Angewandte Chemie International Edition

Cover image for Vol. 44 Issue 43

November 4, 2005

Volume 44, Issue 43

Pages 6967–7143

    1. Cover Picture: Mass Spectrometric Profiling of Intact Biological Tissue by Using Desorption Electrospray Ionization (Angew. Chem. Int. Ed. 43/2005) (page 6967)

      Justin M. Wiseman, Satu M. Puolitaival, Zoltán Takáts, R. Graham Cooks and Richard M. Caprioli

      Article first published online: 31 OCT 2005 | DOI: 10.1002/anie.200590143

      Desorption electrospray ionization is applied to the mass spectrometric profiling of phospholipids. In their Communication on page 7094 ff., R. G. Cooks, R. M. Caprioli, and co-workers report the rapid analysis of untreated biological tissues, including the tumor region of liver tissue. The impact of charged liquid microdroplets on liver tissue in air and the release of lipids and other molecules as ions for analysis is illustrated in the cover picture (prepared by Z. Ouyang, J. Wiseman, and R. Shreve).

    2. Wrapping Peptide Tubes: Merging Biological Self-Assembly and Polymer Synthesis (pages 6986–6989)

      Marco A. Balbo Block and Stefan Hecht

      Article first published online: 31 OCT 2005 | DOI: 10.1002/anie.200502436

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      It's a wrap: Self-assembling peptide tubes are wrapped in polymer sheaths by using efficient graft-from or attach-to routes (see scheme). The properties of the peptide tubes are tuned by the polymer sheath, and the resulting peptide–polymer hybrids could prove useful for various future applications.

    3. The Catalysis Gold Rush: New Claims (pages 6990–6993)

      A. Stephen K. Hashmi

      Article first published online: 31 OCT 2005 | DOI: 10.1002/anie.200502735

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      Staking claims: New aspects of gold catalysis—nucleophilic additions to unactivated olefins, auraoxetanes as the first observed organometallic intermediates, and the exciting experiments addressing the oxidation state of the catalyst—are discussed, and future challenges in this dynamic field are pointed out.

    4. The Metal Flux: A Preparative Tool for the Exploration of Intermetallic Compounds (pages 6996–7023)

      Mercouri G. Kanatzidis, Rainer Pöttgen and Wolfgang Jeitschko

      Article first published online: 31 OCT 2005 | DOI: 10.1002/anie.200462170

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      In flux: Syntheses in metal fluxes have a huge potential for generating new intermetallic species, and in recent years many new phases, sometimes with very unusual compositions, have been prepared by this method. The advantages of this approach lie in the enhanced diffusion of the elements that are dissolved in the metal solvent and the lower reaction temperatures that can be employed.

    5. Proline-Based Macrocyclic Inhibitors of the Hepatitis C Virus: Stereoselective Synthesis and Biological Activity (pages 7024–7028)

      Kevin X. Chen, F. George Njoroge, Bancha Vibulbhan, Andrew Prongay, John Pichardo, Vincent Madison, Alexei Buevich and Tze-Ming Chan

      Article first published online: 7 OCT 2005 | DOI: 10.1002/anie.200501553

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      Life-saving donut: Macrocyclization through a Mitsunobu reaction was used to synthesize a 17-membered macrocycle. The bicyclic acetal core was prepared completely diastereoselectively. The macrocyclic peptidomimetic surrogate of the P2–P3 dipeptide moiety was designed to function as a hepatitis C virus (HCV) NS3 serine protease inhibitor, and the pentapeptide α-ketoamides derived from the macrocycle were shown to be potent HCV inhibitors.

    6. The Origin of Stereoselectivity in Primary Amino Acid Catalyzed Intermolecular Aldol Reactions (pages 7028–7032)

      Arianna Bassan, Weibiao Zou, Efraim Reyes, Fahmi Himo and Armando Córdova

      Article first published online: 31 OCT 2005 | DOI: 10.1002/anie.200502388

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      Combined forces: Theory and experiment are used together to determine the mechanism of primary amino acid catalyzed intermolecular aldol reactions. A six-membered chairlike structure is determined to be the transition state for the reaction between benzaldehyde and cyclohexanone catalyzed by (S)-alanine (see scheme), and a carboxylic acid catalyzed enamine mechanism is shown to be the most favorable reaction pathway.

