Angewandte Chemie International Edition

Cover image for Vol. 44 Issue 46

November 25, 2005

Volume 44, Issue 46

Pages 7485–7647

    1. Cover Picture: A Phthalocyanine Clathrate of Cubic Symmetry Containing Interconnected Solvent-Filled Voids of Nanometer Dimensions (Angew. Chem. Int. Ed. 46/2005) (page 7485)

      Neil B. McKeown, Saad Makhseed, Kadhum J. Msayib, Li-Ling Ooi, Madeleine Helliwell and John E. Warren

      Version of Record online: 21 NOV 2005 | DOI: 10.1002/anie.200590153

      A clathrate formed from a zinc phthalocyanine has an unusual crystal structure with exceptionally large solvent-filled voids (>8 nm3). The “fold-up cube” in the cover picture shows how six phthalocyanine molecules assemble to form each nanovoid. Solvent molecules, including water, can be exchanged between the voids, while the metal centers embedded in each face offer the potential for catalysis. For more details, see the Communication by N. B. McKeown and co-workers on page 7546 ff.

    2. Extending Mechanistic Routes in Heterazolium Catalysis–Promising Concepts for Versatile Synthetic Methods (pages 7506–7510)

      Kirsten Zeitler

      Version of Record online: 21 NOV 2005 | DOI: 10.1002/anie.200502617

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      A broad spectrum of valuable cyclic and acyclic products are available in diastereo- and/or enantioselective form by sustainable, organocatalytic processes like the heterazolium-catalyzed transformations shown in the scheme. The carbene-mediated generation of activated carboxylate intermediates provides new possibilities for the straightforward synthesis of multifunctionalized compounds.

    3. 1,4-Migration of Rhodium and Palladium in Catalytic Organometallic Reactions (pages 7512–7517)

      Shengming Ma and Zhenhua Gu

      Version of Record online: 7 NOV 2005 | DOI: 10.1002/anie.200501298

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      A key mechanistic step in a number of rhodium- and palladium-catalyzed reactions is the 1,4-migration of the metal center, which can be understood as the oxidative addition of the metal into a C[BOND]H or C[BOND]X bond followed by reductive elimination. Although concrete evidence for the transition state is lacking, the synthetic applications are numerous.

    4. Atmospheric Aerosols: Composition, Transformation, Climate and Health Effects (pages 7520–7540)

      Ulrich Pöschl

      Version of Record online: 21 NOV 2005 | DOI: 10.1002/anie.200501122

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      An esthetic example of the wide variety of biological aerosol particles found in the atmosphere are the pictured brochosomes, which are released by insects. Atmospheric chemistry and physics, the biosphere, the hydrological cycle, climate, and human health are all strongly influenced by natural and anthropogenic particles in the nanometer to micrometer size range.

    5. Structural Preference versus Metal within the MB2C2 (M=Mg, Sc, Ca, Y, Ln) Phases: The Coloring Problem Revisited by DFT Calculations (pages 7542–7545)

      Xavier Rocquefelte, Salah Eddine Boulfelfel, Mouna Ben Yahia, Josef Bauer, Jean-Yves Saillard and Jean-François Halet

      Version of Record online: 7 NOV 2005 | DOI: 10.1002/anie.200503080

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      The question of coloring: Calculations present a definite solution to the “coloring problem” in the MB2C2 phases (M=Mg, Sc, Ca, Y, Ln; see picture of the four structure types). Electric-field gradient tensor components from NMR spectroscopy readily allow differentiation between the different B/C topologies and give support to the theoretical results.

    6. A Phthalocyanine Clathrate of Cubic Symmetry Containing Interconnected Solvent-Filled Voids of Nanometer Dimensions (pages 7546–7549)

      Neil B. McKeown, Saad Makhseed, Kadhum J. Msayib, Li-Ling Ooi, Madeleine Helliwell and John E. Warren

      Version of Record online: 5 OCT 2005 | DOI: 10.1002/anie.200502668

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      A void apart! A clathrate based on zinc octa(2,6-diisopropylphenoxy)phthalocyanine contains solvent-filled voids of exceptionally large volume (>8 nm3; see picture for the packing arrangement). Each nanovoid is enclosed by a cubic assembly of six phthalocyanine molecules and contains 18 molecules of water and an estimated 65 molecules of acetone, which may be exchanged for methanol or water molecules without loss of order.

