Angewandte Chemie International Edition

Cover image for Vol. 43 Issue 12

March 12, 2004

Volume 43, Issue 12

Pages 1443–1603

    1. Cover Picture: Combinatorial Catalysis with Bimetallic Complexes: Robust and Efficient Catalysts for Atom-Transfer Radical Additions (Angew. Chem. Int. Ed. 12/2004) (page 1443)

      Laurent Quebatte, Rosario Scopelliti and Kay Severin

      Version of Record online: 9 MAR 2004 | DOI: 10.1002/anie.200490032

      Highly efficient Rh–Ru catalysts for atom-transfer radical additions have been discovered in a fast screening assay. The catalyst library used in this assay was generated in situ by mixing chloro-bridged complexes of RuII, RuIII, RuIV, RhI, RhIII, IrI, IrIII, PdII, and PtII with three different RuII–phosphane complexes. On page 1520 ff., K. Severin and co-workers describe the structures and reactivities of the new catalysts.

    2. Amine-Catalyzed Epoxidation of Alkenes: A New Mechanism for the Activation of Oxone (pages 1460–1462)

      Alan Armstrong

      Version of Record online: 9 MAR 2004 | DOI: 10.1002/anie.200301716

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      Some of the most promising systems emerging for the catalytic asymmetric epoxidation of alkenes involve the activation of oxone (active constituent KHSO5). The discovery of catalysis by amines is an exciting development in this area of organocatalysis, and a new mechanism for the activation of oxone has been advanced with important consequences (see scheme).

    3. A New Arene Synthesis—Or: How Inert Is the Cyclopentadienyl Ligand? (pages 1463–1464)

      Rhett Kempe

      Version of Record online: 9 MAR 2004 | DOI: 10.1002/anie.200301717

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      A nice Cp recipe: The reaction of 1 with benzonitrile is a novel arene synthesis developed by Xi, Takahashi, and co-workers. Formally it is the breakdown of a cyclopentadienyl ligand into a C2 fragment and a C3 fragment which are then incorporated into a benzene and pyridine derivative, respectively. This synthetic variant has possible interesting applications in the preparation of oligoarenes.

    4. Metal Carboxylates with Open Architectures (pages 1466–1496)

      C. N. R. Rao, Srinivasan Natarajan and R. Vaidhyanathan

      Version of Record online: 9 MAR 2004 | DOI: 10.1002/anie.200300588

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      Metal carboxylates form a variety of fascinating open-framework structures (see picture). In this Review the synthesis, structure, and properties of various families of metal carboxylates, as well as organic–inorganic hybrid structures involving carboxylates, are presented. The use of carboxylate ligands as linking groups is of particularly interest.

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      A Red, Green, and Blue (RGB) Polymeric Electrochromic Device (PECD): The Dawning of the PECD Era (pages 1498–1502)

      Gursel Sonmez, Clifton K. F. Shen, Yves Rubin and Fred Wudl

      Version of Record online: 27 JAN 2004 | DOI: 10.1002/anie.200352910

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      Completing RGB color space: The electrochemical and optical properties of the first electrochemically prepared conducting polymer that is green in its neutral form are reported. The extreme stability of this polymer after 10 000 double potential steps makes it the best and only candidate for providing the missing third leg of RGB color space (red, blue, and green reflection; see picture) required for polymeric electrochromics.

    6. Three-Dimensional Frameworks of Gallium Selenide Supertetrahedral Clusters (pages 1502–1505)

      Xianhui Bu, Nanfeng Zheng, Xiqing Wang, Bing Wang and Pingyun Feng

      Version of Record online: 9 MAR 2004 | DOI: 10.1002/anie.200352880

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      Humidity-dependent electrical conductivity, which suggests possible applications in sensors, is exhibited by OCF-6GaSe, an open-framework gallium selenide assembled from T3 (Ga10Se2010−) supertetrahedral clusters (picture, left). Furthermore, materials based on T4 (Zn4Ga16Se3514−, right), the largest supertetrahedral selenide cluster so far, were also obtained.