    7. Polymorphism in Benzamide (pages 7032–7035)

      W. I. F. David, K. Shankland, C. R. Pulham, N. Blagden, R. J. Davey and M. Song

      Article first published online: 12 OCT 2005 | DOI: 10.1002/anie.200501146

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      At long last, the crystal structure of the metastable form of benzamide, whose existence has been known of for over 170 years, has finally been solved by using a combination of in situ crystallization, high-speed synchrotron X-ray powder diffraction, and global-optimization methods of structure determination (see picture).

    8. Structural Evidence of Mechanical Shuttling in Condensed Monolayers of Bistable Rotaxane Molecules (pages 7035–7039)

      Kasper Nørgaard, Bo W. Laursen, Sune Nygaard, Kristian Kjaer, Hsian-Rong Tseng, Amar H. Flood, J. Fraser Stoddart and Thomas Bjørnholm

      Article first published online: 11 OCT 2005 | DOI: 10.1002/anie.200501538

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      On the move! Upon oxidation in situ, a positively charged ring travels a few nanometers along the dumbbell-shaped component of a monolayer of soaplike, bistable [2]rotaxanes on water (see picture). This motion was probed by surface-sensitive X-ray scattering and establishes that bistable rotaxanes retain their switching capabilities even in condensed monolayer phases.

    9. Banana-Shaped Oligo(aryleneethynylene)s: Synthesis and Light-Emitting Characteristics (pages 7040–7044)

      Yoshihiro Yamaguchi, Shigeya Kobayashi, Tateaki Wakamiya, Yoshio Matsubara and Zen-ichi Yoshida

      Article first published online: 11 OCT 2005 | DOI: 10.1002/anie.200502214

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      Pick of the bunch: Banana-shaped molecules 1 and 2 containing dimethoxybenzene and pyridine units are highly efficient emitters of violet light despite the interruption of the π conjugation because of meta substitution. The contrasting solvent dependencies of the fluorescence quantum yield values of 1 and 2 are explained by the disparity between the difference density distributions in the excited states of the molecules.

    10. Systematic Investigation of the Escherichia coli Metabolome for the Biosynthetic Origin of an Isocyanide Carbon Atom (pages 7045–7048)

      Sean F. Brady and Jon Clardy

      Article first published online: 11 OCT 2005 | DOI: 10.1002/anie.200501942

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      Feeding studies were conducted in which E. coli metabolism was controlled through the systematic use of strains that carry mutations in primary metabolic pathways, thus allowing the origin of the isocyanide carbon atom in antibiotic 1 to be determined. This carbon atom was shown to be derived from the C2 atom of ribulose-5P, or a tautomerically equivalent sugar (see scheme; isnA and isnB are the genes responsible for the biosynthetic pathway of 1).

    11. Thermolysis of a Hybrid Organic–Inorganic Supramolecular Coordination Assembly: Templating the Formation of Nanostructured Fibrous Materials and Carbon-Based Microcapsules (pages 7048–7053)

      Wolfgang Schmitt, Jonathan P. Hill, Sharali Malik, Cynthia A. Volkert, Izumi Ichinose, Christopher E. Anson and Annie K. Powell

      Article first published online: 13 OCT 2005 | DOI: 10.1002/anie.200501748

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      Burning a honeycomb: An exceptional hybrid organic–inorganic coordination assembly with an extended 3D structure that contains vast separated organic and inorganic regions has been prepared (see picture of its supramolecular structure and a scanning electron micrograph image). This hybrid is used as a template in thermolysis reactions to yield nano- and microsized products whose properties are determined by those of the precursor compounds.

    12. Ordered Mesoporous Polymers and Homologous Carbon Frameworks: Amphiphilic Surfactant Templating and Direct Transformation (pages 7053–7059)

      Yan Meng, Dong Gu, Fuqiang Zhang, Yifeng Shi, Haifeng Yang, Zheng Li, Chengzhong Yu, Bo Tu and Dongyuan Zhao

      Article first published online: 12 OCT 2005 | DOI: 10.1002/anie.200501561

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      Ultrahigh stability (>1400 °C) is found for the highly ordered mesoporous polymers and carbon frameworks synthesized from polymerization of phenol and formaldehyde around triblock copolymer templates. Calcination and carbonization lead to removal of the templates and formation of hexagonal and cubic carbon mesostructures with large uniform pores and surface areas (see schematic diagram).

