Angewandte Chemie International Edition

Cover image for Vol. 50 Issue 22

May 23, 2011

Volume 50, Issue 22

Pages 4991–5225

  1. Cover Picture

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Back Cover
    5. Graphical Abstract
    6. Corrigendum
    7. News
    8. Author Profile
    9. News
    10. Highlight
    11. Essay
    12. Minireview
    13. Review
    14. Communications
    15. Preview
    1. Cover Picture: Cooperative Transition-Metal and Chiral Brønsted Acid Catalysis: Enantioselective Hydrogenation of Imines To Form Amines (Angew. Chem. Int. Ed. 22/2011) (page 4991)

      Shaolin Zhou, Steffen Fleischer, Dr. Kathrin Junge and Prof. Dr. Matthias Beller

      Article first published online: 5 MAY 2011 | DOI: 10.1002/anie.201102496

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      Modern metal catalysis combined with organocatalysis mediated by a chiral Brønsted acid offers an attractive and environmentally favorable alternative to well-established asymmetric hydrogenations with catalysts based on precious metals. M. Beller and co-workers describe in their communication on page 5120 ff. how the key to success is the cooperative action of specific well-defined achiral iron complexes and chiral bulky phosphoric acid esters.

  2. Inside Cover

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Back Cover
    5. Graphical Abstract
    6. Corrigendum
    7. News
    8. Author Profile
    9. News
    10. Highlight
    11. Essay
    12. Minireview
    13. Review
    14. Communications
    15. Preview
    1. Inside Cover: Inhibition of Amyloid Peptide Fibrillation by Inorganic Nanoparticles: Functional Similarities with Proteins (Angew. Chem. Int. Ed. 22/2011) (page 4992)

      Prof. Seong Il Yoo, Dr. Ming Yang, Dr. Jeffrey R. Brender, Dr. Vivekanandan Subramanian, Dr. Kai Sun, Dr. Nam Eok Joo, Prof. Soo-Hwan Jeong, Prof. Ayyalusamy Ramamoorthy and Prof. Nicholas A. Kotov

      Article first published online: 11 MAY 2011 | DOI: 10.1002/anie.201102689

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      Amyloid peptide fibrillation causes many neurodegenerative disorders including Alzheimers disease. Some drugs can inhibit this process by binding to peptides in a 1:1 ratio. In their Communication on page 5110 ff., N. A. Kotov et al. describe the inhibition efficacy of nanoparticles (NPs), which bind to peptide oligomers. The mechanism of NP inhibition is similar to that of proteins responsible for preventing amyloid fibrillation in the human body.

  3. Back Cover

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Back Cover
    5. Graphical Abstract
    6. Corrigendum
    7. News
    8. Author Profile
    9. News
    10. Highlight
    11. Essay
    12. Minireview
    13. Review
    14. Communications
    15. Preview
    1. Back Cover: Coupling Amperometry and Total Internal Reflection Fluorescence Microscopy at ITO Surfaces for Monitoring Exocytosis of Single Vesicles (Angew. Chem. Int. Ed. 22/2011)

      Anne Meunier, Ouardane Jouannot, Dr. Rémy Fulcrand, Dr. Isabelle Fanget, Dr. Marine Bretou, Dr. Erdem Karatekin, Dr. Stéphane Arbault, Dr. Manon Guille, Dr. François Darchen, Dr. Frédéric Lemaître and Prof. Christian Amatore

      Article first published online: 27 APR 2011 | DOI: 10.1002/anie.201102239

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      Exocytosis is a key mechanism by which a cellular organism releases molecular messengers into the extracellular medium. C. Amatore et al. report in their Communication on page 5081 ff. the elaboration of an ITO microdevice that combines two powerful techniques—amperometry at microelectrodes and total internal reflection fluorescence microscopy—which allows the simultaneous real-time monitoring of complementary aspects of single exocytotic events at single living cells.

  4. Graphical Abstract

    1. Top of page
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    3. Inside Cover
    4. Back Cover
    5. Graphical Abstract
    6. Corrigendum
    7. News
    8. Author Profile
    9. News
    10. Highlight
    11. Essay
    12. Minireview
    13. Review
    14. Communications
    15. Preview
    1. Graphical Abstract: Angew. Chem. Int. Ed. 22/2011 (pages 4995–5007)

      Article first published online: 16 MAY 2011 | DOI: 10.1002/anie.201190043

  5. Corrigendum

    1. Top of page
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    4. Back Cover
    5. Graphical Abstract
    6. Corrigendum
    7. News
    8. Author Profile
    9. News
    10. Highlight
    11. Essay
    12. Minireview
    13. Review
    14. Communications
    15. Preview
    1. You have free access to this content
      Corrigendum: Removable Directing Groups in Organic Synthesis and Catalysis (page 5007)

