Chemistry - A European Journal

Cover image for Vol. 18 Issue 32

August 6, 2012

Volume 18, Issue 32

Pages 9737–10035

  1. Cover Picture

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      Cover Picture: Borophosphonate Cages: Easily Accessible and Constitutionally Dynamic Heterocubane Scaffolds (Chem. Eur. J. 32/2012) (page 9737)

      Justus Tönnemann, Dr. Rosario Scopelliti, Konstantin O. Zhurov, Dr. Laure Menin, Prof. Stefanie Dehnen and Prof. Kay Severin

      Article first published online: 28 JUL 2012 | DOI: 10.1002/chem.201290136

      Thumbnail image of graphical abstract

      Dynamic cubes in this case borophosphonate cages with P-O-B linkages, can be obtained in [4+4] condensation reactions of tert-butylphosphonic acid and boronic acids. The cages are constitutionally dynamic scaffolds that can be decorated with reactive groups. These features make borophosphonates attractive building blocks for the thermodynamically controlled synthesis of molecular and polymeric nanostructures. For more details see the Full Paper by K. Severin et al. on page 9939 ff.

  2. Inside Cover

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    1. Inside Cover: Hydrogen-Bonding Induced Alternate Stacking of Donor (D) and Acceptor (A) Chromophores and their Supramolecular Switching to Segregated States (Chem. Eur. J. 32/2012) (page 9738)

      Anindita Das, Mijanur Rahaman Molla, Bholanath Maity, Dr. Debasis Koley and Dr. Suhrit Ghosh

      Article first published online: 28 JUL 2012 | DOI: 10.1002/chem.201290137

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      Bis-amide-functionalized donor (D) and acceptor (A) chromophores with comparable distances between the two amide groups form alternate D–A stacking in the moderately nonpolar solvent tetrachloroethylene (TCE) to produce either a fibrillar gel or spherical reverse vesicles depending on linker length. In the highly nonpolar medium methylcyclohexane (MCH) alternately stacked D and A chromophores switch over to a segregated 1D assembly of individual building blocks. For more details, see the Full Paper by D. Koley, S. Ghosh et al. on page 9849 ff.

  3. Graphical Abstract

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    1. Graphical Abstract: Chem. Eur. J. 32/2012 (pages 9741–9751)

      Article first published online: 28 JUL 2012 | DOI: 10.1002/chem.201290138

  4. News

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  5. Review

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    1. Cross-Coupling

      Addressing Challenges in Palladium-Catalyzed Cross-Coupling Reactions Through Ligand Design (pages 9758–9769)

      Dr. Rylan J. Lundgren and Prof. Dr. Mark Stradiotto

      Article first published online: 11 JUL 2012 | DOI: 10.1002/chem.201201195

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      It's all in the design! Recent advances in palladium-catalyzed cross-coupling reactions that have been enabled through the design and implementation of novel ancillary ligand frameworks are examined, with a particular emphasis placed on highlighting the subtlety of ligation effects in such reactivity applications.

  6. Communications

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    1. Arene Synthesis

      Direct Transformation of Simple Enals to 3,4-Disubstituted Benzaldehydes under Mild Reaction Conditions via an Organocatalytic Regio- and Chemoselective Dimerization Cascade (pages 9770–9774)

      Dr. Xixi Song, Dr. Xinshuai Zhang, Dr. Shilei Zhang, Prof. Dr. Hao Li and Prof. Dr. Wei Wang

      Article first published online: 28 JUN 2012 | DOI: 10.1002/chem.201201709

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      Straight to the point: An organocatalyzed, direct preparation of 3,4-disubstituted benzaldehydes from simple enals under mild conditions without the need for an additional oxidant has been developed. Notably, self-dimerization of an enal precursor and cross-dimerization of two distinct enals have been realized with high regio- and chemoselectivity to give structurally diverse 3,4-substituted benzaldehydes in good yields (76–99 %).

