Chemistry - A European Journal

Cover image for Vol. 18 Issue 52

December 21, 2012

Volume 18, Issue 52

Pages 16585–16961

  1. Cover Picture

    1. Top of page
    2. Cover Picture
    3. Graphical Abstract
    4. News
    5. Communications
    6. Full Papers
    1. You have free access to this content
      Cover Picture: Catalytic Enantioselective Desymmetrisation as a Tool for the Synthesis of Hodgkinsine and Hodgkinsine B (Chem. Eur. J. 52/2012) (page 16585)

      Dr. Robert H. Snell, Dr. Matthew J. Durbin, Dr. Robert L. Woodward and Dr. Michael C. Willis

      Version of Record online: 18 DEC 2012 | DOI: 10.1002/chem.201290220

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      An enantioselective Pd-catalyzed allylation processes has been used to achieve the highly selective desymmetrization of meso-chimonanthine. The desymmetrized material is carried through five subsequent transformations to deliver the alkaloid natural product hodgkinsine B. The naturally occurring alkaloid was originally isolated from the species Hodgkinsonia frutescens (shown as the background image) from the family Rubiaceae. For more details see the Full Paper by M. C. Willis et al. on page 16754 ff. Background image used with permission from Blackdiamond Images.

  2. Graphical Abstract

    1. Top of page
    2. Cover Picture
    3. Graphical Abstract
    4. News
    5. Communications
    6. Full Papers
  3. News

    1. Top of page
    2. Cover Picture
    3. Graphical Abstract
    4. News
    5. Communications
    6. Full Papers
  4. Communications

    1. Top of page
    2. Cover Picture
    3. Graphical Abstract
    4. News
    5. Communications
    6. Full Papers
    1. Hetero Diels–Alder Reaction

      Asymmetric Phospha-Diels–Alder Reaction: A Stereoselective Approach towards P-Chiral Phosphanes through Diastereotopic Face Differentiation (pages 16604–16607)

      M. Sc. Tobias Möller, Menyhárt B. Sárosi and Prof. Dr. Evamarie Hey-Hawkins

      Version of Record online: 30 NOV 2012 | DOI: 10.1002/chem.201203671

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      Old principles, new chemistry: A facile stereoselective synthesis of P-chiral phosphanes is described in which the principle of enantiotopic and diastereotopic face differentiation used in carbon chemistry is extended to a phosphorus atom in a planar environment, that is, 2H-phospholes.

    2. Azidation

      Iron-Catalyzed Chemoselective Azidation of Benzylic Silyl Ethers (pages 16608–16611)

      Dr. Yoshinari Sawama, Saori Nagata, Yuki Yabe, Kosuke Morita, Dr. Yasunari Monguchi and Prof. Dr. Hironao Sajiki

      Version of Record online: 30 NOV 2012 | DOI: 10.1002/chem.201202984

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      Azidation: Siloxy groups derived from secondary and tertiary benzyl alcohols can be transformed into azide groups at room temperature using TMSN3 in the presence of an iron catalyst (see scheme; TMS=trimethylsilyl). Secondary and tertiary benzylic silyl ethers can be transformed in the presence of primary silyl ethers, and other reactive functional groups, such as alkyl chlorides, α,β-unsaturated esters, and aldehydes, are stable under the reaction conditions.

    3. Asymmetric Catalysis

      Catalytic Diastereo- and Enantioselective Annulations between Transient Nitrosoalkenes and Indoles (pages 16612–16615)

      Dr. Yu Zhang, David Stephens, Graciela Hernandez, Rosalinda Mendoza and Prof. Dr. Oleg V. Larionov

      Version of Record online: 30 NOV 2012 | DOI: 10.1002/chem.201203435

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      Caught in transition: An efficient catalytic system is the key to the successful development of the first highly diastereo- and enantioselective annulation reaction between indoles and transient nitrosoalkenes. This robust reaction affords structurally unique architectures with up to three new chiral centers. The products can be readily elaborated into other indoline-based chiral heterocyclic motifs, including those of pyrrolidinoindoline alkaloids.