    13. Multicomponent Organic Alloys Based on Organic Layered Crystals (pages 7059–7062)

      Kazuki Sada, Katsunari Inoue, Tomoyuki Tanaka, Attila Epergyes, Akira Tanaka, Norimitsu Tohnai, Akikazu Matsumoto and Mikiji Miyata

      Article first published online: 12 OCT 2005 | DOI: 10.1002/anie.200501678

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      Random layer: Multicomponent organic solid solutions were obtained by treating equimolar mixtures of two or more aliphatic carboxylic acids with 1-naphthylmethylamine (NMA; see scheme). The single sharp XRD peaks of the crystalline products indicate specific pairing of alkyl groups between the NMA layers to form mixed crystals rather than eutectic mixtures of the components.

    14. Cloning and Heterologous Expression of Isocyanide Biosynthetic Genes from Environmental DNA (pages 7063–7065)

      Sean F. Brady and Jon Clardy

      Article first published online: 5 OCT 2005 | DOI: 10.1002/anie.200501941

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      One gene, isnA, encodes the enzyme that converts the precursor amine functionality of tryptophan into the isocyanide moiety. The isolation and characterization of the isocyanide-containing environmental-DNA-derived antibiotic 1, its biosynthetic genes (isnA and isnB), and the general outline of the biosynthesis of 1 via intermediate 2 are presented (see scheme).

    15. Regioselective Hypervalent-Iodine(III)-Mediated Dearomatizing Phenylation of Phenols through Direct Ligand Coupling (pages 7065–7069)

      Aurélie Ozanne-Beaudenon and Stéphane Quideau

      Article first published online: 6 OCT 2005 | DOI: 10.1002/anie.200501638

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      Dearomatization: Treatment of phenols and naphthols substituted at the ortho position by a small electron-donating group D with chlorodiphenyl-λ3-iodane leads to their regioselective ortho phenylation to give cyclohexa-2,4-dienone derivatives (see scheme). The mechanism of this reaction involves a nonradical direct coupling of the ligands.

    16. Hydrogen-Bond-Mediated Self-Assembly of Aminopyrazolones: Macrocyclic Quartets—Single and Stacked One-Dimensional Motifs (pages 7069–7071)

      Hegui Gong and Michael J. Krische

      Article first published online: 7 OCT 2005 | DOI: 10.1002/anie.200502539

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      The fab four: Aminopyrazolones which incorporate two ditopic hydrogen-bond donor–acceptor pairs of amide and amidine functional groups can self-assemble through formation of four hydrogen bonds. Single-crystal X-ray diffraction analysis reveals that homomeric aggregation (amide–amide, amidine–amidine) affords 1D architectures while heteromeric aggregation (amide–amidine) generates macrocyclic quartets (see picture).

    17. Janus-Faced Aluminum: A Demonstration of Unique Lewis Acid and Lewis Base Behavior of the Aluminum Atom in [LAlB(C6F5)3] (pages 7072–7074)

      Zhi Yang, Xiaoli Ma, Rainer B. Oswald, Herbert W. Roesky, Hongping Zhu, Carola Schulzke, Kerstin Starke, Marc Baldus, Hans-Georg Schmidt and Mathias Noltemeyer

      Article first published online: 11 OCT 2005 | DOI: 10.1002/anie.200502251

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      Some elements go both ways: The reaction of [LAl] (L=HC(CMeNAr)2, Ar=2,6-iPr2C6H3) with BArF3 (ArF=C6F5) yields [LAlBArF3] (see scheme). Crystallographic studies and ab initio calculations show the formation of an Al[BOND]F bond, which shows the aluminum center having both Lewis base and Lewis acid character.

