Angewandte Chemie International Edition

Cover image for Vol. 45 Issue 2

December 23, 2005

Volume 45, Issue 2

Pages 175–325

    1. Cover Picture: Applications of Transition-Metal Catalysts to Textile and Wood-Pulp Bleaching (Angew. Chem. Int. Ed. 2/2006) (page 175)

      Ronald Hage and Achim Lienke

      Version of Record online: 21 DEC 2005 | DOI: 10.1002/anie.200690004

      Bleaching catalysts accelerate the removal of a variety of unwanted chromophores present in stains or wood pulp. The cover picture shows the structures of lignin residues from wood pulp and of lycopene which is found in tomato stains. Peroxo–metal and oxo–metal species are proposed as intermediates in the various catalytic cycles. In their Review on page 206 ff. R. Hage and A. Lienke show that a large variety of transition-metal complexes enhance the activity of H2O2 or O2 towards stain or wood-pulp bleaching.

    2. Ivar K. Ugi (1930–2005): Multicomponent Reactions, Computer and Phosphorus Chemistry (page 193)

      Peter Lemmen, Eric Fontain and Johannes Bauer

      Version of Record online: 21 DEC 2005 | DOI: 10.1002/anie.200503978

    3. The Yandulov/Schrock Cycle and the Nitrogenase Reaction: Pathways of Nitrogen Fixation Studied by Density Functional Theory (pages 196–199)

      Frank Neese

      Version of Record online: 12 DEC 2005 | DOI: 10.1002/anie.200502667

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      Doubling up: Converging results from theory and experiments on model systems as well as the nitrogenase active site have recently given new clues as to how it is possible to split the N[TRIPLE BOND]N bond under ambient conditions during the conversion of nitrogen into ammonia. Quantum chemical methods have been shown to be key to studying reaction mechanisms and unstable intermediates (see graph) which are difficult to characterize experimentally.

    4. Gold-Catalyzed Cyclization of Enynes (pages 200–203)

      Shengming Ma, Shichao Yu and Zhenhua Gu

      Version of Record online: 12 DEC 2005 | DOI: 10.1002/anie.200502999

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      The key step in the gold-catalyzed cycloisomerization of enynes is the nucleophilic attack at the Au-coordinated C[BOND]C triple bonds to form a vinylic gold intermediate (see example). The homogeneous gold-catalyzed reaction of enynes under mild conditions has wide scope and high efficiency and gives access to complex or otherwise inaccessible products.

    5. Applications of Transition-Metal Catalysts to Textile and Wood-Pulp Bleaching (pages 206–222)

      Ronald Hage and Achim Lienke

      Version of Record online: 8 DEC 2005 | DOI: 10.1002/anie.200500525

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      Stain removal: The bleaching of textiles and paper are amongst the most important industrial oxidation processes. Chlorine-based bleaching agents, however, can damage the fibers and lead to chlorinated waste products, and H2O2 is expensive and less efficient. Transition-metal catalysts based on Fe, Mn, or Co, which activate H2O2 or O2 (see picture), offer an alternative. In this way, it should be possible to achieve savings both in terms of the amount of chemicals and the energy required for bleaching processes.

    6. Differential-Frequency Saturation Transfer Difference NMR Spectroscopy Allows the Detection of Different Ligand–DNA Binding Modes (pages 224–228)

      Simone Di Micco, Carla Bassarello, Giuseppe Bifulco, Raffaele Riccio and Luigi Gomez-Paloma

      Version of Record online: 22 NOV 2005 | DOI: 10.1002/anie.200501344

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      Vive la différence! The binding of small molecules of pharmaceutical interest to DNA can be screened by differential-frequency saturation transfer difference spectroscopy (DF-STD). The technique allows the probing of DNA recognition phenomena, such as those of base-pair intercalators, minor groove binders, and external backbone binders (see picture).

    7. Hollow and Polygonous Microtubes of Monocrystalline Indium Germanate (pages 228–231)

      Jinhua Zhan, Yoshio Bando, Junqing Hu, Longwei Yin, Xiaoli Yuan, Takashi Sekiguchi and Dmitri Golberg

      Version of Record online: 29 NOV 2005 | DOI: 10.1002/anie.200502870

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      Carbon-assisted thermal coevaporation of In2O3 and GeO2 generates monocrystalline, sub-micrometer In2Ge2O7 tubes with a laminar crystal structure (see figure). Within an In2Ge2O7 tube, the {InO6} octahedron laminae are parallel to the [100] growth direction. These structures may find applications in waveguides or microlasers since their diameters are close to the wavelength and mean free path of appropriate photons.