    2. Synthetic Methods

      Highly Stereoselective Synthesis of Tertiary Propargylic Centers and Their Isomerization to Enantiomerically Enriched Allenes (pages 9775–9779)

      Prof. José Luis García Ruano, Leyre Marzo, Dr. Vanesa Marcos, Dr. Cuauhtémoc Alvarado and Dr. José Alemán

      Article first published online: 2 JUL 2012 | DOI: 10.1002/chem.201201607

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      Center of attention: A new approach for the synthesis of enantiomerically enriched allenes by isomerization of 2-p-tolylsulfinylphenyl propargylic derivatives is presented, which in turn are prepared by reaction of sulfinylated lithium benzylcarbanions with arylsulfonylacetylenes (see scheme). The high control of stereoselectivity in both steps is exerted by the sulfinyl group.

    3. Radical Complexes

      Deoxygenation of Coordinated Oxaphosphiranes: A New Route to P[DOUBLE BOND]C Double-Bond Systems (pages 9780–9783)

      Carolin Albrecht, Dr. Lili Shi, Janaina Marinas Pérez, Dr. Maurice van Gastel, Dr. Sebastian Schwieger, Prof. Dr. Frank Neese and Prof. Dr. Rainer Streubel

      Article first published online: 10 JUL 2012 | DOI: 10.1002/chem.201201405

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      Phosphaalkenes: Deoxygenation of oxaphosphirane complexes 1 and 2 by using TiIII complexes gave mixtures of E/Z phosphaalkene complexes 3 a, b and 4 a, b. Theoretical calculations of deoxygenation pathways of 1 revealed that the final products are obtained via intermediate 5 providing the final products by reaction with a second [TiCpCl2] unit and C[BOND]O bond cleavage (see scheme).

    4. Quaternary Carbon Atoms

      Al-Catalyzed Facile Construction of Quaternary C[BOND]C Bonds by the Allylic Substitution of Tertiary Alcohols: A Concise and Formal Synthesis of (±)-Mersicarpine (pages 9784–9788)

      Xue Zhong, You Li and Dr. Fu-She Han

      Article first published online: 28 JUN 2012 | DOI: 10.1002/chem.201201344

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      In close quarters: A concise, high-yielding, and more sustainable route for the synthesis of (±)-mersicarpine in nine linear steps from commercially available indole and succinic anhydride is presented (see scheme). It is also demonstrated that the novel protocol can be commonly used for the rapid and flexible construction of a diverse class of mersicarpine analogues.

    5. Synthetic Methods

      Pd-Catalyzed Modifiable Silanol-Directed Aromatic C[BOND]H Oxygenation (pages 9789–9792)

      Chunhui Huang, Dr. Nugzar Ghavtadze, Benhur Godoi and Prof. Vladimir Gevorgyan

      Article first published online: 2 JUL 2012 | DOI: 10.1002/chem.201201616

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      Directing group: A Pd-catalyzed aromatic C[BOND]H oxygenation has been developed, featuring a modifiable silanol-directing group. The resulting oxasilacycles can be efficiently modified into a variety of valuable building blocks (see scheme).

    6. Amides

      Direct Amidation of Alcohols with N-Substituted Formamides under Transition-Metal-Free Conditions (pages 9793–9797)

      Kun Xu, Yanbin Hu, Sheng Zhang, Zhenggen Zha and Prof. Zhiyong Wang

      Article first published online: 28 JUN 2012 | DOI: 10.1002/chem.201201203

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      Go tandem! The first example of the direct amidation of alcohols with N-substituted formamides has been developed. A series of tertiary amides, including the challenging N,N-dimethyl-substituted amides, were obtained in moderate to good yields under transition-metal-free conditions (see scheme). TBHP=tert-butyl hydroperoxide.

    7. Synthetic Methods

      Stereodivergent Zinc-Mediated Three-Component Synthesis of Tri- and Tetrasubstituted Alkenes (pages 9798–9801)

      Anne Miersch and Prof. Dr. Gerhard Hilt

      Article first published online: 11 JUL 2012 | DOI: 10.1002/chem.201201385

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      Zinc simple: The loading-dependent zinc-mediated addition of benzyl bromides to alkynes is the key step for the formation of vinyl bromides. In combination with a palladium-catalyzed Suzuki cross-coupling reaction with boronic acids, tri- and tetrasubstituted alkenes were obtained in good yields and stereoselectivities in a one-pot protocol (see scheme).