    18. Accumulation of an E,E,E-Triene by the Monensin-Producing Polyketide Synthase when Oxidative Cyclization is Blocked (pages 7075–7078)

      Apoorva Bhatt, Christian B. W. Stark, Barbara M. Harvey, Andrew R. Gallimore, Yuliya A. Demydchuk, Jonathan B. Spencer, James Staunton and Peter F. Leadlay

      Article first published online: 11 OCT 2005 | DOI: 10.1002/anie.200501757

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      Evidence for the intermediate in the polyether biosynthesis of the ionophore antibiotic monensin A has been obtained. A tridecaketide E,E,E-triene (see formula) has been isolated by using mutant strains of Streptomyces cinnamonensis. Characterization of this intermediate allows the likely biosynthetic route to monensin to be discriminated.

    19. A Method for Trapping Intermediates of Polyketide Biosynthesis with a Nonhydrolyzable Malonyl-Coenzyme A Analogue (pages 7079–7082)

      Dieter Spiteller, Claire L. Waterman and Jonathan B. Spencer

      Article first published online: 6 OCT 2005 | DOI: 10.1002/anie.200501670

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      Trapped in the middle: To investigate the mechanistic details of polyketide biosynthesis, intermediates are trapped by a nonhydrolyzable malonyl-coenzyme A analogue that reacts with a growing polyketide chain formed by a stilbene synthase. As the reverse transesterification reaction is not possible, the polyketide intermediates accumulate attached to the analogue (see scheme; Enz=enzyme, CoA=coenzyme A).

    20. Catalytic Asymmetric Nitroso-Diels–Alder Reaction with Acyclic Dienes (pages 7082–7085)

      Yuhei Yamamoto and Hisashi Yamamoto

      Article first published online: 13 OCT 2005 | DOI: 10.1002/anie.200501345

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      Bigger, bulkier, better: Catalytic asymmetric nitroso-Diels–Alder reactions of nitrosopyridines with silyloxydienes lead to adducts with excellent enantioselectivities (see scheme). The bulk of the silyl group (TMS=trimethylsilyl, TIPS=triisopropylsilyl) forces the diene to adopt an s-cis configuration in favor of the typical concerted [4+2] cycloaddition. The Diels–Alder adducts can then be converted into protected amino alcohols.

    21. Nickel-Foam-Supported Reticular CoO–Li2O Composite Anode Materials for Lithium Ion Batteries (pages 7085–7089)

      Yan Yu, Chun-Hua Chen, Jiang-Lan Shui and Song Xie

      Article first published online: 7 OCT 2005 | DOI: 10.1002/anie.200501905

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      Although considered to be the inactive component, Li2O plays three important roles in the carbon-free CoO–Li2O composite films (see SEM image) that have now been prepared: It prohibits CoO particle growth during synthesis, it oxidizes Co2+ to Co3+, and it acts as a structural buffer. The composite films, supported on a conducting nickel-foam substrate, were prepared by the electrostatic spray deposition technique. They display large initial discharge capacities and low first-cycle capacity losses.

    22. Tetraazapentalene Chemistry: Unexpected Intramolecular Electron Rearrangement Induced by Highly Reactive ψ-Dinitroso Substituents (pages 7089–7094)

      My Hang V. Huynh, Michael A. Hiskey, David E. Chavez and Richard D. Gilardi

      Article first published online: 12 OCT 2005 | DOI: 10.1002/anie.200502342

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      Off with a bang: The thermally stable high-energy 1 was prepared in a more efficient synthetic route. An unexpected ring scission of the tetraazapentalene T-shaped isomer 1 (distinctive nitrogen atom arrangement indicated in blue) occurs through an intramolecular electron rearrangement activated by highly-reactive ψ-dinitroso substituents of intermediate 2 to give 3.

    23. Mass Spectrometric Profiling of Intact Biological Tissue by Using Desorption Electrospray Ionization (pages 7094–7097)

      Justin M. Wiseman, Satu M. Puolitaival, Zoltán Takáts, R. Graham Cooks and Richard M. Caprioli

      Article first published online: 31 OCT 2005 | DOI: 10.1002/anie.200502362

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      Direct chemical profiling of biological tissues, including metastatic human-liver adenocarcinoma, was carried out by using mass spectrometry under ambient conditions. Desorption electrospray ionization revealed enhanced signals from sphingolipids and increased unsaturation levels of the phospholipids in the tumor region of the tissue (see picture).