    8. γ-Silyl Group Effect in Hydroalumination and Carbolithiation of Propargylic Alcohols (pages 232–234)

      Kazunobu Igawa and Katsuhiko Tomooka

      Version of Record online: 28 NOV 2005 | DOI: 10.1002/anie.200503176

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      Making the right substitution: A remarkable acceleration effect of phenyl-substituted silyl groups in hydroalumination and carbolithiation reactions of propargylic alcohols (see formula) is described. The results show that an aryl silyl group can act not only as a protecting group but also as an activating group of the alkynyl moiety. This work provides an efficient group-selective approach to multifunctionalized alkenes.

    9. Synthesis of Semiconducting Thin Films with Nanometer-Scale Periodicity by Solution-Phase Coassembly of Zintl Clusters with Surfactants (pages 235–241)

      Andrew E. Riley, Scott D. Korlann, Erik K. Richman and Sarah H. Tolbert

      Version of Record online: 28 NOV 2005 | DOI: 10.1002/anie.200501361

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      Inorganic cluster anions (Zintl ions) have been cross-linked by transition metals in the presence of alkyl ammonium surfactants and gold substrates to produce nanostructured thin films (see picture). These films display a variety of phases, including hexagonal, cubic, lamellar, and wormlike. Optical measurements show that the films are semiconductors, and IV measurements indicate rectifying behavior.

    10. Folding a De Novo Designed Peptide into an α-Helix through Hydrophobic Binding by a Bowl-Shaped Host (pages 241–244)

      Shohei Tashiro, Masahide Tominaga, Yoshiki Yamaguchi, Koichi Kato and Makoto Fujita

      Version of Record online: 28 NOV 2005 | DOI: 10.1002/anie.200502802

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      In a twist: Encapsulation of a nine-residue peptide (Trp-Ala-Glu-Ala-Ala-Ala-Glu-Ala-Trp) within a bowl-shaped coordination host in water induces and stabilizes the α-helical conformation. The α-helical peptide is recognized through two types of host–guest interactions: a hydrophobic interaction with both terminal Trp residues and electrostatic interactions between the Glu residues and the high positive charge of the host (12+).

    11. Fivefold Coordination of a CuII–Aqua Ion: A Supramolecular Sandwich Consisting of Two Crown Ether Molecules and a Trigonal-Bipyramidal [Cu(H2O)5]2+ Complex (pages 245–248)

      Vaddypally Shivaiah and Samar K. Das

      Version of Record online: 28 NOV 2005 | DOI: 10.1002/anie.200503096

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      Copper crowned: A trigonal-bipyramidal [Cu(H2O)5]2+ ion, which is inserted between two crown ether molecules ([18]crown-6) to form a unique supramolecular sandwich, [Cu(H2O)5([18]crown-6)2]2+ (see picture), has been characterized unambiguously by single-crystal X-ray diffraction. Isopolyanions, [Mo6O19]2−, facilitate the formation of this new structure.

    12. Short, Enantioselective Total Synthesis of Sceptrin and Ageliferin by Programmed Oxaquadricyclane Fragmentation (pages 249–252)

      Phil S. Baran, Ke Li, Daniel P. O'Malley and Christos Mitsos

      Version of Record online: 30 NOV 2005 | DOI: 10.1002/anie.200503374

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      Absolutely without auxiliaries: The enantioselective syntheses of both enantiomers of the dimeric pyrrole–imidazole alkaloids sceptrin and ageliferin have been achieved by a non-auxiliary-based route, which allows assignment of the absolute configuration of natural ageliferin. The “programming” of the oxaquadricyclane fragmentation leading to enantiopure tetrasubstituted cyclobutanes is the crucial step in the synthesis.

