Angewandte Chemie International Edition

Cover image for Vol. 48 Issue 32

July 27, 2009

Volume 48, Issue 32

Pages 5769–5969

  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 Review
    9. Highlights
    10. Reviews
    11. Communications
    12. Preview
    1. Cover Picture: Multicomponent Reactions for the Synthesis of Complex Piperidine Scaffolds (Angew. Chem. Int. Ed. 32/2009) (page 5769)

      Wei Zhu, Marisa Mena, Eric Jnoff, Na Sun, Patrick Pasau and Léon Ghosez

      Version of Record online: 22 JUL 2009 | DOI: 10.1002/anie.200990164

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      Multicomponent reactions open up a versatile and efficient route to mono- and polycyclic piperidine derivatives, which are common substructures in biologically active natural products. In their Communication on page 5880 ff., L. Ghosez et al. show that the substitution pattern and the configuration of the piperidine rings can be tailor-made, thereby offering opportunities for creating structural, functional, and configurational diversity in the synthesis of alkaloids.

  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 Review
    9. Highlights
    10. Reviews
    11. Communications
    12. Preview
    1. Inside Cover: Addition Reactions of Sulfonylimidates with Imines Catalyzed by Alkaline Earth Metals (Angew. Chem. Int. Ed. 32/2009) (page 5770)

      Huy Van Nguyen, Ryosuke Matsubara and Shū Kobayashi

      Version of Record online: 22 JUL 2009 | DOI: 10.1002/anie.200990165

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      Addition reactions of sulfonylimidates to imines have been successfully catalyzed by alkali earth metal alkoxide salts, which are abundant, inexpensive, and nontoxic. As S. Kobayashi et al. show in their Communication on page 5927 ff., diastereoselectivity is highly dependent on solvents and catalysts: Reactions in DMF proceed with anti selectivity regardless of whether 1,8-diazabicyclo[5.4.0]undec-7-ene or a metal alkoxide is used as catalyst. In THF, syn products can be obtained using a metal alkoxide.

  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 Review
    9. Highlights
    10. Reviews
    11. Communications
    12. 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 Review
    9. Highlights
    10. Reviews
    11. Communications
    12. Preview
    1. You have free access to this content
      A Spiro-Fused Triarylaminium Radical Cation with a Triplet Ground State (page 5785)

      Akihiro Ito, Masashi Urabe and Kazuyoshi Tanaka

      Version of Record online: 22 JUL 2009 | DOI: 10.1002/anie.200990167

      This article corrects:

      A Spiro-Fused Triarylaminium Radical Cation with a Triplet Ground State1

      Vol. 42, Issue 8, 921–924, Version of Record online: 21 FEB 2003

  5. News

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Graphical Abstract
    5. Corrigendum
    6. News
    7. Author Profile
    8. Book Review
    9. Highlights
    10. Reviews
    11. Communications
    12. 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 Review
    9. Highlights
    10. Reviews
    11. Communications
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    1. Hans-Achim Wagenknecht (page 5788)

      Version of Record online: 16 JUN 2009 | DOI: 10.1002/anie.200902700

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      “A good work day begins with a new and exciting experimental result. The biggest challenge facing chemists is to understand the results and to convince other chemists that the unexpected chemical product was in fact desired. …” This and more about Hans-Achim Wagenknecht can be found on page 5788.

  7. Book Review

    1. Top of page
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    3. Inside Cover
    4. Graphical Abstract
    5. Corrigendum
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    8. Book Review
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    10. Reviews
    11. Communications
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    1. Reagents for Radical and Radical Ion Chemistry.Handbook of Reagents for Organic Synthesis. Edited by David Crich. (page 5789)

      Jens Hartung

      Version of Record online: 22 JUL 2009 | DOI: 10.1002/anie.200902787

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      John Wiley & Sons, Hoboken 2008. 722 pp., hardcover € 129.00.—ISBN 978-0470065365