    4. C[BOND]H Activation

      Elements of Regiocontrol in the Direct Heteroarylation of Indoles/Pyrroles: Synthesis of Bi- and Fused Polycyclic Heteroarenes by Twofold or Tandem Fourfold C[BOND]H Activation (pages 16616–16620)

      Dr. Zhen Wang, Dr. Feijie Song, Yinsong Zhao, Yumin Huang, Lei Yang, Dr. Dongbing Zhao, Prof. Dr. Jingbo Lan and Prof. Dr. Jingsong You

      Version of Record online: 29 NOV 2012 | DOI: 10.1002/chem.201203004

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      Cross-coupling: The “chelation-directed control” and “catalytic-system-based control” strategies effectively switch the C2/C3-site selectivity in the heteroarylation of indoles and pyrroles with N-heteroarenes by a palladium-catalyzed twofold C[BOND]H activation to form biheteroarenes and are further extended to the synthesis of complex fused tri- and tetracyclic heteroarenes by a tandem fourfold C[BOND]H activation (see scheme).

    5. Polycyclic Hydrocarbons

      Three-Dimensionally Arranged Cyclic p-Hexaphenylbenzene: Toward a Bottom-Up Synthesis of Size-Defined Carbon Nanotubes (pages 16621–16625)

      Dr. Tomohiko Nishiuchi, Dr. Xinliang Feng, Dr. Volker Enkelmann, Dr. Manfred Wagner and Prof. Dr. Klaus Müllen

      Version of Record online: 7 DEC 2012 | DOI: 10.1002/chem.201203227

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      Go to three dimensions: As a step toward a bottom-up synthesis of size-defined carbon nanotubes (CNTs), [3]cyclo-4′,4′′′′-hexaphenylbenzenes ([3]CHPBs) were synthesized and investigated. Theoretical and experimental results revealed that [3]CHPBs possess highly twisted [9]cyclo-p-phenylene cores. [3]cyclo-2,11-(Hexa-peri-hexabenzocoronene) ([3]CHBC) was also examined for CNT synthesis (see figure).

    6. Nanostructures

      Trisoctahedral Au–Pd Alloy Nanocrystals with High-Index Facets and Their Excellent Catalytic Performance (pages 16626–16630)

      Jong Wook Hong, Minjune Kim, Yena Kim and Prof. Sang Woo Han

      Version of Record online: 29 NOV 2012 | DOI: 10.1002/chem.201203688

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      Alloy allies: Trisoctahedral (TOH) Au–Pd alloy nanocrystals (NCs; see figure) enclosed exclusively by {441} high-index facets have been synthesized. Precise control over the reductant/surfactant concentration and the molar ratio of metal precursors allowed the optimization of growth kinetics of the NCs, which is the key to the successful formation of TOH Au–Pd NCs. The prepared NCs exhibited excellent catalytic performance towards the Suzuki coupling reaction due to their alloyed surfaces with high-index facets.

  5. Full Papers

    1. Top of page
    2. Cover Picture
    3. Graphical Abstract
    4. News
    5. Communications
    6. Full Papers
    1. Hydrogelation

      Unusual Salt-Induced Color Modulation through Aggregation-Induced Emission Switching of a Bis-cationic Phenylenedivinylene-Based π Hydrogelator (pages 16632–16641)

      Prof. Dr. Santanu Bhattacharya and Dr. Suman K. Samanta

      Version of Record online: 23 NOV 2012 | DOI: 10.1002/chem.201201940

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      Worth its salt: The π hydrogelation of a phenylenedivinylene bis-pyridinium salt is described. Variations in the amount of salts or temperature resulted in an aggregation-induced switch of emission colors (see figure). Thus, room-temperature white-light emission is generated from a single chromophore in a single solvent. The effect of different anions and cations on the aggregation follows the Hofmeister series.

    2. Metathesis

      Metal-Ion Metathesis in Metal–Organic Frameworks: A Synthetic Route to New Metal–Organic Frameworks (pages 16642–16648)

      Yonghwi Kim, Dr. Sunirban Das, Saurav Bhattacharya, Soonsang Hong, Dr. Min Gyu Kim, Dr. Minyoung Yoon, Prof. Dr. Srinivasan Natarajan and Prof. Dr. Kimoon Kim

      Version of Record online: 14 NOV 2012 | DOI: 10.1002/chem.201202899

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      Please Mr. POST-65 man: Ion exchange in metal-ion frameworks was demonstrated to be a useful post-synthesis modification method of MOFs to produce a series of isomorphous frameworks and a new framework that were difficult to synthesize directly (see figure).