    8. Annulation Reactions

      [4+2] Annulation of Vinyl Ketones Initiated by a Phosphine-Catalyzed Aza-Rauhut–Currier Reaction: A Practical Access to Densely Functionalized Tetrahydropyridines (pages 9802–9806)

      Zugui Shi, Qinjie Tong, Wendy Wen Yi Leong and Prof. Dr. Guofu Zhong

      Article first published online: 27 JUN 2012 | DOI: 10.1002/chem.201201318

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      The first example of phosphine catalyzed aza-Rauhut–Currier reaction initiated [4+2] annulation of vinyl ketones with N-sulfonyl-1-aza-1,3-dienes has been disclosed. Under the ambient conditions, this protocol provides a practical access to valuable densely functionalized tetrahydropyridines in good to excellent yields and high diastereoselectivities (see scheme).

    9. Molecular Devices

      Bidirectional Redox Molecular Switches: Electron-induced Cyclization and Cycloreversion Processes in Metacyclophanes (pages 9807–9812)

      Prof. Iluminada Gallardo, Dr. Gonzalo Guirado, Prof. Miquel Moreno, Gemma Prats and Prof. Michinori Takeshita

      Article first published online: 11 JUL 2012 | DOI: 10.1002/chem.201200289

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      A reversible bidirectional ring-opening and ring-closing system triggered by electricity has been prepared by using metacyclophan-1-enes, a known thermo-photochromic molecular switch system (see scheme).

    10. Heterogeneous Catalysis

      Evidence of an Oxidative-Addition-Promoted Pd-Leaching Mechanism in the Suzuki Reaction by Using a Pd-Nanostructure Design (pages 9813–9817)

      Zhiqiang Niu, Dr. Qing Peng, Dr. Zhongbin Zhuang, Prof. Wei He and Prof. Yadong Li

      Article first published online: 2 JUL 2012 | DOI: 10.1002/chem.201201224

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      Nanocatalysts behave homogeneously: The structural changes of two rationally designed heterogeneous Pd-based nanocatalysts were examined in a Suzuki reaction (see figure). By taking advantage of additional nanostructural characteristics, direct evidence of the leaching of soluble Pd was obtained; hence, the catalysis is promoted by oxidative addition of aryl halides to the nanoparticles.

    11. Intermetallic Phases

      A Clathrate-I Phase with Li–Ge Framework (pages 9818–9822)

      Dr. Ying Liang, Dr. Bodo Böhme, Dr. Alim Ormeci, Dr. Horst Borrmann, Dipl.-Chem. Oliver Pecher, Prof. Dr. Frank Haarmann, Dr. Walter Schnelle, Dr. Michael Baitinger and Prof. Yuri Grin

      Article first published online: 11 JUL 2012 | DOI: 10.1002/chem.201202069

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      A clathrate containing lithium: K8LixGe44−x/42−3x/4 constitutes the first intermetallic clathrate-I containing lithium. Different to the clathrate phases formed with other alkali metals, Li does not occupy positions within the polyhedral cages but substitutes Ge in the host framework.

    12. Domino Reactions

      Domino Constructions of Pentacyclic Indeno[2,1-c]quinolines and Pyrano[4,3-b]oxepines by [4+1]/[3+2+1]/[5+1] and [4+3] Multiple Cyclizations (pages 9823–9826)

      Dr. Bo Jiang, Bao-Ming Feng, Prof. Shu-Liang Wang, Prof. Shu-Jiang Tu and Prof. Dr. Guigen Li

      Article first published online: 5 JUL 2012 | DOI: 10.1002/chem.201201109

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      New three-component domino reactions have been discovered. The reactions are easy to perform (see scheme; MW=microwave irradiation) and proceed with fast rates, which makes work-up convenient. Most of the multiple stereocenters and the geometry are controlled well. The stereochemistry has been unequivocally determined by X-ray structural analysis.

