Angewandte Chemie International Edition

Cover image for Vol. 43 Issue 15

April 2, 2004

Volume 43, Issue 15

Pages 1895–2041

    1. Cover Picture: Enzymatic Behavior by Intercalating Molecules in a Template-Directed Ligation Reaction (Angew. Chem. Int. Ed. 15/2004) (page 1895)

      Swapan S. Jain, Frank A. L. Anet, Christopher J. Stahle and Nicholas V. Hud

      Article first published online: 30 MAR 2004 | DOI: 10.1002/anie.200490041

      Intercalation-mediated assembly is a powerful method for the template-directed ligation of oligonucleotides. In their Communication on page 2004 ff., Hud and co-workers demonstrate that proflavine, drawn in yellow, enhances the rate of oligonucleotide ligation by three orders of magnitude. The possibility that small molecules played a similar role in the origin of life is suggested by the cover-picture background, which is from M. C. Escher's woodcut The Second Day of Creation (1925).

    2. BioCyc—Genome and Metabolism (page 1908)

      Ralf Petri and Claudia Schmidt-Dannert

      Article first published online: 30 MAR 2004 | DOI: 10.1002/anie.200483067

    3. “Heterogreeneous” Chemistry: Catalysts for Hydrogen Production from Biomass (pages 1912–1914)

      Heiko Jacobsen

      Article first published online: 30 MAR 2004 | DOI: 10.1002/anie.200301700

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      Power to the (bio)masses: Effective (and cheap!) catalysts provide clean and practical sources for hydrogen. The new heterogeneous Pt- and Ni-based catalysts allow the production of H2 from biomass, a renewable resource (see picture). Guided by the principles of Green Chemistry, the new systems have important implications for establishing the role of hydrogen fuel cells as future power sources.

    4. A Perspective of One-Pot Pyrrole–Aldehyde Condensations as Versatile Self-Assembly Processes (pages 1918–1931)

      Abhik Ghosh

      Article first published online: 30 MAR 2004 | DOI: 10.1002/anie.200201603

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      Porphyrins, N-confused porphyrins, sapphyrins, corroles, and a variety of expanded porphyrins are possible products of one-pot pyrrole–aldehyde condensations, depending on the reaction conditions (see picture). A review of these remarkably versatile covalent self-assembly processes is presented.

    5. 8-Oxabicyclo[3.2.1]oct-6-en-3-ones: Application to the Asymmetric Synthesis of Polyoxygenated Building Blocks (pages 1934–1949)

      Ingo V. Hartung and H. Martin R. Hoffmann

      Article first published online: 30 MAR 2004 | DOI: 10.1002/anie.200300622

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      The synthesis of chiral building blocks has been stimulated by the title oxabicyclic compounds (see example) which are readily accessible, simple scaffolds with defined stereochemical features. Strategies for their enantioselective synthesis include asymmetric cycloaddition, desymmetrization, and the “racemic switch” operation.

    6. On the Structure of Liquid Hydrogen Fluoride (pages 1952–1955)

      Sylvia E. McLain, Chris J. Benmore, Joan E. Siewenie, Jacob Urquidi and John F. C. Turner

      Article first published online: 11 FEB 2004 | DOI: 10.1002/anie.200353289

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      Short, bent, strongly hydrogen-bonded chains, with strong interchain interactions and very little branching are the basis of the structure of liquid hydrogen fluoride (see picture), as determined at the partial radial distribution function level.

    7. Molecular and Electronic Structure of Platinum Bis(N-arylamino)phosphenium Complexes including [Pt(phosphane)(phosphenium)(N-heterocyclic carbene)] (pages 1955–1958)

      Ned J. Hardman, Michael B. Abrams, Melanie A. Pribisko, Thomas M. Gilbert, Richard L. Martin, Gregory J. Kubas and R. Tom Baker

      Article first published online: 30 MAR 2004 | DOI: 10.1002/anie.200352326

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      Give and take: A cationic N-heterocyclic carbene (NHC)–phosphenium adduct is prepared (see picture; orange=P, lilac=N, gray=C, white=H). On reaction with [Pt(PPh3)3] it splits into its constituent parts, delivering an NHC ligand (a strong σ donor) and a phosphenium ligand (a π acceptor) from one reagent. These first platinum phosphenium complexes are characterized by short Pt[BOND]P bonds and large Pt–P coupling constants.