    3. Mesoporous Materials

      Enhanced CO2 Adsorption over Polymeric Amines Supported on Heteroatom-Incorporated SBA-15 Silica: Impact of Heteroatom Type and Loading on Sorbent Structure and Adsorption Performance (pages 16649–16664)

      Dr. Yasutaka Kuwahara, Dr. Dun-Yen Kang, John R. Copeland, Praveen Bollini, Prof. Dr. Carsten Sievers, Dr. Takashi Kamegawa, Prof. Dr. Hiromi Yamashita and Prof. Dr. Christopher W. Jones

      Version of Record online: 20 NOV 2012 | DOI: 10.1002/chem.201203144

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      Soaking it up: An array of poly(ethyleneimine)-impregnated mesoporous silica materials containing heteroatoms (Me in illustration) in their matrices was prepared and examined in adsorption experiments. Compared to a conventional adsorbent, the composites showed superior CO2 uptakes, CO2 adsorption/desorption kinetics, and regenerabilities that depended on the heteroatom species and its concentration in the supports.

    4. Substituent Effects

      Exploring the Palladium[BOND] and Platinum[BOND]Bis(pyridine) Complex Motif by NMR Spectroscopy, X-ray Crystallography, (Tandem) Mass Spectrometry, and Isothermal Titration Calorimetry: Do Substituent Effects Follow Chemical Intuition? (pages 16665–16676)

      Dr. Torsten Weilandt, Nora L. Löw, Dr. Gregor Schnakenburg, Dr. Jörg Daniels, Dr. Martin Nieger, Prof. Dr. Christoph A. Schalley and Prof. Dr. Arne Lützen

      Version of Record online: 30 NOV 2012 | DOI: 10.1002/chem.201202771

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      Bang on trend? The effects of substitution on the binding affinity of pyridines towards palladium(II)[BOND] and platinum(II)[BOND]dppp complexes were studied. Interestingly, experimental data, like chemical shifts or bond lengths, did not necessarily follow the expected trends, owing to intermolecular solvation or crystal-packing effects. However, MS and ITC data followed the expected trends more readily (see figure).

    5. Biocatalysis

      Investigation of the Substrate Range of CYP199A4: Modification of the Partition between Hydroxylation and Desaturation Activities by Substrate and Protein Engineering (pages 16677–16688)

      Dr. Stephen G. Bell, Ruimin Zhou, Dr. Wen Yang, Adrian B. H. Tan, Alexander S. Gentleman, Dr. Luet-Lok Wong and Dr. Weihong Zhou

      Version of Record online: 7 NOV 2012 | DOI: 10.1002/chem.201202776

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      Engineering a P450 desaturase: The substrate range of CYP199A4 from Rhodopseudomonas palustris was investigated. The partition between the hydroxylation and desaturation activities of 4-ethylbenzoic acid was studied by changing the substrate and by mutation. The activity of CYP199A4 with 4-ethylbenzoic acid was changed to a desaturase by a single mutation at F185.

    6. Cooperative Catalysis

      Preparation of Bifunctional Mesoporous Silica Nanoparticles by Orthogonal Click Reactions and Their Application in Cooperative Catalysis (pages 16689–16697)

      Arne T. Dickschat, Frederik Behrends, Martin Bühner, Dr. Jinjun Ren, Mark Weiß, Prof. Dr. Hellmut Eckert and Prof. Dr. Armido Studer

      Version of Record online: 6 NOV 2012 | DOI: 10.1002/chem.201200499

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      Cooperative clicking: Bifunctional mesoporous silica particles were synthesized by orthogonal surface chemistry. A thiol–ene reaction, a copper-catalyzed 1,3-dipolar cycloaddition and a radical nitroxide exchange reaction were used as orthogonal processes for the introduction of the acid and base functionalities (see scheme). Catalytic activities of these bifunctionalized inorganic/organic hybrid materials were studied on the Henry reaction.

    7. Molecular Devices

      A Two-Stage Molecular Retractable Cable Featuring Push-Button and Rotary Two-Way Switching Modes (pages 16698–16707)

      Chun-Ju Chuang, Prof. Chien-Chen Lai, Yi-Hung Liu, Prof. Shie-Ming Peng and Prof. Sheng-Hsien Chiu

      Version of Record online: 13 NOV 2012 | DOI: 10.1002/chem.201202820

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      Stepwise elongation and contraction of the linear threadlike component of a molecular-cage-based [2]rotaxane can be controlled in such a way that it mimics a two-stage retractable cable that can be operated in both push-button (free-selection) and rotary (continuous-change) modes, depending on the choice of operating reagents (see figure).

