Angewandte Chemie International Edition

Cover image for Vol. 44 Issue 21

May 20, 2005

Volume 44, Issue 21

Pages 3157–3321

    1. Cover Picture: “On Water”: Unique Reactivity of Organic Compounds in Aqueous Suspension (Angew. Chem. Int. Ed. 21/2005) (page 3157)

      Sridhar Narayan, John Muldoon, M. G. Finn, Valery V. Fokin, Hartmuth C. Kolb and K. Barry Sharpless

      Version of Record online: 17 MAY 2005 | DOI: 10.1002/anie.200590069

      Reactions “on water” offer ease of product isolation and may be substantially faster than the same reactions performed in organic solvents. The cover picture shows the time course of an ene reaction between (S)-β-pinene and diethyl azodicarboxylate performed on water. The insoluble reactants float on water, whereas the product descends under the water layer and is isolated as a colorless oil. For more details on these reactions, see the Communication by K. B. Sharpless and co-workers on page 3275 ff.

    2. Trannulenes with “In-Plane” Aromaticity: Candidates for Harvesting Light Energy (pages 3176–3178)

      Glenn A. Burley

      Version of Record online: 17 MAY 2005 | DOI: 10.1002/anie.200500362

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      Breaking with convention: In the textbook aromatic annulenes the p orbitals are oriented perpendicular to the ring plane. In trannulenes the p orbitals form a cyclic, conjugated π system within the ring plane (see scheme). This concept of “in-plane” aromaticity was first recognized in 1979, and now representative compounds have been synthesized. The all-trans configuration of the annulene ring is stabilized by a fullerene framework, and the novel physicochemical properties of trannulenes open new opportunities for the design of light-harvesting compounds.

    3. DNA Microarrays as Decoding Tools in Combinatorial Chemistry and Chemical Biology (pages 3179–3183)

      Marina Lovrinovic and Christof M. Niemeyer

      Version of Record online: 28 APR 2005 | DOI: 10.1002/anie.200500645

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      Decoding technology: Besides mainstream applications in transcription profiling, DNA microarrays are currently being explored as tools for the deconvolution of synthetic libraries. Current examples include the discovery of a new type of organic reaction and the screening of peptide nucleic acid encoded inhibitor libraries to investigate new proteolytic activities from dust mite extracts (see picture).

    4. Epigenetics—An Epicenter of Gene Regulation: Histones and Histone-Modifying Enzymes (pages 3186–3216)

      Markus Biel, Veit Wascholowski and Athanassios Giannis

      Version of Record online: 17 MAY 2005 | DOI: 10.1002/anie.200461346

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      Wrapped around the finger! It has been known for a long time that histones organize the structure of cellular DNA. The news, however, is that histones are also able to influence elementary DNA-dependent processes. The type and number of specific histone modifications (examples rendered in gray) determine in advance if and when a gene is transcribed. The first modulators of histone-modifying enzymes have already become promising drugs.

    5. Directing the Architecture of Cuprous Oxide Crystals during Electrochemical Growth (pages 3218–3223)

      Matthew J. Siegfried and Kyoung-Shin Choi

      Version of Record online: 6 MAY 2005 | DOI: 10.1002/anie.200463018

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      A new level of programmability and freedom in directing the crystal growth of cuprous oxide was demonstrated by controlling the degree of branching and crystal habit in a systematic manner during electrodeposition. Examples of Cu2O crystals in which these features were directed by rationally designing a growth condition and growth history are shown (scale bar=1 μm).

    6. Real-Time Membrane Fission of Giant Polymer Vesicles (pages 3223–3226)

      Yongfeng Zhou and Deyue Yan

      Version of Record online: 21 APR 2005 | DOI: 10.1002/anie.200462622

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      Cooperation of mother and daughter vesicles, which are self-assembled from an ill-defined hyperbranched copolymer, leads to fission of the daughter membrane in a cytomimetic process (see picture; red: mother vesicle, green: daughter vesicle). This is the first example of giant polymer vesicles (5–200 μm) being used as model membranes.