  7. Full Papers

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Graphical Abstract
    5. News
    6. Review
    7. Communications
    8. Full Papers
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    1. Molecular Dynamics

      Mg/Ca Partitioning Between Aqueous Solution and Aragonite Mineral: A Molecular Dynamics Study (pages 9828–9833)

      Sergio E. Ruiz-Hernandez, Dr. Ricardo Grau-Crespo, Dr. Neyvis Almora-Barrios, Dr. Mariëtte Wolthers, Dr. A. Rabdel Ruiz-Salvador, Prof. Nestor Fernandez and Prof. Nora H. de Leeuw

      Article first published online: 28 JUN 2012 | DOI: 10.1002/chem.201200966

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      Mg concentrations have been calculated in the bulk and surfaces of aragonite CaCO3 in equilibrium with aqueous solution, based on molecular dynamics simulations and grand-canonical statistical mechanics (see figure). Mg was found to be incorporated in the surfaces, in particular in the (001) terraces, rather than in the bulk of aragonite particles.

    2. Protein Engineering

      Photoswitchable, DNA-Binding Helical Peptides Assembled with Two Independently Designed Sequences for Photoregulation and DNA Recognition (pages 9834–9840)

      Dr. Kazuhisa Fujimoto, Dr. Masaoki Kajino, Ikumi Sakaguchi and Prof. Dr. Masahiko Inouye

      Article first published online: 5 JUL 2012 | DOI: 10.1002/chem.201201431

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      Under control: DNA-binding, diarylethene-bridged peptides were developed. The photoregulation of the peptide–DNA interaction (see scheme) was directly detected under photoirradiation in a real-time quartz crystal microbalance measurement.

    3. Electronic Structure

      Atomic Polarizability Dominates the Electronic Properties of Peptide Bonds upon Thioxo or Selenoxo Substitution (pages 9841–9848)

      Yun Huang, Dr. Günther Jahreis, Prof. Gunter Fischer and Dr. Christian Lücke

      Article first published online: 10 JUL 2012 | DOI: 10.1002/chem.201200863

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      Chalcogen polarizability makes the difference! Replacement of oxygen in a peptide bond by either sulfur or selenium has a considerable impact on the electronic structure and physicochemical properties of this amide moiety. Both in thioxo and selenoxo peptides, the nuclear shielding, electronic excitation energy, cis/trans rotation barrier and amide pKa value show direct correlation to the atomic polarizability of the chalcogen.

    4. Self-Assembly

      Hydrogen-Bonding Induced Alternate Stacking of Donor (D) and Acceptor (A) Chromophores and their Supramolecular Switching to Segregated States (pages 9849–9859)

      Anindita Das, Mijanur Rahaman Molla, Bholanath Maity, Dr. Debasis Koley and Dr. Suhrit Ghosh

      Article first published online: 10 JUL 2012 | DOI: 10.1002/chem.201201140

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      Dynamic gel: Hydrogen-bonding mediated co-assembly of a dialkoxynaphthalene (DAN) donor and a naphthalene-diimide (NDI) acceptor was studied. Depending on the solvent and relative distances among the amide groups, segregated or mixed assemblies were observed. In tetrachloroethylene (TCE), 2D reverse vesicles (red sol) or 1D fibers (red gel) were formed by alternate D–A stacking, which supramolecularly reorganized to a more stable segregated state in methylcyclohexane (MCH; see figure).

    5. Hydrogen Bonds

      Hydrogen-Bonding-Mediated Vesicular Assembly of Functionalized Naphthalene–Diimide-Based Bolaamphiphile and Guest-Induced Gelation in Water (pages 9860–9869)

      Mijanur Rahaman Molla and Dr. Suhrit Ghosh

      Article first published online: 5 JUL 2012 | DOI: 10.1002/chem.201201299

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      Fruit and fibers: Vesicular assembly of a NDI-based bolaamphiphile was achieved by using π stacking and hydrogen bonding in water. Pyrene intercalation resulted in a transition from 2D vesicles into 1D fibers and gelation at higher concentrations.