    8. Protein–Protein Interactions

      Multivalent Design of Apoptosis-Inducing Bid-BH3 Peptide–Oligosaccharides Boosts the Intracellular Activity at Identical Overall Peptide Concentrations (pages 16708–16715)

      Dr. Martin Richter, Alokta Chakrabarti, Dr. Ivo R. Ruttekolk, Dr. Burkhard Wiesner, Dr. Michael Beyermann, Prof. Dr. Roland Brock and Prof. Dr. Jörg Rademann

      Version of Record online: 4 NOV 2012 | DOI: 10.1002/chem.201202276

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      A potent blend of sugar and peptides: The intracellular activity of BH3 peptides is boosted upon their multivalent presentation on the oligosaccharide dextran. Induction of apoptosis by the pentavalent BH3 peptide dextran was visualized in cells of the human cell line Jurkat E6.1. by using a protein stain Annexin-V (purple; see figure). This flexible access to peptide dextrans should pave the way to further biological applications of these new materials.

    9. Cross-Coupling

      Efficient Synthesis of Substituted 3-Azabicyclo[3.1.0]hexan-2-ones from 2-Iodocyclopropanecarboxamides Using a Copper-Free Sonogashira Coupling (pages 16716–16727)

      Benoît de Carné-Carnavalet, Alexis Archambeau, Dr. Christophe Meyer, Prof. Dr. Janine Cossy, Dr. Benoît Folléas, Dr. Jean-Louis Brayer and Dr. Jean-Pierre Demoute

      Version of Record online: 23 NOV 2012 | DOI: 10.1002/chem.201203153

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      A copper-free Sonogashira coupling between cis-2-iodocyclopropanecarboxamides and terminal aryl-, heteroaryl-alkynes or enynes followed by 5-exo-dig cyclization provides an efficient access to substituted 4-methylene-3-azabicyclo[3.1.0]hexan-2-ones (see scheme). Protonation of these enamides generates N-acyliminium ions, which can be involved in Pictet–Spengler cyclizations leading to new 3-azabicyclo[3.1.0]hexan-2-ones containing a quaternary stereocenter at C4 with high diastereoselectivities.

    10. Supramolecular Chemistry

      Tuning Chloride Binding, Encapsulation, and Transport by Peripheral Substitution of Pseudopeptidic Tripodal Small Cages (pages 16728–16741)

      Inés Martí, Dr. Jenifer Rubio, Dr. Michael Bolte, Prof. Dr. M. Isabel Burguete, Dr. Cristian Vicent, Dr. Roberto Quesada, Dr. Ignacio Alfonso and Prof. Dr. Santiago V. Luis

      Version of Record online: 13 NOV 2012 | DOI: 10.1002/chem.201202182

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      Caging of chloride: A family of pseudopeptidic molecular cages has been synthesized. They bind chloride in the solid state (X-ray), in solution (ESI-MS and NMR spectroscopy), and in the gas phase (collision-induced dissociation (CID)-MS). Moreover, some of them are able to transport chloride ions through lipid bilayers. The chloride binding, encapsulation, and transport abilities of the cages strongly depend on the peripheral substitution, such as the residues on the tripodal aromatic cap or the amino acid side chain (see figure).

    11. Energetic Materials

      Nitrogen-Rich Bis-1,2,4-triazoles—A Comparative Study of Structural and Energetic Properties (pages 16742–16753)

      Alexander A. Dippold and Prof. Dr. Thomas M. Klapötke

      Version of Record online: 14 NOV 2012 | DOI: 10.1002/chem.201202483

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      Bang, boom, bang: In this contribution the synthesis and full structural and spectroscopic characterization of five bis-1,2,4-triazoles in combination with different energetic moieties like amino, nitro, nitrimino, azido, and dinitromethylene groups is presented (see figure). The main goal is a comparative study on the influence of those energetic moieties on structural and energetic properties.

