Angewandte Chemie International Edition

Cover image for Vol. 46 Issue 37

September 17, 2007

Volume 46, Issue 37

Pages 6933–7131

  1. Cover Picture

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Graphical Abstract
    5. Apology
    6. Corrigendum
    7. News
    8. Book Review
    9. Reviews
    10. Communications
    11. Preview
    1. Cover Picture: Catalytic Enantioselective Tautomerization of Isolated Enols (Angew. Chem. Int. Ed. 37/2007) (page 6933)

      Charles Fehr

      Article first published online: 11 SEP 2007 | DOI: 10.1002/anie.200790181

      Thumbnail image of graphical abstract

      The stereoselective formation and isolation of E enolates can be achieved either from the lithium enolate and isopropylephedrine or from the enol and lithium isopropylephedrate. As shown by C. Fehr on page 7119 ff., both pathways lead to the appreciated fragrance compound (S)-α-damascone which, as suggested by the cover picture, is chiral and smells rosy. The nonlinear effects observed by using a non-enantiomerically rich isopropylephedrine suggest that higher order mixed aggregates are involved in the enantioselective enol tautomerization. (B. Cogerino is thanked for the photo and Dr. A. Herrmann is thanked for assistance with the layout.)

  2. Inside Cover

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Graphical Abstract
    5. Apology
    6. Corrigendum
    7. News
    8. Book Review
    9. Reviews
    10. Communications
    11. Preview
    1. Inside Cover: Pentacoordination of Silicon by Five Different Ligand Atoms: Neutral Silicon(IV) Complexes with SiClSONC and SiISONC Skeletons (Angew. Chem. Int. Ed. 37/2007) (page 6934)

      Stefan Metz, Christian Burschka, Daniela Platte and Reinhold Tacke

      Article first published online: 11 SEP 2007 | DOI: 10.1002/anie.200790182

      Thumbnail image of graphical abstract

      Five different ligands attached to a single silicon atom are found in the pentacoordinate silicon(IV) complexes with SiClSONC and SiISONC skeletons (see picture). R. Tacke and co-workers describe in their Communication on page 7006 ff. the synthesis and structural analysis of both complexes, which exist in both the solid state and in solution.

  3. Graphical Abstract

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Graphical Abstract
    5. Apology
    6. Corrigendum
    7. News
    8. Book Review
    9. Reviews
    10. Communications
    11. Preview
  4. Apology

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Graphical Abstract
    5. Apology
    6. Corrigendum
    7. News
    8. Book Review
    9. Reviews
    10. Communications
    11. Preview
    1. You have free access to this content
  5. Corrigendum

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Graphical Abstract
    5. Apology
    6. Corrigendum
    7. News
    8. Book Review
    9. Reviews
    10. Communications
    11. Preview
    1. You have free access to this content
      Reformatsky Reactions Meet Catalysis and Stereoselectivity (page 6948)

      Pier Giorgio Cozzi

      Article first published online: 11 SEP 2007 | DOI: 10.1002/anie.200790187

      This article corrects:

      Reformatsky Reactions Meet Catalysis and Stereoselectivity1

      Vol. 46, Issue 15, 2568–2571, Article first published online: 20 FEB 2007

  6. News

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Graphical Abstract
    5. Apology
    6. Corrigendum
    7. News
    8. Book Review
    9. Reviews
    10. Communications
    11. Preview
  7. Book Review

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Graphical Abstract
    5. Apology
    6. Corrigendum
    7. News
    8. Book Review
    9. Reviews
    10. Communications
    11. Preview
  8. Reviews

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Graphical Abstract
    5. Apology
    6. Corrigendum
    7. News
    8. Book Review
    9. Reviews
    10. Communications
    11. Preview
    1. The Molecular Basis of Eukaryotic Transcription (Nobel Lecture) (pages 6956–6965)

      Roger Kornberg

      Article first published online: 2 AUG 2007 | DOI: 10.1002/anie.200701832

      Thumbnail image of graphical abstract

      Life under the microscope: Transcription, the copying of a DNA strand to produce an RNA strand, is a central operation in biology. The complex mechanism of eukaryotic transcription has been broken down into molecular details through the work of Roger Kornberg.The Nobel Prize winner for Chemistry describes here first hand the course of his research. The picture shows the pre-initiation complex that must be formed for initiation of transcription.