  8. Highlights

    1. Top of page
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    3. Inside Cover
    4. Graphical Abstract
    5. Corrigendum
    6. News
    7. Author Profile
    8. Book Review
    9. Highlights
    10. Reviews
    11. Communications
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    1. Alkaline Earth Metal Catalysis

      Direct Michael, Aldol, and Mannich Additions Catalyzed by Alkaline Earth Metals (pages 5790–5792)

      Uli Kazmaier

      Version of Record online: 28 MAY 2009 | DOI: 10.1002/anie.200901261

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      Trend-setting: Alkaline earth metals are good catalysts for a number of direct addition reactions with carbonyl compounds. In Mannich reactions the stereochemical outcome can be controlled by the reaction conditions and the alkaline earth metal used (see scheme: Boc=tert-butoxycarbonyl, HMDS=hexamethyldisilazide).

    2. Electronic Structure

      Resonance Structures and Electron Density Analysis (pages 5793–5795)

      Piero Macchi

      Version of Record online: 18 JUN 2009 | DOI: 10.1002/anie.200901298

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      In perfect resonance: The electron density distribution is typically used to analyze chemical bonding, even if strong electron delocalization occurs. The electron densities and electric potentials of picoline and the picolyl anion (see picture) have been analyzed and a detailed description of picolyl lithium complexes has been derived. The next goal is to predict chemical reactivity from electron density.

  9. Reviews

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

      The Search for Infectious Causes of Human Cancers: Where and Why (Nobel Lecture) (pages 5798–5808)

      Harald zur Hausen

      Version of Record online: 8 JUL 2009 | DOI: 10.1002/anie.200901917

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      Viruses are the uniting theme of the 2008 Nobel Prize for Physiology or Medicine. Françoise Barré-Sinoussi and Luc Montagnier received their Prize for the discovery of the human immunodeficiency virus (HIV), and Harald zur Hausen identified that cervical cancer is triggered by papillomaviruses. The Nobel Laureates describe their research first-hand.

    2. HIV/AIDS

      HIV: A Discovery Opening the Road to Novel Scientific Knowledge and Global Health Improvement (Nobel Lecture) (pages 5809–5814)

      Françoise Barré-Sinoussi

      Version of Record online: 27 JUN 2009 | DOI: 10.1002/anie.200901918

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      Viruses are the uniting theme of the 2008 Nobel Prize for Physiology or Medicine. Françoise Barré-Sinoussi and Luc Montagnier received their Prize for the discovery of the human immunodeficiency virus (HIV), and Harald zur Hausen identified that cervical cancer is triggered by papillomaviruses. The Nobel Laureates describe here their research first-hand.

    3. 25 Years after HIV Discovery: Prospects for Cure and Vaccine (Nobel Lecture) (pages 5815–5826)

      Luc Montagnier

      Version of Record online: 17 JUL 2009 | DOI: 10.1002/anie.200902130

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      Viruses are the uniting theme of the 2008 Nobel Prize for Physiology or Medicine. Françoise Barré-Sinoussi and Luc Montagnier received their Prize for the discovery of the human immunodeficiency virus (HIV), and Harald zur Hausen identified that cervical cancer is triggered by papillomaviruses. The Nobel Laureates describe their research first-hand.

  10. Communications

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

      Potassium-Modified Mg(NH2)2/2 LiH System for Hydrogen Storage (pages 5828–5832)

      Jianhui Wang, Tao Liu, Guotao Wu, Wen Li, Yongfeng Liu, C. Moysés Araújo, Ralph H. Scheicher, Andreas Blomqvist, Rajeev Ahuja, Zhitao Xiong, Ping Yang, Mingxia Gao, Hongge Pan and Ping Chen

      Version of Record online: 31 MAR 2009 | DOI: 10.1002/anie.200805264

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      Using KH as an additive to Mg(NH2)2/LiH drastically improves hydrogen desorption, which begins at ca. 80 °C (see graph). Circa 5 wt % of hydrogen can be reversibly desorbed and absorbed at about 107 °C. The presence of potassium in the reacting system weakens the amide N[BOND]H and imide Li[BOND]N bonds, leading to enhanced reaction kinetics.

