Angewandte Chemie International Edition

Cover image for Vol. 48 Issue 12

March 9, 2009

Volume 48, Issue 12

Pages 2055–2243

  1. Cover Picture

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Graphical Abstract
    5. Corrigendum
    6. News
    7. Author Profile
    8. Book Reviews
    9. Highlights
    10. Minireview
    11. Review
    12. Communications
    13. Preview
    1. Cover Picture: Dicationic Sulfur Analogues of N-Heterocyclic Silylenes and Phosphenium Cations (Angew. Chem. Int. Ed. 12/2009) (page 2055)

      Caleb D. Martin, Michael C. Jennings, Michael J. Ferguson and Paul J. Ragogna

      Version of Record online: 3 MAR 2009 | DOI: 10.1002/anie.200990054

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      Highly reactive electrophilic compounds centered around multicationic main-group elements are notoriously difficult to isolate. In the Communication on page 2210 ff., P. J. Ragogna and co-workers describe the synthesis and characterization of salts of sulfur(II) dications stabilized by two chelating nitrogen atoms. These species are the first sulfur-based analogues of N-heterocyclic silylene compounds and are the most recent addition to the family of compounds featuring divalent p-block elements. Mitch Zimmer is acknowledged for the cover design.

  2. Inside Cover

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Graphical Abstract
    5. Corrigendum
    6. News
    7. Author Profile
    8. Book Reviews
    9. Highlights
    10. Minireview
    11. Review
    12. Communications
    13. Preview
    1. Inside Cover: Bifunctional Dendrimers: From Robust Synthesis and Accelerated One-Pot Postfunctionalization Strategy to Potential Applications (Angew. Chem. Int. Ed. 12/2009) (page 2056)

      Per Antoni, Yvonne Hed, Axel Nordberg, Daniel Nyström, Hans von Holst, Anders Hult and Michael Malkoch

      Version of Record online: 3 MAR 2009 | DOI: 10.1002/anie.200990055

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      By taking advantage of “click” chemistry's chemoselective nature, a new platform of bifunctional AB2C dendrimers, having acetylene/azide groups anchored within the interior and hydroxy groups on the periphery, has been realized. In their Communication on page 2126 ff. M. Malkoch and co-workers reveal a simple synthetic route for two sets of frameworks. To illustrate the utility of AB2C dendrimers they were used in a one-pot postfunctionalization protocol, in the development of dendritic nanoparticles, and in the formation of hydrogels.

  3. Graphical Abstract

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

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

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

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Graphical Abstract
    5. Corrigendum
    6. News
    7. Author Profile
    8. Book Reviews
    9. Highlights
    10. Minireview
    11. Review
    12. Communications
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    1. Michael Famulok (page 2077)

      Version of Record online: 3 MAR 2009 | DOI: 10.1002/anie.200900105

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      „My favorite piece of research is the recent progress in the generation of purely synthetic protocells. The secret of being a successful scientist is to recognize an innovative idea and to creatively track it.“ This and more about Michael Famulok can be found on page 2077.

  7. Book Reviews

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

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Graphical Abstract
    5. Corrigendum
    6. News
    7. Author Profile
    8. Book Reviews
    9. Highlights
    10. Minireview
    11. Review
    12. Communications
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    1. Asymmetric Catalysis

      Catalytic, Enantioselective Ring Opening of Aziridines (pages 2082–2084)

      Christoph Schneider

      Version of Record online: 28 JAN 2009 | DOI: 10.1002/anie.200805542

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      Cooperative metal centers in a bimetallic catalyst facilitate the highly enantioselective ring opening of meso aziridines 1 with silyl nucleophiles (see scheme; TMS=trimethylsilyl). The 1,2-azidoamides 2 and 1,2-amidonitriles 3 obtained in this way in high yields and with up to 99 % ee are valuable precursors to enantiomerically pure 1,2-diamines and β-amino acids.