      Dr. Géraldine Rousseau and Prof. Dr. Bernhard Breit

      Article first published online: 16 MAY 2011 | DOI: 10.1002/anie.201101929

      This article corrects:

      Removable Directing Groups in Organic Synthesis and Catalysis

      Vol. 50, Issue 11, 2450–2494, Article first published online: 1 MAR 2011

  6. News

    1. Top of page
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    3. Inside Cover
    4. Back Cover
    5. Graphical Abstract
    6. Corrigendum
    7. News
    8. Author Profile
    9. News
    10. Highlight
    11. Essay
    12. Minireview
    13. Review
    14. Communications
    15. Preview
  7. Author Profile

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Back Cover
    5. Graphical Abstract
    6. Corrigendum
    7. News
    8. Author Profile
    9. News
    10. Highlight
    11. Essay
    12. Minireview
    13. Review
    14. Communications
    15. Preview
    1. Jin-Quan Yu (page 5014)

      Article first published online: 16 MAY 2011 | DOI: 10.1002/anie.201101811

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      “What I look for first in a publication is a surprising phenomenon. The most important thing I learned from my parents is to not give up …” This and more about Jin-Quan Yu can be found on page 5014.

  8. News

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Back Cover
    5. Graphical Abstract
    6. Corrigendum
    7. News
    8. Author Profile
    9. News
    10. Highlight
    11. Essay
    12. Minireview
    13. Review
    14. Communications
    15. Preview
  9. Highlight

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Back Cover
    5. Graphical Abstract
    6. Corrigendum
    7. News
    8. Author Profile
    9. News
    10. Highlight
    11. Essay
    12. Minireview
    13. Review
    14. Communications
    15. Preview
    1. Conjugated Polyelectrolytes

      Counterion Pinning in Conjugated Polyelectrolytes for Applications in Organic Electronics (pages 5016–5017)

      Dr. Ullrich Scherf

      Article first published online: 19 APR 2011 | DOI: 10.1002/anie.201101643

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      Immobilizing counterions: Cationic, conjugated polyelectrolytes can be used to improve the electron injection from low-work-function metal electrodes into the active layers of organic light-emitting diodes. The problem of mobile counterions has now been solved through the use of zwitterionic, conjugated polyelectrolytes as thin injection layers. These polyelectrolytes (see structure) are made from neutral precursor polymers in a simple one-step reaction.

  10. Essay

    1. Top of page
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    6. Corrigendum
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    10. Highlight
    11. Essay
    12. Minireview
    13. Review
    14. Communications
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    1. Synthetic Methods

      Organocatalysis and C[BOND]H Activation Meet Radical- and Electron-Transfer Reactions (pages 5018–5022)

      Prof. Armido Studer and Prof. Dennis P. Curran

      Article first published online: 27 APR 2011 | DOI: 10.1002/anie.201101597

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      A radical outlook: Recently published “organocatalytic C[BOND]H activation reactions” have now been interpreted as base-promoted homolytic substitutions. The addition of an aryl radical to an arene followed by deprotonation (see above) and electron transfer form part of the chain reaction. Although these new results are not conceptual breakthroughs, they could be experimental breakthroughs because they presage new transformations in radical (anion) chemistry.

  11. Minireview

    1. Top of page
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    3. Inside Cover
    4. Back Cover
    5. Graphical Abstract
    6. Corrigendum
    7. News
    8. Author Profile
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    10. Highlight
    11. Essay
    12. Minireview
    13. Review
    14. Communications
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    1. Protein Engineering

      Making and Breaking Peptide Bonds: Protein Engineering Using Sortase (pages 5024–5032)

      Maximilian Wei-Lin Popp and Prof. Dr. Hidde L. Ploegh

      Article first published online: 27 APR 2011 | DOI: 10.1002/anie.201008267

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      It takes all sortases: Enzymatic formation of a peptide bond using the sortase A transpeptidase (SrtA) provides a convenient and mild means for engineering proteins to contain nongenetically templated modifications. Myriad applications are possible, from producing homogeneous post-translational modification mimics, assembling protein domains, to anchoring proteins to solid surfaces.

  12. Review

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

      Nitroxides: Applications in Synthesis and in Polymer Chemistry (pages 5034–5068)

      Dr. Ludger Tebben and Prof. Dr. Armido Studer

      Article first published online: 28 APR 2011 | DOI: 10.1002/anie.201002547

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      The many faces of radicals: Nitroxides can be applied as stoichiometric and catalytic oxidants in the oxidation of alcohols (see scheme) and carbanions, as well as in oxidative C[BOND]C bond-forming reactions. Stable radicals of this class can also be used as precursors for C-centered radicals as well as for the formation of such radicals for synthesis or polymerization.