    7. Solvent Effect on Crystal Polymorphism: Why Addition of Methanol or Ethanol to Aqueous Solutions Induces the Precipitation of the Least Stable β Form of Glycine (pages 3226–3229)

      Isabelle Weissbuch, Vladimir Yu. Torbeev, Leslie Leiserowitz and Meir Lahav

      Version of Record online: 21 APR 2005 | DOI: 10.1002/anie.200500164

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      Crystallization of the thermodynamically metastable β glycine is explained on the basis of its growth at the opposite poles of the crystal (see graph) and by considering the structure of the relevant surfaces of the three polymorphs and their interactions with solvent molecules.

    8. DNA-Based Asymmetric Catalysis (pages 3230–3232)

      Gerard Roelfes and Ben L. Feringa

      Version of Record online: 21 APR 2005 | DOI: 10.1002/anie.200500298

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      A twist in catalysis! The chirality of DNA is transferred directly to a Diels–Alder reaction by using a DNA-tethered catalyst. A catalytically active copper complex with achiral ligands self-assembles with DNA to give products with up to 90 % ee, as is the case for the exo isomer of product 1.

    9. Local Structure and Anisotropic Backbone Dynamics from Cross-Correlated NMR Relaxation in Proteins (pages 3232–3237)

      Phineus R. L. Markwick, Remco Sprangers and Michael Sattler

      Version of Record online: 21 APR 2005 | DOI: 10.1002/anie.200462495

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      Cross-correlated relaxation (CCR) can be used to describe the structure and dynamics of biomolecules (see picture). By combining theoretical and experimental techniques in the study of proteins, for example, it is possible to acquire detailed information concerning the local anisotropic motion of the peptide plane from a single cross-correlation: the C′/N[BOND]H CCR rate.

    10. Electrochemical Addressing of the Optical Properties of a Monolayer on a Transparent Conducting Substrate (pages 3237–3240)

      Atindra D. Shukla, Amitava Das and Milko E. van der Boom

      Version of Record online: 8 APR 2005 | DOI: 10.1002/anie.200461958

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      Don't forget to write! Electrochemical charge storage in a ruthenium-based monolayer on a hydrophilic substrate (for example, indium tin oxide coated glass) produces redox switching of the optical properties of the system (see picture). This read/write process can be carried out at low voltage in air and monitored by UV/Vis spectrophotometry. This makes the monolayer system a suitable candidate for nonvolatile memory devices.

    11. Vapochromic Behavior Accompanied by Phase Transition between Charge-Polarization and Charge-Density-Wave States in a Quasi-One-Dimensional Iodine-Bridged Dinuclear Platinum Compound (pages 3240–3243)

      Hiroyuki Mastuzaki, Hideo Kishida, Hiroshi Okamoto, Kouichi Takizawa, Satoshi Matsunaga, Shinya Takaishi, Hitoshi Miyasaka, Ken-ichi Sugiura and Masahiro Yamashita

      Version of Record online: 11 APR 2005 | DOI: 10.1002/anie.200500091

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      Color sense: A reversible phase transition occurs with a change in color and structural properties on exposure to water vapor of the 1D halogen-bridged dinuclear platinum compound [NH3(C4H8)NH3]2[Pt2(pop)4I]⋅4 H2O (pop=P2O5H22−; see microscope images in reflection mode). This transition takes place between a paramagnetic charge-polarization state (296 K) and a diamagnetic charge-density-wave state (340 K).

    12. A New Minimal Surface and the Structure of Mesoporous Silicas (pages 3243–3248)

      Michael W. Anderson, Chrystelle C. Egger, Gordon J. T. Tiddy, John L. Casci and Kenneth A. Brakke

      Version of Record online: 21 APR 2005 | DOI: 10.1002/anie.200462295

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      The mesoporous silica superstructure SBA-1 was studied to obtain a formulation in terms of curvature that is important for surfactant structures and the mechanism of formation of inorganic replicas. The picture shows an oblique view of the atomistic model used to calculate the X-ray diffraction patterns. Green regions represent the inorganic hydroxylated silica wall of SBA-1, and the blue volume contains micellar surfactant surrounded by adsorbed water.