    8. Lithium-Templated Synthesis of a Donor–Acceptor Pseudorotaxane and Catenane (pages 1959–1962)

      Guido Kaiser, Thibaut Jarrosson, Sijbren Otto, Yiu-Fai Ng, Andrew D. Bond and Jeremy K. M. Sanders

      Article first published online: 30 MAR 2004 | DOI: 10.1002/anie.200353075

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      Simultaneous coordination of an aromatic electron donor and acceptor to lithium leads to the formation of highly stable colored pseudorotaxane complexes (see picture). The lithium templated pseudorotaxane is an effective precursor to a [2]catenane.

    9. A Colorimetric Approach to Anion Sensing: A Selective Chemosensor of Fluoride Ions, in which Color is Generated by Anion-Enhanced π Delocalization (pages 1962–1965)

      Miguel Vázquez, Luigi Fabbrizzi, Angelo Taglietti, Rosa M. Pedrido, Ana M. González-Noya and Manuel R. Bermejo

      Article first published online: 30 MAR 2004 | DOI: 10.1002/anie.200353148

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      A colorless neutral receptor with no particular chromogenic substituents selectively recognizes fluoride ions with a concomitant development of a yellow color (see scheme). The receptor contains two equivalent arms, each equipped with a thiourea fragment. Color originates from the extended π delocalization induced by the strong hydrogen-bonding interaction of the F ion with the internal NH groups of thiourea moieties.

    10. A High Electrode-Reaction Rate for High-Power-Density Lithium-Ion Secondary Batteries by the Addition of a Lewis Acid (pages 1966–1969)

      Yuki Kato, Takenobu Ishihara, Hiromasa Ikuta, Yoshiharu Uchimoto and Masataka Wakihara

      Article first published online: 30 MAR 2004 | DOI: 10.1002/anie.200353220

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      A salt and battery: The charge-transfer reaction at the electrode/electrolyte interfaces is important in the fabrication of high-power-density lithium-ion secondary batteries. This reaction rate is increased by adding a poly(ethylene glycol)–borate ester Lewis acid to the electrolyte. Because the Lewis acid interacts preferentially with anions (X), an increase in the activity of lithium ions is induced by enhancing the dissociation of lithium salts (Li+X, see scheme).

    11. Supramolecular Chirality of Thermotropic Liquid-Crystalline Folic Acid Derivatives (pages 1969–1972)

      Takashi Kato, Toru Matsuoka, Masayuki Nishii, Yuko Kamikawa, Kiyoshi Kanie, Tatsuya Nishimura, Eiji Yashima and Seiji Ujiie

      Article first published online: 30 MAR 2004 | DOI: 10.1002/anie.200353231

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      Helical self-assembled columns form supramolecular chiral cubic and columnar liquid-crystalline phases (see picture). The complexation of hydrogen-bonded disks of folic acid derivatives that have oligo(glutamic acid) moieties and lipophilic alkyl chains with nonchiral ions leads to the self-assembly of chiral Pm3n cubic and hexagonal columnar structures.

    12. Rational Design of Helical Columnar Packing in Single Crystals (pages 1972–1975)

      Zhaohui Wang, Volker Enkelmann, Fabrizia Negri and Klaus Müllen

      Article first published online: 30 MAR 2004 | DOI: 10.1002/anie.200353245

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      A highly ordered helical columnar packing in single crystals (see picture) can be generated from a simple and nonchiral aromatic system based on pyrene by rational design. The packing preference can be attributed to the combined effect of maximized dipole–dipole interaction and the compatible accommodation of bulky tert-butyl groups.

