Version of Record online: 23 MAR 2009 | DOI: 10.1002/anie.200804845

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      Like pearls on a string, molecular building blocks have been preorganized and then interlinked on a surface (see STM images). In this way both the supramolecular self-assembly of the reactants as well as the subsequent thermal activation to release the protecting group are controlled.

    30. Protic Ionic Liquids

      Hydrogen Bonding in Protic Ionic Liquids: Reminiscent of Water (pages 3184–3186)

      Koichi Fumino, Alexander Wulf and Ralf Ludwig

      Version of Record online: 23 MAR 2009 | DOI: 10.1002/anie.200806224

      Thumbnail image of graphical abstract

      Similarities and differences: Far-infrared spectra of protic ionic liquids could be assigned to intermolecular bending and stretching modes of hydrogen bonds. The characteristics of the low-frequency spectra resemble those of water. Both liquids form three-dimensional network structures, but only water is capable of building tetrahedral configurations. EAN: ethylammonium nitrate, PAN: propylammonium nitrate, DMAN: dimethylammonium nitrate.

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