Angewandte Chemie International Edition

Cover image for Vol. 47 Issue 45

October 27, 2008

Volume 47, Issue 45

Pages 8535–8749

  1. Cover Picture

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Graphical Abstract
    5. News
    6. Obituary
    7. Book Reviews
    8. Highlights
    9. Minireview
    10. Review
    11. Communications
    12. Preview
    1. Cover Picture: Highly Stereospecific Generation of Helical Chirality by Imprinting with Amino Acids: A Universal Sensor for Amino Acid Enantiopurity (Angew. Chem. Int. Ed. 45/2008) (page 8535)

      Hyunwoo Kim, Soon Mog So, Cindy Pai-Hui Yen, Elisângela Vinhato, Alan J. Lough, Jong-In Hong, Hae-Jo Kim and Jik Chin

      Version of Record online: 21 OCT 2008 | DOI: 10.1002/anie.200890228

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      A spiral staircase follows the many helical structures in nature. J.-I. Hong, H.-J. Kim, J. Chin, and co-workers describe how amino acids induce helicity with hydrogen bonding into a 2,2′-dihydroxybenzophenone derivative in their Communication on page 8657 ff. Signaling groups can be added to allow the receptors to sense amino acid enantiopurity.

  2. Inside Cover

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Graphical Abstract
    5. News
    6. Obituary
    7. Book Reviews
    8. Highlights
    9. Minireview
    10. Review
    11. Communications
    12. Preview
    1. Inside Cover: An Interrupted [4+3] Cycloaddition Reaction: A Hydride Shift (Ene Reaction) Intervenes (Angew. Chem. Int. Ed. 45/2008) (page 8536)

      Michael Harmata, Chaofeng Huang, Parham Rooshenas and Peter R. Schreiner

      Version of Record online: 21 OCT 2008 | DOI: 10.1002/anie.200890229

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      Chemistry is the study of how atoms and molecules interact and react with each other. Often we can predict and control outcomes; on other occasions nature leads us down an unexpected path, which can lead to the discovery of new or better chemical processes. In the Communication on page 8696 ff., M. Harmata, P. R. Schreiner, and co-workers describe how they were directed away from a [4+3] cycloaddition down a road leading toward an ene reaction of oxyallylic cations that is both synthetically useful and fundamentally interesting.

  3. Graphical Abstract

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

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Graphical Abstract
    5. News
    6. Obituary
    7. Book Reviews
    8. Highlights
    9. Minireview
    10. Review
    11. Communications
    12. Preview
    1. Nobel Prizes 2008 (page 8556)

      Version of Record online: 21 OCT 2008 | DOI: 10.1002/anie.200804933

  5. Obituary

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Graphical Abstract
    5. News
    6. Obituary
    7. Book Reviews
    8. Highlights
    9. Minireview
    10. Review
    11. Communications
    12. Preview
    1. Neil Bartlett (1932–2008) (page 8557)

      Konrad Seppelt

      Version of Record online: 21 OCT 2008 | DOI: 10.1002/anie.200804715

  6. Book Reviews

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

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

      A Magnetoelectric Effect in YMnO3 and HoMnO3 (pages 8562–8564)

      Heiko Lueken

      Version of Record online: 21 OCT 2008 | DOI: 10.1002/anie.200803024

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      A ferroic performance: In crystals with both electric and magnetic order, a coupling between the orderings may exist: An applied electric field induces a change of magnetization and an applied magnetic field induces a change of polarization. This magnetoelectric effect makes so-called multiferroics potential future information technology devices in which data can be written to magnetic memory elements by applied electric fields.

    2. Nanomotors

      A Freight Train of Nanotubes for Cargo Transport on the Nanoscale (pages 8565–8566)

      Marko Burghard

      Version of Record online: 24 SEP 2008 | DOI: 10.1002/anie.200803021

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      An electrically driven nanomotor comprising a short nanotube sheath on a coaxial nanotube axis has been constructed in a further step in the development of rotors based on carbon nanotubes. A current flowing through the axis generates a temperature gradient, which propels the loaded sheath forward a distance in the subnanometer region (see picture).