    7. Squeezing C[BOND]C Bonds (pages 7549–7553)

      Deborah R. Huntley, Georgios Markopoulos, Patrick M. Donovan, Lawrence T. Scott and Roald Hoffmann

      Version of Record online: 31 OCT 2005 | DOI: 10.1002/anie.200502721

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      It's not how short you make it, it's how you make it short! A diverse collection of compounds with short C[BOND]C single bonds whose lengths range from 1.32 Å to 1.46 Å have been theoretically designed (see structure of a “spiderane”). The strategies for squeezing the C[BOND]C bonds (encapsulation, strapping back, and stiffening) allow shorter bonds than hybridization and conjugative effects alone.

    8. Conversion of a Carboxylesterase into a Triacylglycerol Lipase by a Random Mutation (pages 7553–7557)

      Dolores Reyes-Duarte, Julio Polaina, Nieves López-Cortés, Miguel Alcalde, Francisco J. Plou, Kieran Elborough, Antonio Ballesteros, Kenneth N. Timmis, Peter N. Golyshin and Manuel Ferrer

      Version of Record online: 27 OCT 2005 | DOI: 10.1002/anie.200502461

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      A true convert: The carboxylesterase enzyme R.34 (see picture) can be converted into a triacylglycerol lipase without modification of the shape, size, or hydrophobicity of the substrate binding site. The substitution of Asn33 by Asp results in a salt bridge between the Asp33 and Arg49, which causes a distortion of the enzyme structure that makes the catalytic site more accessible to larger substrates but also more labile.

    9. Chain Elongation, Macrolactonization, and Hydrolysis of Natural and Reduced Hexaketide Substrates by the Picromycin/Methymycin Polyketide Synthase (pages 7557–7560)

      Jiaquan Wu, Weiguo He, Chaitan Khosla and David E. Cane

      Version of Record online: 25 OCT 2005 | DOI: 10.1002/anie.200502246

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      Dual action: An analogue of a natural hexaketide thioester substrate is incubated with recombinant picromycin/methymycin synthase (PICS) module 6 with its attached thioesterase (TE). A mixture of 12- and 14-membered-ring macrolactones 10-deoxymethynolide (1) and narbonolide (2) are generated (see scheme) by competing chain elongation and direct lactonization of the substrate. KS=ketosynthase, AT=methylmalonyl transferase, ACP=acyl carrier protein, metmal CoA=methylmalonyl coenzyme A.

    10. Ethylene Oligomerization at Coordinatively and Electronically Unsaturated Low-Valent Nickel (pages 7560–7564)

      Zhiqiang Weng, Shihui Teo, Lip Lin Koh and T. S. Andy Hor

      Version of Record online: 27 OCT 2005 | DOI: 10.1002/anie.200502532

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      Three modes: An iminoferrocenylphosphane ligand stabilizes low-coordinate and low-valent nickel in [{[η-C5H4CH[DOUBLE BOND]N(C6H5)]Fe[η-C5H4P(tBu)2]-N,P}NiICl] (see figure) and similar complexes. The coordination environment is hemilabile as exemplified by three different coordination modes: P,N(σ)-chelate, P,CN(π)-chelate, and P unidentate. These complexes are catalytically active towards ethylene oligomerization.

    11. Diphenylphosphanylsulfoximines as Ligands in Iridium-Catalyzed Asymmetric Imine Hydrogenations (pages 7564–7567)

      Christian Moessner and Carsten Bolm

      Version of Record online: 10 OCT 2005 | DOI: 10.1002/anie.200502482

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      Easily accessible phosphine-substituted sulfoximines 2 have been applied in Ir-catalyzed asymmetric hydrogenations of acylic N-arylated imines 1. The amines 3 are formed under mild conditions in high yields with excellent ee values.

    12. S-Heterocyclic Carbene with a Disilane Backbone (pages 7567–7570)

      Hidefumi Nikawa, Tsukasa Nakahodo, Takahiro Tsuchiya, Takatsugu Wakahara, G. M. Aminur Rahman, Takeshi Akasaka, Yutaka Maeda, Michael T. H. Liu, Akira Meguro, Soichiro Kyushin, Hideyuki Matsumoto, Naomi Mizorogi and Shigeru Nagase

      Version of Record online: 27 OCT 2005 | DOI: 10.1002/anie.200502971

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      Caught in a trap! An S-heterocyclic carbene (SHC) with a cyclotetrasilane backbone is generated by a [2+3] cycloaddition of cyclotetrasilene with CS2 and trapped with C60 as a chemical probe. It is demonstrated that photolysis of anti-dodecaisopropyltricyclo[4.2.0.02,5]octasilane and CS2 in the presence of C60 affords a methanofullerene (see scheme).