    24. Superoxidation of Bisretinoids (pages 7097–7100)

      Ilyas Washington, Steffen Jockusch, Yasuhiro Itagaki, Nicholas J. Turro and Koji Nakanishi

      Article first published online: 12 OCT 2005 | DOI: 10.1002/anie.200501346

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      Up close and personal: Intimate retinoid polyenes, shown on the right chair, were found to react readily with oxygen (shown in red) to give the polyoxygenated species. On the other hand, when the polyenes are separated, shown on the left sofa, the oxidation is limited.

    25. How Many Methyl Groups in [{(η5-C5MenH5−n)2Zr}2222-N2)] Are Needed for Dinitrogen Hydrogenation? A Theoretical Study (pages 7101–7103)

      Petia Bobadova-Parvanova, Qinfang Wang, Keiji Morokuma and Djamaladdin G. Musaev

      Article first published online: 13 OCT 2005 | DOI: 10.1002/anie.200501371

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      Five are too many: It is known experimentally that [(Cp′)2Zr(N2)Zr(Cp′)2] (Cp′=C5H5−nMen) with n=4 activates N2 for hydrogenation, but the complex with n=5 does not. This difference in reactivity arises from the N2 coordination mode (see scheme): For n=0–4, N2 is side-on coordinated—the most suitable mode for hydrogenation—whereas for n=5, N2 is end-on coordinated owing to steric repulsion between five Me groups.

    26. A Diiron Center Stabilized by a Bis-TPA Ligand as a Model of Soluble Methane Monooxygenase: Predominant Alkene Epoxidation with H2O2 (pages 7104–7106)

      Masahito Kodera, Motoharu Itoh, Koji Kano, Takuzo Funabiki and Marius Reglier

      Article first published online: 11 OCT 2005 | DOI: 10.1002/anie.200501825

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      Double act: The diiron(II) complex [Fe2(6-HPA)(O)(OH2)2](ClO4)4 (1) catalyzes alkene epoxidation with H2O2 via a peroxodiiron complex. Detailed isotope-labeling experiments with μ-18O-1 reveal incorporation of both oxo- and peroxo-derived oxygen atoms into the epoxide reaction product (see scheme; 6-HPA=1,2-bis[2-{bis(2-pyridylmethyl)aminomethyl}-6-pyridyl]ethane).

    27. A “Through-Shell” Binding Isotope Effect (pages 7107–7110)

      Yong Liu and Ralf Warmuth

      Article first published online: 11 OCT 2005 | DOI: 10.1002/anie.200501840

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      Small, but very significant: Partial separation of two hemicarceplexes which differed only in the degree of guest deuteration could be achieved by normal-phase chromatography (see picture). The difference in retention time arises from a variation in the interaction between the hemicarceplex and the silica surface as a consequence of a 0.005-Å difference in the C[BOND]H and C[BOND]D bond lengths of the guest molecules.

    28. Hysteretic Magnetic Bistability Based on a Molecular Azide Switch (pages 7111–7114)

      Guido Leibeling, Serhiy Demeshko, Sebastian Dechert and Franc Meyer

      Article first published online: 7 OCT 2005 | DOI: 10.1002/anie.200501987

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      Like a molecular toggle switch, the bridging azide ion in a highly preorganized dinickel(II) complex turns strong antiferromagnetic coupling on or off (see picture). Single crystals of the compound stay intact over the entire temperature range studied and feature hysteretic bistability not far from ambient temperature.

    29. Chemo-, Regio-, and Stereoselective Cobalt-Mediated [2+2+2] Cycloaddition of Alkynyl Boronates to Alkenes: 1,3- and 1,4-Diboryl-1,3-cyclohexadienes (pages 7114–7118)

      Vincent Gandon, David Leboeuf, Sabine Amslinger, K. Peter C. Vollhardt, Max Malacria and Corinne Aubert

      Article first published online: 11 OCT 2005 | DOI: 10.1002/anie.200502038

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      Diborylated compounds are obtained by means of CpCo-mediated cocyclization of alkynyl(pinacol)boronic esters to alkenes followed by oxidative demetalation (see scheme). This strategy for the rapid and efficient construction of highly functionalized 1,3-cyclohexadienes and arenes is compatible with various substrates.