  13. Communications

    1. Top of page
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    5. Graphical Abstract
    6. Corrigendum
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    8. Author Profile
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    10. Highlight
    11. Essay
    12. Minireview
    13. Review
    14. Communications
    15. Preview
    1. Pulsed EPR Spectroscopy in Cells

      Long-Range Distance Measurements on Nucleic Acids in Cells by Pulsed EPR Spectroscopy (pages 5070–5074)

      Ivan Krstić, Robert Hänsel, Dr. Olga Romainczyk, Dr. Joachim W. Engels, Dr. Volker Dötsch and Dr. Thomas F. Prisner

      Article first published online: 19 APR 2011 | DOI: 10.1002/anie.201100886

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      Mapping the structure of nucleic acids: Pulsed electron–electron double-resonance (PELDOR) spectroscopy has been applied for the first time to map the global structure of nucleic acids inside Xenopus laevis oocytes (see picture). The distances measured in vitro and in cells are the same, which implies the existence of stable overall conformations of the hairpin RNA and the neomycin-sensing riboswitch studied.

    2. Protein Chemistry

      Modular Assembly of Macrocyclic Organo–Peptide Hybrids Using Synthetic and Genetically Encoded Precursors (pages 5075–5080)

      Jessica M. Smith, Dr. Francesca Vitali, Steven A. Archer and Prof. Dr. Rudi Fasan

      Article first published online: 19 APR 2011 | DOI: 10.1002/anie.201101331

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      Mix, click, cyclize: Conformationally constrained organo–peptide hybrids can be constructed by a tandem chemoselective reaction between a synthetic molecule and a recombinant protein. Diverse macrocyclic structures were obtained in cyclic, lariat, and protein-tethered configurations by varying the nature of the synthetic and biosynthetic precursors.

    3. Bioanalysis

      Coupling Amperometry and Total Internal Reflection Fluorescence Microscopy at ITO Surfaces for Monitoring Exocytosis of Single Vesicles (pages 5081–5084)

      Anne Meunier, Ouardane Jouannot, Dr. Rémy Fulcrand, Dr. Isabelle Fanget, Dr. Marine Bretou, Dr. Erdem Karatekin, Dr. Stéphane Arbault, Dr. Manon Guille, Dr. François Darchen, Dr. Frédéric Lemaître and Prof. Christian Amatore

      Article first published online: 27 APR 2011 | DOI: 10.1002/anie.201101148

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      More transparency in bioanalysis: A microdevice based on transparent indium tin oxide (ITO) electrodes allows simultaneous total internal reflection fluorescence microscopy and amperometric measurements. Use of the device in the coupled optical and electrochemical detection of single exocytotic events is demonstrated with enterochromaffin BON cells (see picture).

    4. Folding Processes

      Single-Chain Polymeric Nanoparticles by Stepwise Folding (pages 5085–5089)

      Tristan Mes, Rob van der Weegen, Dr. Anja R. A. Palmans and Prof. Dr. E. W. Meijer

      Article first published online: 18 APR 2011 | DOI: 10.1002/anie.201100104

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      Light-induced self-assembly leads to the folding of synthetic random-coil polymers into highly stable single-chain polymeric chiral nanoparticles (see picture; green: side chains, blue: phenyl rings, red: nitrophenyl leaving groups). The folding of the polymer was aided by heating and cooling steps.

    5. Gold Catalysis

      Taking Advantage of the Ambivalent Reactivity of Ynamides in Gold Catalysis: A Rare Case of Alkyne Dimerization (pages 5090–5094)

      Søren Kramer, Yann Odabachian, Dr. Jacob Overgaard, Dr. Mario Rottländer, Dr. Fabien Gagosz and Prof. Troels Skrydstrup

      Article first published online: 19 APR 2011 | DOI: 10.1002/anie.201100327

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      A gold mine of results: A series of ynamides have been dimerized in the presence of a gold(I) complex. This unprecedented transformation involves the formation of a key keteniminium intermediate that reacts to form a variety of cyclic and acyclic products. The substitution pattern of the ynamide determines which product is formed (see scheme; EWG=electron-withdrawing group, Ts=p-toluenesulfonyl).