    2. Gene Silencing by Double-Stranded RNA (Nobel Lecture) (pages 6966–6984)

      Andrew Z. Fire

      Article first published online: 23 AUG 2007 | DOI: 10.1002/anie.200701979

      Thumbnail image of graphical abstract

      Shhh! Gene silencing is a cell process in which the action of double-stranded RNA molecules suppresses the expression of single genes. Decisive contributions to this area have been made by Andrew Fire and Craig C. Mello, for which they have been awarded the Nobel Prize for Medicine. The Nobel Laureates describe here first hand their research.

    3. Return to the RNAi World: Rethinking Gene Expression and Evolution (Nobel Lecture) (pages 6985–6994)

      Craig C. Mello

      Article first published online: 21 AUG 2007 | DOI: 10.1002/anie.200701713

      Shhh! Gene silencing is a cell process in which the action of double-stranded RNA molecules suppresses the expression of single genes. Decisive contributions to this area have been made by Andrew Fire and Craig C. Mello, for which they have been awarded the Nobel Prize for Medicine. The Nobel Laureates describe here first hand their research.

  9. Communications

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Graphical Abstract
    5. Apology
    6. Corrigendum
    7. News
    8. Book Review
    9. Reviews
    10. Communications
    11. Preview
    1. Adenosine Triphosphate Biosynthesis Catalyzed by FoF1 ATP Synthase Assembled in Polymer Microcapsules (pages 6996–7000)

      Li Duan, Qiang He, Kewei Wang, Xuehai Yan, Yue Cui, Helmuth Möhwald and Junbai Li

      Article first published online: 6 JUL 2007 | DOI: 10.1002/anie.200700331

      Thumbnail image of graphical abstract

      Energy spheres: A biomimetic system consisting of the assembly of FoF1 ATPase in lipid-modified polyelectrolyte microcapsules enables adenosine triphosphate (ATP) to be synthesized and stored in the hollow shells, which thereby act as containers for energy storage (see schematic representation; ADP: adenosine diphosphate; Pi: inorganic phosphate).

    2. Unusual Silicon Coordination Polyhedra: Non-VSEPR Structures of Zwitterionic λ5-Si Silicon(IV) Complexes with an SiS2N2C or SiS2O2C Skeleton (pages 7001–7005)

      Dennis Troegel, Christian Burschka, Sebastian Riedel, Martin Kaupp and Reinhold Tacke

      Article first published online: 8 AUG 2007 | DOI: 10.1002/anie.200700785

      Thumbnail image of graphical abstract

      Trading places: The pentavalent silicon compounds 1 and 2 with distorted trigonal-bipyramidal Si coordination polyhedra contain sulfur atoms that occupy axial positions, which contradicts VSEPR predictions for these zwitterionic compounds. These findings are supported by DFT and MP2 calculations (S yellow, Si magenta, O red, N blue, C gray).

    3. Pentacoordination of Silicon by Five Different Ligand Atoms: Neutral Silicon(IV) Complexes with SiClSONC and SiISONC Skeletons (pages 7006–7009)

      Stefan Metz, Christian Burschka, Daniela Platte and Reinhold Tacke

      Article first published online: 12 JUL 2007 | DOI: 10.1002/anie.200700910

      Thumbnail image of graphical abstract

      Take five: Pentacoordinate silicon with five different ligand atoms (SiClSONC and SiISONC skeletons) has been realized with the synthesis of the neutral silicon(IV) compound 1 and its iodo analogue, both of which exist in the solid state and in solution. The chloro ligand of 1 can be easily replaced to give further pentacoordinate silicon compounds.