    2. Protein Patterns

      Making Protein Patterns by Writing in a Protein-Repelling Matrix (pages 5833–5836)

      Nirmalya Ballav, Heidi Thomas, Tobias Winkler, Andreas Terfort and Michael Zharnikov

      Version of Record online: 6 JUL 2009 | DOI: 10.1002/anie.200900950

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      Write on target: An efficient and versatile approach to fabricate protein patterns of any shape on a variable length scale is developed. The patterns are directly written in an oligo- or poly(ethylene glycol)-based protein-repelling film by electron-beam lithography.

    3. Boride Ligands

      Low-Coordinate Boride Ligands: A True Trimetalloborane (pages 5837–5840)

      Holger Braunschweig, Rian D. Dewhurst, Katharina Kraft and Krzysztof Radacki

      Version of Record online: 7 JUL 2009 | DOI: 10.1002/anie.200901211

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      Boron trifecta: The first true trimetalloborane has been synthesized by simple salt elimination from a dimanganese bromoborylene and Na[Co(CO)4]. The complex was structurally characterized, and features only first-row transition metals, a planar boron atom, and two semi-bridging CO ligands between the cobalt and one manganese atom (see picture).

    4. Solid-Phase Synthesis

      Polystyrene Sulfonyl Chloride: A Highly Orthogonal Linker Resin for the Synthesis of Nitrogen-Containing Heterocycles (pages 5841–5844)

      Matthias Mentel, Axel M. Schmidt, Michael Gorray, Peter Eilbracht and Rolf Breinbauer

      Version of Record online: 6 JUL 2009 | DOI: 10.1002/anie.200901643

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      One linker, broad application: A simple sulfonamide linker for primary and secondary amines was used for the construction of small libraries of privileged indole and quinolone structures on a solid phase. After the synthesis, the products can be liberated ion a traceless manner under electron transfer conditions or according to a “safety catch” principle.

    5. Bond-Stretch Isomerism

      The Two Structures of the Hexafluorobenzene Radical Cation C6F6.+ (pages 5845–5847)

      Hashem Shorafa, Doreen Mollenhauer, Beate Paulus and Konrad Seppelt

      Version of Record online: 6 JUL 2009 | DOI: 10.1002/anie.200900666

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      Ring, ring! C6F6.+ Os2F11 and C6F6.+Sb2F11 have isomorphous crystal structures and each contain two different C6F6.+ cations. One is a quinoid structure, the other bisallyl structure. Calculations show that indeed two such Jahn–Teller distorted structures coexist with essentially the same energy. This seems to be a case of bond-stretch isomerism.

    6. Synthetic Methods

      Gold Catalysis: Switching the Pathway of the Furan-Yne Cyclization (pages 5848–5852)

      A. Stephen K. Hashmi, Matthias Rudolph, Jürgen Huck, Wolfgang Frey, Jan W. Bats and Melissa Hamzić

      Version of Record online: 27 JUN 2009 | DOI: 10.1002/anie.200900887

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      Changing tracks: By the use of alkynyl ethers as directing elements, the furan-yne cyclization enters a new reaction pathway. Instead of phenols, tetracycles containing two heteroatoms and two new stereocenters are formed (see scheme).

    7. Protein–Protein Complex Inhibition

      Molecular Mechanism of Inhibition of the Human Protein Complex Hsp90–Cdc37, a Kinome Chaperone–Cochaperone, by Triterpene Celastrol (pages 5853–5855)

      Sridhar Sreeramulu, Santosh Lakshmi Gande, Michael Göbel and Harald Schwalbe

      Version of Record online: 7 JUL 2009 | DOI: 10.1002/anie.200900929

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      The correct target: The cell division cycle protein 37 (Cdc37) and the heat shock protein (Hsp90) are molecular chaperones crucial for the folding and stabilization of protein kinases including the oncogenic kinases. NMR studies show that celastrol, a recently identified triterpene targeting Hsp90, in fact binds to Cdc37 and disrupts the Cdc37–Hsp90 complex. Celastrol inactivates Cdc37 through a thiol-mediated mechanism.

