Angewandte Chemie International Edition

Cover image for Vol. 43 Issue 29

July 19, 2004

Volume 43, Issue 29

Pages 3739–3861, 3748a–3749

    1. Cover Picture: Cobalt(I)-Catalyzed Asymmetric [2+2+2] Cycloaddition of Alkynes and Nitriles: Synthesis of Enantiomerically Enriched Atropoisomers of 2-Arylpyridines (Angew. Chem. Int. Ed. 29/2004) (page 3739)

      Andrey Gutnov, Barbara Heller, Christine Fischer, Hans-Joachim Drexler, Anke Spannenberg, Bernd Sundermann and Corinna Sundermann

      Version of Record online: 12 JUL 2004 | DOI: 10.1002/anie.200490093

      Nature decided in favor of the left-handed helical isomer for the hop vine shown in the cover picture. In contrast, the [2 + 2 + 2] cycloaddition yielding biaryl nitrogen heterocycles gives access to both enantiomers. In their Communication on p. 3795 ff. A. Gutnov, B. Heller et al. describe this photochemical reaction which is conducted with a chiral cobalt catalyst. (The picture of the hop plant is taken from the book by H. Brunner, Rechts oder Links. In der Natur und anderswo, Wiley-VCH, 1999.)

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      Continuous Glucose Sensing with a Fluorescent Thin-Film Hydrogel (page 3748)

      Jeff T. Suri, David B. Cordes, Frank E. Cappuccio, Ritchie A. Wessling and Bakthan Singaram

      Version of Record online: 12 JUL 2004 | DOI: 10.1002/anie.200490095

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      The Circumambulation of a Phosphirane: Taking 9-Phenyl-9-phosphabicyclo[6.1.0]nona-2,4,6-triene for a “Walk” (pages 3748a–3748)

      Rosa E. Bulo, Helen Jansen, Andreas W. Ehlers, Fransiscus J. J. de Kanter, Marius Schakel, Martin Lutz, Anthony L. Spek and Koop Lammertsma

      Version of Record online: 12 JUL 2004 | DOI: 10.1002/anie.200490098

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      Size-Dependent Magnetic Properties of Colloidal Mn3O4 and MnO Nanoparticles (pages 3749a–3749)

      Won Seok Seo, Hyong Hoon Jo, Kwangyeol Lee, Bongsoo Kim, Sang Jun Oh and Joon T. Park

      Version of Record online: 12 JUL 2004 | DOI: 10.1002/anie.200490099

    6. When Chemistry Met Biology (pages 3750–3751)

      Thorsten Berg

      Version of Record online: 12 JUL 2004 | DOI: 10.1002/anie.200460998

    7. Organotin Chemistry. Second Edition. By Alwyn G. Davies. (page 3753)

      Manfred Weidenbruch

      Version of Record online: 12 JUL 2004 | DOI: 10.1002/anie.200385202

    8. Two Birds with One Metallic Stone: Single-Pot Catalysis of Fundamentally Different Transformations (pages 3754–3760)

      Alain Ajamian and James L. Gleason

      Version of Record online: 15 JUN 2004 | DOI: 10.1002/anie.200301727

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      Multitasking catalysts: Metal catalysis has been pushed to a new level with the development of methods that use a single catalyst for several fundamentally different transformations in a single reaction flask (see example). Several examples from the recent literature are highlighted, including methods in which a single catalyst mediates two reactions simultaneously. Mes=2,4,6-trimethylphenyl, Cy=cyclohexyl.

    9. Tailor-Made Polyelectrolyte Microcapsules: From Multilayers to Smart Containers (pages 3762–3783)

      Claire S. Peyratout and Lars Dähne

      Version of Record online: 15 JUN 2004 | DOI: 10.1002/anie.200300568

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      Wrap artists: Hollow polyelectrolyte microcapsules have promising perspectives in numerous applications, such as engineering, biotechnology, and medicine. In this Review, the recent advances in this field are presented, with a focus on the permeability properties of the capsules as well as on their application as microreactors. The picture shows a library of 15 dye-modified capsules of poly(allylamine)/poly(styrene sulfonate).