    13. Stereoselective Palladium-Catalyzed Four-Component Cascade Synthesis of Pyrrolidinyl-, Pyrazolidinyl-, and Isoxazolidinyl Isoquinolines (pages 7570–7574)

      H. Ali Dondas, Colin W. G. Fishwick, Xinjie Gai, Ronald Grigg, Colin Kilner, Nuethip Dumrongchai, Boonsong Kongkathip, Ngampong Kongkathip, Chatchwan Polysuk and Visuvanathar Sridharan

      Version of Record online: 25 OCT 2005 | DOI: 10.1002/anie.200502066

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      Two paths diverge: Four-component cascades that involve the cycloaddition of azomethine ylides, azomethine imines, or nitrones generated in situ, coupled with allene incorporation, give rise to five new bonds, two rings, and two to four stereocenters through two possible pathways (see picture for an example).

    14. Oriented Nanoporous Lamellar Organosilicates Templated from Topologically Unsymmetrical Dendritic-Linear Block Copolymers (pages 7574–7580)

      Teddie Magbitang, Victor Y. Lee, Jennifer N. Cha, Hsiao-Lin Wang, W. Richard Chung, Robert D. Miller, Geraud Dubois, Willi Volksen, Ho-Cheol Kim and James L. Hedrick

      Version of Record online: 25 OCT 2005 | DOI: 10.1002/anie.200501577

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      Dendrimers between the sheets: Environmentally responsive dendritic-linear block copolymers, based on poly(ethylene oxide) and a dendron derived from 2,2′-bis(hydroxymethyl)propionic acid (see structure), were used to organize organosilicate vitrificates into nanostructured lamellar morphologies. Upon thermolysis of the template, a perforated porous lamellar structure (4 nm) between organosilicate sheets (6–9 nm) was obtained.

    15. A DNA-Templated Aldol Reaction as a Model for the Formation of Pentose Sugars in the RNA World (pages 7580–7583)

      Michael Oberhuber and Gerald F. Joyce

      Version of Record online: 20 OCT 2005 | DOI: 10.1002/anie.200503387

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      Sugar on a stick: A DNA template can bind two complementary oligonucleotides, one derivatized with glyceraldehyde (blue) and the other with glycolaldehyde (red), resulting in a cross-aldol reaction that forms pentose sugars. This reaction system serves as a model for the RNA-catalyzed synthesis of ribose, which is relevant to a presumed RNA-based metabolism during the early history of life on Earth.

    16. A Highly Active Anion-Selective Aminocyclodextrin Ion Channel (pages 7584–7587)

      Nandita Madhavan, Erin C. Robert and Mary S. Gin

      Version of Record online: 25 OCT 2005 | DOI: 10.1002/anie.200501625

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      Negative beats positive: A channel composed of oligoether chains attached by amine groups to β-cyclodextrin mediates the transport of halides across a phospholipid bilayer (see scheme) at faster rates than those observed for monovalent cations. Protonation of the amine linkages likely explains the preferential anion transport.

    17. “Hydrogen-Catalyzed” Dehydrogenation: A Supercritical Conundrum (pages 7588–7591)

      Jason R. Hyde, Ben Walsh and Martyn Poliakoff

      Version of Record online: 31 OCT 2005 | DOI: 10.1002/anie.200502049

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      Hot spots: The surprising, apparently catalytic effect of H2 in the dehydrogenation of 1 in supercritical CO2 is the result of thermal hot spots (see thermal image of reactor) generated in the catalyst bed by an initial exothermic hydrogenation. The localized heating forces the dehydrogenation reaction which also gives the diene 2 by a route that is potentially much simpler than the established procedure.

    18. Molecular AND Logic Gate Based on Electric Dichroism of a Photochromic Dihydroindolizine (pages 7591–7594)

      Joakim Andréasson, Yuichi Terazono, Bo Albinsson, Thomas A. Moore, Ana L. Moore and Devens Gust

      Version of Record online: 27 OCT 2005 | DOI: 10.1002/anie.200502420

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      Very ANDy: A photochromic molecular switch has been found to act as an AND Boolean logic gate. The switch takes as input both UV light, which causes photoisomerization of a dihydroindolizine to an open, dipolar form, and an electric field, which aligns this isomer in solution (see scheme). The output of the gate is read as the electric linear dichroism response of the open isomer. The gate can be reset with visible light.