    6. Asymmetric Catalysis

      Asymmetric Organocatalytic 1,6-Conjugate Addition of Aldehydes to Dienic Sulfones (pages 5095–5098)

      John J. Murphy, Adrien Quintard, Prof. Patrick McArdle, Prof. Dr. Alexandre Alexakis and Dr. John C. Stephens

      Article first published online: 28 APR 2011 | DOI: 10.1002/anie.201100804

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      An unprecedented 1,6-enamine conjugate addition exploiting the charge delocalization in 1,3-bis(sulfonyl) butadienes has been developed. By appropriately designing a Michael acceptor, unique reactivities were obtained for the formation of highly valuable dienes containing two versatile vinyl sulfones (see scheme, TMS=trimethylsilyl).

    7. Polyphenolic Natural Products

      Binding of Filamentous Actin and Winding into Fibrillar Aggregates by the Polyphenolic C-Glucosidic Ellagitannin Vescalagin (pages 5099–5104)

      Prof. Stéphane Quideau, Dr. Céline Douat-Casassus, Daniela Melanie Delannoy López, Dr. Carmelo Di Primo, Dr. Stefan Chassaing, Rémi Jacquet, Dr. Frédéric Saltel and Dr. Elisabeth Genot

      Article first published online: 27 APR 2011 | DOI: 10.1002/anie.201006712

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      Winding it up: The plant polyphenolic metabolite vescalagin fulfills all the requirements for use as an antiactin agent in cellular biological investigations. Despite its high hydrophilicity, it rapidly enters cells and disturbs the organization of the actin cytoskeleton in a dose-dependent reversible manner by binding fibrillar actin and forcing the actin filaments (left) to wind themselves into ball-like fibrillar aggregates (right).

    8. Chemosensors

      Protease Probes Built from DNA: Multispectral Fluorescent DNA–Peptide Conjugates as Caspase Chemosensors (pages 5105–5109)

      Nan Dai, Jia Guo, Yin Nah Teo and Prof. Dr. Eric T. Kool

      Article first published online: 31 MAR 2011 | DOI: 10.1002/anie.201007805

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      Shaken, not stirred: A novel design for protease sensors is described, in which peptides are conjugated to a DNA backbone carrying multiple fluorophores. The multispectral oligodeoxyfluoroside (ODF) fluorophores are strongly quenched by a dabcyl group at the end of each peptide. In vitro and cellular selectivity assays showed that a mixture of three sensors could be used to identify different caspase activities by the fluorescence outcome (see picture).

    9. Protein Functionalities

      Inhibition of Amyloid Peptide Fibrillation by Inorganic Nanoparticles: Functional Similarities with Proteins (pages 5110–5115)

      Prof. Seong Il Yoo, Dr. Ming Yang, Dr. Jeffrey R. Brender, Dr. Vivekanandan Subramanian, Dr. Kai Sun, Dr. Nam Eok Joo, Prof. Soo-Hwan Jeong, Prof. Ayyalusamy Ramamoorthy and Prof. Nicholas A. Kotov

      Article first published online: 14 APR 2011 | DOI: 10.1002/anie.201007824

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      Nanoparticles for amyloid diseases: CdTe nanoparticles (NPs) can efficiently prevent fibrillation of amyloid peptides; the process is based on the multiple binding of Aβ oligomers to CdTe NPs. The molar efficiency and the inhibition mechanism displayed by the NPs are analogous to the mechanism found for proteins responsible for the prevention of amyloid fibrillation in the human body.

    10. Smart Soft Materials

      Bending and Stretching Actuation of Soft Materials through Surface-Initiated Polymerization (pages 5116–5119)

      Dr. Yuquan Zou, Adriel Lam, Prof. Dr. Donald E. Brooks, Prof. Dr. A. Srikantha Phani and Prof. Dr. Jayachandran N. Kizhakkedathu

      Article first published online: 21 APR 2011 | DOI: 10.1002/anie.201008252

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      A redhead: Surface-grafted hydrophilic polymer brushes (see picture) with high molecular weight and graft density caused reversible bending and stretching of soft polymeric substrates on a macroscale. The shape change of the substrate was tuned to respond to different stimuli including humidity, temperature, and pH.

    11. Iron Catalysis

      Cooperative Transition-Metal and Chiral Brønsted Acid Catalysis: Enantioselective Hydrogenation of Imines To Form Amines (pages 5120–5124)

      Shaolin Zhou, Steffen Fleischer, Dr. Kathrin Junge and Prof. Dr. Matthias Beller

      Article first published online: 15 APR 2011 | DOI: 10.1002/anie.201100878

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      Control with an iron hand: A broad range of ketimines underwent enantioselective hydrogenation in the presence of a chiral Brønsted catalyst and a well-defined nonchiral iron catalyst (see scheme). This procedure constitutes an attractive and environmentally favorable alternative to well-established asymmetric hydrogenation reactions with precious-metal catalysts.