    10. Stereospecific and Stereodivergent Construction of Quaternary Carbon Centers through Switchable Directed/Nondirected Allylic Substitution (pages 3786–3789)

      Bernhard Breit, Peter Demel and Christopher Studte

      Version of Record online: 26 MAY 2004 | DOI: 10.1002/anie.200453991

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      Selectivity at the flick of a switch: Through 1,3-chirality transfer, a directing/nondirecting leaving group facilitates the stereospecific and stereodivergent construction of quaternary carbon centers by copper-mediated allylic substitution with Grignard and organozinc reagents (see scheme; the use of the corresponding phosphane oxide leads to selective anti substitution).

    11. Iterative Deoxypropionate Synthesis Based on a Copper-Mediated Directed Allylic Substitution (pages 3790–3792)

      Bernhard Breit and Christian Herber

      Version of Record online: 26 MAY 2004 | DOI: 10.1002/anie.200453990

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      Can't have too much of a good thing: A flexible, iterative strategy based on a highly selective copper-mediated allylic substitution makes the preparation of any desired oligo(deoxypropionate) stereoisomer possible (see scheme; RDG=reagent-directing group). This approach differs from the established enolate-alkylation methodology through the reversed polarity of the reaction partners and avoids several problems associated with the latter method.

    12. Two Metal Ions Coordinated to a Purine Residue Tolerate Each Other Well (pages 3793–3795)

      Bernd Knobloch, Roland K. O. Sigel, Bernhard Lippert and Helmut Sigel

      Version of Record online: 12 JUL 2004 | DOI: 10.1002/anie.200453987

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      The catalytic sites of ribozymes generally contain two or more metal ions. Guanine is the nucleobase most often involved in binding to metal ions. The repulsion between two M2+ ions simultaneously coordinated to guanine in aqueous solution was investigated by using complex 1 (see picture; dien=diethylenetriamine, R=C2H5) as a model, for which the stability constants for the binding of Mg2+ and Cu2+ were determined.

    13. Cobalt(I)-Catalyzed Asymmetric [2+2+2] Cycloaddition of Alkynes and Nitriles: Synthesis of Enantiomerically Enriched Atropoisomers of 2-Arylpyridines (pages 3795–3797)

      Andrey Gutnov, Barbara Heller, Christine Fischer, Hans-Joachim Drexler, Anke Spannenberg, Bernd Sundermann and Corinna Sundermann

      Version of Record online: 26 MAY 2004 | DOI: 10.1002/anie.200454164

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      A new flavor of chiral induction in the [2+2+2] cycloaddition yielding pyridines: Atropoisomers were prepared in the reaction of alkynes and nitriles in the presence of 1 mol % chiral CoI catalysts such as 1 with high yields and up to 93 % ee.

    14. Highly Sensitive Protease Assay Using Fluorescence Quenching of Peptide Probes Based on Photoinduced Electron Transfer (pages 3798–3801)

      Nicole Marmé, Jens-Peter Knemeyer, Jürgen Wolfrum and Markus Sauer

      Version of Record online: 12 JUL 2004 | DOI: 10.1002/anie.200453835

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      Making the cut and then detecting it: Short fluorophore-labeled peptide substrates (see scheme) show strong fluorescence quenching due to electron transfer from a tryptophan residue (blue) to the dye (gray, red). Upon specific cleavage of the peptide by proteolytic enzymes, quenching is prevented and the fluorescence intensity increases. The method can be used to assay proteolytic enzymes with detection limits in the picomolar range.

    15. Fabrication of Polymer Nanofibers and Carbon Nanofibers by Using a Salt-Assisted Microemulsion Polymerization (pages 3803–3806)

      Jyongsik Jang and Joonwon Bae

      Version of Record online: 12 JUL 2004 | DOI: 10.1002/anie.200353580

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      Salt-assisted sphere-to-cylinder micelle conversion in the microemulsion polymerization process is the crucial step for the formation of polyacrylonitrile nanofibers (see picture). Iron(III) chloride is used as a structure-directing agent and is coordinated by polyacrylonitrile nanoparticles, which is essential for the formation of the nanofibers.

    16. Enzyme Microarrays: On-Chip Determination of Inhibition Constants Based on Affinity-Label Detection of Enzymatic Activity (pages 3806–3810)

      Jörg Eppinger, Daniel P. Funeriu, Masato Miyake, Lucile Denizot and Jun Miyake

      Version of Record online: 12 JUL 2004 | DOI: 10.1002/anie.200353623

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      High-throughput screening of libraries of potential inhibitors is possible by using an enzyme microarray method that combines low sample consumption with accuracy and speed. Information about enzyme inhibition can be obtained “on-chip” by the addition of a fluorescently tagged affinity label to a microarray of functional enzymes (see picture).