    19. An Efficient Design for the Rigid Assembly of Four Bidentate Chromophores in Water-Stable Highly Luminescent Lanthanide Complexes (pages 7595–7598)

      Nicholas Chatterton, Yann Bretonnière, Jacques Pécaut and Marinella Mazzanti

      Version of Record online: 21 NOV 2005 | DOI: 10.1002/anie.200502231

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      A simple bridge solves a difficult architectural problem. Ligand H4tpaen, with an ethylenediamine backbone that has ten donor atoms, yields ten-coordinate lanthanide complexes, thus providing highly effective protection of the metal center from interaction with the solvent molecules. As a result, the EuIII and TbIII complexes of (tpaen)4− show a bright and long-lived luminescence in H2O combined with high solubility and stability.

    20. Acyl 1,3-Migration in Rhodium-Catalyzed Reactions of Acetylenic β-Ketoesters with Aryl Boronic Acids: Application to Two-Carbon-Atom Ring Expansions (pages 7598–7600)

      Tomoya Miura, Masahiko Shimada and Masahiro Murakami

      Version of Record online: 31 OCT 2005 | DOI: 10.1002/anie.200502650

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      Expanding rings: An intermediate organorhodium(I) species formed in the RhI-catalyzed reaction of acetylenic β-ketoesters and β-diketones with aryl boronic acids undergoes intramolecular nucleophilic addition to a ketone carbonyl group. The ensuing ring-opening reaction of the resulting cyclobutanols results in acyl 1,3-migration leading to the development of a two-carbon-atom ring-expansion reaction.

    21. Oxygen Storage at the Metal/Oxide Interface of Catalyst Nanoparticles (pages 7601–7605)

      Tobias Schalow, Mathias Laurin, Björn Brandt, Swetlana Schauermann, Sebastien Guimond, Helmut Kuhlenbeck, David E. Starr, Shamil K. Shaikhutdinov, Jörg Libuda and Hans-Joachim Freund

      Version of Record online: 25 OCT 2005 | DOI: 10.1002/anie.200502160

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      Holding its breath: Small Pd particles on an Fe3O4 support reversibly store large quantities of oxygen in the form of a thin Pd oxide layer at the particle/support interface. Oxygen from this reservoir can be released during oxidation reactions, as shown by a combination of molecular beam methods, scanning tunneling microscopy, and photoelectron spectroscopy.

    22. Short De Novo Synthesis of Fully Functionalized Uronic Acid Monosaccharides (pages 7605–7607)

      Mattie S. M. Timmer, Alexander Adibekian and Peter H. Seeberger

      Version of Record online: 3 NOV 2005 | DOI: 10.1002/anie.200502742

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      Short and Sweet: A convergent route leads to orthogonally protected D-glucuronic and L-iduronic acid thioglycoside building blocks, commonly used in heparin oligosaccharide assembly (see scheme). Rapid access to substantial quantities of these key intermediates feeds the growing need for monosaccharide building blocks for use in the assembly of bioactive oligosaccharides. PG=protecting group.

    23. A High-Throughput Investigation of the Role of pH, Temperature, Concentration, and Time on the Synthesis of Hybrid Inorganic–Organic Materials (pages 7608–7611)

      Paul M. Forster, Norbert Stock and Anthony K. Cheetham

      Version of Record online: 24 OCT 2005 | DOI: 10.1002/anie.200501766

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      Four reaction parameters and their effects on the formation of cobalt succinate phases were studied by high-throughput methods. In addition to identifying two new phases, we show that higher reaction temperatures lead to products containing less water, more basic conditions favor increasingly condensed M-O-M networks (see phase diagram), and depending on the reaction time the products are formed under either kinetic or thermodynamic control.

    24. Quantum Dots as Efficient Energy Acceptors in a Time-Resolved Fluoroimmunoassay (pages 7612–7615)

      Niko Hildebrandt, Loïc J. Charbonnière, Michael Beck, Raymond F. Ziessel and Hans-Gerd Löhmannsröben

      Version of Record online: 25 OCT 2005 | DOI: 10.1002/anie.200501552

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      On the dot: Efficient energy transfer from Tb complexes to quantum dots with an extremely large Förster radius of 81 Å is achieved by formation of a streptavidin–biotin coupled donor–acceptor complex. The long luminescence lifetime of the Tb donor and the high absorption of the quantum dots make this couple a powerful tool for analyzing biological and biochemical interactions.

