Angewandte Chemie International Edition

Cover image for Vol. 47 Issue 39

September 15, 2008

Volume 47, Issue 39

Pages 7369–7563

  1. Cover Picture

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Graphical Abstract
    5. News
    6. Book Review
    7. Highlights
    8. Review
    9. Communications
    10. Preview
    1. Cover Picture: Heterolytic Dihydrogen Activation by a Frustrated Carbene–Borane Lewis Pair / Hydrogen and Amine Activation by a Frustrated Lewis Pair of a Bulky N-Heterocyclic Carbene and B(C6F5)3 (Angew. Chem. Int. Ed. 39/2008) (page 7369)

      Dirk Holschumacher, Thomas Bannenberg, Cristian G. Hrib, Peter G. Jones, Matthias Tamm, Preston A. Chase and Douglas W. Stephan

      Version of Record online: 9 SEP 2008 | DOI: 10.1002/anie.200890190

      Thumbnail image of graphical abstract

      Forcing a square peg into a round hole:tBu2ImC: and B(C6F5)3 form a frustrated Lewis pair (FLP), allowing the synergistic activation of H2. On page 7428 ff., M. Tamm et al. describe how the irreversible formation of an abnormal carbene–borane adduct eliminates mismatching between acid and base so that this system can circumvent frustration at the expense of activity. In addition, D. W. Stephan and P. A. Chase demonstrate on page 7433 ff. that this FLP combination not only effects heterolytic cleavage of H2, but also of amine N[BOND]H bonds.

  2. Inside Cover

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Graphical Abstract
    5. News
    6. Book Review
    7. Highlights
    8. Review
    9. Communications
    10. Preview
    1. Inside Cover: The Role of Bent Acyclic Allene Gold Complexes in Axis-to-Center Chirality Transfers (Angew. Chem. Int. Ed. 39/2008) (page 7370)

      Vincent Gandon, Gilles Lemière, Alexandra Hours, Louis Fensterbank and Max Malacria

      Version of Record online: 9 SEP 2008 | DOI: 10.1002/anie.200890191

      Thumbnail image of graphical abstract

      Activation of allenes towards nucleophilic attack by gold complexes often proceeds with axis-to-center chirality transfer. In their Communication on page 7534 ff., V. Gandon, L. Fensterbank, M. Malacria et al. show that stereochemical information is maintained in not only η2 allene complexes, but also in bent η1 allene complexes.

  3. Graphical Abstract

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

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

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

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

      Nanocatalysis Beyond the Gold-Rush Era (pages 7390–7392)

      Lars C. Grabow and Manos Mavrikakis

      Version of Record online: 8 AUG 2008 | DOI: 10.1002/anie.200802592

      Thumbnail image of graphical abstract

      All that glitters is not gold: A powerful computational approach using density functional theory and kinetic modeling leads the field of nanoparticle catalysis into a new era. Not only gold exhibits unique properties on the nanoscale, but also other noble and transition metals should show similar effects for a variety of catalytic reactions.

    2. Radical Ligands

      Metal Complexes of Aminyl Radicals (pages 7393–7395)

      Robin G. Hicks

      Version of Record online: 29 AUG 2008 | DOI: 10.1002/anie.200802713

      Thumbnail image of graphical abstract

      Innocent until proven … non-innocent! Until recently, metal complexes of neutral aminyl radicals have proven very elusive in comparison to the more common metal amide valence isomer. Recent publications are discussed in which the synthesis and elucidation of genuine, isolable metal aminyl radical complexes have been realized.

  7. Review

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Graphical Abstract
    5. News
    6. Book Review
    7. Highlights
    8. Review
    9. Communications
    10. Preview
    1. Metalated Porphyrins

      Merging Porphyrins with Organometallics: Synthesis and Applications (pages 7396–7421)

      Bart M. J. M. Suijkerbuijk and Robertus J. M. Klein Gebbink

      Version of Record online: 25 AUG 2008 | DOI: 10.1002/anie.200703362

      Thumbnail image of graphical abstract

      Ringing the changes: The combination of organometallic structural elements with porphyrin systems has led to many molecular metalloporphyrins with fascinating properties. This Review presents an overview of the syntheses and structural diversity of such compounds.