    8. Multicomponent Reactions

      The Efficient One-Pot Reaction of up to Eight Components by the Union of Multicomponent Reactions (pages 5856–5859)

      Niels Elders, Dion van der Born, Loes J. D. Hendrickx, Brian J. J. Timmer, Alrik Krause, Elwin Janssen, Frans J. J. de Kanter, Eelco Ruijter and Romano V. A. Orru

      Version of Record online: 3 JUL 2009 | DOI: 10.1002/anie.200902683

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      E=MCR2! The introduction of orthogonal functional groups in multicomponent reactions (MCRs) with unique solvent and functional-group compatibility enables their combination with other multicomponent reactions in one pot. The resulting novel 5- and 6CRs and an unprecedented 8CR afford very complex products in up to 80 % yields (see picture), with up to nine new bond formations and eleven diversity points in a single reaction.

    9. Natural Products

      Synthesis of the Monomeric Unit of the Lomaiviticin Aglycon (pages 5860–5863)

      K. C. Nicolaou, Andrea L. Nold and Hongming Li

      Version of Record online: 2 JUL 2009 | DOI: 10.1002/anie.200902509

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      The right building blocks: The monomeric unit of the lomaiviticin aglycon (see structures) was synthesized through an enantioselective route featuring an Ullmann coupling, a benzoin-type cyclization, and a novel SmI2-mediated allylic alcohol formal transposition.

    10. Graphene

      A Strategy for Producing Pure Single-Layer Graphene Sheets Based on a Confined Self-Assembly Approach (pages 5864–5868)

      Weixia Zhang, Jiecheng Cui, Cheng-an Tao, Yiguang Wu, Zhanping Li, Li Ma, Yuquan Wen and Guangtao Li

      Version of Record online: 3 JUL 2009 | DOI: 10.1002/anie.200902365

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      Carbon sandwich: When a pyrrole-containing surfactant is polymerized between layers of silica (see picture; pyrrole is red), subsequent carbonization and removal of the silica template yields large, pure, single-layer graphene sheets. The procedure, which employs mild conditions, is controllable and can be used to produce micrometer-sized graphene sheets on a gram scale.

    11. Spontaneous Resolution

      Total Spontaneous Resolution of Five-Coordinate Complexes (pages 5869–5871)

      Anders Lennartson and Mikael Håkansson

      Version of Record online: 6 JUL 2009 | DOI: 10.1002/anie.200902206

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      Talking about a resolution: Bulk quantities of five-coordinate complexes have been resolved for the first time using zinc and cadmium diethyldithiocarbamate species. The stereochemical outcome can be controlled by seeding with the desired isomer, giving access to either enantiomer in high enantiomeric excess and yield.

    12. Microelectrode Arrays

      Building Addressable Libraries: Site-Selective Lewis Acid (Scandium(III)) Catalyzed Reactions (pages 5872–5874)

      Bo Bi, Karl Maurer and Kevin D. Moeller

      Version of Record online: 6 JUL 2009 | DOI: 10.1002/anie.200902350

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      Reagent confinement: Lewis acid catalyzed reactions have been conducted on arrays with either 1024 or 12 544 microelectrodes cm−2. A ScIII species generated at the electrodes is employed as the Lewis acid, and the reagent is confined to the electrodes through the use of a solution-phase reductant. A multicomponent synthesis of a tetrahydropyran (see scheme), a Diels–Alder reaction, and an esterification reaction are all compatible with this strategy.

    13. Magnetic Colloids

      Highly Water-Dispersible Biocompatible Magnetite Particles with Low Cytotoxicity Stabilized by Citrate Groups (pages 5875–5879)

      Jia Liu, Zhenkun Sun, Yonghui Deng, Ying Zou, Chunyuan Li, Xiaohui Guo, Liqin Xiong, Yuan Gao, Fuyou Li and Dongyuan Zhao

      Version of Record online: 3 JUL 2009 | DOI: 10.1002/anie.200901566

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      Uniform magnetite particles stabilized by citrate groups were successfully synthesized by a modified high-temperature solvothermal reaction. Cell imaging reveals that the water-dispersible particles can readily penetrate into cells without destroying them, indicating an excellent biocompatibility. A high enrichment capacity of the magnetite particles for separation of trace peptides is observed.