    6. Carbon Dioxide Fixation

      Mechanism of the Cycloaddition of Carbon Dioxide and Epoxides Catalyzed by Cobalt-Substituted 12-Tungstenphosphate (pages 9870–9876)

      Dr. Fawang Chen, Dr. Xiaofang Li, Prof. Dr. Bo Wang, Dr. Tiegang Xu, Dr. Shi-Lu Chen, Dr. Peng Liu and Prof. Dr. Changwen Hu

      Article first published online: 4 JUL 2012 | DOI: 10.1002/chem.201201042

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      Organometallic radical intermediate: Cobalt-substituted α-Keggin-type 12-tungstenphosphate is used as an efficient single-component catalyst for the synthesis of cyclic carbonates from CO2 and epoxides. DFT calculations indicate that the cycloaddition reaction occurs through single-electron transfer from the doublet CoII cluster to the epoxide, thus leading to homolytic cleavage of the C[BOND]O bond and formation of a carbon radical intermediate, followed by cyclization with CO2 (see scheme).

    7. Functional Nanoparticles

      Interfacial Synthesis and Functionality of Self-Stabilized Polydiaminonaphthalene Nanoparticles (pages 9877–9885)

      Prof. Dr. Xin-Gui Li, Dr. Jia-Li Zhang and Prof. Mei-Rong Huang

      Article first published online: 10 JUL 2012 | DOI: 10.1002/chem.201200860

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      Spheres of influence: Functional polydiaminonaphthalene nanoparticles are synthesized at mobile interfaces without a template (see figure; PC= propylene carbonate). The particle properties include self-stability, semiconductivity, electroactivity, and fluorescence emission, which enable the production of chemosensors for the detection of ZnII ions in a wide linear concentration range with a detection limit of 1 nM.

    8. Substituent Effects

      Dramatic Substituent Effects on the Photoluminescence of Boron Complexes of 2-(Benzothiazol-2-yl)phenols (pages 9886–9893)

      Mithun Santra, Hyunsoo Moon, Min-Ho Park, Prof. Tae-Woo Lee, Dr. Young Kook Kim and Prof. Kyo Han Ahn

      Article first published online: 10 JUL 2012 | DOI: 10.1002/chem.201200726

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      The rainbow connection: Boron complexes of 2-(benzothiazol-2-yl)phenols emit bright deep-blue or orange-red in solution and in solid states, depending on the position of amino substituents (see figure). Analyses reveal that the boron complexes show little absorption–emission spectral overlap and lack π–π stacking interactions in the crystal packing structures.

    9. Cycloaddition Reactions

      A Density Functional Theory Investigation of the Cobalt-Mediated η5-Pentadienyl/Alkyne [5+2] Cycloaddition Reaction: Mechanistic Insight and Substituent Effects (pages 9894–9900)

      Dr. Kai E. O. Ylijoki, Prof. Dr. Peter H. M. Budzelaar and Prof. Dr. Jeffrey M. Stryker

      Article first published online: 9 JUL 2012 | DOI: 10.1002/chem.201200319

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      Release and catch: DFT studies have been used to elucidate the mechanism of the η5-pentadienyl cobalt/alkyne [5+2] cycloaddition reaction that can provide η23-cycloheptadienyl complexes under kinetic control. The initial cyclization is a stepwise process of rate-limiting olefin decoordination/alkyne capture, C[BOND]C bond formation, olefin arm capture, and a second C[BOND]C bond formation (see scheme).

    10. Flow Chemistry

      Establishing a Flow Process to Coumarin-8-Carbaldehydes as Important Synthetic Scaffolds (pages 9901–9910)

      Jaroslav Zak, Prof. David Ron, Dr. Elena Riva, Dr. Heather P. Harding, Dr. Benedict C. S. Cross and Dr. Ian R. Baxendale

      Article first published online: 10 JUL 2012 | DOI: 10.1002/chem.201201039

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      Aldehyde on tap: Despite their usefulness as fluorophores and synthetic precursors, efficient and reliable routes to coumarin-8-carbaldehydes are lacking. A high-yielding continuous flow synthesis that requires no manual intermediate purification or work-up is described, giving access to multigram quantities of aldehyde product (see scheme).