    17. Supramolecular Control over the Stereochemistry of Diene Polymers (pages 3811–3814)

      Sadamu Nagahama, Toshihiro Tanaka and Akikazu Matsumoto

      Version of Record online: 12 JUL 2004 | DOI: 10.1002/anie.200453738

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      The intermolecular interactions that lead to translational and alternate molecular stacking of 1,3-diene monomers in the solid state (see example, X=CO2CH2C6H4OCH3) as well as the molecular symmetry of muconic acid derivatives have been utilized in controlling the stereoregularity of polymers. This crystal engineering approach has enabled the four kinds of stereoregular diene polymers to be synthesized in a solid-state polymerization.

    18. A Molecular Ball Bearing Mediated by Multiligand Exchange in Concert (pages 3814–3818)

      Shuichi Hiraoka, Kaori Hirata and Mitsuhiko Shionoya

      Version of Record online: 12 JUL 2004 | DOI: 10.1002/anie.200453753

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      A thrust in the right direction: Two different disk-shaped ligands (a tris-monodentate and a hexa-monodentate ligand) and three Ag+ ions have been used as bearings and balls, respectively, in the construction of a molecular thrust ball bearing (see schematic representation). Rotation occurs through a combination of intramolecular, reversible multipoint ligand exchange and flip motions that act in concert.

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      The C-Glycoside Analogue of the Immunostimulant α-Galactosylceramide (KRN7000): Synthesis and Striking Enhancement of Activity (pages 3818–3822)

      Guangli Yang, John Schmieg, Moriya Tsuji and Richard W. Franck

      Version of Record online: 30 JUN 2004 | DOI: 10.1002/anie.200454215

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      Which source provides the better drug? The fully synthetic C-glycoside 1 (Y=CH2) is about 1000 times more potent against malaria in mice than the corresponding O-glycoside (Y=O), which is derived from a natural product and itself known to show remarkable activity against a wide range of diseases. The results of comparative biological assays emphasize the potential of C-glycosides as therapeutic agents.

    20. Synthesis and Structure of [Ag26In18S36Cl6(dppm)10(thf)4][InCl4(thf)]2—A Combined Approach of Theory and Experiment (pages 3823–3827)

      Reinhart Ahlrichs, Andreas Eichhöfer, Dieter Fenske, Oliver Hampe, Manfred M. Kappes, Paola Nava and Jolanta Olkowska-Oetzel

      Version of Record online: 12 JUL 2004 | DOI: 10.1002/anie.200460052

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      Difficult to determine, the molecular structure of the ionic cluster [Ag26In18S36Cl6(dppm)10(thf)4]2+[InCl4(thf)]2 (see picture, dppm=bis(diphenylphosphanyl)methane) was independently resolved by theoretical (density functional theory) and experimental (single-crystal XRD, FTMS) methods. The cluster was synthesized by the reaction of AgOOCPh and InCl3 with S(SiMe3)2 in the presence of the bidentate phosphane dppm.

    21. Ga2O3 and GaN Semiconductor Hollow Spheres (pages 3827–3831)

      Xiaoming Sun and Yadong Li

      Version of Record online: 12 JUL 2004 | DOI: 10.1002/anie.200353212

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      Carbon spheres are used as templates to prepare semiconductor hollow spheres of Ga2O3 (depicted) and GaN. The thickness and uniformity of the final products are predetermined by the thickness of the active layer of the carbon spheres. The diameter of the spheres can be adjusted in the range of 100 nm to 1.5 μm, which covers the band gaps in the spectral regime from UV to near infrared.

    22. Polyhedral Ferrous and Ferric Siloxanes (pages 3832–3835)

      Umesh N. Nehete, Ganapathi Anantharaman, Vadapalli Chandrasekhar, Ramaswamy Murugavel, Mrinalini G. Walawalkar, Herbert W. Roesky, Denis Vidovic, Jörg Magull, Konrad Samwer and Björn Sass

      Version of Record online: 12 JUL 2004 | DOI: 10.1002/anie.200453740

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      The synthesis, isolation, and single-crystal X-ray structures of the first polyhedral ferrous and ferric siloxanes (see scheme) suggest that similar synthetic strategies will allow the preparation of other transition-metal siloxane frameworks.