    2. Asymmetric Ring-Closing Metathesis with a Twist (pages 2085–2089)

      Hendrik F. T. Klare and Martin Oestreich

      Version of Record online: 6 FEB 2009 | DOI: 10.1002/anie.200806254

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      A double flip! The catalyst shown, with a molybdenum stereocenter and monodentate ligands (Si=SitBuMe2), promotes asymmetric ring-closing metathesis of a broad range of substrates. Its unprecedented activity originates from its structural fluxionality, which enables double inversion at the metal center in the course of a single catalytic cycle. The catalyst passed the test in a metathesis reaction en route to (+)-quebrachamine (see scheme).

  9. Minireview

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Graphical Abstract
    5. Corrigendum
    6. News
    7. Author Profile
    8. Book Reviews
    9. Highlights
    10. Minireview
    11. Review
    12. Communications
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    1. Synthetic Methods

      Acetylides from Alkyl Propiolates as Building Blocks for C3 Homologation (pages 2090–2098)

      David Tejedor, Sara López-Tosco, Fabio Cruz-Acosta, Gabriela Méndez-Abt and Fernando García-Tellado

      Version of Record online: 14 JAN 2009 | DOI: 10.1002/anie.200801987

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      Three that matter: Metal acetylides from alkyl propiolates allow C3 homologations with transference of their versatile reactivity profile to products that can then react without further elaboration. Metal-free acetylides, which are generated by the action of a good nucleophile on the alkyl propiolate, react with suitable electrophiles through different domino reactions to generate skeletal diversity.

  10. Review

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

      Enantioselective Catalysis Based on Cationic Oxazaborolidines (pages 2100–2117)

      E. J. Corey

      Version of Record online: 23 FEB 2009 | DOI: 10.1002/anie.200805374

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      Chiral oxazaborolidines can be activated by N-protonation using strong protic acids or by N-coordination with AlBr3 to form very strong chiral Lewis acids. The resulting chiral boron electrophiles (see structure) are powerful chiral catalysts that effectively promote [4+2], [3+2], and [2+2]-cycloaddition reactions with high enantioselectivity.

  11. Communications

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

      Unique Identification of Supramolecular Structures in Amyloid Fibrils by Solid-State NMR Spectroscopy (pages 2118–2121)

      Jakob T. Nielsen, Morten Bjerring, Martin D. Jeppesen, Ronnie O. Pedersen, Jan M. Pedersen, Kim L. Hein, Thomas Vosegaard, Troels Skrydstrup, Daniel E. Otzen and Niels C. Nielsen

      Version of Record online: 7 JAN 2009 | DOI: 10.1002/anie.200804198

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      The fibril structure formed by the amyloidogenic fragment SNNFGAILSS of the human islet amyloid polypeptide (hIAPP) is determined with 0.52 Å resolution. Symmetry information contained in the easily obtainable resonance assignments from solid-state NMR spectra (see picture), along with long-range constraints, can be applied to uniquely identify the supramolecular organization of fibrils.

    2. Metal Nanoclusters

      Color Tunability and Electrochemiluminescence of Silver Nanoclusters (pages 2122–2125)

      Isabel Díez, Matti Pusa, Sakari Kulmala, Hua Jiang, Andreas Walther, Anja S. Goldmann, Axel H. E. Müller, Olli Ikkala and Robin H. A. Ras

      Version of Record online: 10 FEB 2009 | DOI: 10.1002/anie.200806210

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      Colorful clusters: Silver nanoclusters consisting of only a few atoms exhibit large chemical-environment-responsive shifts of their optical absorption and emission bands, that is, large solvatochromism (see picture). The photophysical characteristics and electrochemiluminescence of the Ag clusters give them remarkable advantages over larger nanoparticles in applications such as molecular sensing.

    3. Supramolecular Chemistry

      Bifunctional Dendrimers: From Robust Synthesis and Accelerated One-Pot Postfunctionalization Strategy to Potential Applications (pages 2126–2130)

      Per Antoni, Yvonne Hed, Axel Nordberg, Daniel Nyström, Hans von Holst, Anders Hult and Michael Malkoch

      Version of Record online: 30 DEC 2008 | DOI: 10.1002/anie.200804987

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      A fourth wheel: Two sets of bifunctional AB2C dendrimers having internal acetylene/azides and external hydroxy groups were constructed utilizing benign synthetic protocols. An in situ postfunctionalization strategy was successfully carried out to illustrate the chemoselective nature of these dendrimers. The dendrimers were also transformed into dendritic nanoparticles or utilized as dendritic crosslinkers for the fabrication hydrogels.