    12. Natural Product Synthesis

      Catalytic Enantioselective Desymmetrisation as a Tool for the Synthesis of Hodgkinsine and Hodgkinsine B (pages 16754–16764)

      Dr. Robert H. Snell, Dr. Matthew J. Durbin, Dr. Robert L. Woodward and Dr. Michael C. Willis

      Version of Record online: 30 NOV 2012 | DOI: 10.1002/chem.201203150

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      Two palladium-catalysed amination protocols are deployed in the desymmetrisation of the complex dimeric alkaloid meso-chimonanthine. The power of these transformations is showcased in efficient formal and total synthesis of the natural products hodgkinsine and hodgkinsine B (see figure), respectively.

    13. Reaction Mechanisms

      Mechanistic Origin of Cross-Coupling Selectivity in Ni-Catalysed Tishchenko Reactions (pages 16765–16773)

      Dr. Haizhu Yu and Prof. Yao Fu

      Version of Record online: 30 OCT 2012 | DOI: 10.1002/chem.201202623

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      Origin of the species: A computational mechanistic study on a nickel-catalysed Tishchenko reaction reveals the origin of the cross-coupling selectivity. DFT calculations favour a mono-carbonyl activation mechanism (MCA) and indicate that oxidative addition is the rate-determining step (see scheme).

    14. Hydrogen Generation

      Visible-Light Photocatalytic Hydrogen Generation by Using Dye-Sensitized Graphene Oxide as a Photocatalyst (pages 16774–16783)

      Marcos Latorre-Sánchez, Cristina Lavorato, Marta Puche, Prof. Dr. Vicente Fornés, Prof. Dr. Raffaele Molinari and Prof. Dr. Hermenegildo Garcia

      Version of Record online: 30 OCT 2012 | DOI: 10.1002/chem.201202372

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      Super sandwich! Incorporation of a ruthenium polypyridyl complex in the intergallery space of a few layers of graphene oxide (see figure) results in a semiconductor suitable for the generation of hydrogen from water under visible light, with a rate that is two orders of magnitude higher than some titania-based photocatalysts.

    15. Host–Guest Systems

      Lanthanide(III) Complexes of Bis-semicarbazone and Bis-imine-Substituted Phenanthroline Ligands: Solid-State Structures, Photophysical Properties, and Anion Sensing (pages 16784–16792)

      Sandeep Nadella, Dr. Paulraj M. Selvakumar, Dr. Eringathodi Suresh, Dr. Palani S. Subramanian, Prof. Dr. Markus Albrecht, Dr. Michael Giese and Dr. Roland Fröhlich

      Version of Record online: 13 NOV 2012 | DOI: 10.1002/chem.201201705

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      Illuminating the ion: Hexadentate bis-semicarbazone-based achiral and bis-imine chiral ligands of phenathroline together with their respective lanthanide complexes were synthesized. The crystal structures obtained for bis- semicarbazone-based LnIII complexes reveal coordination numbers of 9 and 10. Among the bis-imine chiral complexes, a luminescent EuIII complex was investigated for sensing various anions, and selectivity towards adenosine-5′-triphosphate (ATP) was achieved in an aqueous medium (see picture).

    16. Solid-Phase Synthesis

      Solid-Phase Synthesis of Structurally Diverse Heterocycles by an Amide–Ketone Condensation/N-Acyliminium Pictet–Spengler Sequence (pages 16793–16800)

      Vitaly V. Komnatnyy, Prof. Dr. Michael Givskov and Prof. Dr. Thomas E. Nielsen

      Version of Record online: 6 NOV 2012 | DOI: 10.1002/chem.201202745

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      Scaffold builders: An efficient method for the solid-phase synthesis of structurally diverse heterocyclic compounds relies on mutually reactive combinations of ketone-derived N-acyliminium ions with nucleophiles. The latter can be conveniently synthesized from amino acids with functionalized side chains, such as tryptophan, substituted phenylalanines, and cysteine. In this way, a range of pharmaceutically interesting heterocycles was synthesized in excellent purities and yield.

    17. Liquid Crystals

      New Liquid Crystalline Materials Based on Two Generations of Dendronised Cyclophosphazenes (pages 16801–16814)

      Dr. Josefina Jiménez, Prof. Antonio Laguna, Elena Gascón, José Antonio Sanz, Prof. José Luis Serrano, Prof. Joaquín Barberá and Dr. Luis Oriol

      Version of Record online: 7 NOV 2012 | DOI: 10.1002/chem.201202748

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      The generation game: A divergent approach was used for the synthesis of first- and second-generation dendritic structures based on a cyclotriphosphazene core (see figure). These structures were functionalised with mono- or polycatenar pro-mesogenic units. The liquid crystalline properties of the resulting materials were studied.