    30. Experimental and Theoretical Investigation of the Electronic and Geometrical Structures of the Au32 Cluster (pages 7119–7123)

      Min Ji, Xiao Gu, Xi Li, Xingao Gong, Jun Li and Lai-Sheng Wang

      Article first published online: 11 OCT 2005 | DOI: 10.1002/anie.200502795

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      A heart of gold: The structure of the Au32 cluster has been elucidated by comparison of the results from photoelectron spectroscopy with those from theoretical calculations. Although DFT calculations suggest a high-symmetry hollow-cage structure (Ih, left) to be the lowest in energy at 0 K, the spectrum calculated for a low-symmetry (C1, right) distorted cage containing three Au atoms inside agrees best with the experimental results.

    31. Development of an Arming Participating Group for Stereoselective Glycosylation and Chemoselective Oligosaccharide Synthesis (pages 7123–7126)

      James T. Smoot, Papapida Pornsuriyasak and Alexei V. Demchenko

      Article first published online: 13 OCT 2005 | DOI: 10.1002/anie.200502694

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      Armed and dangerous: A new armed–disarmed glycosylation strategy (see picture) allows chemoselective introduction of a 1,2-trans glycosidic linkage prior to other linkages through the use of a 2-O-picolyl moiety. This neighbouring group is capable of efficient participation through a six-membered intermediate while retaining the glycosyl donor in the armed state. Bn=benzyl, Bz=benzoyl, Tf=trifluoromethanesulfonyl, Pic=picolyl.

    32. Synthesis, Structure, and Chemoselective Reactivity of N-(2-Iodylphenyl)acylamides: Hypervalent Iodine Reagents Bearing a Pseudo-Six-Membered Ring Scaffold (pages 7127–7131)

      Uladzimir Ladziata, Alexey Y. Koposov, Ka Y. Lo, Jeff Willging, Victor N. Nemykin and Viktor V. Zhdankin

      Article first published online: 31 OCT 2005 | DOI: 10.1002/anie.200502707

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      A pseudo-benziodoxazine structure with intramolecular secondary I⋅⋅⋅O bonding, as shown by X-ray analysis, is seen in a series of N-(2-iodylphenyl)acylamides prepared from 2-iodoaniline (see scheme). These compounds contain a six-membered pseudocyclic scaffold about an iodine(V) center and are able to oxidize either alcohols or sulfides, with the reactivity depending largely on the substitution pattern on the amide group adjacent to the iodyl moiety.

    33. Catalysis by Gold: Isolated Surface Au3+ Ions are Active Sites for Selective Hydrogenation of 1,3-Butadiene over Au/ZrO2 Catalysts (pages 7132–7135)

      Xin Zhang, Hui Shi and Bo-Qing Xu

      Article first published online: 7 OCT 2005 | DOI: 10.1002/anie.200502101

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      A small number of isolated Au3+ ions (0.02 Au3+/nm2) heterogenized on a zirconia surface from a cheap inorganic source (HAuCl4) is able to grant high catalytic activity for the selective hydrogenation of 1,3-butadiene (see picture). The catalytic turnover and mass activity rates of the Au3+ ions are respectively one and two orders of magnitude higher than those of metallic gold nanoparticles.

    34. Stereospecific Synthesis of Hetero[7]helicenes by Pd-Catalyzed Double N-Arylation and Intramolecular O-Arylation (pages 7136–7138)

      Koji Nakano, Yuko Hidehira, Keita Takahashi, Tamejiro Hiyama and Kyoko Nozaki

      Article first published online: 6 OCT 2005 | DOI: 10.1002/anie.200502855

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      Enantioenriched aza- and oxa[7]helicenes are synthesized from an enantiopure biphenanthryldiol in a highly stereoselective manner. An N-phenylaza[7]helicene is prepared by a palladium-catalyzed double N-arylation of aniline with disulfonate derivatives (see scheme, right), whereas an oxa[7]helicene is obtained by a palladium-catalyzed intramolecular O-arylation of monosulfonate derivatives (see scheme, left).

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