    13. Ditopic Complexation and Release of Neutral Guest Molecules by a Hydrogen-Bonded “EndoExo” Receptor (pages 3248–3253)

      Miguel A. Mateos-Timoneda, Jessica M. C. A. Kerckhoffs, Mercedes Crego-Calama and David N. Reinhoudt

      Version of Record online: 21 APR 2005 | DOI: 10.1002/anie.200500134

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      A complex situation: Two different types of neutral guest molecules are recognized through a combination of noncovalent interactions by a hydrogen-bonded receptor which displays two different modes of complexation: nonselective-exo and selective-endo complexation (see schematic representation). Furthermore, the hydrogen-bonded trimer can be selectively released.

    14. Intermolecular Tandem Pd-Catalyzed Cross-Coupling/[4+4] and [4+2] Cycloadditions: A One-Pot, Five-Component Assembly of Bicyclo[6.4.0]dodecanes (pages 3253–3256)

      Phil Ho Lee and Kooyeon Lee

      Version of Record online: 21 APR 2005 | DOI: 10.1002/anie.200461957

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      Starting from α-bromovinylarenes, propargyl bromides, and dienophiles, a novel intermolecular tandem Pd-catalyzed cross-coupling/[4+4] and [4+2] cycloaddition sequence provides bicyclo[6.4.0]dodecane derivatives by a rapid synthesis in one reaction vessel. Five components are assembled into one molecule in this process. EWG=electron-withdrawing group.

    15. Rare-Earth Oxide Nanopolyhedra, Nanoplates, and Nanodisks (pages 3256–3260)

      Rui Si, Ya-Wen Zhang, Li-Ping You and Chun-Hua Yan

      Version of Record online: 21 APR 2005 | DOI: 10.1002/anie.200462573

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      Thermolysis of benzoylacetonate complexes proved successful in the synthesis of rare-earth oxide nanocrystals. CeO2 nanopolyhedra, Eu2O3 nanodisks, and Pr2O3 nanoplates display 2D ordering on copper grids (see figure), and the former two show interesting optical properties arising from surface-modification effects.

    16. Self-Assembled Diamide Nanotubes in Organic Solvents (pages 3260–3264)

      Nancy Díaz, François-Xavier Simon, Marc Schmutz, Michel Rawiso, Gero Decher, Jacques Jestin and Philippe J. Mésini

      Version of Record online: 21 APR 2005 | DOI: 10.1002/anie.200500536

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      Hydrogen bonding and π–π interactions are the driving forces for the self-assembly of a diamide organogelator into nanotubes in organic solution. Freeze-fracture electron microscopy (see image) and small angle neutron scattering studies show the tubes have a diameter of (24.2±0.3) nm with a wall thickness of (3.3±0.4) nm and an aspect ratio of 1:50 or higher.

    17. Stereoselective Lewis Acid Mediated [1,3] Ring Contraction of 2,5-Dihydrooxepins as a Route to Polysubstituted Cyclopentenes (pages 3264–3267)

      Christopher G. Nasveschuk and Tomislav Rovis

      Version of Record online: 21 APR 2005 | DOI: 10.1002/anie.200500088

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      A room-temperature diastereoselective [1,3] rearrangement results from treatment of 2,5-dihydrooxepins with EtAlCl2 (see scheme). A modular synthesis of dihydrooxepins allows substituents to be incorporated at any position on the ring, which means that various polysubstituted cyclopentenes can be prepared through this Lewis acid mediated [1,3] ring contraction.

    18. Dimetallic Dioxygen Activation Leading to a Doubly Oxygen-Bridged Dirhodium Complex (pages 3267–3271)

      Cristina Tejel, Miguel A. Ciriano, Eduardo Sola, M. Pilar del Río, Gustavo Ríos-Moreno, Fernando J. Lahoz and Luis A. Oro

      Version of Record online: 21 APR 2005 | DOI: 10.1002/anie.200463073

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      Ready cleavage of dioxygen and its selective insertion into Rh–alkene bonds occurs in the presence of [{Rh(PhN3Ph)(C8H12)}n] (n=1 and 2). The structure of the resulting dirhodadioxetane complex (see picture) and kinetic measurements support a dimetallic mechanism for this process that occurs with 100 % atom economy.

    19. Synthesis and Solid-State Structure of a Metal Complex of a Diphosphineimine (pages 3271–3275)

      Leonard E. Anagho, Jamie F. Bickley, Alexander Steiner and Lothar Stahl

      Version of Record online: 21 APR 2005 | DOI: 10.1002/anie.200462588

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      A stabilizing influence: Heterocyclic diaminophosphines can stabilize diphosphineimines sufficiently to allow the preparation of metal complexes. A kinetically stable diphosphineimine is isolated and its coordination chemistry investigated through the preparation of molybdenum (see picture) and nickel complexes with such P[BOND]P[DOUBLE BOND]N ligands.