    13. Studies into Asymmetric Catalysis of the Nozaki–Hiyama Allenylation (pages 252–255)

      Masahiro Inoue and Masahisa Nakada

      Version of Record online: 30 NOV 2005 | DOI: 10.1002/anie.200502871

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      From aldehydes to allenic alcohols: Studies into the asymmetric catalysis of the Nozaki–Hiyama allenylation are described. Ligand 1 a is effective for the enantioselective allenylations of various aldehydes, with the generation of products with ee values ranging from 72–83 %. The products can be easily desilylated or used as allenylsilanes. DIPEA=diisopropylethylamine, DMI=1,3-dimethyl-2-imidazolidinone, DMS=dimethylsilyl, TMS=trimethylsilyl.

    14. Enantioselective PhSe-Group-Transfer Tandem Radical Cyclization Reactions Catalyzed by a Chiral Lewis Acid (pages 255–258)

      Dan Yang, Bao-Fu Zheng, Qiang Gao, Shen Gu and Nian-Yong Zhu

      Version of Record online: 28 NOV 2005 | DOI: 10.1002/anie.200503056

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      A radical change: α-Phenylselenyl-β-ketoesters (e.g., 1) undergo radical cyclization in the presence of a chiral Lewis acid complex Mg(ClO4)23 with Et3B/O2 as the radical initiator. Monocyclic compounds, such as 2 (or bicyclic products from diene precursors), were obtained in good yields (33–82 %) with 65–97 % ee in this first enantioselective PhSe-group-transfer radical cyclization.

    15. Copper(I)-Directed Formation of a Cyclic Pseudorotaxane Tetramer and Its Trimeric Homologue (pages 258–261)

      Tomáš Kraus, Miloš Buděšínský, Josef Cvačka and Jean-Pierre Sauvage

      Version of Record online: 28 NOV 2005 | DOI: 10.1002/anie.200503163

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      A matter of concentration: Cyclic pseudorotaxanes are formed by the addition of copper(I) ions to a ligand consisting of a ring containing a chelating unit and, appended to the ring, a rigid fragment containing another chelating unit. The tetramer is formed as the major product in concentrated solution, and the analogous trimer prevails in more dilute solution; both species are connected through a concentration-dependent slow equilibrium.

    16. Template-Free Synthesis and Assembly of Single-Crystalline Tungsten Oxide Nanowires and their Gas-Sensing Properties (pages 261–265)

      Julien Polleux, Alexander Gurlo, Nicolae Barsan, Udo Weimar, Markus Antonietti and Markus Niederberger

      Version of Record online: 28 NOV 2005 | DOI: 10.1002/anie.200502823

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      A nonaqueous approach that involves the reaction of tungsten isopropoxide with benzyl alcohol leads to tungsten oxide nanowire bundles without the use of any additional structure-directing templates. The bundles consist of crystalline nanowires with highly uniform diameters of about 1 nm and aspect ratios exceeding 500 (see picture). Gas-sensing tests show a high sensitivity to NO2.

    17. Ru Nanoparticles Immobilized on Montmorillonite by Ionic Liquids: A Highly Efficient Heterogeneous Catalyst for the Hydrogenation of Benzene (pages 266–269)

      Shiding Miao, Zhimin Liu, Buxing Han, Jun Huang, Zhenyu Sun, Jianling Zhang and Tao Jiang

      Version of Record online: 28 NOV 2005 | DOI: 10.1002/anie.200502632

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      In three steps to ruthenium-based heterogeneous catalysts: The central element of this novel and simple route is the immobilization of Ru0 nanoparticles on montmorillonite (see picture; the arrows indicate a Ru nanoparticle intercalated in the interlaminar space of montmorillonite) with the help of an ionic liquid. The resulting catalyst is highly efficient for the hydrogenation of benzene.

    18. Measuring Biomolecular Binding Events with a Compact Disc Player Device (pages 270–273)

      Sebastian A. Lange, Günter Roth, Silke Wittemann, Thilo Lacoste, Andreas Vetter, Jürgen Grässle, Susanne Kopta, Matthias Kolleck, Beate Breitinger, Manfred Wick, J. K. Heinrich Hörber, Stefan Dübel and André Bernard

      Version of Record online: 21 DEC 2005 | DOI: 10.1002/anie.200501243

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      Read the fine print: Biomolecular binding events can be counted with a readout system based on compact disc (CD) pickup technology. An immunoassay of C-reactive protein was performed by microcontact printing of antibodies onto a support, autometallography, and imaging by a CD reader mounted on an optical microscope (see picture). The dynamic range was four orders of magnitude with a detection limit of 1 pM.