    18. Cycloisomerisation

      Experimental and Theoretical Studies on the Bismuth-Triflate-Catalysed Cycloisomerisation of 1,6,10-Trienes and Aryl Polyenes (pages 16815–16822)

      Dr. Julien Godeau, Dr. Fabien Fontaine-Vive, Dr. Sylvain Antoniotti and Dr. Elisabet Duñach

      Version of Record online: 9 NOV 2012 | DOI: 10.1002/chem.201202263

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      Round and round: Cycloisomerisation reaction mechanisms involving polyenes and aryl trienes catalysed by bismuth triflate were studied experimentally and theoretically. The diastereoselectivity observed during the reaction of E or Z olefins in favour of trans-fused bicyclic products is discussed. The nature of the active catalytic species derived from bismuth triflate was also investigated, and formation of a hybrid Lewis acid/Brønsted acid catalyst with water molecules is proposed (see figure).

    19. Reductive Coupling

      Ruthenium-Catalyzed Reductive Coupling of 1,3-Enynes and Aldehydes by Transfer Hydrogenation: anti-Diastereoselective Carbonyl Propargylation (pages 16823–16827)

      Dr. Laina M. Geary, Joyce C. Leung and Prof. Dr. Michael J. Krische

      Version of Record online: 12 NOV 2012 | DOI: 10.1002/chem.201202446

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      Unprotected coupling is better! Ruthenium-catalyzed transfer hydrogenation of enynes in the presence of aldehydes promotes reductive C[BOND]C coupling to provide products of propargylation with good to complete levels of anti-diastereoselectivity (see scheme). The unprotected hydroxy group of the isopropoxy-substituted enyne is required to enforce high levels of anti-diastereoselectivity.

    20. Protein Modifications

      Squaric Acid Mediated Chemoselective PEGylation of Proteins: Reactivity of Single-Step-Activated α-Amino Poly(ethylene glycol)s (pages 16828–16835)

      Carsten Dingels, Dr. Frederik Wurm, Dr. Manfred Wagner, Prof. Dr. Harm-Anton Klok and Prof. Dr. Holger Frey

      Version of Record online: 7 NOV 2012 | DOI: 10.1002/chem.201200182

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      A square PEG: Squaric acid diethyl ester was established as a universal one-step activation agent for amino-terminated poly(ethylene glycol)s (PEGs) and was proven to be chemoselective towards the single amidation of α-amino-ω-hydroxy-PEG. Squaric acid ester amido PEGs exhibit a remarkable hydrolytic stability over a period of days in basic environments, which allows the stoichiometric PEGylation of proteins by formation of the squaric acid diamide with lysine groups (see figure).

    21. Stereochemical Elucidation

      Stereochemical Studies on Ovatoxin-a (pages 16836–16843)

      Prof. Patrizia Ciminiello, Dr. Carmela Dell'Aversano, Dr. Emma Dello Iacovo, Prof. Ernesto Fattorusso, Dr. Martino Forino, Dr. Laura Grauso and Dr. Luciana Tartaglione

      Version of Record online: 29 OCT 2012 | DOI: 10.1002/chem.201201357

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      Ovatoxin-a stereostructure: The benthic dinoflagellate Ostreopsis ovata has bloomed across the Mediterranean basin over the past years, inflicting grave human and environmental suffering. The main toxin produced by O. ovata, ovatoxin-a, has been stereostructurally characterized by NMR techniques as a palytoxin analogue (see figure); this paves the way towards the evaluation of its toxicity.

    22. Porphyrinoids

      Synthesis and Properties of Fused-Ring-Expanded Porphyrins that were Core-Modified with Group 16 Heteroatoms (pages 16844–16867)

      Dr. Hai-Jun Xu, Dr. John Mack, Dr. Di Wu, Dr. Zhao-Li Xue, Dr. Ana B. Descalzo, Dr. Knut Rurack, Prof. Nagao Kobayashi and Prof. Zhen Shen

      Version of Record online: 13 NOV 2012 | DOI: 10.1002/chem.201200956

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      Core-modified porphyrinoids: The synthesis of a series of novel core-modified and fused-ring-expanded tetraphenylporphyrins is reported (see figure). Theoretical calculations, magnetic circular dichroism (MCD), and fluorescence emission spectroscopy are used to analyze the effect of core modification with Group 16 oxygen, sulfur, selenium, and tellurium atoms on the optical properties and electronic structures.