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      “On Water”: Unique Reactivity of Organic Compounds in Aqueous Suspension (pages 3275–3279)

      Sridhar Narayan, John Muldoon, M. G. Finn, Valery V. Fokin, Hartmuth C. Kolb and K. Barry Sharpless

      Version of Record online: 21 APR 2005 | DOI: 10.1002/anie.200462883

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      Water, the medium of choice: Many reactions, such as Claisen rearrangements (see scheme), are dramatically accelerated when performed in aqueous suspension (“on water”) relative to organic solvents or even neat conditions. Low miscibility of organic compounds with water is not detrimental: in fact, it facilitates the isolation of products.

    21. Biomimetic Synthesis of Grossularines-1 (pages 3280–3282)

      Fumiko Y. Miyake, Kenichi Yakushijin and David A. Horne

      Version of Record online: 28 APR 2005 | DOI: 10.1002/anie.200500055

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      Like a sea squirt: An efficient biomimetic synthesis of the antitumor α-carboline marine alkaloids grossularine-1 (1) and N,N-didesmethylgrossularine-1 (2) is based on a novel oxidative dimerization of 2-amino-4-(3-indolyl)imidazole.

    22. 2D NMR Characterization of the La@C82 Anion (pages 3282–3285)

      Takahiro Tsuchiya, Takatsugu Wakahara, Yutaka Maeda, Takeshi Akasaka, Markus Waelchli, Tatsuhisa Kato, Hiroshi Okubo, Naomi Mizorogi, Kaoru Kobayashi and Shigeru Nagase

      Version of Record online: 18 APR 2005 | DOI: 10.1002/anie.200500039

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      Mapping of bond connectivity in the carbon cage of the endohedral metallofullerene anion [La@C82-A] (see picture, bottom) and definitive assignment of all the NMR signals were achieved for the first time by means of 2D INADEQUATE NMR spectroscopy measurements (see picture, top). The position of the encapsulated lanthanum atom (red sphere) was also confirmed by measurements of relaxation time T1 for the cage carbon atoms.

    23. Evidence for Carbon–Carbon Meisenheimer–Wheland Complexes between Superelectrophilic and Supernucleophilic Carbon Reagents (pages 3285–3289)

      Carla Boga, Erminia Del Vecchio, Luciano Forlani, Andrea Mazzanti and Paolo E. Todesco

      Version of Record online: 18 APR 2005 | DOI: 10.1002/anie.200500238

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      Proposal accepted: NMR experiments have shown unequivocally that the previously only proposed zwitterionic carbon–carbon Meisenheimer–Wheland complexes are formed in the reaction of 4,6-dinitrobenzofuroxan (DNBF) with 1,3,5-tris(N,N-dialkylamino)benzenes. Increasing the temperature results in a rapid exchange between three homomeric forms of the complex (see scheme; NR2=piperidyl, morpholinyl, pyrrolidinyl).

    24. Infrared, UV/Vis, and W-band EPR Spectroscopic Characterization and Photochemistry of Triplet Mesitylphosphinidene (pages 3289–3293)

      Götz Bucher, Mark L. G. Borst, Andreas W. Ehlers, Koop Lammertsma, Stefano Ceola, Martina Huber, Dirk Grote and Wolfram Sander

      Version of Record online: 21 APR 2005 | DOI: 10.1002/anie.200462862

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      Monitoring the cleavage of phosphiranes 1 and 2 by using a variety of low-temperature and time-resolved spectroscopic techniques has shown that triplet mesitylphosphinidene (3) is the principal product of this photolytic reaction (see scheme). Results obtained by using laser flash photolysis show that 3 is readily quenched by reactive π systems.