    14. Synthetic Methods

      Multicomponent Reactions for the Synthesis of Complex Piperidine Scaffolds (pages 5880–5883)

      Wei Zhu, Marisa Mena, Eric Jnoff, Na Sun, Patrick Pasau and Léon Ghosez

      Version of Record online: 23 MAR 2009 | DOI: 10.1002/anie.200806065

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      Creating diversity: Multicomponent reactions for the synthesis of complex piperidine scaffolds lead to high levels of skeletal, functional, and stereochemical diversity in an efficient way (see scheme, X=OR, NR2). Connecting the acid chloride component to the dienophile generates polycyclic piperidine scaffolds by an intramolecular Diels–Alder reaction of the in situ generated azadienes.

    15. Molecular Gates

      Enzyme-Responsive Controlled Release Using Mesoporous Silica Supports Capped with Lactose (pages 5884–5887)

      Andrea Bernardos, Elena Aznar, María Dolores Marcos, Ramón Martínez-Máñez, Félix Sancenón, Juan Soto, José Manuel Barat and Pedro Amorós

      Version of Record online: 2 JUL 2009 | DOI: 10.1002/anie.200900880

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      The great escape: A biocontrolled gated material has been prepared by grafting a lactose derivative onto the pore outlets of a mesoporous support. The galactosidase-induced hydrolysis of the β1[RIGHTWARDS ARROW]4 glycosidic bond in the lactose moiety (red box in picture) allows the release of a dye entrapped in the pores of the hybrid material to the bulk solution.

    16. Magnetic Materials

      Fe3O4 Core/Layered Double Hydroxide Shell Nanocomposite: Versatile Magnetic Matrix for Anionic Functional Materials (pages 5888–5892)

      Liang Li, Yingjun Feng, Yongsheng Li, Wenru Zhao and Jianlin Shi

      Version of Record online: 2 JUL 2009 | DOI: 10.1002/anie.200901730

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      Layering up: The title nanocomposite shows high anion loading capacity. The demonstration of the assembly of a W7O246− catalyst by this method may provide a general route to the facile and direct fabrication of composite structures with magnetic cores and shells functionalized with various anions (see scheme; LDH=layered double hydroxide).

    17. Spirocyclization

      Triflic Acid Catalyzed Synthesis of Spirocycles via Acetylene Cations (pages 5893–5896)

      Tienan Jin, Masafumi Himuro and Yoshinori Yamamoto

      Version of Record online: 6 JUL 2009 | DOI: 10.1002/anie.200901771

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      Rings of various shapes and sizes: Spirocyclic hydrocarbons 2 were obtained in good to excellent yield through the triflic acid (TfOH) catalyzed cyclization of alkynyl-substituted cyclic tertiary alcohols 1 under mild conditions with good control of ring size (see scheme). The method was extended to the synthesis of bridged bicyclic ketones with high stereoselectivity.

    18. Direct Electron Transfer

      Deglycosylation of Glucose Oxidase for Direct and Efficient Glucose Electrooxidation on a Glassy Carbon Electrode (pages 5897–5899)

      Olivier Courjean, Feng Gao and Nicolas Mano

      Version of Record online: 30 JUN 2009 | DOI: 10.1002/anie.200902191

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      Down to the bare bones: When a glucose oxidase (GOx, left) was deglycosylated, the modified enzyme (right) immobilized on a vitreous carbon electrode came into closer electrical contact with the surface than the native enzyme. Glucose was electrooxidized directly on a monolayer of deglycosylated GOx on a carbon electrode at the unprecedented reducing potential of −200 mV versus Ag/AgCl and with a current density of 235 μA cm−2.