    19. Highly Enantioselective Addition of Diphenylzinc to Aliphatic and Aromatic Aldehydes Catalyzed by a Readily Available H8-Binol Derivative (pages 273–277)

      Ying-Chuan Qin and Lin Pu

      Version of Record online: 29 NOV 2005 | DOI: 10.1002/anie.200503206

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      All sorts of aldehydes 2 (R=aryl, vinyl, branched, and linear alkyl) undergo the highly enantioselective addition of diphenylzinc (1) in the presence of catalytic (S)-4 to give α-substituted benzyl alcohols 3 in high yields. In contrast to previous catalysts, no additive is required, the reaction is carried out at room temperature, and the reaction is equally effective with linear aldehydes.

    20. High-Pressure Probing of a Changeover in the Charge-Transfer Mechanism for Intact Cytochrome c at Gold/Self-Assembled Monolayer Junctions (pages 277–281)

      Dimitri E. Khoshtariya, Tina D. Dolidze, David Sarauli and Rudi van Eldik

      Version of Record online: 28 NOV 2005 | DOI: 10.1002/anie.200502386

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      Free trade: The electron exchange of cytochrome c freely diffusing to gold electrodes modified by hydroxy-terminated alkanethiol self-assembled monolayers (SAMs; see picture) is examined by high-pressure kinetic studies. The SAM thickness, solution viscosity, and hydrostatic pressure influence a changeover in the charge-transfer mechanism and the corresponding kinetic response.

    21. A Building-Up Process in Open-Framework Metal Carboxylates that Involves a Progressive Increase in Dimensionality (pages 281–285)

      Meenakshi Dan and C. N. R. Rao

      Version of Record online: 30 NOV 2005 | DOI: 10.1002/anie.200502413

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      Zero- and one-dimensional metal carboxylates are shown to transform into higher-dimensional structures (see figure), thereby indicating the presence of a progressive building-up process.

    22. Ferrocene-Mediated Proton-Coupled Electron Transfer in a Series of Ferrocifen-Type Breast-Cancer Drug Candidates (pages 285–290)

      Elizabeth Hillard, Anne Vessières, Laurent Thouin, Gérard Jaouen and Christian Amatore

      Version of Record online: 28 NOV 2005 | DOI: 10.1002/anie.200502925

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      A double-barreled approach: The addition of ferrocene to an antiestrogen drug skeleton was found to induce cytotoxicity towards breast-cancer cells that are resistant to the common antiestrogen drug. The efficacy of this drug has been related to the proton-coupled electron transfer observed in the presence of pyridine as a base (see picture).

    23. The C[BOND]H⋅⋅⋅π Hydrogen Bond in the Benzene–Trifluoromethane Adduct: A Rotational Study (pages 290–293)

      Juan C. López, Walther Caminati and José L. Alonso

      Version of Record online: 28 NOV 2005 | DOI: 10.1002/anie.200503097

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      Free to rotate: The rotational spectrum of unlabeled and 13C-labeled benzene species reveals that the benzene–trifluoromethane complex is stabilized by a CH⋅⋅⋅π weak hydrogen bond and undergoes an almost-free rotation of the two subunits with respect to each other (see picture). The estimated dissociation energy is 8.4 kJ mol−1.

    24. Photoelectron Spectroscopic Study of the First Singlet and Triplet States of the Cyclopentadienyl Cation (pages 293–296)

      Hans Jakob Wörner and Frédéric Merkt

      Version of Record online: 30 NOV 2005 | DOI: 10.1002/anie.200503032

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      From radical to biradical: The pulsed-field-ionization zero-kinetic-energy photoelectron spectrum of the C5H5 radical is recorded after direct excitation from the X̃ 2equation image ground state and two-photon excitation via the à 2equation image electronically excited state. The intensity distributions of the spectra enables the characterization of the energetics, symmetry, and structure of the lowest two electronic states of the cation (see picture).

    25. Diels–Alder Ligation and Surface Immobilization of Proteins (pages 296–301)

      Aline Dantas de Araújo, Jose M. Palomo, Janina Cramer, Maja Köhn, Hendrik Schröder, Ron Wacker, Christof Niemeyer, Kirill Alexandrov and Herbert Waldmann

      Version of Record online: 29 NOV 2005 | DOI: 10.1002/anie.200502266

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      Mild attachment: Proteins can be ligated chemoselectively and immobilized on functionalized glass surfaces by means of Diels–Alder cycloadditions (see scheme).