  8. Minireview

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Graphical Abstract
    5. News
    6. Obituary
    7. Book Reviews
    8. Highlights
    9. Minireview
    10. Review
    11. Communications
    12. Preview
    1. Magnetic Resonance Imaging

      High-Relaxivity MRI Contrast Agents: Where Coordination Chemistry Meets Medical Imaging (pages 8568–8580)

      Eric J. Werner, Ankona Datta, Christoph J. Jocher and Kenneth N. Raymond

      Version of Record online: 29 SEP 2008 | DOI: 10.1002/anie.200800212

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      The unique electronic properties of GdIII make it ideal for use in contrast agents for magnetic resonance imaging, but toxic GdIII must be complexed before administration. Designing ligands to form stable complexes while keeping the hydration number high and the water exchange rate optimal remains a challenge. Complexes of hydroxypyridinone chelates combine all the favorable properties for the high relaxivities required in high-field-strength applications.

  9. Review

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

      Proteins in Mesoporous Silicates (pages 8582–8594)

      Sarah Hudson, Jakki Cooney and Edmond Magner

      Version of Record online: 2 OCT 2008 | DOI: 10.1002/anie.200705238

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      Inner beauty: Since the discovery of mesoporous silicates, novel syntheses have led to precise control over their pore size and structure, particle size, chemical composition, and stability, allowing the adsorption of a wide variety of biological macromolecules. This Review discusses the development of ordered, large-pore, functionalized mesoporous silicates and their application to the immobilization of proteins for biocatalysis.

  10. Communications

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

      Micro- and Nanopatterning of Spin-Transition Compounds into Logical Structures (pages 8596–8600)

      Massimiliano Cavallini, Ilaria Bergenti, Silvia Milita, Giampiero Ruani, Ivan Salitros, Zhi-Rong Qu, Rajadurai Chandrasekar and Mario Ruben

      Version of Record online: 1 OCT 2008 | DOI: 10.1002/anie.200802085

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      Changing stripes: The spin-transition compound 1 can be nanopatterned by unconventional and soft lithography to give crystalline, well-oriented, μm-scale structures arranged in stripes on a silica surface. These findings have potential applications in electronic devices and information storage.

    2. TNT Sensor

      A Simple Assay for Direct Colorimetric Visualization of Trinitrotoluene at Picomolar Levels Using Gold Nanoparticles (pages 8601–8604)

      Ying Jiang, Hong Zhao, Ningning Zhu, Yuqing Lin, Ping Yu and Lanqun Mao

      Version of Record online: 8 OCT 2008 | DOI: 10.1002/anie.200804066

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      An explosive situation: By using gold nanoparticles and taking advantage of the donor–acceptor interaction between trinitrotoluene (TNT) and cysteamine, the visualization of TNT can be achieved at picomolar levels (see picture). The color change from red to blue can be seen with the naked eye, which allows sensitive on-the-spot detection.

    3. Natural Products

      Total Synthesis of the Originally Assigned Structure of Vannusal B (pages 8605–8610)

      K. C. Nicolaou, Hongjun Zhang, Adrian Ortiz and Philippe Dagneau

      Version of Record online: 10 OCT 2008 | DOI: 10.1002/anie.200804228

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      The truth is out there: The chase for the originally assigned structure of vannusal B (see structural formula) by total synthesis ended successfully, but created a new puzzle, that of the true structure of this intriguing marine natural product.

    4. Structure–Activity Relationships

      Critical Importance of the Nine-Membered F Ring of Ciguatoxin for Potent Bioactivity: Total Synthesis and Biological Evaluation of F-Ring-Modified Analogues (pages 8611–8614)

      Masayuki Inoue, Nayoung Lee, Keisuke Miyazaki, Toyonobu Usuki, Shigeru Matsuoka and Masahiro Hirama

      Version of Record online: 9 OCT 2008 | DOI: 10.1002/anie.200803921

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      Playing a central role: Ciguatoxins, potent neurotoxins, span a length of over 3 nm and consist of 13 fused ether rings (from the A to the M ring; see energy-minimized structure). The finding that two fully synthetic F-ring-modified analogues have markedly diminished biological activities demonstrates that the central F ring plays a major role in organizing the ciguatoxin molecule into a shape suitable for bioactivity.