    4. “Cassette” In Situ Enzymatic Screening Identifies Complementary Chiral Scaffolds for Hydrolytic Kinetic Resolution Across a Range of Epoxides (pages 7010–7014)

      Sangeeta Dey, Douglas R. Powell, Chunhua Hu and David B. Berkowitz

      Article first published online: 14 AUG 2007 | DOI: 10.1002/anie.200701280

      Thumbnail image of graphical abstract

      Put the cassette in: An in situ enzymatic screen can give real-time estimates of the sense and magnitude of enantioselectivity across more than one substrate. Screening identified CoIII–salen catalysts with β-pinene- and α-naphthylalanine-derived chiral scaffolds with broad, yet complementary, substrate specificities. ADH=alcohol dehydrogenase, HL=horse liver, LK=Lactobacillus kefir, salen=(salicylidene)ethylenediamine.

    5. Photoreversible Fluorescence Modulation of a Rhodamine Dye by Supramolecular Complexation with Photosensitive Cyclodextrin (pages 7015–7018)

      Shuizhu Wu, Yulan Luo, Fang Zeng, Jian Chen, Yanan Chen and Zhen Tong

      Article first published online: 7 AUG 2007 | DOI: 10.1002/anie.200701396

      Thumbnail image of graphical abstract

      A complex light switch: Photoreversible fluorescence modulation was achieved by supramolecular complexation of a guest rhodamine molecule (RhB) with spiropyran-modified cyclodextrin (see picture). Upon UV irradiation, the chromophore within the cyclodextrin cavity can transfer its energy to the spiropyran moiety, while upon visible-light irradiation, no energy transfer occurs. Thus, light can be used to turn “on” and “off” the fluorescence emission of a dye inside the cyclodextrin cavity.

    6. Signal-Amplifying Resonance Energy Transfer: A Dynamic Multichromophore Array for Allosteric Switching (pages 7019–7022)

      Justin A. Riddle, Xuan Jiang, John Huffman and Dongwhan Lee

      Article first published online: 6 AUG 2007 | DOI: 10.1002/anie.200701410

      Thumbnail image of graphical abstract

      Cooperative structural folding and unfolding of a dynamic multichromophore array provides an unusual signal amplification as part of a resonance energy transfer from the central donor unit to peripheral acceptor ensembles. The stepwise addition and removal of chemical input signals resulted in reversible, sigmoidal response curves in both the turn-on and turn-off scans (see picture).

    7. Designing Facial Amphiphiles for the Stabilization of Integral Membrane Proteins (pages 7023–7025)

      Qinghai Zhang, Xingquan Ma, Andrew Ward, Wen-Xu Hong, Veli-Pekka Jaakola, Raymond C. Stevens, M. G. Finn and Geoffrey Chang

      Article first published online: 9 AUG 2007 | DOI: 10.1002/anie.200701556

      Thumbnail image of graphical abstract

      An added dimension: Amphiphiles with two-dimensional hydrophobic and hydrophilic faces represent a departure from traditional one-dimensional polar-head/nonpolar-tail molecules for the stabilization of integral membrane proteins. A prototypical example of this design has been synthesized from cholic acid (see picture), and was successfully used in the stabilization of two integral membrane proteins (represented by the blue/green cylinder).

    8. Pt-Catalyzed Formation of Ni Nanoshells on Carbon Nanotubes (pages 7026–7030)

      Marek Grzelczak, Miguel A. Correa-Duarte, Verónica Salgueiriño-Maceira, Benito Rodríguez-González, José Rivas and Luis M. Liz-Marzán

      Article first published online: 14 AUG 2007 | DOI: 10.1002/anie.200701671

      Thumbnail image of graphical abstract

      Full metal jacket: Carbon nanotubes (CNTs) are used as templates to form well-defined anisotropic magnetic nanowires with ferromagnetic behavior at room temperature. Uniform assembly of catalytic Pt nanoparticles on the CNTs yields organic–inorganic hybrid composites that serve as 1D substrates for the preparation of magnetic CNT-supported Ni/NiO nanotubes (see picture).