    7. Preparation of Mesoporous Silica Monoliths with Ordered Arrays of Macrochannels Templated from Electric-Field-Oriented Hydrogels (pages 1505–1507)

      Paul R. Giunta, Randy P. Washington, Tedric D. Campbell, Oliver Steinbock and A. E. Stiegman

      Version of Record online: 9 MAR 2004 | DOI: 10.1002/anie.200352813

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      Silica monoliths with ordered arrays of micrometer-scale columns were fabricated from polyacrylamide gel templates. The preparation of the template involves the charged comonomer, N-acryloyl glycine, and is controlled by an externally applied electric field. This approach gives rise to the self-organization of columnar density patterns in the template (left; bar=10μm) that are recovered in the silica monoliths upon impregnation with tetramethylorthosilicate and subsequent calcination (right).

    8. A 3D Hybrid Network Containing Large Spherical Cavities Formed through a Combination of Metal Coordination and Hydrogen Bonding (pages 1507–1511)

      Reyes García-Zarracino and Herbert Höpfl

      Version of Record online: 9 MAR 2004 | DOI: 10.1002/anie.200352862

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      The hole story: A microporous material with cavities that have an internal volume of 1850 Å3 has been formed from simple starting materials by combining them first through covalent coordination, and then through hydrogen-bonding interactions. The capsules in the 3D network can function as hosts for guest molecules such as triphenylmethane, sodium tetraphenylborate, and triptycene (see picture).

    9. Ordered Self-Assembly and Electronic Behavior of C60–Anthrylphenylacetylene Hybrid (pages 1512–1516)

      Seok Ho Kang, Hong Ma, Mun-Sik Kang, Kyoung-Soo Kim, Alex K.-Y. Jen, M. Hadi Zareie and Mehmet Sarikaya

      Version of Record online: 9 MAR 2004 | DOI: 10.1002/anie.200353001

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      A functional hybrid molecule, C60–MPAA, has been designed and synthesized by taking advantage of the excellent physical and chemical properties of C60 and nanoscale ordering of anthryl-based self-assembled monolayers (SAMs). The SAM of C60–MPAA exhibits stable and highly ordered 2D arrays that form an oblique lattice at room temperature and exhibit interesting electronic properties.

    10. Site-Specific Introduction of Sialic Acid into Insulin (pages 1516–1520)

      Masaaki Sato, Reiko Sadamoto, Kenichi Niikura, Kenji Monde, Hirosato Kondo and Shin-Ichiro Nishimura

      Version of Record online: 9 MAR 2004 | DOI: 10.1002/anie.200353058

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      More gain, less pain: A new long-acting insulin (see structure) was created by the enzymatic introduction of sialyllactose into mutant insulins. The glycosylation site was introduced into the insulin by point mutation without loss of biological activity. The experimental results with mice clearly demonstrated that the introduction of a sialic acid residue is crucial in prolonging glucose-lowering activity in the blood.

    11. Combinatorial Catalysis with Bimetallic Complexes: Robust and Efficient Catalysts for Atom-Transfer Radical Additions (pages 1520–1524)

      Laurent Quebatte, Rosario Scopelliti and Kay Severin

      Version of Record online: 16 FEB 2004 | DOI: 10.1002/anie.200353084

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      A radical alternative? Two highly efficient catalysts for atom-transfer radical additions were discovered in a parallel screening of bimetallic complexes. Both catalysts contain a rhodium-centered fragment (blue), which is connected through three chloro bridges to a ruthenium-centered fragment (red).

    12. Thermal and Photochemical Properties of 4′,7-Dihydroxyflavylium in Water–Ionic Liquid Biphasic Systems: A Write–Read–Erase Molecular Switch (pages 1525–1527)

      Fernando Pina, João C. Lima, A. Jorge Parola and Carlos A. M. Afonso

      Version of Record online: 9 MAR 2004 | DOI: 10.1002/anie.200353131

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      Switching colors: 4′,7-Dihydroxyflavylium (AH+) in water–ionic liquid biphasic systems can be used as a write–read–erase system. In acid media, the chalcone (Ct) form is soluble in ionic liquids and is thermally metastable, but reacts photochemically (write) to give the yellow flavylium salt, which can be optically read without being erased. The system is prepared for a new cycle by two consecutive pH “jumps”.