    5. Catalysis

      Hydrogenation of Arenes by Dual Activation: Reduction of Substrates Ranging from Benzene to C60 Fullerene under Ambient Conditions (pages 8615–8617)

      Ravindra R. Deshmukh, Ji Woong Lee, Ueon Sang Shin, Jin Yong Lee and Choong Eui Song

      Version of Record online: 8 OCT 2008 | DOI: 10.1002/anie.200803850

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      Tackling aromaticity: The title reaction was accomplished by simultaneous activation of molecular hydrogen and the aromatic substrate by Pd/C and a Lewis acidic ionic liquid, respectively. Even benzene and C60 fullerene were hydrogenated under ambient conditions (1 bar of H2 at room temperature). An ionic hydrogenation mechanism (see scheme) is supported by characterization of a stabilized arenium intermediate.

    6. Thermoelectricity

      Large Enhancements in the Thermoelectric Power Factor of Bulk PbTe at High Temperature by Synergistic Nanostructuring (pages 8618–8622)

      Joseph R. Sootsman, Huijun Kong, Ctirad Uher, Jonathan James D'Angelo, Chun-I Wu, Timothy P. Hogan, Thierry Caillat and Mercouri G. Kanatzidis

      Version of Record online: 8 OCT 2008 | DOI: 10.1002/anie.200803934

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      Co-nanostructuring of PbTe with two kinds of metallic nanoparticles (Pb and Sb) can significantly increase its power factor at high temperatures (up to 87 % at 700 K; see picture, ZT=figure of merit). The electrical conductivity is dramatically increased at high temperatures without degrading the thermopower. This emergent synergy results only when both Pb and Sb nanocrystals are present.

    7. Chiral Microporous Materials

      Three-Dimensional Chiral Microporous Germanium Antimony Sulfide with Ion-Exchange Properties (pages 8623–8626)

      Mei-Ling Feng, De-Nian Kong, Zai-Lai Xie and Xiao-Ying Huang

      Version of Record online: 8 OCT 2008 | DOI: 10.1002/anie.200803406

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      Chiral hole: The first chiral microporous germanium antimony sulfide with 3D helical channels was constructed by the unprecedented combination of {GeS4} tetrahedra and ψ-{SbS4} trigonal bipyramids. The dimethylammonium cations present in the structure are easily exchanged with alkali metal cations present in aqueous solution. The title compound has high ion-exchange capacity and high selectivity for Cs+ ions.

    8. Protein Microarrays

      Fabrication of an Oriented Fc-Fused Lectin Microarray through Boronate Formation (pages 8627–8630)

      Mu-Lin Chen, Avijit Kumar Adak, Nai-Chia Yeh, Wen-Bin Yang, Yung-Jen Chuang, Chi-Huey Wong, Kuo-Chu Hwang, Jih-Ru Reuben Hwu, Shih-Liang Hsieh and Chun-Cheng Lin

      Version of Record online: 10 OCT 2008 | DOI: 10.1002/anie.200803377

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      A stable, covalent, and highly active protein microarray was created through the formation of cyclic esters between surface boronic acids and the carbohydrate moiety of a fusion protein, Fc-dectin-1 (see picture). A biotin-labeled polysaccharide was used as a probe to investigate the binding activity of the protein. Staining of the product array with streptavidin-Cy3 revealed the effectiveness of this immobilization strategy.

    9. High Oxidation States

      Is Allred's [Hg(cyclam)]3+ a True Mercury(III) Complex? (pages 8631–8633)

      Peter Hrobárik, Martin Kaupp and Sebastian Riedel

      Version of Record online: 16 SEP 2008 | DOI: 10.1002/anie.200802233

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      Relativistic density functional calculations are used to examine the spectroscopic parameters of [Hg(cyclam)]3+ (cyclam=1,4,8,11-tetraazacyclotetradecane; see picture), which is thought to contain Hg3+, and to analyze its electronic structure. Although the computed EPR parameters and excitation energies are consistent with the experimental data, a detailed analysis of the electronic structure contradicts the assignment as an HgIII complex.