    12. Atropisomeric Scaffolds

      Synthesis of Atropisomerically Defined, Highly Substituted Biaryl Scaffolds through Catalytic Enantioselective Bromination and Regioselective Cross-Coupling (pages 5125–5129)

      Jeffrey L. Gustafson, Dr. Daniel Lim, Kimberly T. Barrett and Prof. Dr. Scott J. Miller

      Article first published online: 21 APR 2011 | DOI: 10.1002/anie.201101147

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      A selective sequence: An enantioselective synthesis (see scheme) of atropisomerically defined p-terphenyls, as well as tetra- and pentaaryl compounds is reported. The synthesis proceeds through sequential atropisomer-selective electrophilic aromatic substitution and regioselective palladium-catalyzed cross-coupling reactions.

    13. Multiplex Protease Assay

      Lanthanide-Coded Protease-Specific Peptide–Nanoparticle Probes for a Label-Free Multiplex Protease Assay Using Element Mass Spectrometry: A Proof-of-Concept Study (pages 5130–5133)

      Dr. Xiaowen Yan, Limin Yang and Prof. Dr. Qiuquan Wang

      Article first published online: 18 APR 2011 | DOI: 10.1002/anie.201101087

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      Coded messages: Lanthanide (Ln) coded protease-specific peptide–nanoparticle (NPs) conjugates act as probes for a multiplex protease assay (MPA) using inductively coupled plasma mass spectrometry (ICP-MS; see picture). MPA can be achieved by centrifugal separation of the protease-cleaved and uncleaved probes and subsequent determination of the released Ln tags.

    14. Regioselective Hydroacylation

      Rhodium-Catalyzed Branched-Selective Alkyne Hydroacylation: A Ligand-Controlled Regioselectivity Switch (pages 5134–5138)

      Dr. Carlos González-Rodríguez, Rebekah J. Pawley, Dr. Adrian B. Chaplin, Dr. Amber L. Thompson, Prof. Andrew S. Weller and Dr. Michael C. Willis

      Article first published online: 19 APR 2011 | DOI: 10.1002/anie.201100956

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      It's all in the ligand: By choice of the appropriate diphosphine ligand a previously linear-selective alkyne hydroacylation process can be “switched” to be highly branched-selective (see scheme, l=linear, b=branched). Structural data for the ortho-iPr-dppe–rhodium catalyst suggest restricted rotation of the phosphine aryl units may be responsible for the observed selectivity.

    15. Oxidative Esterification

      General and Selective Palladium-Catalyzed Oxidative Esterification of Alcohols (pages 5139–5143)

      Dr. Saravanan Gowrisankar, Dr. Helfried Neumann and Prof. Dr. Matthias Beller

      Article first published online: 27 APR 2011 | DOI: 10.1002/anie.201008035

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      Selectively esterified: Primary alcohols react with dioxygen as a benign oxidant in a palladium-catalyzed oxidative esterification (see scheme). The corresponding aldehydes and esters are formed highly selectively depending on the catalyst system. The reactions take place in the presence of commercially available ligands without the need for additional organic hydrogen acceptors.

    16. Palladium-Catalyzed Aerobic Oxidative Direct Esterification of Alcohols (pages 5144–5148)

      Chao Liu, Jing Wang, Lingkui Meng, Yi Deng, Yao Li and Prof. Aiwen Lei

      Article first published online: 7 APR 2011 | DOI: 10.1002/anie.201008073

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      One step from alcohol to ester: A palladium-catalyzed oxidative esterification of various benzylic alcohols with methanol and long-chain aliphatic alcohols was carried out in the presence of molecular oxygen as the oxidant (see scheme). By considering the effects of substitution and potential mechanistic pathways, the applicability of this method to a range of different substrates was shown.

    17. Natural Product Synthesis

      An Expedient Synthesis of a Functionalized Core Structure of Bielschowskysin (pages 5149–5152)

      Prof. Dr. K. C. Nicolaou, Dr. Vikrant A. Adsool and Christopher R. H. Hale

      Article first published online: 26 APR 2011 | DOI: 10.1002/anie.201101360

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      Photons in action: Cascade sequences, brevity, and efficiency are the hallmarks of the synthesis of a functionalized tricyclo[9.3.0.0]tetradecane ring system of the marine natural product bielschowskysin. The synthesis is achieved in five steps, with the key step being an exquisite intramolecular [2+2] photocycloaddition of a macrocyclic precursor (see scheme).