    26. Substrate Ambiguity and Catalytic Promiscuity Within a Bacterial Proteome Probed by an Easy Phenotypic Screen for Aldehydes (pages 301–305)

      Guillaume Krebs, Laure Hugonet and John D. Sutherland

      Version of Record online: 29 NOV 2005 | DOI: 10.1002/anie.200503031

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      Seeing the light: The use of a coupled assay with bacterial luciferase results in a common light-emission screen for a variety of potential biotransformations. Screening the E. coli proteome for the oxidation of simple alcohols to good and bad luciferase substrates reveals examples of substrate ambiguity and catalytic promiscuity. Reactions leading to aldehydes can easily be screened by this method.

    27. The Total Synthesis of the Fungal Metabolite Diversonol (pages 307–309)

      Carl F. Nising, Ulrike K. Ohnemüller (née Schmid) and Stefan Bräse

      Version of Record online: 9 DEC 2005 | DOI: 10.1002/anie.200502913

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      Mission accomplished. The fungal metabolite diversonol has been synthesized for the first time. A key step in the total synthesis was the domino oxa-Michael–aldol condensation of salicylic aldehyde 1 and 4-hydroxycyclohexenone (2) that afforded the tricyclic scaffold of the target compound.

    28. Bi-3H-diazirin-3-yls as Precursors of Highly Strained Cycloalkynes (pages 309–311)

      Mohammad Al-Omari, Klaus Banert and Manfred Hagedorn

      Version of Record online: 21 DEC 2005 | DOI: 10.1002/anie.200503124

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      No reagents and very mild conditions are required for the transformation of isolable precursors 3 into highly strained cycloalkynes 4 (cycloheptyne, cyclohexyne, norbornyne), which can be trapped by cycloaddition reactions.

    29. Porous Silicon and Alumina as Chemically Reactive Templates for the Synthesis of Tubes and Wires of SnSe, Sn, and SnO2 (pages 311–315)

      Lili Zhao, Maekele Yosef, Martin Steinhart, Petra Göring, Herbert Hofmeister, Ulrich Gösele and Sabine Schlecht

      Version of Record online: 30 NOV 2005 | DOI: 10.1002/anie.200502665

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      Three in one: Ordered nanostructures of SnSe, SnO2, and elemental tin (see SEM image) were prepared by template-assisted synthesis in porous alumina and macroporous silicon. The use of the templates as chemical reactants allowed the preparation of all three target materials from the same single-source precursor, Sn(SePh)4.

    30. Enantiomerically Pure Copper(II) Cubanes [Cu4L2(OMe)4] from Chiral Bis-1,3-diketones H2L through Diastereoselective Self-Assembly (pages 315–318)

      Rolf W. Saalfrank, Christine Schmidt, Harald Maid, Frank Hampel, Walter Bauer and Andreas Scheurer

      Version of Record online: 28 NOV 2005 | DOI: 10.1002/anie.200502477

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      Loaded dice: Copper cubanes 1 and ent-1 were generated in a one-pot reaction by diastereoselective self-assembly, starting from ligands derived from L- and D-tartaric acid, respectively. Both structures were confirmed by X-ray structure analysis.

    31. Complex Sequence Dependence by Excess-Electron Transfer through DNA with Different Strength Electron Acceptors (pages 318–321)

      Antonio Manetto, Sascha Breeger, Chryssostomos Chatgilialoglu and Thomas Carell

      Version of Record online: 29 NOV 2005 | DOI: 10.1002/anie.200502551

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      An independent jump: Excess electrons move through DNA by using a hopping-type mechanism in which the pyrimidine bases dT and dC act as ‘stepping stones’. It was shown that GC base pairs, in contrast to AT base pairs, lower the efficiency of the excess-electron transfer through the duplex. Through the use of the shown DNA hairpins, three different electron acceptors (

      ) were investigated with the electron donor, reduced flavin (

      ).

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      Preview: Angew. Chem. Int. Ed. 2/2006 (page 325)

      Version of Record online: 21 DEC 2005 | DOI: 10.1002/anie.200690006

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