  8. Communications

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Graphical Abstract
    5. News
    6. Book Review
    7. Highlights
    8. Review
    9. Communications
    10. Preview
    1. Asymmetric Cyclopropanation

      Synthesis of Optically Active Boron–Silicon Bifunctional Cyclopropane Derivatives through Enantioselective Copper(I)-Catalyzed Reaction of Allylic Carbonates with a Diboron Derivative (pages 7424–7427)

      Hajime Ito, Yuki Kosaka, Kousuke Nonoyama, Yusuke Sasaki and Masaya Sawamura

      Version of Record online: 25 AUG 2008 | DOI: 10.1002/anie.200802342

      Thumbnail image of graphical abstract

      Two for the show: A copper(I)-catalyzed reaction forms boron–silicon bifunctional cyclopropane derivatives from γ-silylated allylic carbonates and a diboron species (see scheme). The reaction is highly enantioselective when a chiral bisphosphine ligand is used. The stereoelectronic effect of the silyl group induces unusual regioselectivity of the borylcopper(I) addition across the C[BOND]C double bond.

    2. H2 Activation

      Heterolytic Dihydrogen Activation by a Frustrated Carbene–Borane Lewis Pair (pages 7428–7432)

      Dirk Holschumacher, Thomas Bannenberg, Cristian G. Hrib, Peter G. Jones and Matthias Tamm

      Version of Record online: 29 JUL 2008 | DOI: 10.1002/anie.200802705

      Thumbnail image of graphical abstract

      Relief from frustration: The sterically demanding carbene 1,3-di-tert-butylimidazolin-2-ylidene and B(C6F5)3, a “frustrated” Lewis pair, is a viable system for the activation of C[BOND]O, H[BOND]H, and C[BOND]H bonds. However, slow rearrangement to an abnormal carbene–borane adduct allows the irreversible formation of a strong B[BOND]C bond and enables this system to circumvent frustration at the expense of its activity.

    3. Hydrogen and Amine Activation by a Frustrated Lewis Pair of a Bulky N-Heterocyclic Carbene and B(C6F5)3 (pages 7433–7437)

      Preston A. Chase and Douglas W. Stephan

      Version of Record online: 25 JUL 2008 | DOI: 10.1002/anie.200802596

      Thumbnail image of graphical abstract

      Size matters: The frustrated Lewis pair derived from B(C6F5)3 and the sterically encumbered N-heterocyclic carbene N,N′-tBu2C3H2N2 (1) cleaves dihydrogen heterolytically to give a imidazolium borate (see scheme, left), and cleaves amine N[BOND]H bonds to form aminoborate salts (right) or aminoboranes.

    4. Peptide Microarrays

      Rapid Affinity-Based Fingerprinting of 14-3-3 Isoforms Using a Combinatorial Peptide Microarray (pages 7438–7441)

      Candy H. S. Lu, Hongyan Sun, Farhana B. Abu Bakar, Mahesh Uttamchandani, Wei Zhou, Yih-Cherng Liou and Shao Q. Yao

      Version of Record online: 13 AUG 2008 | DOI: 10.1002/anie.200801395

      Thumbnail image of graphical abstract

      Specifying 14-3-3: A fragment-based combinatorial peptide microarray generates affinity-based fingerprints of seven mammalian 14-3-3 isoforms. High-affinity motifs are identified against the highly homologous isoforms. Putative 14-3-3σ-specific peptides were also delineated by a dual-color ratiometric screening strategy (see picture).