    10. Hybrid Materials

      Comparison of Chiral and Racemic Forms of Zinc Cyclohexane trans-1,2-Dicarboxylate Frameworks: A Structural, Computational, and Calorimetric Study (pages 8634–8637)

      Andrew J. Bailey, Clare Lee, Russell K. Feller, James B. Orton, Caroline Mellot-Draznieks, Ben Slater, William T. A. Harrison, P. Simoncic, A. Navrotsky, Martin C. Grossel and Anthony K. Cheetham

      Version of Record online: 2 OCT 2008 | DOI: 10.1002/anie.200802564

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      An integrated study of the organic–inorganic framework material zinc cyclohexane trans-1,2-dicarboxylate involving synthesis, structure elucidation, computer simulation, and calorimetry shows that the chiral R,R form (right in picture) is less stable than its racemic R,R/S,S analogue (left) and adopts a layered structure with a fundamentally different topology. The results point to the possibility that the structural diversity of racemic frameworks and their homochiral analogues may be much greater than has hitherto been suspected.

    11. CdSe Nanocrystals

      Synthesis of Metal–Selenide Nanocrystals Using Selenium Dioxide as the Selenium Precursor (pages 8638–8641)

      Ou Chen, Xian Chen, Yongan Yang, Jared Lynch, Huimeng Wu, Jiaqi Zhuang and Y. Charles Cao

      Version of Record online: 10 OCT 2008 | DOI: 10.1002/anie.200804266

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      Quality and quantity: A non-injection synthesis of high-quality CdSe nanocrystals can be conducted in air, that is without the need for any oxygen-free manipulation. The synthesis, which uses SeO2 as the selenium precursor, is suitable for the large-scale industrial synthesis of high-quality nanocrystals at low cost and has been generalized for the formation of other metal selenides, such as PbSe and Pd4.5Se nanocrystals.

    12. Fullerenes

      Bis-Carbene Adducts of Non-IPR La2@C72: Localization of High Reactivity around Fused Pentagons and Electrochemical Properties (pages 8642–8645)

      Xing Lu, Hidefumi Nikawa, Takahiro Tsuchiya, Yutaka Maeda, Midori O. Ishitsuka, Takeshi Akasaka, Makoto Toki, Hiroshi Sawa, Zdenek Slanina, Naomi Mizorogi and Shigeru Nagase

      Version of Record online: 2 OCT 2008 | DOI: 10.1002/anie.200803529

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      Candylike fullerene: Two adamantylidene (Ad) groups are covalently bonded to the two fused-pentagon sites of the non-IPR endohedral metallofullerene La2@C72 in bis-adduct La2@C72Ad2. Its open-cage structure, reminiscent of a wrapped candy, was determined by single-crystal X-ray diffraction (see picture), and it retains the electronic structure of pristine La2@C72.

    13. Mass Spectrometry

      Peptide Fragmentation Assisted by Surfaces Treated with a Low-Temperature Plasma in NanoESI (pages 8646–8649)

      Yu Xia, Zheng Ouyang and R. Graham Cooks

      Version of Record online: 1 OCT 2008 | DOI: 10.1002/anie.200803477

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      A softy toughens up: When a nanoelectrospray (nanoESI) emitter was exposed first to a helium plasma (see illustration of experimental setup), ESI, a widely accepted “soft” ionization technique, caused significant and useful peptide fragmentation. The appearance of abundant peptide-fragment ions in the mass spectrum was ascribed to electrolyte release into the solution. Labile phosphate groups on the peptide were preserved during fragmentation.

    14. Zeolite Subnanoparticles

      Indirect Observation of Structured Incipient Zeolite Nanoparticles in Clear Precursor Solutions (pages 8650–8653)

      Lubomira Tosheva, Boriana Mihailova, Lik H. Wee, Biliana Gasharova, Krassimir Garbev and Aidan M. Doyle

      Version of Record online: 10 OCT 2008 | DOI: 10.1002/anie.200802941

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      Subcolloidal zeolite particles having all the structural features of the zeolite framework but sizes of only a few unit cells which are insufficient to generate a diffraction pattern exist in silicalite-1 synthesis solutions, as revealed by synchrotron-based reflection–absorption IR spectroscopy on zeolite films prepared from clear precursor solutions by the Langmuir–Blodgett method or by spin coating (see picture).