    11. Asymmetric Catalysis

      Nanosheet-Enhanced Enantioselectivity in the Vanadium-Catalyzed Asymmetric Epoxidation of Allylic Alcohols (pages 9911–9918)

      Li-Wei Zhao, Hui-Min Shi, Jiu-Zhao Wang and Prof. Jing He

      Article first published online: 10 JUL 2012 | DOI: 10.1002/chem.201201659

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      Handy tricks for asymmetric catalysis: The inorganic layer serves as a huge and rigid planar substituent to effectively enhance the enantioselectivity in the vanadium-catalyzed asymmetric epoxidation of allylic alcohols.

    12. Protein–Ligand Interactions

      High Relaxivity Supramolecular Adducts Between Human-Liver Fatty-Acid-Binding Protein and Amphiphilic GdIII Complexes: Structural Basis for the Design of Intracellular Targeting MRI Probes (pages 9919–9928)

      Dr. Mariapina D'Onofrio, Dr. Eliana Gianolio, Alberto Ceccon, Francesca Arena, Dr. Serena Zanzoni, Prof. David Fushman, Prof. Silvio Aime, Prof. Henriette Molinari and Dr. Michael Assfalg

      Article first published online: 4 JUL 2012 | DOI: 10.1002/chem.201103778

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      Sensitive MRI probes: Lipid-based gadolinium complexes display good affinity towards the most abundant human liver intracellular lipid carrier, hL-FABP, and increase the relaxivity in the supramolecular adducts. The NMR-derived structural details and results of competition experiments provide the grounds for the design of sensitive magnetic resonance probes (see figure). The formation of heterotypic adducts makes targeting of hL-FABP possible in the presence of the physiological lipid pool.

    13. Solid-State Emitters

      Systemic Studies of Tetraphenylethene–Triphenylamine Oligomers and a Polymer: Achieving Both Efficient Solid-State Emissions and Hole-Transporting Capability (pages 9929–9938)

      Dr. Yang Liu, Xihan Chen, Yun Lv, Shuming Chen, Dr. Jacky W. Y. Lam, Dr. Faisal Mahtab, Prof. Hoi Sing Kwok, Xutang Tao and Prof. Ben Zhong Tang

      Article first published online: 10 JUL 2012 | DOI: 10.1002/chem.201201400

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      Glowing recommendation: A series of oligomers and a polymer composed of different numbers and configuration of tetraphenylethene and triphenylamine units have been synthesised. Their optical and electroluminescence behaviours were studied systematically. All the molecules demonstrate aggregation-induced emission (see figure) and have very high quantum yields in the solid state.

    14. Cage Compounds

      Borophosphonate Cages: Easily Accessible and Constitutionally Dynamic Heterocubane Scaffolds (pages 9939–9945)

      Justus Tönnemann, Dr. Rosario Scopelliti, Konstantin O. Zhurov, Dr. Laure Menin, Prof. Stefanie Dehnen and Prof. Kay Severin

      Article first published online: 4 JUL 2012 | DOI: 10.1002/chem.201201287

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      Dynamic covalent chemistry: Direct condensation of tert-butylphosphonic acid with boronic acids gives borophosphonate cages of the general formula [tBuPO3BR′]4 in good yields. Furthermore, it is demonstrated that borophosphonates are constitutionally dynamic scaffolds that can be decorated with reactive groups (see scheme).

    15. Spin Crossover

      Synthesis of Spin-Crossover Nano- and Micro-objects in Homogeneous Media (pages 9946–9954)

      Il'ya A. Gural'skiy, Carlos M. Quintero, Dr. Gábor Molnár, Prof. Igor O. Fritsky, Dr. Lionel Salmon and Dr. Azzedine Bousseksou

      Article first published online: 10 JUL 2012 | DOI: 10.1002/chem.201201063

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      In a spin: Spin-crossover nano- and micro-objects with different sizes (6 nm–2 μm) and morphologies (nanorods, nanoplates, small spherical particles, and nano- and micro-crystals) that are based on the spin-crossover complex [Fe(hptrz)3](OTs)2 (hptrz=4-heptyl-1,2,4-triazole, Ts=para-toluenesulfonyl) were prepared in homogeneous media. Size-reduction and matrix effects on the spin-crossover properties are discussed.