    13. Ionic Perylenetetracarboxdiimides: Highly Fluorescent and Water-Soluble Dyes for Biolabeling (pages 1528–1531)

      Jianqiang Qu, Christopher Kohl, Mark Pottek and Klaus Müllen

      Version of Record online: 9 MAR 2004 | DOI: 10.1002/anie.200353208

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      Dying to be seen: A series of water-soluble and highly fluorescent perylenetetracarboxdiimides (PDIs) have been synthesized in high yields by introducing charged groups into the bay region of PDI (see picture; C gray, H white, S yellow, O red). They can be used for staining living cells as they are nontoxic.

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      Minimal Functional Model of Hemostasis in a Biomimetic Microfluidic System (pages 1531–1536)

      Matthew K. Runyon, Bethany L. Johnson-Kerner and Rustem F. Ismagilov

      Version of Record online: 24 FEB 2004 | DOI: 10.1002/anie.200353428

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      The proof of the model is in the function: A minimal model of hemostasis (a complex biochemical network responsible for blood coagulation) may be implemented with only three chemical reactions, which creates a biomimetic functional microfluidic system that is capable of repairing itself (as modeled in the figure). This simple system shows threshold response and sensitivity to flow similar to that observed in hemostasis.

    15. Shape Effect in Nanoparticle Self-Assembly (pages 1536–1540)

      Nikhil R. Jana

      Version of Record online: 9 MAR 2004 | DOI: 10.1002/anie.200352260

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      Particle anisotropy determines the way nanoparticles self-assemble, as shown in the picture. Gold and silver spheroids, rods, and plates with length-to-width ratios ranging from 1 to 25 show different liquid-crystalline order structures. These structures are analogous to the entropy-driven ordering that occurs at high volume fractions and is useful for large-scale ordering or shape separation.

    16. Pt Hollow Nanospheres: Facile Synthesis and Enhanced Electrocatalysts (pages 1540–1543)

      Han-Pu Liang, Hui-Min Zhang, Jin-Song Hu, Yu-Guo Guo, Li-Jun Wan and Chun-Li Bai

      Version of Record online: 9 MAR 2004 | DOI: 10.1002/anie.200352956

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      A facile large-scale preparation of Pt hollow nanospheres (see TEM image) makes use of Co nanoparticle as sacrificial templates. The nanospheres exhibit enhanced electrocatalytic activity. This method has been extended to the fabrication of industrially potentially useful Au, Pd, and other mono- and multimetallic hollow nanospheres.

    17. The X-ray Structure of a Vinyl Cation (pages 1543–1546)

      Thomas Müller, Mark Juhasz and Christopher A. Reed

      Version of Record online: 16 FEB 2004 | DOI: 10.1002/anie.200352986

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      Thermodynamic stabilization by two β-silyl substituents and essentially nonnucleophilic reaction conditions are prerequisites for the preparation of the first structurally well-characterized vinyl cation 1 (see structure). The occurrence of β-Si[BOND]C hyperconjugation in 1 is indicated by unusually long Si[BOND]Cβ bonds.

    18. A Three-Dimensional Mesoporous Titanosilicate Support for Gold Nanoparticles: Vapor-Phase Epoxidation of Propene with High Conversion (pages 1546–1548)

      Anil K. Sinha, Sindhu Seelan, Susumu Tsubota and Masatake Haruta

      Version of Record online: 9 MAR 2004 | DOI: 10.1002/anie.200352900

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      Direct selective gas-phase epoxidation of propene with commercially viable conversion has been achieved with catalysts consisting of gold nanoparticles (3–5 nm) supported on large-pore (>7 nm) silylated mesoporous titanosilicates with Ba(NO3)2 as a promoter. The picture provides a plausible mechanism for the synergetic cooperation of the Au and Ti sites, which is superimposed onto a TEM image of the material.

    19. Renewable Alkanes by Aqueous-Phase Reforming of Biomass-Derived Oxygenates (pages 1549–1551)

      George W. Huber, Randy D. Cortright and James A. Dumesic

      Version of Record online: 9 MAR 2004 | DOI: 10.1002/anie.200353050

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      A clean stream of alkanes from renewable biomass resources is obtained through aqueous-phase reforming in a single reactor. Alkanes are produced from biomass-derived sorbitol through a bifunctional pathway (see scheme) that involves the dehydration of sorbitol on acid sites (SiO2/Al2O3) and hydrogenation of intermediates on a metal catalyst under a H2 atmosphere. Hydrogen is produced from sorbitol and water on the metal catalyst in the same reactor.