    18. Microreactors

      Indirect Cation-Flow Method: Flash Generation of Alkoxycarbenium Ions and Studies on the Stability of Glycosyl Cations (pages 5153–5156)

      Dr. Kodai Saito, Koji Ueoka, Dr. Kouichi Matsumoto, Prof. Seiji Suga, Dr. Toshiki Nokami and Prof. Jun-ichi Yoshida

      Article first published online: 20 APR 2011 | DOI: 10.1002/anie.201100854

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      Go with the flow: The indirect cation-flow method based on the generation of highly reactive organic cations from their precursors using electrochemically generated [ArS(ArSSAr)]+ was developed in flow microreactor systems (see scheme; Bn=benzyl, M=micromixer, R=microtube reactor). The method was applied to evaluate glycosyl cations such as A or their equivalents and glycosylation reactions.

    19. Allylation

      Migratory Decarboxylative Coupling of Coumarins: Synthetic and Mechanistic Aspects (pages 5157–5161)

      Ranjan Jana, James J. Partridge and Prof. Jon A. Tunge

      Article first published online: 19 APR 2011 | DOI: 10.1002/anie.201100765

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      On the move: Decarboxylative coupling of allyl 4-methyl-3-carboxycoumarins provides the products of γ-allylation of the methyl group rather than the typical regiospecific α-allylation. Mechanistic studies show that intramolecular proton transfer from the 4-methyl group to the 3-carboxylate allows allylation of the remote methyl group. The resulting 4-butenyl-3-carboxyl coumarin undergoes Pd0-catalyzed decarboxylation to provide the observed products (see scheme).

    20. Alkaloid Synthesis

      Core Modification of Cytisine: A Modular Synthesis (pages 5162–5165)

      Dr. Christoph Hirschhäuser, Claire A. Haseler and Prof. Dr. Timothy Gallagher

      Article first published online: 21 APR 2011 | DOI: 10.1002/anie.201100441

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      Getting down to the core: A novel, modular, and more robust synthesis of cytisine, a partial agonist selective for the α4β2 nicotinic acetylcholine receptor, also allows modification of the core structure, as exemplified by the first azacytisine and a cytisine–varenicline hybrid. Key steps include Stille coupling of heteroarylstannanes with a bromolactam motif and an in situ epimerization/alkylative cyclization to complete the tricyclic core (see scheme).

    21. Organic Solar Cells

      1,4-Fullerene Derivatives: Tuning the Properties of the Electron Transporting Layer in Bulk-Heterojunction Solar Cells (pages 5166–5169)

      Dr. Alessandro Varotto, Neil D. Treat, Dr. Jang Jo, Dr. Christopher G. Shuttle, Nicolas A. Batara, Dr. Fulvio G. Brunetti, Dr. Jung Hwa Seo, Prof. Michael L. Chabinyc, Prof. Craig J. Hawker, Prof. Alan J. Heeger and Prof. Fred Wudl

      Article first published online: 19 APR 2011 | DOI: 10.1002/anie.201100029

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      Tune me up: The increasing number of new donor materials for organic solar cells requires compatible electron acceptors. A series of 1,4-fullerene adducts with tunable chemical, electronic, and material properties is introduced to effectively influence the photovoltaic characteristics of solar cells.

    22. Nanoparticles

      Stabilization of 200-Atom Platinum Nanoparticles by Organosilane Fragments (pages 5170–5173)

      Dr. Katrin Pelzer, Dr. Michael Hävecker, Dr. Malika Boualleg, Prof. Jean-Pierre Candy and Prof. Jean-Marie Basset

      Article first published online: 19 APR 2011 | DOI: 10.1002/anie.201008209

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      Three's a charm: Platinum nanoparticles of 2 nm diameter and containing approximately 200 atoms covered with n-octylsilyl groups (see picture, right; Pt blue, Si red, C gray, H turquoise) form when [Pt(dba)2] (dba=dibenzylideneacetone) decomposes in the presence of n-octylsilane. The particles adopt a cuboctahedral structure with an edge length of three atoms.

    23. Heterogeneous Catalysis

      The Energy Dependence of the Ratio of Step and Terrace Reactivity for H2 Dissociation on Stepped Platinum (pages 5174–5177)

      Dr. Irene M. N. Groot, Prof. Dr. Aart W. Kleyn and Dr. Ludo B. F. Juurlink

      Article first published online: 19 APR 2011 | DOI: 10.1002/anie.201007093

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      The fraction of dissociation processes fD for H2 on platinum that take place on low-coordinate sites of nanoparticles is strongly dependent on the gas temperature of the incoming molecules and on the diameter d of the nanoparticles (see picture). For high gas temperatures and large nanoparticles, dissociation occurs mostly on terraces. Therefore, assumptions that steps always dominate reaction in heterogeneous catalysis cannot be justified.