    19. Insertion Reactions

      Towards Photocatalytic Alkane Oxidation: The Insertion of Dioxygen into a Platinum(II)–Methyl Bond (pages 5900–5903)

      Russell A. Taylor, David J. Law, Glenn J. Sunley, Andrew J. P. White and George J. P. Britovsek

      Version of Record online: 30 JUN 2009 | DOI: 10.1002/anie.200806187

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      Always look on the bright side: The light-driven insertion of dioxygen into a platinum–methyl bond results in a methylperoxo complex (see picture) which decomposes to formaldehyde and a platinum hydroxo complex. This reaction occurs at 1 atm O2 and room temperature within minutes, and proceeds via the formation of singlet oxygen.

    20. Halogenated Fullerenes

      Fusing Pentagons in a Fullerene Cage by Chlorination: IPR D2-C76 Rearranges into non-IPR C76Cl24 (pages 5904–5907)

      Ilya N. Ioffe, Alexey A. Goryunkov, Nadezhda B. Tamm, Lev N. Sidorov, Erhard Kemnitz and Sergey I. Troyanov

      Version of Record online: 30 JUN 2009 | DOI: 10.1002/anie.200902253

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      Spectacular skeletal rearrangement of the C76 fullerene cage was observed as a result of chlorination of D2-C76 to give C76Cl24 (see structure; gray C, green Cl, orange bonds highlight the pentagons), which features a significantly flattened carbon cage that violates the isolated pentagon rule. This transformation is likely to include seven single Stone–Wales rearrangements, which are facilitated by chlorination of the fullerene cage.

    21. Microfluidics

      Microfluidic Confinement of Single Cells of Bacteria in Small Volumes Initiates High-Density Behavior of Quorum Sensing and Growth and Reveals Its Variability (pages 5908–5911)

      James Q. Boedicker, Meghan E. Vincent and Rustem F. Ismagilov

      Version of Record online: 29 JUN 2009 | DOI: 10.1002/anie.200901550

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      One is a quorum: As few as one to three cells of Pseudomonas aeruginosa bacteria are confined in small volumes by the use of microfluidics. These small numbers of cells are able to activate quorum sensing (QS) pathways and achieve QS-dependent growth. The results also show that at low numbers of cells, initiation of QS is highly variable within a clonal population.

    22. C[BOND]N Bond Formation

      Copper-Catalyzed Alkylation of Sulfonamides with Alcohols (pages 5912–5915)

      Feng Shi, Man Kin Tse, Xinjiang Cui, Dirk Gördes, Dirk Michalik, Kerstin Thurow, Youquan Deng and Matthias Beller

      Version of Record online: 6 JUL 2009 | DOI: 10.1002/anie.200901510

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      Water is the only by-product in an efficient and atom-economical Cu(OAc)2-catalyzed coupling of alcohols with sulfonamides (see proposed mechanism; Ts= p-toluenesulfonyl). It was discovered that bissulfonylated amidines formed as intermediates when the transhydrogenative C[BOND]N bond-forming reaction is carried out in air act as novel ligands to stabilize the catalyst.

    23. Heterogeneous Catalysis

      Functionalized Chitosan as a Green, Recyclable, Biopolymer-Supported Catalyst for the [3+2] Huisgen Cycloaddition (pages 5916–5920)

      Mélanie Chtchigrovsky, Ana Primo, Philippe Gonzalez, Karine Molvinger, Mike Robitzer, Françoise Quignard and Frédéric Taran

      Version of Record online: 2 JUL 2009 | DOI: 10.1002/anie.200901309

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      Clean and green: Copper(I) complexes of phenanthroline-based ligands anchored on the chitosan polymer are good catalysts for the “click” cycloaddition of azides with terminal alkynes (see scheme; the scanning electron microscopy image shows the porous structure of the catalyst). These heterogeneous catalytic systems do not require a base or reducing agent and operate in alcohol or water.