    15. Catalytic Hybrid Materials

      A Tailored Organometallic–Inorganic Hybrid Mesostructured Material: A Route to a Well-Defined, Active, and Reusable Heterogeneous Iridium-NHC Catalyst for H/D Exchange (pages 8654–8656)

      Tarun K. Maishal, Johan Alauzun, Jean-Marie Basset, Christophe Copéret, Robert J. P. Corriu, Erwan Jeanneau, Ahmad Mehdi, Catherine Reyé, Laurent Veyre and Chloé Thieuleux

      Version of Record online: 7 OCT 2008 | DOI: 10.1002/anie.200802956

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      A tailored hybrid mesostructured material containing regularly distributed imidazolium units, and subsequent transformation of these imidazolium moieties into Ir-NHC (NHC=N-heterocyclic carbene) complexes via the formation of Ag-NHC species in situ and further transmetalation with [{IrCp*Cl2}2], gives a well-defined, active, and reusable Ir-NHC heterogeneous catalyst for H/D exchange reactions (see picture).

    16. Chirality Sensors

      Highly Stereospecific Generation of Helical Chirality by Imprinting with Amino Acids: A Universal Sensor for Amino Acid Enantiopurity (pages 8657–8660)

      Hyunwoo Kim, Soon Mog So, Cindy Pai-Hui Yen, Elisângela Vinhato, Alan J. Lough, Jong-In Hong, Hae-Jo Kim and Jik Chin

      Version of Record online: 7 OCT 2008 | DOI: 10.1002/anie.200803116

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      Helical chirality can be imprinted onto a 2,2′-dihydroxybenzophenone derivative (see picture) in a highly stereospecific manner. A single amino acid combines with the receptor to form an imine with two internal hydrogen bonds. The azo group allows sensing of amino acid enantiopurity by circular dichroism spectroscopy.

    17. Homogeneous Catalysis

      Selective Synthesis of Primary Amines Directly from Alcohols and Ammonia (pages 8661–8664)

      Chidambaram Gunanathan and David Milstein

      Version of Record online: 7 OCT 2008 | DOI: 10.1002/anie.200803229

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      Air stable and waterproof: Selective and efficient synthesis of primary amines directly from alcohols and ammonia is achieved under mild conditions (see scheme). The reaction is homogenously catalyzed by a novel air-stable ruthenium pincer complex and can proceed in toluene or even in the absence of solvent or “on water”.

    18. Microgels

      A Water Soluble Diruthenium–Gold Organometallic Microgel (pages 8665–8669)

      Manuel Serrano Ruiz, Antonio Romerosa, Benjamín Sierra-Martin and Antonio Fernandez-Barbero

      Version of Record online: 2 OCT 2008 | DOI: 10.1002/anie.200803232

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      Bridging the gap: Two metal-containing moieties, [CpRuCNRuCp]+ and [Au(CN)4], are bridged through a pta ligand in the P,N coordination mode in a water-soluble, air-stable heterobimetallic coordination polymer (see picture, Au orange, Ru turquoise, C gray, N blue, P purple). This complex exhibits gel-like behavior in water, specifically a thermally controlled volume transition. pta=1,3,5-triaza-7-phosphaadamantane, Cp=cyclopentadienyl.

    19. Asymmetric Catalysis

      Asymmetric Intramolecular Oxa-Michael Addition of Activated α,β-Unsaturated Ketones Catalyzed by a Chiral N,N′-Dioxide Nickel(II) Complex: Highly Enantioselective Synthesis of Flavanones (pages 8670–8673)

      Lijia Wang, Xiaohua Liu, Zhenhua Dong, Xuan Fu and Xiaoming Feng

      Version of Record online: 8 OCT 2008 | DOI: 10.1002/anie.200803326

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      The title reaction provides a promising approach for the synthesis of chiral flavanones with broad substrate scope and is tolerant to air and moisture. Good to excellent enantioselectivities and high yields were achieved for most substrates under mild conditions.

    20. Phosphorus Heterocycles

      A Truly Multifunctional Heterocycle: Iminophosphorane, N,P Chelate, and Dihydropyridine (pages 8674–8677)

      Dan A. Smith, Andrei S. Batsanov, Karinne Miqueu, Jean-Marc Sotiropoulos, David C. Apperley, Judith A. K. Howard and Philip W. Dyer

      Version of Record online: 2 OCT 2008 | DOI: 10.1002/anie.200803373

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      Three in one: The anellated σ4-1λ5-[1,3,2]diazaphosphole 2 exists in tautomeric equilibrium with isomer 1 (see scheme) and undergoes three completely different types of reaction: trimethyl aluminum binds at the N terminus of the P[DOUBLE BOND]N bond with ring retention, the dihydropyridine fragment reacts with an activated acetylene in a pseudo-[2+2] cycloaddition, and P[BOND]N bond cleavage is possible with RhI.