    23. Electron Transfer in a Hg-SAM//SAM-Hg Junction Mediated by Redox Centers (pages 3835–3839)

      Elizabeth Tran, Maria A. Rampi and George M. Whitesides

      Version of Record online: 12 JUL 2004 | DOI: 10.1002/anie.200453945

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      Current affairs: The electron-transport properties of a metal–molecule–metal junction based on two contacting redox-active self-assembled monolayers of [Ru(NH3)5(NC5H4-4-CH2NHCO(CH2)10SH](PF6)2 (see picture) is described. The junction becomes conductive when the electrode potentials are adjusted to the formal potential of the redox centers and shows diode- and transistor-like characteristics analogous to those of solid-state devices.

    24. Dehydroxylation Route to Surface Modification of Mesoporous Silicas by Using Grignard Reagents (pages 3839–3842)

      Jung Eun Lim, Chang Bo Shim, Ji Man Kim, Bun Yeoul Lee and Jae Eui Yie

      Version of Record online: 12 JUL 2004 | DOI: 10.1002/anie.200454076

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      Electron-deficient silicon atoms, which are generated on a silica surface by evacuation above 900 K, are attacked by Grignard reagents (see picture). This reactivity provides a novel route for the surface modification of mesoporous silicas as the organic groups are strongly bound to the surface through the formation of Si[BOND]C bonds. The pore structures of the mesoporous silicas are not destroyed by the modification.

    25. Molecular {(SnO)6} Trapped by Two {R2Si2O3} Fragments: X-ray Single-Crystal Structure of [(SnO)6(R2Si2O3)2] (pages 3842–3844)

      Umesh N. Nehete, Vadapalli Chandrasekhar, Ganapathi Anantharaman, Herbert W. Roesky, Denis Vidovic and Jörg Magull

      Version of Record online: 23 JUN 2004 | DOI: 10.1002/anie.200454149

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      The hexatin(II) cage containing siloxane ligands is obtained by the addition of Sn[N(SiMe3)2]2 to a suspension of RSi(OH)3 in a hexane/THF mixture (see scheme). The X-ray crystal structure analysis of compound 1 reveals a central {(SnO)6} motif enclosed by two outer {R2Si2O3} siloxane ligands.

    26. Transition-Metal-Catalyzed Reactions Involving Imidazolium Salt/N-Heterocyclic Carbene Couples as Substrates (pages 3845–3847)

      Nicolas D. Clement and Kingsley J. Cavell

      Version of Record online: 12 JUL 2004 | DOI: 10.1002/anie.200454166

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      Reactive Couples: Imidazolium salts react with alkenes under mild conditions in the presence of a Ni0-based catalyst to produce 2-alkyl imidazolium salts (see scheme, cod=1,5-cyclooctadiene). The mechanism involves oxidative addition of an imidazolium C[BOND]H bond to M0 to give a (carbene)M[BOND]H intermediate and finally bond formation between the carbene and an alkyl ligand through reductive elimination.

    27. A Dimetallic Cage with a Long Ellipsoidal Cavity for the Fluorescent Detection of Dicarboxylate Anions in Water (pages 3847–3852)

      Massimo Boiocchi, Marco Bonizzoni, Luigi Fabbrizzi, Giulio Piovani and Angelo Taglietti

      Version of Record online: 12 JUL 2004 | DOI: 10.1002/anie.200460036

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      Fits like a glove! The dicopper(II) complex 1 of a bistren cage containing ditolyl spacers binds dicarboxylate anions in aqueous solutions. The inclusion is highly selective on the basis of the distance between the COO groups. For example, terephthalate (see picture) is discriminated from isophthalate and phthalate.

    28. Kinetic Control over the Thermal Stability of the In[BOND]H Bond: Synthesis and Characterization of Amido Indium Hydride Complexes (pages 3852–3855)

      Robert J. Baker, Cameron Jones, Peter C. Junk and Marc Kloth

      Version of Record online: 12 JUL 2004 | DOI: 10.1002/anie.200460304

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      High thermal stability is a characteristic feature of the depicted amido indium hydride complex (In red; hydride yellow), which is amongst the first to be synthesized and characterized. The stability arises from steric shielding of the In[BOND]H bond, which frustrates the formation of the intermolecular In[BOND]H[BOND]In bridges.

    29. Preview: Angew. Chem. Int. Ed. 29/2004 (page 3861)

      Version of Record online: 12 JUL 2004 | DOI: 10.1002/anie.200490097

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