    24. Metal Nanoparticles

      Silver Nanoparticles with Broad Multiband Linear Optical Absorption (pages 5921–5926)

      Osman M. Bakr, Vincenzo Amendola, Christine M. Aikens, Wim Wenseleers, Rui Li, Luca Dal Negro, George C. Schatz and Francesco Stellacci

      Version of Record online: 6 JUL 2009 | DOI: 10.1002/anie.200900298

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      A simple one-pot method produces silver nanoparticles coated with aryl thiols that show intense, broad nonplasmonic optical properties. The synthesis works with many aryl-thiol capping ligands, including water-soluble 4-mercaptobenzoic acid. The nanoparticles produced show linear absorption that is broader, stronger, and more structured than most conventional organic and inorganic dyes.

    25. Homogeneous Catalysis

      Addition Reactions of Sulfonylimidates with Imines Catalyzed by Alkaline Earth Metals (pages 5927–5929)

      Huy Van Nguyen, Ryosuke Matsubara and Shū Kobayashi

      Version of Record online: 2 APR 2009 | DOI: 10.1002/anie.200900309

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      Cheaper, safer: Addition reactions of sulfonylimidates to imines are catalyzed by alkaline-earth-metal alkoxide salts, which are abundant, inexpensive, and nontoxic. Diastereoselectivity is highly dependent on solvent and catalyst, and both syn and anti adducts are obtained in high yields and with high diastereoselectivity (see scheme). The first catalytic asymmetric Mannich-type reaction of a sulfonylimidate is also presented.

    26. Macromolecular Architectures

      Imaging of Catenated, Figure-of-Eight, and Trefoil Knot Polymer Rings (pages 5930–5933)

      Michel Schappacher and Alain Deffieux

      Version of Record online: 2 JUL 2009 | DOI: 10.1002/anie.200900704

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      A knotty problem: Macrocyclic topological isomers formed during the end-to-end cyclization of linear polymer chains are imaged by using atomic force microscopy (AFM). Images of isolated molecules (see picture) were obtained after magnification of the initial polymer rings by grafting polystyrene oligomers to the macrocyles. This technique allows the visualization of nontrivial macrocyclic architectures.

    27. Polyoxometalates

      Supramolecular Chemistry on a Cluster Surface: Fixation/Complexation of Potassium and Ammonium Ions with Crown-Ether-Like Rings (pages 5934–5937)

      Achim Müller, Filipa L. Sousa, Alice Merca, Hartmut Bögge, Pere Miró, Jorge A. Fernández, Josep M. Poblet and Carles Bo

      Version of Record online: 6 JUL 2009 | DOI: 10.1002/anie.200902137

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      Integrated but separate: A strongly nucleophilic cluster surface allows the selective complexation and separation of ammonium and potassium ions. Six {Mo4VKO6} rings with crown-ether-like functionality (see picture; Mo blue, V green, K pink, O red) present in the holes of the investigated cluster complex integrate six ammonium ions (N orange, H yellow).

    28. Solar Cells

      An Efficient Dye-Sensitized Solar Cell with an Organic Sensitizer Encapsulated in a Cyclodextrin Cavity (pages 5938–5941)

      Hyunbong Choi, Sang Ook Kang, Jaejung Ko, Guohua Gao, Hong Seok Kang, Moon-Sung Kang, Md. K. Nazeeruddin and Michael Grätzel

      Version of Record online: 6 JUL 2009 | DOI: 10.1002/anie.200902013

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      Dying to get inside: Charge recombination is retarded and dye aggregation is prevented in solar cells that contain the JK-2 dye encapsulated in a cyclodextrin (CD) cavity (see picture). The β-CD/JK-2 device with a polymer gel electrolyte gave an overall conversion efficiency of 7.40 %, which is the highest value reported to date for DSSCs based on the organic sensitizers, and showed excellent stability.