    4. Emulsions

      Polymer-Mediated Hierarchical and Reversible Emulsion Droplet Assembly (pages 2131–2134)

      Jonathan V. M. Weaver, Steven P. Rannard and Andrew I. Cooper

      Version of Record online: 10 FEB 2009 | DOI: 10.1002/anie.200805448

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      Making and breaking: Stable, functional micrometer-sized emulsion droplets can be assembled into various complex macroscopic liquid structures (see picture). The hierarchical assembly process is mediated by interactions between polymeric surfactant molecules located on the droplet surfaces. These interdroplet interactions are reversible, therefore these “engineered emulsions” can be readily disassembled by using a simple pH switch.

    5. Nanoassembly

      Assembly of Nanocrystal Arrays by Block-Copolymer-Directed Nucleation (pages 2135–2139)

      Stephen A. Morin, Young-Hye La, Chi-Chun Liu, Jeremy A. Streifer, Robert J. Hamers, Paul F. Nealey and Song Jin

      Version of Record online: 6 FEB 2009 | DOI: 10.1002/anie.200805471

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      Growing in line: The surface chemistry of self-assembled nanostructured block copolymers is used to control the sites at which semiconducting metal sulfide nanocrystals nucleate and grow on a surface directly from aqueous solutions. This process is a new and general strategy for the bottom-up assembly of functional nanocrystalline materials for a variety of applications.

    6. Organic–Inorganic Hybrid

      A Thermally and Hydrolytically Stable Microporous Framework Exhibiting Single-Chain Magnetism: Structure and Properties of [Co2(H0.67bdt)3]⋅20 H2O (pages 2140–2143)

      Wayne Ouellette, Andrey V. Prosvirin, Kelly Whitenack, Kim R. Dunbar and Jon Zubieta

      Version of Record online: 6 FEB 2009 | DOI: 10.1002/anie.200804805

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      Fixing a hole: Hydrothermal chemistry has been exploited in the preparation of a 3D framework material exhibiting 48 % accessible void volume and 1.5 % hydrogen uptake by weight at 120 kPa (see picture). The title compound also exhibits single-chain magnetic behavior and reversible changes in magnetic properties upon solvation and desolvation.

    7. Mass Transport

      Photocontrolled Translational Motion of a Microscale Solid Object on Azobenzene-Doped Liquid-Crystalline Films (pages 2144–2147)

      Abu Kausar, Hiroto Nagano, Tomonari Ogata, Takamasa Nonaka and Seiji Kurihara

      Version of Record online: 9 FEB 2009 | DOI: 10.1002/anie.200804762

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      On the move: Irradiation of azobenzene-doped liquid crystalline films with UV/Vis light results in the photocontrolled translational motion of microscale solid object on the surface, which occurs through cistrans isomerization of the azobenzene unit. Irradiation with an Ar+ laser (488 nm) resulted in precise control of the translational motion so that the particle always moved away from the irradiation position (see picture).

    8. Antimicrobial Photochemistry

      Exploiting a Bacterial Drug-Resistance Mechanism: A Light-Activated Construct for the Destruction of MRSA (pages 2148–2151)

      Xiang Zheng, Ulysses W. Sallum, Sarika Verma, Humra Athar, Conor L. Evans and Tayyaba Hasan

      Version of Record online: 10 FEB 2009 | DOI: 10.1002/anie.200804804

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      A cunning and dangerous plan foiled! An enzyme-specific molecular construct exploits the overexpression of β-lactamase in several drug-resistant bacteria. Specific photodynamic toxicity was detected towards β-lactam-resistant methicillin-resistant Staphylococcus aureus (MRSA), whereby the usual mechanism for antibiotic resistance (cleavage of the β-lactam ring) releases the phototoxic component from the prodrug (see picture; Q=quencher).