    25. Preparation of Enolate–Homoenolate Species as (Z)-γ-Siloxyallylmetal Equivalents: Sequential 1,4-Addition of Bis(iodozincio)methane to 1,4-Dicarbonylbutenes and Cyclopropanation (pages 3293–3296)

      Takaharu Hirayama, Koichiro Oshima and Seijiro Matsubara

      Version of Record online: 21 APR 2005 | DOI: 10.1002/anie.200500133

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      Enolate–homoenolate equivalents 1 can be prepared in one step by the title reaction. They act as functionalized Z-γ-siloxyallyl zinc reagents 2 by undergoing ring opening in the presence of a Lewis acid. Addition of 2 to tosylimines gives vic-amino alcohols with high diastereoselectivity, presumably due to a fixed conformation resulting from coordination of the metal atom.

    26. Peptide–Polymer Hybrid Nanotubes (pages 3297–3301)

      Julien Couet, J. D. Jeyaprakash S. Samuel, Alexey Kopyshev, Svetlana Santer and Markus Biesalski

      Version of Record online: 14 APR 2005 | DOI: 10.1002/anie.200462993

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      Disguise tactics: Peptide–polymer hybrid nanotubes are constructed in which self-assembled cyclic peptides govern the structure, and a synthetic polymer coating determines the surface chemistry. Formation of the latter is initiated in situ from preorganized peptide building blocks. The picture shows an AFM image of nanotubes on a silicon wafer.

    27. Asymmetric Spin Density Distribution in the Copper(II) Complex of N-Confused Tetraphenylporphyrin: A Multifrequency Continuous-Wave and Pulse EPR Study (pages 3301–3303)

      George Mitrikas, Carlos Calle and Arthur Schweiger

      Version of Record online: 28 APR 2005 | DOI: 10.1002/anie.200500155

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      The magnetic interactions between the unpaired electron and the nitrogen donors of the porphyrin ring in the copper(II) complex of N-confused tetraphenylporphyrin, [CuII(nctpp)], were studied by continuous-wave (cw) and pulse EPR methods (see picture). A pronounced asymmetric distribution of the spin density on the three core nitrogen nuclei was found, in contrast to the spin density distribution in the symmetric [CuII(tpp)] complex.

    28. Efficient 1,5-Chirality Transfer in Palladium-Catalyzed Allylic Alkylations of Chelated Amino Acid Ester Enolates (pages 3303–3306)

      Uli Kazmaier and Thomas Lindner

      Version of Record online: 25 APR 2005 | DOI: 10.1002/anie.200500095

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      Neither the olefin geometry nor the configuration of secondary allylic substrates in palladium-catalyzed allylic alkylations of chelated enolates has an influence on the newly formed stereogenic center of the amino acid (see scheme, TBDPS=tert-butyldiphenylsilyl, Tfa=trifluoroacetyl). This is controlled exclusively by the protecting group on the chiral center. Therefore, the choice of the protecting group on the allylic alcohol can lead to either of the diastereomeric amino acids in a highly stereoselective fashion.

    29. Magnetic Moments of the Endohedral Cluster Fullerenes Ho3N@C80 and Tb3N@C80: The Role of Ligand Fields (pages 3306–3309)

      Manfred Wolf, Karl-Hartmut Müller, Yurii Skourski, Dieter Eckert, Petra Georgi, Matthias Krause and Lothar Dunsch

      Version of Record online: 28 APR 2005 | DOI: 10.1002/anie.200461500

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      Wait a moment: The strong ligand field within the M3N cluster of the endohedral cluster fullerenes Ho3N@C80 and Tb3N@C80 accounts for the unusual net magnetic moment of the compounds. As a result of these interactions the individual magnetic moments m of the metal ions (M = Ho or Tb) are not parallel or antiparallel to each other, but parallel to the M[BOND]N bond (see scheme).

    30. Gas-Filled Polyelectrolyte Capsules (pages 3310–3314)

      Dmitry G. Shchukin, Karen Köhler, Helmuth Möhwald and Gleb B. Sukhorukov

      Version of Record online: 21 APR 2005 | DOI: 10.1002/anie.200462889

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      Full of air: Electrostatic layer-by-layer assembly of polyelectrolyte multilayers was successfully accomplished on the surface of an air microbubble (core). The resulting polyelectrolyte shell stabilizes the air microbubbles against collapse and prevents the dissolution of air in aqueous media. Air-containing polyallylamine/poly(styrene sulfonate)(PAH/PSS) microcapsules have a broad size distribution (1–20 μm).

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