    21. Sigmatropic Rearrangement

      Stereospecific Diaza-Cope Rearrangement Driven by Steric Strain (pages 8678–8681)

      Hyunwoo Kim, Yen Nguyen, Alan J. Lough and Jik Chin

      Version of Record online: 10 OCT 2008 | DOI: 10.1002/anie.200801974

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      Buckling under the strain: Steric strain was used to drive the diaza-Cope rearrangement to completion (see scheme) with a high degree of stereospecificity (>99.5 % ee), as evidenced by chiral-phase HPLC and crystal data. There is good agreement between the experimental and computational values for the rate and equilibrium constants for the rearrangement.

    22. Mesoporous Materials

      A General Route to Diverse Mesoporous Metal Oxide Submicrospheres with Highly Crystalline Frameworks (pages 8682–8686)

      Chia-Kuang Tsung, Jie Fan, Nanfeng Zheng, Qihui Shi, Arnold J. Forman, Jianfang Wang and Galen D. Stucky

      Version of Record online: 7 OCT 2008 | DOI: 10.1002/anie.200802487

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      Brilliant orbs: A facile and highly efficient synthetic strategy combines evaporation-induced assembly and acetic acid mediated sol–gel chemistry for the production of various single- and multicomponent mesoporous metal oxide spheres. These spheres, which are micrometer-sized and have high surface areas and high framework crystallinity, will find many applications in catalysis and photocatalysis.

    23. Low-Spin Iron Complex

      Dramatic Remote Substitutent Effects on the Electronic Spin State of Bis(scorpionate) Iron(II) Complexes (pages 8687–8691)

      Paul Hamon, Jean-Yves Thépot, Marie Le Floch, Marie-Emmanuelle Boulon, Olivier Cador, Stéphane Golhen, Lahcène Ouahab, Lotfi Fadel, Jean-Yves Saillard and Jean-René Hamon

      Version of Record online: 2 OCT 2008 | DOI: 10.1002/anie.200802567

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      A molecular vise: The purple-colored bis(tert-butylscorpionate) iron(II) complex is fully low-spin at room temperature, despite the steric hindrance brought about by the six methyl groups in the equatorial belt. The remotely situated bulky tert-butyl substituent on boron acts like a locking screw for a vise, forcing the tripod-shaped ligand to close, thus favoring low-spin complex formation.

    24. Organometallic Chemistry

      Structurally Distinct Homoleptic Anthracene Complexes, [M(C14H10)3]2−, M=Titanium, Zirconium, Hafnium: Tris(arene) Complexes for a Triad of Transition Metals (pages 8692–8695)

      Robert E. Jilek, Meehae Jang, Eric D. Smolensky, J. Doyle Britton and John E. Ellis

      Version of Record online: 2 OCT 2008 | DOI: 10.1002/anie.200802780

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      Being positive about anions: Hydrocarbon complexes containing negative-valent Hf are obtained for the first time as tris(polyarene)hafnates(2−), polyarene=anthracene (An) and naphthalene, where the latter functions as a synthon for the unknown atomic Hf2− (see scheme, cot=1,3,5,7-cyclooctatetraene). Tris(anthracene)metalates(2−) of Ti and Zr were also accessed, which completes an unprecedented triad of tris(arene)metal complexes.

    25. Long-Range Hydride Shift

      An Interrupted [4+3] Cycloaddition Reaction: A Hydride Shift (Ene Reaction) Intervenes (pages 8696–8699)

      Michael Harmata, Chaofeng Huang, Parham Rooshenas and Peter R. Schreiner

      Version of Record online: 18 SEP 2008 | DOI: 10.1002/anie.200803487

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      The road less traveled does indeed make all the difference. The reaction of oxyallylic cations with cyclopentadiene usually yields a [4+3] cycloadduct. Instead, a hydride shift can supersede this cycloadditon process and proceed in synthetically useful yields (see scheme). Computational analyses suggest that substantial electronic effects influence the “road” taken by the oxyallylic cation.