    25. Fibrous Red Phosphorus (pages 7616–7619)

      Michael Ruck, Diana Hoppe, Bernhard Wahl, Paul Simon, Yuekui Wang and Gotthard Seifert

      Version of Record online: 24 OCT 2005 | DOI: 10.1002/anie.200503017

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      A new form of P: The crystal structure of a fibrous type of red phosphorus was solved using single-crystal X-ray diffraction methods and transmission electron microscopy. It consists of double tubes (see picture) and is closely related to the structure of Hittorf's phosphorus. Density functional calculations confirm the experimental results.

    26. Kinetic Resolution of Chiral Secondary Alcohols by Dehydrogenative Coupling with Recyclable Silicon-Stereogenic Silanes (pages 7620–7624)

      Sebastian Rendler, Gertrud Auer and Martin Oestreich

      Version of Record online: 27 OCT 2005 | DOI: 10.1002/anie.200502631

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      Fishing for enantiomers: A novel kinetic resolution of racemic alcohols capable of two-point binding makes use of silanes with silicon-centered chirality. This strategy is based on a diastereoselective dehydrogenative silicon–oxygen coupling under copper catalysis (see scheme). The resolving silane is completely recovered without erosion of stereochemical information at silicon.

    27. Synthetic Vaccines Consisting of Tumor-Associated MUC1 Glycopeptide Antigens and Bovine Serum Albumin (pages 7624–7630)

      Sebastian Dziadek, Danuta Kowalczyk and Horst Kunz

      Version of Record online: 25 OCT 2005 | DOI: 10.1002/anie.200501593

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      Sweet medicine: The mucin MUC1 is highly overexpressed on epithelial tumor cells. Glycopeptides 1 (from the repeating unit of MUC1) carrying various important sialylated tumor-associated carbohydrate antigens R were synthesized and coupled to bovine serum albumin (to generate anticancer vaccines) and to microtiter plates (to test the selectivity of the immune response).

    28. A Fully Synthetic Vaccine Consisting of a Tumor-Associated Glycopeptide Antigen and a T-Cell Epitope for the Induction of a Highly Specific Humoral Immune Response (pages 7630–7635)

      Sebastian Dziadek, Alexandra Hobel, Edgar Schmitt and Horst Kunz

      Version of Record online: 25 OCT 2005 | DOI: 10.1002/anie.200501594

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      On target: With the fully synthetic vaccine 1 consisting of a tumor-associated sialyl-Tn glycopeptide antigen from the epithelial mucin MUC1 and a T-cell epitope from ovalbumin, a strong, highly specific immune response (IgG) directed against the glycopeptide antigen was induced in a mouse thereby realizing the most important requirement for the development of synthetic vaccines for the initiation of the body's own immune defense against tumors.

    29. Direct Readout of Protein–Protein Interactions by Mass Spectrometry from Protein–DNA Microarrays (pages 7635–7639)

      Christian F. W. Becker, Ron Wacker, Werner Bouschen, Ralf Seidel, Branko Kolaric, Pascal Lang, Hendrick Schroeder, Oliver Müller, Christof M. Niemeyer, Bernhard Spengler, Roger S. Goody and Martin Engelhard

      Version of Record online: 24 OCT 2005 | DOI: 10.1002/anie.200502908

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      Catching proteins: Proteins from a protein–DNA microarray can be directly detected by using MALDI mass spectrometry. Capture proteins are attached to silicon chips in a highly selective and reversible way by DNA-directed immobilization (see picture). The analyte proteins bound specifically to their partners on the microarray can be detected from cell lysates.

    30. [Tl8]6− in Cs8Tl8O: A Naked Eight-Vertex closo-Deltaeder as a Cluster Anion (pages 7639–7643)

      Andrey Karpov and Martin Jansen

      Version of Record online: 25 OCT 2005 | DOI: 10.1002/anie.200502283

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      Structures to count on: The title compound crystallizes in a unique crystal-structure type which can be regarded as a rock-salt derivative composed of a suboxide group [OCs6+2]6+ (yellow) and a novel thallium cluster [Tl8]6− (blue). The valence electron count of the eight-vertex cluster obeys the Wade–Mingos condensation rules when considering it as a condensation of an octahedron with two tetrahedra.

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