    20. Side-Wall Opening of Single-Walled Carbon Nanotubes (SWCNTs) by Chemical Modification: A Critical Theoretical Study (pages 1552–1554)

      Zhongfang Chen, Shigeru Nagase, Andreas Hirsch, Robert C Haddon, Walter Thiel and Paul von Ragué Schleyer

      Version of Record online: 9 MAR 2004 | DOI: 10.1002/anie.200353087

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      In contrast to earlier theoretical studies and experimental expectation, full high-level (B3LYP/6-31G*) computations on various nanotube models reveal that SWCNTs with O, NH, CH2, and SiH2 addends favor opened structures rather than three-membered rings. Furthermore, the diagonal C[BOND]C bonds in (8,0) zigzag nanotubes, rather than C[BOND]C bonds parallel to the axis, are the favorable sites for chemical modification.

    21. Self-Assembled Aggregates of IgGs as Templates for the Growth of Clusters of Gold Nanoparticles (pages 1555–1558)

      Jerry Yang, Michael Mayer, Jennah K. Kriebel, Piotr Garstecki and George M. Whitesides

      Version of Record online: 9 MAR 2004 | DOI: 10.1002/anie.200353161

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      Immunoglobulin G templates: Clusters of gold nanoparticles are grown (see picture) from templates formed from the self-assembly of immunoglobulin Gs (IgGs) by using a synthetic divalent antigen. Carbohydrates inherent to IgGs create local nucleation centers for the electroless deposition of gold.

    22. Enantioselective Total Synthesis of Batzelladine A (pages 1559–1562)

      Jun Shimokawa, Koji Shirai, Aya Tanatani, Yuichi Hashimoto and Kazuo Nagasawa

      Version of Record online: 9 MAR 2004 | DOI: 10.1002/anie.200353200

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      One-step formation of an enone from a primary alcohol has been effectively applied in the total synthesis of batzelladine A (1). Successive 1,3-dipolar cycloadditions with a subsequent cyclization were used to form the tricyclic guanidine subunit of this natural product, which has the strongest inhibitory activity of HIV gp120-CD4 binding among the batzelladines.

    23. Dimeric Aminoglycosides as Antibiotics (pages 1562–1566)

      Fabio Agnelli, Steven J. Sucheck, Kenneth A. Marby, David Rabuka, Su-Lan Yao, Pamela S. Sears, Fu-Sen Liang and Chi-Huey Wong

      Version of Record online: 9 MAR 2004 | DOI: 10.1002/anie.200353225

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      Double duty: Dimeric aminoglycoside antibiotics were designed by linking neamine or nebramine cores with various tethers differing in length and composition. The resulting dimeric aminoglycosides displayed high affinity for the 16S A site of ribosomal RNA (a representation of the complex is shown here) and were effective against various aminoglycoside-resistant bacterial strains.

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      Enantioselective Mannich-Type Reaction Catalyzed by a Chiral Brønsted Acid (pages 1566–1568)

      Takahiko Akiyama, Junji Itoh, Koji Yokota and Kohei Fuchibe

      Version of Record online: 9 MAR 2004 | DOI: 10.1002/anie.200353240

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      No metal required: The Mannich-type reaction of ketene silyl acetals 2 with aldimines 1 proceeded highly enantioselectively to afford the syn isomer of β-aminoesters 3 with up to 96 % ee under the influence of a chiral Brønsted acid 4 derived from (R)-BINOL.

    25. Chemical Synthesis of a Skeleton Structure of Sperm CD52—A GPI-Anchored Glycopeptide (pages 1569–1573)

      Ning Shao, Jie Xue and Zhongwu Guo

      Version of Record online: 9 MAR 2004 | DOI: 10.1002/anie.200353251

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      Going native: A highly convergent synthetic strategy was established to prepare a skeleton structure of sperm CD52 antigen (depicted), which represents the first chemical synthesis of a complex, all natively linked glycosylphosphatidylinositol (GPI)–glycopeptide conjugate.