    16. Theoretical Chemistry

      Supramolecular Binding Thermodynamics by Dispersion-Corrected Density Functional Theory (pages 9955–9964)

      Prof. Dr. Stefan Grimme

      Article first published online: 10 JUL 2012 | DOI: 10.1002/chem.201200497

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      Unprecedented accuracy for computed association free enthalpies of supramolecular host–guest complexes (some examples are shown here) in solution has been achieved by a combination of high-level quantum chemical procedures. The approach is quite general, includes all basic physical effects quantitatively and requires no special empirical adjustments.

    17. Intermolecular Interactions

      The Structural Diversity Triggered by Intermolecular Interactions between AuIS2 Groups: Aurophilia and Beyond (pages 9965–9976)

      Mohammad-Reza Azani, Dr. Oscar Castillo, Dr. M. Luz Gallego, Dr. Teodor Parella, Dr. Gabriel Aullón, Dr. Olga Crespo, Prof. Dr. Antonio Laguna, Prof. Dr. Santiago Alvarez, Dr. Rubén Mas-Ballesté and Dr. Félix Zamora

      Article first published online: 10 JUL 2012 | DOI: 10.1002/chem.201200999

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      Gold compounds love each other: The assembly of AuI centers and dithiocarboxylato or xanthato ligands results in a surprising structural diversity. Computational studies show that Au⋅⋅⋅Au interactions, but also Au⋅⋅⋅S and S⋅⋅⋅S interactions, play a role in the structure and energetic of the supramolecular assemblies (see figure).

    18. Natural Product Synthesis

      Stereocontrolled Total Synthesis of (+)-trans-Dihydronarciclasine (pages 9977–9982)

      Soonho Hwang, Prof. Dr. Deukjoon Kim and Prof. Dr. Sanghee Kim

      Article first published online: 10 JUL 2012 | DOI: 10.1002/chem.201201649

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      A highly selective and efficient total synthesis of (+)-trans-dihydronarciclasine was developed. The synthesis defines two of the five stereocenters in an amino acid ester–enolate Claisen rearrangement. The other three stereocenters are created via a cyclic vinylogous ester intermediate, which was generated from the γ,δ-unsaturated ester functional group of the rearrangement product. The B ring is constructed by a Friedel–Crafts-type cyclization, exemplifying the use of an N-Boc group to generate an isocyanate intermediate (see scheme).

    19. Metallaboranes

      Synthesis and Structural Characterization of New Divanada- and Diniobaboranes Containing Chalcogen Atoms (pages 9983–9991)

      Dipak Kumar Roy, Dr. Shubhankar Kumar Bose, K. Geetharani, Kiran Kumar Varma Chakrahari, Dr. Shaikh M. Mobin and Dr. Sundargopal Ghosh

      Article first published online: 10 JUL 2012 | DOI: 10.1002/chem.201200189

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      Group 5 alive: Divanadatellura- and divanadathiaboranes were obtained from the treatment of Group 5 metal polychlorides with dichalcogenides and monoboranes. The treatment of [Cp2VCl2] with monoboranes yielded an oxavanadaborane and a divanadaborane (see structures).

    20. Hydroformylation

      New Tetraphosphorus Ligands for Highly Linear Selective Hydroformylation of Allyl and Vinyl Derivatives (pages 9992–9998)

      Dr. Chaoxian Cai, Dr. Shichao Yu, Bonan Cao and Prof. Dr. Xumu Zhang

      Article first published online: 10 JUL 2012 | DOI: 10.1002/chem.201201396

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      New tetraphosphorus ligands have been developed and applied in the rhodium-catalyzed regioselective hydroformylation of a variety of allyl and vinyl olefins (see scheme). Remarkably high linear selectivities were obtained by these ligands. Linear-to-branch ratios of 26:1 and 10:1 were obtained for the hydroformylation of styrene and allyl cyanide, respectively.