    26. Asymmetric Organocatalysis (1)

      Aminocatalytic Enantioselective anti-Mannich Reaction of Aldehydes with In Situ Generated N-Cbz and N-Boc Imines (pages 8700–8702)

      Chiara Gianelli, Letizia Sambri, Armando Carlone, Giuseppe Bartoli and Paolo Melchiorre

      Version of Record online: 8 OCT 2008 | DOI: 10.1002/anie.200803819

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      The title reaction catalyzed by the commercially available chiral secondary amine 1 proceeds with high stereocontrol and allows the in situ generation of N-carbamate-protected imines from stable α-amido sulfones 2. This organocatalytic approach provides easy and convenient access to valuable compounds 3 in high yield, with very good anti selectivity, and in high enantiomeric purity.

    27. Asymmetric Organocatalysis (2)

      Organocatalytic Asymmetric Aziridination of Enones (pages 8703–8706)

      Fabio Pesciaioli, Francesco De Vincentiis, Patrizia Galzerano, Giorgio Bencivenni, Giuseppe Bartoli, Andrea Mazzanti and Paolo Melchiorre

      Version of Record online: 8 OCT 2008 | DOI: 10.1002/anie.200803647

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      A primary amine derived from cinchona alkaloids as a salt with D-N-Boc phenylglycine (Boc=tert-butoxycarbonyl) is an efficient catalyst for the aziridination of α,β-unsaturated ketones. This method is effective with both linear and cyclic substrates, leading to chiral aziridines in high yield, with complete diastereoselectivity, and with very high enantioselectivity (Cbz=benzyloxycarbonyl).

    28. Asymmetric Organocatalysis (3)

      Proline-Catalyzed Asymmetric Formal α-Alkylation of Aldehydes via Vinylogous Iminium Ion Intermediates Generated from Arylsulfonyl Indoles (pages 8707–8710)

      Rafik R. Shaikh, Andrea Mazzanti, Marino Petrini, Giuseppe Bartoli and Paolo Melchiorre

      Version of Record online: 8 OCT 2008 | DOI: 10.1002/anie.200803947

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      Proline strikes again: The intermolecular enamine-catalyzed asymmetric “formal” α-alkylation of aldehydes is described. Alkylating reagent 1 generates a highly stabilized carbocation, which can readily intercept the enamine intermediate. L-Proline proved to be the best catalyst, providing an easy route to relevant 3-indolyl derivatives 2 with high diastereo- and enantiocontrol.

    29. Hydrothermal Synthesis

      A3(U2O4)(Ge2O7) (A=Rb, Cs): Mixed-Valence Uranium(V,VI) Germanates (pages 8711–8713)

      Chia-Hui Lin and Kwang-Hwa Lii

      Version of Record online: 2 OCT 2008 | DOI: 10.1002/anie.200803658

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      An unusual mix: The first mixed-valence uranium(V,VI) germanates are synthesized under hydrothermal conditions. The structure of A3(U2O4)(Ge2O7) (A=Rb, Cs) contains chains of corner-sharing U5+O6 octahedra (purple) and U6+O6 tetragonal bipyramids (yellow), which are interconnected by GeO4 tetrahedra (green) to form a 3D framework (see picture; A blue).

    30. Antiaromatic Rings

      The Isomers of [12]Annulyne and their Reactive Relationships to Heptalene and Biphenyl (pages 8714–8718)

      Brad D. Rose, Richard C. Reiter and Cheryl D. Stevenson

      Version of Record online: 2 OCT 2008 | DOI: 10.1002/anie.200803863

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      [12]Annulyne not like benzyne: The base-initiated condensation of hexadiyne in nonpolar solvents leads directly to the symmetrical isomers of [12]annulyne, i.e. the all cis isomer, which exists as its cumulene, and the 6,9-trans,trans isomer. One-electron transfer to this mixture leads to the formation of an unsymmetrical [12]annulyne radical anion, which transfers an electron to the all cis system leading to the biphenyl radical anion, while reduction of the other isomer leads to heptalene (see scheme).