    9. A Bioluminogenic Substrate for In Vivo Imaging of β-Lactamase Activity (pages 7031–7034)

      Hequan Yao, Min-kyung So and Jianghong Rao

      Article first published online: 3 AUG 2007 | DOI: 10.1002/anie.200701931

      Thumbnail image of graphical abstract

      Reporting live: A caged β-lactam–D-luciferin (Bluco) conjugate can image β-lactamase activity in vivo through a two-step enzymatic process. This novel bioluminogenic probe should facilitate the detection of β-lactamase and widen its applications as a reporter.

    10. Geminal Bismethylation Prevents Polyketide Oxidation and Dimerization in the Benastatin Pathway (pages 7035–7038)

      Angéla Schenk, Zhongli Xu, Corina Pfeiffer, Christoph Steinbeck and Christian Hertweck

      Article first published online: 9 AUG 2007 | DOI: 10.1002/anie.200702033

      Thumbnail image of graphical abstract

      A 'gem' of an enzyme: Geminal enzymatic bismethylation in the biosynthetic pathway leading to the cytotoxic polyketide benastatin blocks the highly reactive benzylic position of an anthrone-type intermediate. In a mutant lacking the C-methyl transferase, quinones and structurally intriguing meso and rac dimers (see calculated structure) are formed, which were elucidated by a combination of spectroscopy and computational simulations.

    11. A Magnetically Recyclable Nanocomposite Catalyst for Olefin Epoxidation (pages 7039–7043)

      Mohammadreza Shokouhimehr, Yuanzhe Piao, Jaeyun Kim, Youngjin Jang and Taeghwan Hyeon

      Article first published online: 8 AUG 2007 | DOI: 10.1002/anie.200702386

      Thumbnail image of graphical abstract

      Attractive” catalyst: Molybdenum oxide nanoparticles have been incorporated into a mesoporous silica shell and coated on silica-coated magnetite nanoparticles for use as a magnetically separable heterogeneous epoxidation catalyst. This catalyst, which has a low Mo loading of 1 mol %, can be recycled and reused six times in the epoxidation of cis-cyclooctene with no major loss of activity (see picture).

    12. Macrocyclic Helix-Threading Peptides for Targeting RNA (pages 7044–7047)

      Malathy Krishnamurthy, Kristina Simon, Anita M. Orendt and Peter A. Beal

      Article first published online: 9 AUG 2007 | DOI: 10.1002/anie.200702247

      Thumbnail image of graphical abstract

      Hanging on by a thread: RNA-binding macrocyclic helix-threading peptides were synthesized by solid-phase ring-closing metathesis. The cyclic peptide shows improved affinity to a target RNA over its linear precursor. This compound also binds a naturally occurring precursor microRNA target and may be valuable for regulating microRNA function.

    13. Sixty Years after Wittig: Gas-Phase Synthesis of Lithium Trimethylammonium Methylide, [(CH3)3NCH2Li]+ (pages 7048–7051)

      Richard A. J. O'Hair, Tom Waters and Benjamin Cao

      Article first published online: 9 AUG 2007 | DOI: 10.1002/anie.200701972

      Thumbnail image of graphical abstract

      Very Wittig: Collisional activation of the lithiated betaine cation [(CH3)3NCH2CO2Li]+ (m/z 124) in the gas phase results in decarboxylation to form the lithiated ylide [(CH3)3NCH2Li]+ (m/z 80). Calculations and ion–molecule reactions with water confirm the identity and reactivity of this species.

    14. Carbene Activation of P4 and Subsequent Derivatization (pages 7052–7055)

      Jason D. Masuda, Wolfgang W. Schoeller, Bruno Donnadieu and Guy Bertrand

      Article first published online: 17 AUG 2007 | DOI: 10.1002/anie.200703055

      Thumbnail image of graphical abstract

      Broken down and added onto: An enantiomerically pure cyclic (alkyl)(amino)carbene cleanly activates P4, affording highly reactive products that can be further used for the diastereoselective construction of P4-containing molecules that feature phosphorus–carbon bonds (see scheme; DMB=2,3-dimethylbutadiene; portions of the products have been omitted, * denotes a stereogenic carbon center).