    9. Nitrogen Chains

      Assembly of an R3N52− Chain by Cycloaddition of a Hydrazinediide and an Azide at Zirconium and its Thermal Fragmentation (pages 2152–2156)

      Thorsten Gehrmann, Julio Lloret Fillol, Hubert Wadepohl and Lutz H. Gade

      Version of Record online: 9 FEB 2009 | DOI: 10.1002/anie.200805631

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      Breaking the chain: Reaction of a zirconium hydrazinediide with organoazides gives 2-pentazene-1,4-diyl complexes, such as [Zr(N2TBSNpy){N(Ad)N3NPh2}] (C gray, N blue, Si green, Zr turquoise), by formal [2+3] cycloaddition. Bonding within the N5 chain is investigated using density functional calculations. These complexes thermally eject N2 to give side-on bonded diazenides.

    10. Gold(I) Complexes

      Hexa- and Octagold Chains from Flexible Tetragold Molecular Units Supported by Linear Tetraphosphine Ligands (pages 2157–2161)

      Yukie Takemura, Hiroe Takenaka, Takayuki Nakajima and Tomoaki Tanase

      Version of Record online: 9 FEB 2009 | DOI: 10.1002/anie.200806012

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      A flexible building block: Flexible tetragold(I) chain complexes supported by a new single methylene-bridged tetraphosphine ligand were synthesized and further transformed into discrete linear octagold(I) {Au8} and cyclic hexagold(I) {Au6} structures by reaction with KI and NaAuCl4, respectively (see picture, Au purple, Cl dark green, PF6 light green, I pink). The tetragold complexes are also luminescent at room temperature.

    11. Asymmetric Catalysis

      Singly Hydrogen Bonded Supramolecular Ligands for Highly Selective Rhodium-Catalyzed Hydrogenation Reactions (pages 2162–2165)

      Pierre-Alain R. Breuil, Frederic W. Patureau and Joost N. H. Reek

      Version of Record online: 10 FEB 2009 | DOI: 10.1002/anie.200806177

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      H bonds make the catalysts! A single hydrogen bond between ligands coordinated to a rhodium center is critical for the formation of pure supramolecular catalysts for asymmetric hydrogenation reactions. The ester group of the amidite ligand (see scheme) also forms a hydrogen bond with the coordinated substrate. Use of the heterocomplex afforded the highest enantioselectivity reported to date for the hydrogenation of several ester substrates.

    12. Fullerenes

      Self-Assembly Made Durable: Water-Repellent Materials Formed by Cross-Linking Fullerene Derivatives (pages 2166–2170)

      Jiaobing Wang, Yanfei Shen, Stefanie Kessel, Paulo Fernandes, Kaname Yoshida, Shiki Yagai, Dirk G. Kurth, Helmuth Möhwald and Takashi Nakanishi

      Version of Record online: 10 FEB 2009 | DOI: 10.1002/anie.200900106

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      Fullerene flakes: A diacetylene-functionalized fullerene derivative self-organizes into flakelike microparticles (see picture). Both the diacetylene and C60 moieties can be effectively cross-linked, which leads to supramolecular materials with remarkable resistivity to solvent, heat, and mechanical stress. Moreover, the surface of the cross-linked flakelike objects is highly durable and water-repellent.

    13. Foldamers

      Design of Peptidic Foldamer Helices: A Stereochemical Patterning Approach (pages 2171–2175)

      István M. Mándity, Edit Wéber, Tamás A. Martinek, Gábor Olajos, Gábor K. Tóth, Elemér Vass and Ferenc Fülöp

      Version of Record online: 11 FEB 2009 | DOI: 10.1002/anie.200805095

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      Assembly language: The programmed sequences of stereochemical building blocks lead to novel biomimetic helices. The rational design approach offers new possibilities for creating periodic secondary structures.

    14. Polyester Synthesis

      Ring-Opening Polymerization of Cyclic Esters by an Enantiopure Heteroscorpionate Rare Earth Initiator (pages 2176–2179)

      Antonio Otero, Juan Fernández-Baeza, Agustín Lara-Sánchez, Carlos Alonso-Moreno, Isabel Márquez-Segovia, Luis F. Sánchez-Barba and Ana M. Rodríguez

      Version of Record online: 11 FEB 2009 | DOI: 10.1002/anie.200806202

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      With a sting in its tail: An enantiopure neodymium complex (see scheme) acts as an efficient single-site initiator for the controlled ring-opening polymerization of rac-lactide, forming isotactic polyester. The heteroscorpionate complex was characterized spectroscopically and by X-ray diffraction.