    13. Efficient Energy Transfer in Mixed Columnar Stacks of Hydrogen-Bonded Oligo(p-phenylene vinylene)s in Solution (pages 1976–1979)

      Freek J. M. Hoeben, Laura M. Herz, Clément Daniel, Pascal Jonkheijm, Albertus P. H. J. Schenning, Carlos Silva, Stefan C. J. Meskers, David Beljonne, Richard T. Phillips, Richard H. Friend and E. W. Meijer

      Article first published online: 30 MAR 2004 | DOI: 10.1002/anie.200353451

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      Ultrafast energy transfer has been observed in mixed supramolecular stacks of mono-functionalized oligo(phenylene vinylene)s (MOPVs) in solution. Extended columnar aggregates of MOPV3 incorporating MOPV4 show a very efficient quenching of the MOPV3 fluorescence, which indicates that energy transfer (ENT) occurs within the supramolecular stacks from the shorter oligomer to the longer one (see schematic representation).

    14. Gd5Si2B8: A Ternary Rare-Earth-Metal Silicide Boride Compound (pages 1979–1983)

      Volodymyr Babizhetskyy, Jérome Roger, Stéphanie Députier, Roland Guérin, Régis Jardin, Josef Bauer, Kurt Hiebl, Christophe Jardin, Jean-Yves Saillard and Jean-François Halet

      Article first published online: 30 MAR 2004 | DOI: 10.1002/anie.200352468

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      Two compounds in one: The boron-rich ternary compound Gd5Si2B8 represents a new structure type containing independent ordered boron and silicon substructures of compositions GdB4 and Gd3Si2, respectively, alternating along the c direction (see structure). The compound exhibits metallic character, which is supported by theoretical investigations, and has a rather complex magnetic structure.

    15. Asymmetric Direct Aldol Reaction Assisted by Water and a Proline-Derived Tetrazole Catalyst (pages 1983–1986)

      Hiromi Torii, Masakazu Nakadai, Kazuaki Ishihara, Susumu Saito and Hisashi Yamamoto

      Article first published online: 16 MAR 2004 | DOI: 10.1002/anie.200352724

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      Just add water to improve the performance of direct aldol reactions like that shown. Previously, aldehydes with high water-affinity or -solubility were considered unsuitable for asymmetric synthesis.

    16. The Magnitude of Hyperconjugation in Ethane: A Perspective from Ab Initio Valence Bond Theory (pages 1986–1990)

      Yirong Mo, Wei Wu, Lingchun Song, Menghai Lin, Qianer Zhang and Jiali Gao

      Article first published online: 30 MAR 2004 | DOI: 10.1002/anie.200352931

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      Steric effect dominates: Ab initio valence bond and block-localized wavefunction methods are used to estimate the contributions of hyperconjugation and steric effects to the ethane rotation barrier. The results show that hyperconjugation stabilizes the staggered conformer by about 4 kJ mol−1 relative to the eclipsed form (see picture) and steric hindrance is the major driving force behind the favoring of the staggered conformation in ethane.

    17. Incremental Contribution to Protein Stability from a β Hairpin “Finger”: Limits on the Stability of Designed β Hairpin Peptides (pages 1991–1994)

      Mark S. Searle, Geoffrey W. Platt, Roger Bofill, Stephen A. Simpson and Barbara Ciani

      Article first published online: 30 MAR 2004 | DOI: 10.1002/anie.200352955

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      Back to the fold: A new method to determining the stability of a β hairpin is described. A β hairpin forming sequence (β4) is introduced into native ubiquitin (see structure) enabling the contribution to protein stability of this structural motif to be estimated. This data provides both an upper limit on stability for autonomously folding β hairpins, and a spectroscopic reference state for estimating the stability of related peptides in solution.