    15. Thermodynamic Analysis of β-Sheet Secondary Structure by Backbone Thioester Exchange (pages 7056–7059)

      Erik B. Hadley, Alex M. Witek, Felix Freire, Aaron J. Peoples and Samuel H. Gellman

      Article first published online: 9 AUG 2007 | DOI: 10.1002/anie.200702449

      Thumbnail image of graphical abstract

      No need for references: The conformational stability of β hairpins has been examined by replacing a backbone amide group by a thioester (see picture). The increased flexibility causes a decrease in the β-hairpin stability without changing the structure of the folded conformation and allows the stability of the folded state to be measured under native conditions, without the need for reference compounds for the fully unfolded and folded states.

    16. A Practical Synthesis of the Phytosiderophore 2′-Deoxymugineic Acid: A Key to the Mechanistic Study of Iron Acquisition by Graminaceous Plants (pages 7060–7063)

      Kosuke Namba, Yoshiko Murata, Manabu Horikawa, Takashi Iwashita and Shoichi Kusumoto

      Article first published online: 9 AUG 2007 | DOI: 10.1002/anie.200702403

      Thumbnail image of graphical abstract

      Ironing out plant uptake: The phytosiderophores mugineic acid (MA) and deoxymugineic acid (DMA) were synthesized in a few steps with minimum use of protecting groups and workup/purification procedures (see scheme; Boc: tert-butoxycarbonyl) and their potencies in transporter-mediated iron(III) acquisition were tested. The sufficient supply of these compounds will enable study of the molecular mechanism of iron acquisition and utilization by graminaceous plants.

    17. Cleavage Agents for Soluble Oligomers of Amyloid β Peptides (pages 7064–7067)

      Junghun Suh, Sang Ho Yoo, Min Gyum Kim, Keunhong Jeong, Jae Young Ahn, Myoung-soon Kim, Pil Seok Chae, Tae Yeon Lee, Jaehwa Lee, Jeongkuk Lee, Yun Ah Jang and Eun Hwa Ko

      Article first published online: 20 AUG 2007 | DOI: 10.1002/anie.200702399

      Thumbnail image of graphical abstract

      Clearing the mind: Peptide-cleaving agents for amyloid β-42 (Aβ42) oligomers (see scheme), the intermediate neurotoxic species in the pathology of Alzheimer's disease, have been obtained from a combinatorial library built using the CoIII complex of 1,4,7,10-tetraazacyclododecane as the reaction center. Effective cleavage of the Aβ42 oligomers occurs at submicromolar concentrations of the agents.

    18. Highly Regioselective Synthesis of Spirocyclic Compounds by a Palladium-Catalyzed Intermolecular Tandem Reaction (pages 7068–7071)

      Hai-Peng Bi, Xue-Yuan Liu, Fa-Rong Gou, Li-Na Guo, Xin-Hua Duan, Xing-Zhong Shu and Yong-Min Liang

      Article first published online: 7 AUG 2007 | DOI: 10.1002/anie.200702238

      Thumbnail image of graphical abstract

      Bicycles built for two: The palladium-catalyzed intermolecular tandem reaction of propargylic compounds with 2-iodophenols offers an efficient, direct route to spirocyclic compounds with high regioselectivity. The reaction conditions and the scope of the process are examined, and a possible mechanism is proposed.

    19. Direct Detection of Individual Bis(arene) Rotational Isomers in the Gas Phase by Mass-Analyzed Threshold Ionization Spectroscopy (pages 7072–7074)

      Sergey Y. Ketkov, Heinrich L. Selzle and F. Geoffrey N. Cloke

      Article first published online: 3 AUG 2007 | DOI: 10.1002/anie.200702233

      Thumbnail image of graphical abstract

      It's a gas! Mass-analyzed threshold ionization (MATI) spectroscopy provides high-resolution ionization potentials and low-energy vibrational frequencies of individual conformers of jet-cooled [(η6-PhMe)2Cr]. The signals arising from distinct structural isomers were identified on the basis of DFT calculations and comparison of the [(η6-PhMe)2Cr] and [(η6-1,3-Me2C6H4)(η6-PhH)Cr] spectra (see picture).