    5. Surface Patterning

      Selective Surface Patterning with an Electric Discharge in the Fabrication of Microfluidic Structures (pages 7442–7445)

      Niina M. Suni, Markus Haapala, Ari Mäkinen, Lauri Sainiemi, Sami Franssila, Elina Färm, Esa Puukilainen, Mikko Ritala and Risto Kostiainen

      Version of Record online: 29 AUG 2008 | DOI: 10.1002/anie.200801569

      Thumbnail image of graphical abstract

      Patterned chips: Organic self-assembled monolayers on Si–SiO2 surfaces are patterned with an electric discharge between a patterning tip and the silicon substrate (see picture). The method allows rapid patterning with simple equipment on planar, curved, and textured surfaces. It is used in the fabrication of microfluidic structures for microchip-based mass spectrometric drug analysis.

    6. Heteroaromatic Oxidation

      Formation of α-Hydroxy-β-diketones through Hydroxylation of Isoxazolium Salts: Stereoselective Approach to Angular cis-Diols in Polycyclic Systems (pages 7446–7449)

      Hiroshi Takikawa, Akiomi Takada, Katsuyoshi Hikita and Keisuke Suzuki

      Version of Record online: 19 AUG 2008 | DOI: 10.1002/anie.200801586

      Thumbnail image of graphical abstract

      Only two steps were needed for the unprecedented oxidation of isoxazoles, which is exploited in the stereocontrolled introduction of an “angular cis-diol” characteristic of polyketide-derived polycyclic natural products, such as 3. In this two-step process, 1) N-methylation of isoxazole 1 and 2) stereoselective epoxidation of isoxazolium salt 2 with sodium hypochlorite followed by hydrolysis are carried out (Bn: benzyl).

    7. Oxygen Sensors

      Reversible Optical Sensor Strip for Oxygen (pages 7450–7453)

      Xu-dong Wang, Xi Chen, Zhao-xiong Xie and Xiao-ru Wang

      Version of Record online: 26 AUG 2008 | DOI: 10.1002/anie.200801733

      Thumbnail image of graphical abstract

      Seeing red: An optical sensor based on CdTe quantum dots (QDs) and [meso-tetrakis(pentafluorophenyl)porphyrinato]platinum(II) (PtF20TPP; λem,max=648 nm, red), achieves both colorimetric and quantitative determination of oxygen. The sensor strip is reversible in its response and can be reused.

    8. Click Chemistry

      Visual Detection of Copper(II) by Azide- and Alkyne-Functionalized Gold Nanoparticles Using Click Chemistry (pages 7454–7456)

      Yang Zhou, Shixing Wang, Ke Zhang and Xingyu Jiang

      Version of Record online: 13 AUG 2008 | DOI: 10.1002/anie.200802317

      Thumbnail image of graphical abstract

      Just one click, and the color's gone: In the presence of Cu2+ with sodium ascorbate as a reductant, gold nanoparticles that have azide- and alkyne-terminated groups undergo aggregation as the result of CuI-catalyzed click chemistry. This process can be monitored by eye without the aid of instruments (NPs=nanoparticles).

    9. Asymmetric Hydrogenation

      Highly Enantioselective Hydrogenation of Aryl Vinyl Ketones to Allylic Alcohols Catalyzed by the Tol-Binap/Dmapen Ruthenium(II) Complex (pages 7457–7460)

      Noriyoshi Arai, Keita Azuma, Noriyuki Nii and Takeshi Ohkuma

      Version of Record online: 27 AUG 2008 | DOI: 10.1002/anie.200802533

      Thumbnail image of graphical abstract

      Binap catalyst doesn't dmapen expectations: In basified 2-propanol, [RuCl2{(S)-tol-binap}{(R)-dmapen}] (1, see picture, Ar=4-CH3C6H4) catalyzes the highly enantioselective hydrogenation of a series of aryl vinyl ketones and affords the allylic alcohols in high yields with up to 98 % ee. Formation of the saturated ketones and alcohols is suppressed with triphenylphosphine when necessary.