    24. Natural Product Synthesis

      Total Synthesis of the Protein Phosphatase 2A Inhibitor Lactodehydrothyrsiferol (pages 5178–5181)

      Dane J. Clausen, Dr. Shuangyi Wan and Prof. Dr. Paul E. Floreancig

      Article first published online: 21 APR 2011 | DOI: 10.1002/anie.201007757

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      Cascading epoxides: The squalene-derived polyether lactodehydrothyrsiferol (1) has been prepared through a convergent sequence that features an epoxide-opening cascade to construct the tetrahydrofuran and tetrahydropyran subunits. Additional features include a stereodivergent diene diepoxidation, a monodeoxygenation of a triol, and complex fragment couplings through Suzuki and Nozaki–Hiyama–Kishi reactions.

    25. Blackberry Structures

      Viral-Capsid-Type Vesicle-Like Structures Assembled from M12L24 Metal–Organic Hybrid Nanocages (pages 5182–5187)

      Dong Li, Dr. Wu Zhou, Prof. Dr. Kai Landskron, Dr. Sota Sato, Prof. Dr. Christopher J. Kiely, Prof. Dr. Makoto Fujita and Prof. Dr. Tianbo Liu

      Article first published online: 18 APR 2011 | DOI: 10.1002/anie.201007829

      Thumbnail image of graphical abstract

      Without the thorn: In polar solvents, cationic M12L24 nanocages slowly assembled into hollow spherical “blackberry” structures, the size of which could be tuned by changing the counterion concentration or solvent polarity. The self-assembly process showed similar kinetic and thermodynamic features to viral-capsid formation. (Copyright (2005) National Academy of Sciences, USA. The image of the hepatitis B virus capsid is from the RCSB PDB (ID: 1QGT).)

    26. Tandem Reactions

      Synthesis of Heterocycles through a Ruthenium-Catalyzed Tandem Ring-Closing Metathesis/Isomerization/N-Acyliminium Cyclization Sequence (pages 5188–5191)

      Erhad Ascic, Dr. Jakob F. Jensen and Dr. Thomas E. Nielsen

      Article first published online: 21 APR 2011 | DOI: 10.1002/anie.201100417

      Thumbnail image of graphical abstract

      Tandem bicycle: In the title reaction double bonds created during ring-closing metathesis isomerize to generate reactive iminium intermediates that undergo intramolecular cyclization reactions with tethered heteroatom and carbon nucleophiles. In this way, a series of biologically interesting heterocyclic compounds can be made, including a known precursor for the total synthesis of the antiparasitic natural product harmicine.

    27. C[BOND]H Functionalization

      A Practical Strategy for the Structural Diversification of Aliphatic Scaffolds through the Palladium-Catalyzed Picolinamide-Directed Remote Functionalization of Unactivated C(sp3)[BOND]H Bonds (pages 5192–5196)

      Dr. Gang He and Prof. Dr. Gong Chen

      Article first published online: 27 APR 2011 | DOI: 10.1002/anie.201100984

      Thumbnail image of graphical abstract

      Hats off to the director: High levels of regio- and stereoselectivity were observed for a broad range of amine substrates with aryl and vinyl iodide coupling partners in the title reaction. The synthetic utility of this strategy was highlighted by the ready preparation from threonine of 1, with a removable picolinamide auxiliary PAr, and its coupling with 2 in a concise formal synthesis of (+)-obafluorin. TBS=tert-butyldimethylsilyl.

    28. Asymmetric Hydroxylation

      Ruthenium-Catalyzed Regio- and Enantioselective Allylic Substitution with Water: Direct Synthesis of Chiral Allylic Alcohols (pages 5197–5199)

      Naoya Kanbayashi and Prof. Kiyotaka Onitsuka

      Article first published online: 21 APR 2011 | DOI: 10.1002/anie.201101078

      Thumbnail image of graphical abstract

      Less is more: A new route to access chiral allylic alcohols through the regio- and enantioselective substitution of monosubstituted allylic chlorides with water has been developed. The reaction is catalyzed effectively by planar-chiral cyclopentadienyl ruthenium complexes (see scheme).

    29. Fischer–Tropsch Synthesis

      Mesoporous Zeolite-Supported Ruthenium Nanoparticles as Highly Selective Fischer–Tropsch Catalysts for the Production of C5–C11 Isoparaffins (pages 5200–5203)

      Dr. Jincan Kang, Kang Cheng, Lei Zhang, Prof. Dr. Qinghong Zhang, Jiansheng Ding, Dr. Weiqi Hua, Dr. Yinchuan Lou, Qingge Zhai and Prof. Dr. Ye Wang

      Article first published online: 21 APR 2011 | DOI: 10.1002/anie.201101095

      Thumbnail image of graphical abstract

      A highly selective catalyst based on mesoporous zeolites for the production of C5–C11 isoparaffins from syngas has been developed. The selectivity to C5–C11 hydrocarbons over Ru/meso-ZSM-5 reaches about 80 % with a ratio of isoparaffins to n-paraffins of 2.7:1. The mesoporous structure and the unique acidity of meso-ZSM-5 play key roles in tuning the product selectivity by controlling the secondary hydrocracking reactions.