    31. Nucleoside Diphosphate Prodrugs

      Bioreversible Protection of Nucleoside Diphosphates (pages 8719–8722)

      Henning Jacob Jessen, Tilmann Schulz, Jan Balzarini and Chris Meier

      Version of Record online: 2 OCT 2008 | DOI: 10.1002/anie.200803100

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      Going incognito: A new prodrug approach has been developed to facilitate the diffusion of highly polar polyphosphorylated nucleosides across cell membranes (see scheme). Inside the cell, the masking groups on the nucleoside diphosphate should be cleaved rapidly by enzymes to release the antiviral active cargo.

    32. Organocatalysis

      Electrophilic Reactivities of α,β-Unsaturated Iminium Ions (pages 8723–8726)

      Sami Lakhdar, Takahiro Tokuyasu and Herbert Mayr

      Version of Record online: 16 SEP 2008 | DOI: 10.1002/anie.200802889

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      How fast do nucleophiles add to iminium ions? Kinetic studies of the reactions of seven iminium ions 1 with cyclic ketene acetals 2 rendered electrophilicity parameters E for these iminium ions. Because N and s parameters are known for numerous nucleophiles, the correlation log k(20 °C)=s(N+E) makes it possible to calculate rate constants for nucleophilic attack at the iminium ions 1.

    33. Aldehyde Oxidation

      Biomimetic Carbene-Catalyzed Oxidations of Aldehydes Using TEMPO (pages 8727–8730)

      Joyram Guin, Suman De Sarkar, Stefan Grimme and Armido Studer

      Version of Record online: 9 OCT 2008 | DOI: 10.1002/anie.200802735

      Thumbnail image of graphical abstract

      Transition-metal-free organocatalytic oxidations of various aldehydes proceed with the TEMPO radical as a mild organic oxidant; the resulting TEMPO esters are formed in moderate to excellent yields (see scheme). N-Heterocyclic carbenes (NHCs) are efficient catalysts and activate aldehydes for electron-transfer reactions. The TEMPO esters are readily hydrolyzed and the nitroxide can be regenerated by aerobic oxidation.

    34. Infrared Spectroscopy

      Strong, Localized, and Directional Hydrogen Bonds Fluidize Ionic Liquids (pages 8731–8734)

      Koichi Fumino, Alexander Wulf and Ralf Ludwig

      Version of Record online: 8 OCT 2008 | DOI: 10.1002/anie.200803446

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      Opposite effect of hydrogen bonding: Whereas molecular liquids are stabilized, ionic liquids can be fluidized by hydrogen bonds. Highly directional H bonds introduce “defects” into the Coulomb network resulting in reduced melting points and decreased viscosities. This is shown by the mid- and far-FTIR spectra of two ionic liquids. (Structure in black: all H bonds are possible, structure in white: methyl group prevents one H bond.)

    35. Superoxide Dismutase Mimics

      NO Dismutase Activity of Seven-Coordinate Manganese(II) Pentaazamacrocyclic Complexes (pages 8735–8739)

      Miloš R. Filipović, Katharina Duerr, Miloš Mojović, Vladica Simeunović, Robert Zimmermann, Vesna Niketić and Ivana Ivanović-Burmazović

      Version of Record online: 16 OCT 2008 | DOI: 10.1002/anie.200801325

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      Redox selectivity? Seven-coordinate manganese(II) pentaazamacrocyclic complexes stimulate NO disproportionation by a novel dismutation mechanism based on the formation of labile metal–nitrosyl adducts and which is associated with the MnII/MnIII redox cycle. The metal-bound NO in these aducts has the character and reactivity of NO and NO+ species. Ex vivo studies suggest that superoxide dismutase mimics of this kind could interfere with NO-mediated processes in biological milieu.

    36. Mg[BOND]Mg Bonds

      MgCl and Mg2Cl2: From Theoretical and Thermodynamic Considerations to Spectroscopy and Chemistry of Species with Mg[BOND]Mg Bonds (pages 8740–8744)

      Ralf Köppe, Patrick Henke and Hansgeorg Schnöckel

      Version of Record online: 1 OCT 2008 | DOI: 10.1002/anie.200802960

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      Happy together: When HCl is passed over heated MgB2, the magnesium subhalide MgCl is formed, which converts into the dimeric linear Mg[BOND]Mg species Mg2Cl2 upon matrix isolation. The two compounds were characterized by vibrational spectroscopy and by computations; special attention was given to the Mg[BOND]Mg bond. The results are compared to recent findings concerning ligand-stabilized Mg[BOND]Mg species.

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