    23. Natural Products

      Total Synthesis of (−)-Zampanolide and Structure–Activity Relationship Studies on (−)-Dactylolide Derivatives (pages 16868–16883)

      Dr. Didier Zurwerra, M. Sc. Chem. Florian Glaus, M. Sc. Chem. Leo Betschart, Julia Schuster, Prof. Dr. Jürg Gertsch, Dr. Walter Ganci and Prof. Dr. Karl-Heinz Altmann

      Version of Record online: 7 NOV 2012 | DOI: 10.1002/chem.201202553

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      It's the side chain that matters: The marine macrolide (−)-zampanolide (1) has been synthesized via (−)-dactylolide (ent-2), the non-natural enantiomer of the marine natural product (+)-dactylolide (2), employing a high-yielding intramolecular Horner–Wadsworth–Emmons reaction to close the macrolactone ring. While the hemiaminal-linked side chain in 1 is crucial for nanomolar antiproliferative activity, the methylene group and the aldehyde functionality in ent-2 are dispensable. A monocyclic destetrahydropyran derivative of 1 shows equal activity as ent-2.

    24. Molecular Recognition

      Rational Design of a Nonbasic Molecular Receptor for Selective NH4+/K+ Complexation in the Gas Phase (pages 16884–16889)

      Ainoa Rueda-Zubiaurre, Noelia Herrero-García, María del Rosario Torres, Dr. Israel Fernández and Prof. Dr. José Osío Barcina

      Version of Record online: 6 NOV 2012 | DOI: 10.1002/chem.201201642

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      Only carbon atoms! The first non-basic receptor based only on a carbonated skeleton (see figure) has been rationally designed. This molecule is able to form 1:1 complexes with NH4+ and K+ through multiple cation–π interactions and selectively binds NH4+ over K+ in its pre-organised cavity due to the presence of stabilising NH⋅⋅⋅π interactions.

    25. Total Synthesis

      Total Synthesis of (+)-trans-Trikentrin A (pages 16890–16901)

      Iris R. M. Tébéka, Giovanna B. Longato, Dr. Marcus V. Craveiro, Prof. João E. de Carvalho, Dr. Ana L. T. G. Ruiz and Prof. Luiz F. Silva Jr.

      Version of Record online: 4 NOV 2012 | DOI: 10.1002/chem.201202413

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      Simple target? Take a look again! The first stereoselective synthesis of a trans-trikentrin is described (see scheme). In contrast, all cis-related natural products have already been synthesized. An enzymatic kinetic resolution and a ring contraction are the key steps. Potent antitumor compounds have been discovered during this study.

    26. Quinone Derivatives

      Highly Selective 1,4- and 1,6-Addition of P(O)[BOND]H Compounds to p-Quinones: A Divergent Method for the Synthesis of C- and O-Phosphoryl Hydroquinone Derivatives (pages 16902–16910)

      Biquan Xiong, Ruwei Shen, Midori Goto, Shuang-Feng Yin and Li-Biao Han

      Version of Record online: 9 NOV 2012 | DOI: 10.1002/chem.201202074

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      Adding phosphorus: The reaction of P(O)[BOND]H compounds with p-quinones could proceed through either 1,4- or 1,6-addition pathways by employing different additives to selectively give the corresponding C- and O-phosphoryl-substituted hydroquinone derivatives in good yields (see scheme). Optically active H-phosphinates also showed that all the addition reactions took place stereospecifically with retention of the configuration at the phosphorus center.

    27. Molecular Machines

      Chiral Supramolecular Switches Based on (R)-Binaphthalene–Bipyridinium Guests and Cucurbituril Hosts (pages 16911–16921)

      Chao Gao, Dr. Serena Silvi, Dr. Xiang Ma, Prof. He Tian, Prof. Alberto Credi and Prof. Margherita Venturi

      Version of Record online: 7 NOV 2012 | DOI: 10.1002/chem.201202378

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      Host–guest complexes: Three molecular tweezers containing a bipyridinium unit in each of the two arms and a 1,1-binaphthyl unit as the chiral centre and the hinge of the structure have been investigated (see figure). A detailed analysis of the UV/Vis absorption and circular dichroism spectra shows that chemical or photochemical reduction of the bipyridinium units and/or their complexation with cucurbit[n]urils in water cause changes in the helicity of the binaphthyl unit.