    15. Surface Enhanced Raman Scattering

      Isolating and Probing the Hot Spot Formed between Two Silver Nanocubes (pages 2180–2184)

      Pedro H. C. Camargo, Matthew Rycenga, Leslie Au and Younan Xia

      Version of Record online: 6 FEB 2009 | DOI: 10.1002/anie.200806139

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      Out of the frying pan: Hot spots can greatly increase the sensitivity of surface-enhanced Raman scattering, but they remain poorly understood. A new strategy based on plasma etching (see picture) can be used to isolate and exclusively probe the SERS-active molecules adsorbed in the hot-spot region between two silver nanocubes.

    16. C[BOND]F Bond Activation

      Selective C[BOND]F Bond Activation of Tetrafluorobenzenes by Nickel(0) with a Nitrogen Donor Analogous to N-Heterocyclic Carbenes (pages 2185–2187)

      Meghan E. Doster and Samuel A. Johnson

      Version of Record online: 6 FEB 2009 | DOI: 10.1002/anie.200806048

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      N, not NHC: A neutral, basic, strong σ-donor nitrogen ancillary ligand with properties analogous to those of N-heterocyclic carbenes (NHCs) was developed to aid in the oxidative additions of challenging substrates to late transition metals. Selective, room-temperature C[BOND]F bond activation was observed with hexa-, penta-, and all three isomers of tetrafluorobenzene using a nickel(0) source in the presence of this donor.

    17. G-Quadruplex DNA

      Engineering Bisquinolinium/Thiazole Orange Conjugates for Fluorescent Sensing of G-Quadruplex DNA (pages 2188–2191)

      Peng Yang, Anne De Cian, Marie-Paule Teulade-Fichou, Jean-Louis Mergny and David Monchaud

      Version of Record online: 6 FEB 2009 | DOI: 10.1002/anie.200805613

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      Lighting up: A G-quadruplex-specific fluorescent probe was designed combining the specificity of the pyridodicarboxamide motif for guanine quadruplexes and the fluorescence properties of thiazole orange. While the assembly of the two partners through a flexible linker leads to a nonselective probe, merging them in a single, rigid scaffold leads to a dye that elicits the properties required for G-quadruplex sensing.

    18. Multicomponent Reactions

      Nickel-Catalyzed Borylative Coupling of Alkynes, Enones, and Bis(pinacolato)diboron as a Route to Substituted Alkenyl Boronates (pages 2192–2195)

      Subramaniyan Mannathan, Masilamani Jeganmohan and Chien-Hong Cheng

      Version of Record online: 11 FEB 2009 | DOI: 10.1002/anie.200805293

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      Three-component coupling reactions of an alkyne, an enone, and a diboron reagent provide access to highly substituted alkenyl boronates in good to excellent yields (see scheme). The coupling is highly regio- and stereoselective, and the products are amenable to further functional-group transformations. R1,R2=H, alkyl, aryl, CO2Me; R3=alkyl, Ph; R4,R5=H, alkyl.

    19. Synthetic Methods

      Intermolecular Double Prins-Type Cyclization: A Facile and Efficient Synthesis of 1,6-Dioxecanes (pages 2196–2200)

      Punna Reddy Ullapu, Sun-Joon Min, Satish N. Chavre, Hyunah Choo, Jae Kyun Lee, Ae Nim Pae, Youseung Kim, Moon Ho Chang and Yong Seo Cho

      Version of Record online: 9 FEB 2009 | DOI: 10.1002/anie.200804576

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      Double or nothing: The title reaction converts a range of aromatic aldehydes and allenylmethyl/allyl silanes into 1,6-dioxecane derivatives in good to excellent yields (see scheme; Ar=aryl, Tf=triflate, THF=tetrahydrofuran, TMS=trimethylsilyl). In addition, the bisdiene product has been transformed into the corresponding tricyclic compound through a Diels–Alder reaction.