    20. Mechanism of Methyl Esterification of Carboxylic Acids by Trimethylsilyldiazomethane (pages 7075–7078)

      Erik Kühnel, David D. P. Laffan, Guy C. Lloyd-Jones, Teresa Martínez del Campo, Ian R. Shepperson and Jennifer L. Slaughter

      Article first published online: 9 AUG 2007 | DOI: 10.1002/anie.200702131

      Thumbnail image of graphical abstract

      Minimal hazard: A deuterium-labeling study reveals that, contrary to prior assumption, the safe, reliable, and widely adopted method for methyl esterification of carboxylic acids using trimethylsilyldiazomethane (TMS[BOND]CHN2) proceeds through the concurrent acid-catalyzed methanolytic liberation of diazomethane (see scheme).

    21. Hybrid Co–Au Nanorods: Controlling Au Nucleation and Location (pages 7079–7081)

      Fabienne Wetz, Katerina Soulantica, Andrea Falqui, Marc Respaud, Etienne Snoeck and Bruno Chaudret

      Article first published online: 8 AUG 2007 | DOI: 10.1002/anie.200702017

      Thumbnail image of graphical abstract

      Au Co-ntraire: The growth of gold nanoparticles on magnetic cobalt nanorods could be initiated either selectively on the tips of the nanorods (see picture, left) or nonselectively over the whole nanorod surface (right) by the proper choice of ligand concentration and temperature. Heterogeneous nucleation was selected over galvanic displacement by the choice of the gold(I) precursor.

    22. Organocuprate Cross-Coupling: The Central Role of the Copper(III) Intermediate and the Importance of the Copper(I) Precursor (pages 7082–7085)

      Steven H. Bertz, Stephen Cope, Donna Dorton, Michael Murphy and Craig A. Ogle

      Article first published online: 22 AUG 2007 | DOI: 10.1002/anie.200703035

      Thumbnail image of graphical abstract

      CuIIIin focus: The key intermediate in copper-mediated cross-coupling reactions has long been believed to be a “copper(III) intermediate”. Investigation of reactions of a variety of methyl Gilman reagents Me2CuLi⋅LiX with EtI using rapid-injection NMR spectroscopy conditions reveals a number of formally CuIII tetracoordinate square-planar intermediates (see scheme) with a surprising range of stabilities.

    23. A Convergent Strategy for the Pamamycin Macrodiolides: Total Synthesis of Pamamycin-607, Pamamycin-593, and Pamamycin-621D Precursors (pages 7086–7089)

      Steve Lanners, Hassan Norouzi-Arasi, Xavier J. Salom-Roig and Gilles Hanquet

      Article first published online: 7 AUG 2007 | DOI: 10.1002/anie.200701749

      Thumbnail image of graphical abstract

      A convergent total synthesis of pamamycin-607 (1), isolated from Streptomyces alboniger, was achieved by an EZ isomerization of a tetrahydrofuran alkylidene and a regio- and diastereoselective solvent-dependent cyclo-C6H11BCl/Et3N-mediated aldol reaction as the key steps. The second key step was extended to other ketones, opening the route to new pamamycin macrodiolides, for example, pamamycin-593 and pamamycin-621D.

    24. Organocatalytic Enantioselective Protonation of Silyl Enolates Mediated by Cinchona Alkaloids and a Latent Source of HF (pages 7090–7093)

      Thomas Poisson, Vincent Dalla, Francis Marsais, Georges Dupas, Sylvain Oudeyer and Vincent Levacher

      Article first published online: 9 AUG 2007 | DOI: 10.1002/anie.200701683

      Thumbnail image of graphical abstract

      Hidden benefits: The enantioselective organocatalytic protonation of silyl enolates has been achieved by using readily available cinchona alkaloid catalysts (1) and a latent source of HF that delivers “at will” the active catalytic hydrogen fluoride salt (1-HF). This approach leads to enantioselective proton transfer with high enantioselectivities of up to 92 % under mild, neutral, and metal-free conditions (see scheme, TMS=trimethylsilyl).