    29. Hyperbranched Polymers

      Synthesis of Well-Defined Hyperbranched Polyamides by Condensation Polymerization of AB2 Monomer through Changed Substituent Effects (pages 5942–5945)

      Yoshihiro Ohta, Shuichi Fujii, Akihiro Yokoyama, Taniyuki Furuyama, Masanobu Uchiyama and Tsutomu Yokozawa

      Version of Record online: 30 JUN 2009 | DOI: 10.1002/anie.200901714

      Thumbnail image of graphical abstract

      Branching out: Condensation polymerization of AB2 monomer proceeds selectively from a core molecule owing to the change of substituent effects between the monomer and the polymer (see scheme). Hyperbranched polyamides are obtained with very low polydispersity and controlled molecular weight determined by the monomer/core feed ratio.

    30. Nanostructures

      Light-Triggered Bioactivity in Three Dimensions (pages 5946–5949)

      Takahiro Muraoka, Chung-Yan Koh, Honggang Cui and Samuel I. Stupp

      Version of Record online: 6 JUL 2009 | DOI: 10.1002/anie.200901524

      Thumbnail image of graphical abstract

      Photocleavage of a 2-nitrobenzyl group in a bioactive peptide amphiphile containing the Arg-Gly-Asp (RGD) epitope triggers a sol-to-gel transition as nanospheres are converted to nanofibers (see picture). This morphological change enhances the bioactivity of the nanostructures surrounding cells in three dimensions.

    31. Photocaging

      A Light-Activated DNA Polymerase (pages 5950–5953)

      Chungjung Chou, Douglas D. Young and Alexander Deiters

      Version of Record online: 30 JUN 2009 | DOI: 10.1002/anie.200901115

      Thumbnail image of graphical abstract

      When the time is right: The widely applied Thermus aquaticus DNA polymerase was rendered light-activatable by incorporation of the photocaged amino acid ortho-nitrobenzyl tyrosine in place of a key tyrosine residue in the active site (see picture). As the modified enzyme was completely inactive until irradiated with UV light, temporal regulation of polymerase activity was possible.

    32. Oligohelicenes

      Noncovalent Interactions in the Asymmetric Synthesis of Rigid, Conjugated Helical Structures (pages 5954–5957)

      Makoto Miyasaka, Maren Pink, Suchada Rajca and Andrzej Rajca

      Version of Record online: 30 JUN 2009 | DOI: 10.1002/anie.200901349

      Thumbnail image of graphical abstract

      From helical folding to helical locking: Tetrakis(β-trithiophene) 1 folds into a helical conformation (RRR) that facilitates double ring annelation, with high diastereoselectivity and modest enantioselectivity, to provide bis[7]helicene 2 (MRM). This rigid, helically locked structure has enhanced chiroptical properties similar to the corresponding [15]helicene.

    33. Diene Oxidation

      Mechanistic Insight into the Palladium-Catalyzed 1,4-Oxidation of 1,3-Dienes to 1,4-Dicarboxy-alk-2-enes (pages 5958–5961)

      Martin D. Eastgate and Frederic G. Buono

      Version of Record online: 30 JUN 2009 | DOI: 10.1002/anie.200901614

      Thumbnail image of graphical abstract

      Side products get involved: The 1,4-oxidation of a diene transforms a simple hydrocarbon into an extremely useful intermediate. A complex formed in situ between palladium and a bicyclic Diels–Alder adduct, which is produced as a side product during the reaction, was responsible for the high rate and high diastereoselectivity observed in the oxidation of cyclohexadiene (see scheme).

    34. Chirality Transfer

      Quantifying End-to-End Conformational Communication of Chirality through an Achiral Peptide Chain (pages 5962–5965)

      Jonathan Clayden, Alejandro Castellanos, Jordi Solà and Gareth A. Morris

      Version of Record online: 30 JUN 2009 | DOI: 10.1002/anie.200901892

      Thumbnail image of graphical abstract

      Successful communication: Two diastereotopic protons more than 60 bonds from the nearest chiral center appear as an AB system, showing that the intervening structure is a well-ordered helix. Decay of anisochronicity quantifies the linear persistence of a helix of achiral amino acids: as little as 3.5 % of the chiral influence is lost with each additional achiral residue.

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