    30. Peptidomimetics

      Maintaining Biological Activity by Using Triazoles as Disufide Bond Mimetics (pages 5204–5206)

      Dr. Kai Holland-Nell and Prof. Morten Meldal

      Article first published online: 29 MAR 2011 | DOI: 10.1002/anie.201005846

      Thumbnail image of graphical abstract

      Click into place: Tachyplesin-I (TP-I) analogues in which both disulfide bridges (1) have been replaced with triazoles (2) represent structural mimetics of TP-I that display similar or slightly improved antibacterial activity. Optimized structures were obtained by replacing the cysteine residues in TP-I by azido- and alkyno-functionalized amino acids.

    31. Disulfide Mimics

      “Triazole Bridge”: Disulfide-Bond Replacement by Ruthenium-Catalyzed Formation of 1,5-Disubstituted 1,2,3-Triazoles (pages 5207–5211)

      Martin Empting, Dr. Olga Avrutina, Dr. Reinhard Meusinger, Sebastian Fabritz, Michael Reinwarth, Prof. Dr. Markus Biesalski, Stephan Voigt, Prof. Dr. Gerd Buntkowsky and Prof. Dr. Harald Kolmar

      Article first published online: 4 MAY 2011 | DOI: 10.1002/anie.201008142

      Thumbnail image of graphical abstract

      A good impression: A modular approach using a ruthenium(II) catalyst during peptide synthesis gives rigid and well-defined triazole bridges as tailor-made substitutes for natural disulfide bridges (see structures). The corresponding modification of the monocyclic sunflower trypsin inhibitor-1 yielded an equally potent peptidomimetic containing a redox stable 1,5-disubstituted 1,2,3-triazole bridge.

    32. Polyoxometalates

      Molecular Growth of a Core–Shell Polyoxometalate (pages 5212–5216)

      Dr. Xikui Fang, Prof. Dr. Paul Kögerler, Prof. Dr. Yuji Furukawa, Dr. Manfred Speldrich and Prof. Dr. Marshall Luban

      Article first published online: 19 APR 2011 | DOI: 10.1002/anie.201008225

      Thumbnail image of graphical abstract

      In a nutshell: A 4.3 nm core–shell aggregate of 16 polyoxotungstate building units (see picture of the W/Mn skeleton) delineates the upper limit for structural complexity in molecular metal oxide cluster chemistry to date. This structure is defined by a backbone network of dual Mn[BOND]O[DOUBLE BOND]W bridges; a retroanalysis of their formation suggests the importance of templation and kinetic control in the self-assembly of the {MnIII40WVI224} polyanion.

    33. C[BOND]H Functionalization

      Palladium-Catalyzed Double C[BOND]H Activation Directed by Sulfoxides in the Synthesis of Dibenzothiophenes (pages 5217–5220)

      Dr. Rajarshi Samanta and Dr. Andrey P. Antonchick

      Article first published online: 19 APR 2011 | DOI: 10.1002/anie.201100775

      Thumbnail image of graphical abstract

      S[DOUBLE BOND]O shows where to go: A novel double C[BOND]H activation of aromatic compounds with a sulfoxide as a directing group results in the highly regioselective synthesis of polysubstituted dibenzothiophenes (see scheme). The reaction cascade consists of palladium-catalyzed double C[BOND]H activation and a Pummerer rearrangement followed by palladium-catalyzed C[BOND]S bond formation.

    34. Sb–N Chemistry

      An Unusual Isomerization to Tetraazastiboles (pages 5221–5224)

      Mathias Lehmann, Prof. Dr. Axel Schulz and Dr. Alexander Villinger

      Article first published online: 21 APR 2011 | DOI: 10.1002/anie.201100663

      Thumbnail image of graphical abstract

      A protective shield makes it possible: The synthesis and full characterization of a tetraazastibole is presented for the first time. The conversion of [N3Sb(μ-NMes*)2SbN3] (Mes*=2,4,6-Me3C6H2) into tetraazastibole, Mes*N4Sb, is an unusual isomerization triggered by the action of the Lewis acid B(C6F5)3, which is also needed for adduct formation: the N4Sb ring is kinetically protected between the large Mes* and B(C6F5)3 units.

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      Article first published online: 16 MAY 2011 | DOI: 10.1002/anie.201190044

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