    25. On the Mechanism of Formation of Metal Nanowires by Self-Assembly (pages 7094–7097)

      Francesc Viñes, Francesc Illas and Konstantin M. Neyman

      Article first published online: 7 AUG 2007 | DOI: 10.1002/anie.200701613

      Thumbnail image of graphical abstract

      Model nanowires (Pdn)x were constructed from isolated cuboctahedral clusters Pdn (n=38, 79, 140, 225), as depicted for n=225. Periodic density functional calculations show that the elasticity of the nanoparticles plays a key role in the self-assembly mechanism. The results are also relevant to sintering in the catalysts by supported metal nanoparticles.

    26. Metalated Nitriles: Internal 1,2-Asymmetric Induction (pages 7098–7100)

      Fraser F. Fleming, Wang Liu, Somraj Ghosh and Omar W. Steward

      Article first published online: 9 AUG 2007 | DOI: 10.1002/anie.200701550

      Thumbnail image of graphical abstract

      Steric screening: In alkylations of metalated nitriles containing vicinal methyl groups and a trisubstituted C[DOUBLE BOND]C bond, the butene moiety screens electrophilic attack from one diastereotopic face as the quaternary stereocenter is installed (see scheme; LDA=LiNiPr2). Excellent stereoselectivity is maintained with a wide range of electrophiles to yield acyclic nitriles with contiguous tertiary and quaternary stereocenters.

    27. Stereoselective Synthesis of α-Allenols by Rhodium-Catalyzed Reaction of Alkynyl Oxiranes with Arylboronic Acids (pages 7101–7103)

      Tomoya Miura, Masahiko Shimada, Sung-Yu Ku, Tomohiro Tamai and Masahiro Murakami

      Article first published online: 9 AUG 2007 | DOI: 10.1002/anie.200701505

      Thumbnail image of graphical abstract

      Better than Cu, Pd, and Fe catalysts: The rhodium-catalyzed reaction of alkynyl oxiranes with arylboronic acids provides syn-configured α-allenols with excellent diastereoselectivity. Precoordination of the oxygen atom of the oxirane ring to rhodium is assumed to contribute to the high stereoselectivity as well as high reactivity.

    28. Reversible Surface Switching of Nanogel Triggered by External Stimuli (pages 7104–7107)

      Xiaochen Shen, Leyang Zhang, Xiqun Jiang, Yong Hu and Jian Guo

      Article first published online: 8 AUG 2007 | DOI: 10.1002/anie.200701368

      Thumbnail image of graphical abstract

      Inside out and back again: A novel nanogel composed of two biocompatible components, namely chitosan and ethylenediaminetetraacetic acid, is presented and shows novel surface switching of both composition and charge in response to pH changes in the medium (see picture). The pH-dependent surface switch of this nanogel is fully reversible and the particle integrity is maintained in the entire pH range owing to the gel nature of the system.

    29. Spirodiepoxides: Heterocycle Synthesis and Mechanistic Insight (pages 7108–7111)

      Stephen D. Lotesta, Sezgin Kiren, Ronald R. Sauers and Lawrence J. Williams

      Article first published online: 9 AUG 2007 | DOI: 10.1002/anie.200701401

      Thumbnail image of graphical abstract

      In concert but out of sync: Reactions of spirodiepoxides (SDEs) with an amide, amidine, and thioamide and the first crystal structure of an SDE are reported (see scheme for reaction with amide; DMDO=2,2-dimethyldioxirane). Nucleophilic SDE opening is rationalized in terms of a reactivity continuum involving the concerted, asynchronous opening of both epoxides, which is facilitated by coordination to the oxygen atom destined to become the hydroxy group.