    18. The Preparation and X-ray Crystal Structure of [(AgI2)n]⋅n MF6 (M=Sb, As): Diiodine Acting as a Donor in the Planar Polymeric [(AgI2)n]n+ (pages 1995–1998)

      T. Stanley Cameron, Jack Passmore and Xinping Wang

      Article first published online: 30 MAR 2004 | DOI: 10.1002/anie.200352969

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      Generous diiodine? [(AgI2)n]⋅n MF6 (M=Sb, As) prepared by the reactions of AgMF6 with I2 in liquid SO2, contain polymeric 1D chains [(AgI2)n]n+ stacked down the c axis separated by sheets of [MF6] ions (see picture). The [(AgI2)n]n+ ion is the first example in which a dihalogen molecule is coordinated to an uncomplexed metal cation, that is, a metal dihalogen homoleptic species and is a simple and rare example of molecular diiodine acting as a donor.

    19. Synthesis of the Furanosteroidal Antibiotic Viridin (pages 1998–2001)

      Edward A. Anderson, Erik J. Alexanian and Erik J. Sorensen

      Article first published online: 30 MAR 2004 | DOI: 10.1002/anie.200353129

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      A rhodium-catalyzed alkyne cyclotrimerization, domino electrocyclic reactions, and a hydroxy-directed dihydroxylation are key steps in an efficient synthesis of the bioactive furanosteroid viridin (1) from a simple acyclic triyne.

    20. Three-Component Sequential Aza[4+2] Cycloaddition/Allylboration/Retro-Sulfinyl-Ene Reaction: A New Stereocontrolled Entry to Palustrine Alkaloids and Other 2,6-Disubstituted Piperidines (pages 2001–2004)

      Barry B. Touré and Dennis G. Hall

      Article first published online: 30 MAR 2004 | DOI: 10.1002/anie.200353152

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      Step-economy and stereocontrol are highlighted in a novel three-component sequential reaction to access substituted piperidines (see scheme). Through combining boronate-substituted hydrazonobutadienes, chiral sulfinimide dienophiles, and aldehydes in a highly regio- and diastereoselective fashion, a concise synthesis of the palustrine derivative (−)-methyl dihydropalustramate was accomplished.

    21. Enzymatic Behavior by Intercalating Molecules in a Template-Directed Ligation Reaction (pages 2004–2008)

      Swapan S. Jain, Frank A. L. Anet, Christopher J. Stahle and Nicholas V. Hud

      Article first published online: 16 FEB 2004 | DOI: 10.1002/anie.200353155

      Thumbnail image of graphical abstract

      Molecular midwifery: A nucleic acid intercalating molecule, proflavine (represented by blue lines), increases the coupling rate of short oligonucleotides in a template-directed synthesis by three orders of magnitude. Several proflavine molecules act cooperatively to function as a concentration-dependent multimolecular “enzyme”.

    22. 1-(o-Nitrophenyl)-2,2,2-trifluoroethyl Ether Derivatives as Stable and Efficient Photoremovable Alcohol-Protecting Groups (pages 2008–2012)

      Alexandre Specht and Maurice Goeldner

      Article first published online: 30 MAR 2004 | DOI: 10.1002/anie.200353247

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      The caging and photolytic release of alcohols has enormous potential for application in biological chemistry. A variety of stable 1-(2-nitrophenyl)-2,2,2-trifluoroethyl ether derivatives, which were readily prepared through Mitsunobu coupling reactions with an alcohol (ROH), underwent photolytic cleavage in high quantum yields (see scheme; R=alkyl, R′=H, OCH3).

    23. A Super-Hydrophobic and Super-Oleophilic Coating Mesh Film for the Separation of Oil and Water (pages 2012–2014)

      Lin Feng, Zhongyi Zhang, Zhenhong Mai, Yongmei Ma, Biqian Liu, Lei Jiang and Daoben Zhu

      Article first published online: 30 MAR 2004 | DOI: 10.1002/anie.200353381

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      An example from nature: Analogous to the surface structure of the lotus leaf, the micro- and nanostructured rough surfaces of a teflon-coated mesh film engender it with both super-hydrophobic and super-oleophilic properties. The result is a variable film with contact angles of ≈150° for water and almost 0° for diesel oil, which makes it an ideal tool for the separation of oil and water (see figure).