    28. Electron Transfer

      Photochemical Evidence of Electronic Interwall Communication in Double-Wall Carbon Nanotubes (pages 16922–16930)

      María Vizuete, Dr. María J. Gómez-Escalonilla, Dr. Sergio García-Rodriguez, Prof. Dr. José Luis G. Fierro, Dr. Pedro Atienzar, Prof. Dr. Hermenegildo García and Prof. Dr. Fernando Langa

      Version of Record online: 7 NOV 2012 | DOI: 10.1002/chem.201202000

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      Interwall communication: Photophysical studies, including Raman spectroscopy, XPS, thermogravimetry, and high-resolution transmission electron microscopy, revealed enhanced charge mobility in double-wall carbon nanotubes with respect to single-wall carbon nanotubes (see figure).

    29. Hypergolic Mixtures

      Boronium-Cation-Based Ionic Liquids as Hypergolic Fluids (pages 16931–16937)

      Kai Wang, Dr. Yanqiang Zhang, Deepak Chand, Dr. Damon A. Parrish and Prof. Dr. Jean'ne M. Shreeve

      Version of Record online: 7 NOV 2012 | DOI: 10.1002/chem.201201347

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      Ignition! Bis(1-allyl-1H-imidazole-3-yl)dihydroboronium dicyanoborohydride (see figure) exhibits one of the lowest viscosities (35 mPa s) and the shortest ignition-delay times (14 ms) of any reported ionic-liquid fuel component of a hypergolic mixture with white-fuming nitric acid. These remarkable properties seem to be due to the highly reactive reducing nature of the B[BOND]H bonds present in both the cation and anion.

    30. Carbenes

      Reactivity of a Frustrated Lewis Pair and Small-Molecule Activation by an Isolable Arduengo Carbene[BOND]B{3,5-(CF3)2C6H3}3 Complex (pages 16938–16946)

      Dr. Eugene L. Kolychev, Dr. Thomas Bannenberg, Dr. Matthias Freytag, Dr. Constantin G. Daniliuc, Prof. Dr. Peter G. Jones and Prof. Dr. Matthias Tamm

      Version of Record online: 13 NOV 2012 | DOI: 10.1002/chem.201202840

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      Frustrated but not frustrating: Arduengo carbene 1,3-di-tert-butylimidazolin-2-ylidene and tris[3,5-bis(trifluoromethyl)phenyl]borane form an isolable adduct (see scheme) that shows frustrated-Lewis-pair (FLP) reactivity towards H2, CO2, and other small molecules.

    31. Ruthenium Catalysis

      Application and Mechanistic Studies of a Water-Oxidation Catalyst in Alcohol Oxidation by Employing Oxygen-Transfer Reagents (pages 16947–16954)

      Oscar Verho, Marléne D. V. Dilenstam, Markus D. Kärkäs, Dr. Eric V. Johnston, Dr. Torbjörn Åkermark, Prof. Jan-E. Bäckvall and Prof. Björn Åkermark

      Version of Record online: 13 NOV 2012 | DOI: 10.1002/chem.201202266

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      Biphasinating: The use of a dimeric ruthenium complex in the oxidation of alcohols to their corresponding carbonyl compounds in high yields with various oxygen-transfer reagents is reported. This provides support for a mechanism that involves a high-valent RuV–oxo species (see scheme).

    32. Nanostructures

      In Situ Gel-to-Crystal Transition and Synthesis of Metal Nanoparticles Obtained by Fluorination of a Cyclic β-Aminoalcohol Gelator (pages 16955–16961)

      Yang Xu, Dr. Chuanqing Kang, Yu Chen, Dr. Zheng Bian, Prof. Dr. Xuepeng Qiu, Prof. Dr. Lianxun Gao and Dr. Qingxin Meng

      Version of Record online: 4 NOV 2012 | DOI: 10.1002/chem.201202615

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      Just add fluorine: Fluorination of a gelator brings new features to the resulting gel, that is, the in situ gel-to-crystal transition for selective recognition of o-xylene by the gelator, which indicates the structural evolution of the gel architecture, and also the synthesis of Au and Pt nanoparticles by using a toluene gel as a template that provides enhanced stability towards the ions (see figure; TOA-Au=(C8H17)4N+[AuCl4]; TOA-Pt=(C8H17)4N+[PtCl6]).