    21. Fluorescent Probes

      Structure–Activity Studies on the Fluorescent Indicator in a Displacement Assay for the Screening of Small Molecules Binding to RNA (pages 9999–10008)

      Dr. Shiori Umemoto, Seongwang Im, Dr. Jinhua Zhang, Dr. Masaki Hagihara, Dr. Asako Murata, Yasue Harada, Dr. Takeo Fukuzumi, Takahiro Wazaki, Shin-ichi Sasaoka and Prof. Dr. Kazuhiko Nakatani

      Article first published online: 4 JUL 2012 | DOI: 10.1002/chem.201103932

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      Indicating RNA binding: A fluorescent indicator displacement assay using 2,7-bis(aminoethoxy)xanthone (X2S) as the indicator is reported for the study of small-molecule–RNA interactions (see figure). The substituents at the two alkoxy moieties modulate the binding selectivity. The X2S derivative with N,N-dimethylaminoethoxy substituents is the best fluorescent indicator in the screening of molecules binding to Rev response element (RRE).

    22. Ammonia Activation

      Activation and Coordination of Ammonia at [Cp*Ir(H)2]: NMR and Matrix Isolation Studies (pages 10009–10013)

      Dr. Ann-Katrin Jungton, Dr. Christian Herwig, Prof. Dr. Thomas Braun and Prof. Dr. Christian Limberg

      Article first published online: 10 JUL 2012 | DOI: 10.1002/chem.201201295

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      A fair exchange: The reactivity of ammonia towards [Cp*Ir(H)4] (1; Cp*=1,2,3,4,5-pentamethylcyclopentadienyl) was investigated in C6D6 solution and in a frozen argon matrix (see scheme). 1H NMR exchange spectroscopy revealed H/D exchange between ND3 and the hydrido ligands in C6D6. Photolysis of 1 in an argon matrix doped with ammonia yielded the ammine complex [Cp*Ir(H)2(NH3)].

    23. Diels–Alder Reactions

      Symmetry-Enthalpy Correlations in Diels–Alder Reactions (pages 10014–10020)

      Dr. Inbal Tuvi-Arad and Prof. David Avnir

      Article first published online: 10 JUL 2012 | DOI: 10.1002/chem.201200927

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      Rules are made to be broken: Correlations are established between the degree of symmetry of the transition state, estimated by the continuous symmetry measure (CSM), and the activation enthalpy for a series of Diels–Alder reactions in various solvents (see figure). These findings quantitatively “gray” the strict Woodward–Hoffmann rules for cases that are devoid of ideal symmetry.

    24. Carbohydrates

      Strong Aphicidal Activity of GlcNAc(β1[RIGHTWARDS ARROW]4)Glc Disaccharides: Synthesis, Physiological Effects, and Chitinase Inhibition (pages 10021–10028)

      Dr. Christophe Dussouy, Dr. Laurent Bultel, Dr. Julien Saguez, Dr. Anas Cherqui, Dr. Mounia Khelifa, Dr. Eric Grand, Prof. Philippe Giordanengo and Prof. José Kovensky

      Article first published online: 4 JUL 2012 | DOI: 10.1002/chem.201200887

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      Sugar-based insecticides: Four GlcNAc(β1[RIGHTWARDS ARROW]4)Glc disaccharides containing acetyl and/or sulfate groups were synthesized in high yields with 1,2-trans stereoselectivity. These compounds are candidates for insect chitinase inhibition and aphicidal activity (see figure).

    25. Subvalent Compounds

      Univalent Gallium and Indium Phosphane Complexes: From Pyramidal M(PPh3)3+ to Carbene-Analogous Bent M(PtBu3)2+ (M=Ga, In) Complexes (pages 10029–10034)

      Alexander Higelin, Ulf Sachs, Sarah Keller and Prof. Dr. Ingo Krossing

      Article first published online: 23 MAY 2012 | DOI: 10.1002/chem.201104040

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      Nothing to lose, everything to Ga,In: A new oxidative route to indium(I) salts of weakly coordinating anions is described. The applicability of the M[Al(ORF)4] salts (M=Ga, In) is demonstrated by the preparation of the first indium(I) phosphane complexes and their Ga(I) analogues, including unprecedented carbene-analogous MI–(bis-phosphane) complexes (see figure).

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      Preview: Chem. Eur. J. 33/2012 (page 10035)

      Article first published online: 28 JUL 2012 | DOI: 10.1002/chem.201290135

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