    10. Lithium Batteries

      The Design of a LiFePO4/Carbon Nanocomposite With a Core–Shell Structure and Its Synthesis by an In Situ Polymerization Restriction Method (pages 7461–7465)

      Yonggang Wang, Yarong Wang, Eiji Hosono, Kaixue Wang and Haoshen Zhou

      Version of Record online: 20 AUG 2008 | DOI: 10.1002/anie.200802539

      Thumbnail image of graphical abstract

      Truly long-life: A LiFePO4/carbon composite containing a highly crystalline LiFePO4 core with a size of about 20–40 nm and a semi-graphitic carbon shell with a thickness of about 1–2 nm provides both high power and very long cycling life (see picture). The synthetic method can be extended to the preparation of other materials, such as Li4Ti5O12/carbon and Mn3O4/carbon composites.

    11. Bioorganic Chemistry

      An Apoptosis-Inducing Small Molecule That Binds to Heat Shock Protein 70 (pages 7466–7469)

      Darren R. Williams, Sung-Kyun Ko, Sungjin Park, Myung-Ryul Lee and Injae Shin

      Version of Record online: 26 AUG 2008 | DOI: 10.1002/anie.200802801

      Thumbnail image of graphical abstract

      A cell-based screening approach in which annexin V was used as a staining agent identified apoptozole (Az; see scheme) as an imidazole-based molecule which induces apoptosis. Az binds to Hsc70 and Hsp70 (anti-apoptotic chaperone proteins), with dissociation constants of 0.21 and 0.14 μM, respectively, thereby inhibiting their function. Thus, Az possesses antitumor activity and is, therefore, a potential cancer therapeutic agent.

    12. Interlocked Molecules

      An Acid–Base-Controllable [c2]Daisy Chain (pages 7470–7474)

      Jishan Wu, Ken Cham-Fai Leung, Diego Benítez, Ja-Young Han, Stuart J. Cantrill, Lei Fang and J. Fraser Stoddart

      Version of Record online: 26 AUG 2008 | DOI: 10.1002/anie.200803036

      Thumbnail image of graphical abstract

      The long and the short of it: A bistable molecular muscle, based on a doubly threaded Janus-type [2]rotaxane, is assembled using a template-directed self-assembly process. Under the influence of changes in the pH value, the two identical matching components glide along one another through terminal crown ether moieties, bringing about expansion and contraction of the molecule.

    13. Supramolecular Chemistry

      Solvent-Free Synthesis of the Smallest Rotaxane Prepared to Date (pages 7475–7478)

      Chi-Chieh Hsu, Nai-Chia Chen, Chien-Chen Lai, Yi-Hung Liu, Shie-Ming Peng and Sheng-Hsien Chiu

      Version of Record online: 29 AUG 2008 | DOI: 10.1002/anie.200803056

      Thumbnail image of graphical abstract

      Small is beautiful: The [2]pseudorotaxane formed from dipropargylammonium tetrafluoroborate and the crown ether [21]crown-7 on SiO2 was stoppered with 1,2,4,5-tetrazine in a ball-milling process (see X-ray structure). This new and efficient solvent-free reaction led to the isolation in high yield (81 %) of the smallest [2]rotaxane reported to date.

    14. Cell Recognition

      Cell-Specific Gene Transfection from a Gene-Functionalized Poly(d,l-lactic acid) Substrate Fabricated by the Layer-by-Layer Assembly Technique (pages 7479–7481)

      Kaiyong Cai, Yan Hu, Zhong Luo, Ting Kong, Min Lai, Xiaojing Sui, Yuanliang Wang, Li Yang and Linhong Deng

      Version of Record online: 19 AUG 2008 | DOI: 10.1002/anie.200800412

      Thumbnail image of graphical abstract

      The surface matters: Along with the degradation of the multilayer structure, galactosylated chitosan/plasmid DNA complexes (see picture) were simultaneously formed in situ for cell uptake and gene transfection. Surface-induced cell-specific recognition and in situ gene transfection were achieved.