      Corrected by:

      Corrigendum: Intermolecular Double Prins-Type Cyclization: A Facile and Efficient Synthesis of 1,6-Dioxecanes

      Vol. 48, Issue 34, 6190, Version of Record online: 7 AUG 2009

    20. Hydrogen Storage

      The Role of Free N-Heterocyclic Carbene (NHC) in the Catalytic Dehydrogenation of Ammonia–Borane in the Nickel NHC System (pages 2201–2205)

      Paul M. Zimmerman, Ankan Paul, Zhiyong Zhang and Charles B. Musgrave

      Version of Record online: 9 FEB 2009 | DOI: 10.1002/anie.200803211

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      Enders' N-heterocyclic carbene (NHC) dehydrogenates ammonia–borane with a relatively low barrier, producing NH2BH2 and NHC–(H)2. The nickel NHC catalyst present in the reaction media can activate the NHC–(H)2 produced to regenerate the free NHC and release H2. The release of free NHC enables further dehydrogenation of ammonia–borane.

    21. Ionothermal Synthesis

      Ionothermal Synthesis of Zirconium Phosphates and Their Catalytic Behavior in the Selective Oxidation of Cyclohexane (pages 2206–2209)

      Lei Liu, Yang Li, Haibo Wei, Mei Dong, Jianguo Wang, Alexandra M. Z. Slawin, Jinping Li, Jinxiang Dong and Russell E. Morris

      Version of Record online: 6 FEB 2009 | DOI: 10.1002/anie.200804891

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      On their best behavior: Three zirconium compounds with one-, two-, and three-dimensional structures have been successfully synthesized by the ionothermal approach. The 3D zirconium phosphate (see picture; F green, H white, O red, P pink, Zr yellow) exhibits high catalytic performance, with a cyclohexane conversion ratio of 32 % and cyclohexanone selectivity of up to 83 %.

    22. Sulfur Dications

      Dicationic Sulfur Analogues of N-Heterocyclic Silylenes and Phosphenium Cations (pages 2210–2213)

      Caleb D. Martin, Michael C. Jennings, Michael J. Ferguson and Paul J. Ragogna

      Version of Record online: 9 JAN 2009 | DOI: 10.1002/anie.200805198

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      DABling with sulfur: Sulfur(II) dications can be prepared using α-diimines to stabilize the positive charge (see scheme; DAB=diazabutadiene, Dipp=2,6-diisopropylphenyl, OTf=CF3SO3). The bonding is best described as that of a N,N-chelated sulfur(II) dication; these species represent the first sulfur-based structural mimics of N-heterocyclic silylene compounds and phosphenium cations.

    23. Guanyl Radicals

      A Reevaluation of the Ambident Reactivity of the Guanine Moiety Towards Hydroxyl Radicals (pages 2214–2217)

      Chryssostomos Chatgilialoglu, Mila D'Angelantonio, Maurizio Guerra, Panagiotis Kaloudis and Quinto G. Mulazzani

      Version of Record online: 18 FEB 2009 | DOI: 10.1002/anie.200805372

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      Radically different: Contrary to previous proposals, the main reaction of the HO. radical with guanosine or 2′-deoxyguanosine is the hydrogen abstraction from the NH2 moiety to give a guanyl radical. This radical, characterized by a broad band in the visible region (around 610 nm), undergoes tautomerization to the most stable isomer.

    24. Asymmetric Synthesis

      A Stable Homodinuclear Biscobalt(III)–Schiff Base Complex for Catalytic Asymmetric 1,4-Addition Reactions of β-Keto Esters to Alkynones (pages 2218–2220)

      Zhihua Chen, Makoto Furutachi, Yuko Kato, Shigeki Matsunaga and Masakatsu Shibasaki

      Version of Record online: 9 FEB 2009 | DOI: 10.1002/anie.200805967

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      Two metal cooperation: A homodinuclear Co2–Schiff base complex Co2(OAc)21 promoted the asymmetric 1,4-addition of β-keto esters to alkynones under solvent-free conditions in air (see scheme). The reactions proceeded without air or moisture sensitivity in high yields and with high enantioselectivities (99–91 % ee) at room temperature under highly concentrated conditions (neat–20 M) with 0.1–2.5 mol % catalyst loading.