    24. Diels–Alder Reaction of Thiophene: Dramatic Effects of High-Pressure/Solvent-Free Conditions (pages 2015–2017)

      Koji Kumamoto, Isao Fukada and Hiyoshizo Kotsuki

      Article first published online: 30 MAR 2004 | DOI: 10.1002/anie.200353487

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      The extraordinary power of high-pressure/solvent-free conditions for the Diels–Alder reaction of thiophene has been established. For example, maleic anhydride (X=O) reacted with thiophene at 0.8 GPa and 100 °C to give the desired exo adduct in almost quantitative yield (see scheme). Further application of this method to maleimide (X=NR) and acrylic dienophiles demonstrated its remarkable potential.

    25. Thermally Stable Silicate Nanotubes (pages 2017–2020)

      Xun Wang, Jing Zhuang, Jun Chen, Kebin Zhou and Yadong Li

      Article first published online: 30 MAR 2004 | DOI: 10.1002/anie.200353507

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      Silicates, the most abundant minerals in the Earth's crust, have been successfully prepared as uniform nanotubes with high surface area and thermal stability (see picture). Preliminary studies suggest that such materials have great potential for use in gas adsorption and separation, as well as in catalytic processes.

    26. Asymmetric Total Synthesis of (−)-Nakadomarin A (pages 2020–2023)

      Koji Ono, Masako Nakagawa and Atsushi Nishida

      Article first published online: 30 MAR 2004 | DOI: 10.1002/anie.200453673

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      A key intermediate in the first asymmetric synthesis of the marine alkaloid (−)-nakadomarin A (1), isolated from the marine sponge Amphimedon sp., was the optically active hydroisoquinoline 2. Two separate ring-closing-metathesis reactions were crucial to the construction of the 15- and 8-membered rings.

    27. A Chemically Modified Platinum Electrode as a Bidentate Diamine Ligand for Forming Well-Defined, Immobilized Bis(η1-P-ether phosphane)(diamine)ruthenium(II) Complexes (pages 2025–2028)

      Filip Novak, Bernd Speiser, Ekkehard Lindner, Zhong-Lin Lu and Hermann A. Mayer

      Article first published online: 30 MAR 2004 | DOI: 10.1002/anie.200353399

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      Ligands with potential: Hydrogenation catalysts similar to Noyori's complexes are assembled on the surface of a chemically modified platinum electrode, and the immobilized organometallic species are characterized by cyclic voltammetry, revealing a chelate-type structure. The organometallic compound is bound by a single chain to the modified platinum surface (see picture).

    28. Directed Evolution of Noble-Metal-Free Catalysts for the Oxidation of CO at Room Temperature (pages 2028–2031)

      Jens W. Saalfrank and Wilhelm F. Maier

      Article first published online: 30 MAR 2004 | DOI: 10.1002/anie.200351935

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      Directed catalyst evolution: IR-thermography and combinatorial library design (doping and composition spread) lead in a few generations to new, noble-metal-free catalysts for the low-temperature oxidation of CO in air. The picture shows the emissivity-corrected IR thermographic image of a catalyst library; the red dots denote the hits.

    29. Li–Cu Exchange in Intercalated Cu3N—With a Remark on Cu4N (pages 2032–2034)

      Fakhili Gulo, Arndt Simon, Jürgen Köhler and Reinhard K. Kremer

      Article first published online: 30 MAR 2004 | DOI: 10.1002/anie.200353424

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      A surprising substitution of Cu by Li has been observed during the intercalation reaction of Cu3N with n-butyllithium, besides an expected incorporation of Li. The twofold coordinated Cu+ ions are shifted into cuboctahedral cavities along with a reduction to Cu0 (see picture). The chemical bonding of the compounds LixCu3N is analyzed in comparison to Cu4N on the basis of band-structure calculations.

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