    30. Electrochemical and Photochemical Behavior of a Ruthenium(II) Complex Bearing Two Redox Sites as a Model for the NAD+/NADH Redox Couple (pages 7112–7115)

      Hidenori Tannai, Take-aki Koizumi, Tohru Wada and Koji Tanaka

      Article first published online: 7 AUG 2007 | DOI: 10.1002/anie.200701204

      Thumbnail image of graphical abstract

      Four by four: The mononuclear ruthenium(II) complex [1]2+ is reversibly converted into the four-electron-reduced form [1-H4]2+ through electrochemical and photochemical redox reactions in aqueous solution. The 2,6-bis(benzo[b]-1,5-naphthyridin-6-yl)-4-tert-butylpyridine ligand acts alteratively as a reservoir/source of four electrons or four protons.

    31. Surprises from a Simple Material—The Structure and Properties of Nickel Cyanide (pages 7116–7118)

      Simon J. Hibble, Ann M. Chippindale, Alexander H. Pohl and Alex C. Hannon

      Article first published online: 7 AUG 2007 | DOI: 10.1002/anie.200701246

      Thumbnail image of graphical abstract

      The cyanide switch. The bonding of the cyanide ligand of Ni(CN)2n H2O changes dramatically on dehydration to Ni(CN)2, equalizing the Ni[BOND]C and Ni[BOND]N bonds and switching the Ni2+ ion bound to nitrogen from high spin to low spin. Total neutron diffraction studies on Ni(CN)2 provide for the first time accurate structural data on this simple layered metal cyanide. Ni(CN)2 is a model two-dimensional negative thermal-expansion material.

    32. Catalytic Enantioselective Tautomerization of Isolated Enols (pages 7119–7121)

      Charles Fehr

      Article first published online: 26 JUN 2007 | DOI: 10.1002/anie.200701428

      Thumbnail image of graphical abstract

      Smells like roses: The catalytic enantioselective ketonization of two isolated enols was successful and made possible the discussion of the important mechanistic implications of these findings. The indirect enolate protonation occurs via enols and higher-order mixed aggregates (see scheme). The reaction was used to synthesize the rose-smelling fragrance compound (S)-α-damascone.

    33. Rhodium-Catalyzed Enantioselective 1,2-Addition of Aluminum Organyl Compounds to Cyclic Enones (pages 7122–7124)

      Jürgen Siewert, René Sandmann and Paultheo von Zezschwitz

      Article first published online: 14 AUG 2007 | DOI: 10.1002/anie.200701087

      Thumbnail image of graphical abstract

      A question of the ligand: The chemoselectivity of the rhodium-catalyzed addition of AlMe3 to cyclohex-2-enone is guided by the type of ligand used. Whereas use of an achiral {Rh(cyclooctadiene)} complex leads to a 1,4-addition, use of a {Rh(binap)} species gives highly enantioselective 1,2-additions. This unprecedented reaction can be used for stereoselective 1,2-methylations and arylations of cyclic enones (see scheme).

    34. Exploring the Nickel-Catalyzed Oxidation of Alkenes: A Diamination by Sulfamide Transfer (pages 7125–7127)

      Kilian Muñiz, Jan Streuff, Claas H. Hövelmann and Ana Núñez

      Article first published online: 10 AUG 2007 | DOI: 10.1002/anie.200702160

      Thumbnail image of graphical abstract

      Nickel can oxidize, too! Nickel(II) salts such as nickel chloride and nickel acetylacetonate catalyze the intramolecular diamination of alkenes with urea and guanidine derivatives as well as sulfamides as nitrogen sources. The latter represent particularly attractive starting materials, as they allow for a selective and convenient liberation of the diamines from the oxidation products (see scheme).

  10. Preview

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Graphical Abstract
    5. Apology
    6. Corrigendum
    7. News
    8. Book Review
    9. Reviews
    10. Communications
    11. Preview
    1. You have free access to this content
      Preview: Angew. Chem. Int. Ed. 38/2007 (page 7131)

      Article first published online: 11 SEP 2007 | DOI: 10.1002/anie.200790186

SEARCH

SEARCH BY CITATION