    25. Integrated Oxidative Folding

      Integrated Oxidative Folding of Cysteine/Selenocysteine Containing Peptides: Improving Chemical Synthesis of Conotoxins (pages 2221–2224)

      Aleksandra Walewska, Min-Min Zhang, Jack J. Skalicky, Doju Yoshikami, Baldomero M. Olivera and Grzegorz Bulaj

      Version of Record online: 10 FEB 2009 | DOI: 10.1002/anie.200806085

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      Building bridges: The use of diselenide and selectively (15N/13C)-labeled disulfide bridges is combined to give improvements in oxidative folding and disulfide mapping. Conotoxin analogues, each with a pair of selenocysteines (Sec) and labeled cysteines (see scheme, red), exhibited significantly improved folding and the labeled cysteines allow correctly folded species to be rapidly identified by NMR spectroscopy.

    26. Asymmetric Catalysis

      Phosphine-Catalyzed Enantioselective Synthesis of Oxygen Heterocycles (pages 2225–2227)

      Ying Kit Chung and Gregory C. Fu

      Version of Record online: 11 FEB 2009 | DOI: 10.1002/anie.200805377

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      Chiral phosphepine 1 catalyzes the transformation of an array of hydroxy-2-alkynoates into saturated oxygen heterocycles with good enantioselectivity. Phenols are also shown to participate in such phosphine-catalyzed cyclizations, including an asymmetric variant. This method provides a new approach to the enantioselective synthesis of tetrahydrofurans, tetrahydropyrans, and dihydrobenzopyrans.

    27. Natural Product Synthesis

      Stereoselective Synthesis of Enantiomerically Pure Nupharamine Alkaloids from Castoreum (pages 2228–2230)

      Alexander Stoye, Gabriele Quandt, Björn Brunnhöfer, Elissavet Kapatsina, Julia Baron, André Fischer, Markus Weymann and Horst Kunz

      Version of Record online: 6 FEB 2009 | DOI: 10.1002/anie.200805606

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      An animalic note: The first total synthesis of the all-cis nupharamine 2, an alkaloid from beaver castoreum, is based on the stereoselective domino Mannich–Michael reaction of N-galactosylfurylaldimine to give 1 (Piv=pivaloyl), subsequent conjugate cuprate addition, and stereoselective protonation of the enolate. These reactions are all controlled by the carbohydrate. Protonation of the enolate after cleavage of the auxiliary leads to epimer 3.

    28. Aerosol Chemistry

      Suppressed Particle Formation by Kinetically Controlled Ozone Removal: Revealing the Role of Transient-Species Chemistry during Alkene Ozonolysis (pages 2231–2235)

      Jan L. Wolf, Martin A. Suhm and Thomas Zeuch

      Version of Record online: 10 FEB 2009 | DOI: 10.1002/anie.200805189

      Thumbnail image of graphical abstract

      The new approach of kinetically controlled ozone removal suppresses particle formation in laboratory ozonolysis experiments for methylcyclohexene and methylenecyclohexane (MCHa) at excess alkene concentrations (see graph). The results support the hypothesis that peroxy radicals are involved in organic nucleation and particle-growth mechanisms.

    29. Indium Reagents

      LiCl-Mediated Preparation of Functionalized Benzylic Indium(III) Halides and Highly Chemoselective Palladium-Catalyzed Cross-Coupling in a Protic Cosolvent (pages 2236–2239)

      Yi-Hung Chen, Mai Sun and Paul Knochel

      Version of Record online: 6 FEB 2009 | DOI: 10.1002/anie.200805588

      Thumbnail image of graphical abstract

      Sensitive functional groups such as COR, CHO, or CH2OH can be present in benzylic indium reagents prepared by the direct insertion of indium in the presence of LiCl. These reagents undergo palladium-catalyzed cross-coupling reactions in the presence of a protic cosolvent after activation with iPrMgCl⋅LiCl (see scheme). Remarkable chemoselectivities are achieved by using various electrophiles containing NH or OH groups.

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