    26. Theoretical Search for Very Short Metal–Actinide Bonds: NUIr and Isoelectronic Systems (pages 1573–1576)

      Laura Gagliardi and Pekka Pyykkö

      Version of Record online: 9 MAR 2004 | DOI: 10.1002/anie.200353261

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      Cumulated triple bonds: A new class of molecules, the isoelectronic series of NUIr, (depicted) has been postulated and theoretically studied. The bond between the actinide and the 5d-metal atom is very short and is shown to correspond to triple bonding. The N[BOND]U bond is also a triple bond.

    27. Efficient Hydration of Nitriles to Amides in Water, Catalyzed by Ruthenium Hydroxide Supported on Alumina (pages 1576–1580)

      Kazuya Yamaguchi, Mitsunori Matsushita and Noritaka Mizuno

      Version of Record online: 9 MAR 2004 | DOI: 10.1002/anie.200353461

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      A broad range of amides is accessible in excellent yield (>99 %) by hydration of the corresponding nitriles in water in the presence of the supported ruthenium catalyst Ru(OH)x/Al2O3 (see scheme). For example, the industrially important conversion of acrylonitrile into acrylamide was achieved in quantitative yield and better than 99 % selectivity. The catalyst can be reused without loss of catalytic activity and selectivity.

    28. Modular Synthesis of Ruthenium-Labeled Diaryl Ether Peptoids (pages 1581–1583)

      Alexander Schmid and Thomas Lindel

      Version of Record online: 9 MAR 2004 | DOI: 10.1002/anie.200352927

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      A packet of sandwiches: A new concept of modular assembly of novel, metal-labeled biooligomers starting from amino acid sandwich complexes is introduced. The first diaryl ether tetrapeptoid containing two ruthenium-sandwich labels is prepared (see picture; Boc=tert-butoxycarbonyl), it should now be possible to prepare longer peptoids by repetitive methods.

    29. Directed Reduction of Six-Membered Nitrogen Heterocycles—Selective Formation of Polynuclear Titanium Complexes (pages 1583–1587)

      Susanne Kraft, Rüdiger Beckhaus, Detlev Haase and Wolfgang Saak

      Version of Record online: 23 FEB 2004 | DOI: 10.1002/anie.200353021

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      Two, three, four, or eight N-heterocycles react in the coordination sphere of titanium(II) compounds to give polynuclear titanium complexes (see picture, red=TiCp2, blue=N, white=C). Simultaneously occurring C[BOND]C couplings mark a new strategy for the synthesis of self-assembled compounds of the early transition metals.

    30. Efficient, Copper-Catalyzed, Aerobic Oxidation of Primary Alcohols (pages 1588–1591)

      István E. Markó, Arnaud Gautier, Raphaël Dumeunier, Kanae Doda, Freddi Philippart, Stephen M. Brown and Christopher J. Urch

      Version of Record online: 9 MAR 2004 | DOI: 10.1002/anie.200353458

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      An additive is the key to success: Catalytic amounts of N-methylimidazole are crucial for the aerobic oxidation of primary aliphatic alcohols in the presence of CuCl, 1,10-phenanthroline (phen), and di-tert-butyl azodicarboxylate (DBAD). This reaction, under neutral conditions, yields the aldehydes quantitatively and selectively without overoxidation to the carboxylic acids.

    31. Aminoglycoside Microarrays To Study Antibiotic Resistance (pages 1591–1594)

      Matthew D. Disney, Sophie Magnet, John S. Blanchard and Peter H. Seeberger

      Version of Record online: 9 MAR 2004 | DOI: 10.1002/anie.200353236

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      On to the next round! A sensitive microarray of immobilized aminoglycosides was used to study the binding of antibiotics to resistance-causing enzymes (see picture). This, in combination with other methods, will lead to the identification of new antibiotics that bind weakly to these enzymes and strongly to the therapeutic targets.

    32. Mixed Helices—A General Folding Pattern in Homologous Peptides? (pages 1594–1597)

      Carsten Baldauf, Robert Günther and Hans-Jörg Hofmann

      Version of Record online: 9 MAR 2004 | DOI: 10.1002/anie.200353249

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      You may now exchange rings! “Mixed helices” along a peptide sequence, in which rings of different sizes are held together by hydrogen bonds in alternating directions (see picture), prove to be a general folding principle in homologous α-, β-, γ-, and δ-peptides.