    15. Medicinal Chemistry

      Small-Molecule Inhibitors of MicroRNA miR-21 Function (pages 7482–7484)

      Kiranmai Gumireddy, Douglas D. Young, Xin Xiong, John B. Hogenesch, Qihong Huang and Alexander Deiters

      Version of Record online: 19 AUG 2008 | DOI: 10.1002/anie.200801555

      Thumbnail image of graphical abstract

      Short, but significant, microRNAs (miRNAs) are an important class of gene regulators. Small-molecule modifiers of miRNA function, such as 1 (see schematic representation), were identified in a cellular screen for miRNA-pathway inhibitors. Such compounds are expected to be useful tools for the elucidation of detailed mechanisms of miRNA action and may serve as lead structures for the development of new therapeutic agents.

    16. Host–Guest Complexes

      Halide Recognition by Tetraoxacalix[2]arene[2]triazine Receptors: Concurrent Noncovalent Halide–π and Lone-pair–π Interactions in Host–Halide–Water Ternary Complexes (pages 7485–7488)

      De-Xian Wang, Qi-Yu Zheng, Qi-Qiang Wang and Mei-Xiang Wang

      Version of Record online: 29 AUG 2008 | DOI: 10.1002/anie.200801705

      Thumbnail image of graphical abstract

      Cleft of center: The self fine-tuning π-deficient cleft of 1,3-dichloro-substituted tetraoxacalix[2]arene[2]triazine forms noncovalent π–halide and π–lone-pair-electron interactions with halides Cl and Br, and water, giving rise to ternary complexes in the solid state (see structure, N blue). In solution, the host molecule, formed by a different mechanism, complexes with fluoride, giving Ka (1:1) of over 4000 M−1.

    17. Phosphanylidenes

      Synergistic Binding of Both Lewis Acids and Bases to Phosphinidenes (pages 7489–7492)

      David V. Partyka, Marlena P. Washington, James B. Updegraff III, Robert A. Woloszynek and John D. Protasiewicz

      Version of Record online: 25 AUG 2008 | DOI: 10.1002/anie.200801741

      Thumbnail image of graphical abstract

      Unlike the mythical Pushmi–Pullyu beast, push–pull stabilization of phosphinidenes is a reality. [ArP(AuCl)2PMe3] (Ar=aryl) represent interesting examples of phosphinidenes having both main group Lewis acid (LA) and Lewis base (LB) adducts. These materials have been structurally authenticated and show longer P[BOND]P bonds and greater stabilization than of purely base-stabilized phosphinidenes (in ArP[DOUBLE BOND]PMe3).

    18. Hydrogen Storage

      In Situ Multinuclear NMR Spectroscopic Studies of the Thermal Decomposition of Ammonia Borane in Solution (pages 7493–7496)

      Wendy J. Shaw, John C. Linehan, Nathaniel K. Szymczak, David J. Heldebrant, Clem Yonker, Donald M. Camaioni, R. Tom Baker and Tom Autrey

      Version of Record online: 29 AUG 2008 | DOI: 10.1002/anie.200802100

      Thumbnail image of graphical abstract

      Looking to the future: The decomposition in solution of a potential hydrogen-storage compound, ammonia borane (AB), was investigated by in situ 11B NMR spectroscopy and ex situ 15N NMR spectroscopy. The reaction was found to be second order in AB with an activation barrier of (25±2) kcal mol−1. The second-order kinetics have implications for the use of solutions containing AB in high concentrations for hydrogen storage.

    19. Synthetic Methods

      Iron-Catalyzed C[BOND]C Bond Formation by Direct Functionalization of C[BOND]H Bonds Adjacent to Heteroatoms (pages 7497–7500)

      Zhiping Li, Rong Yu and Haijun Li

      Version of Record online: 13 AUG 2008 | DOI: 10.1002/anie.200802215

      Thumbnail image of graphical abstract

      Iron/oxidant can do: Heteroatom-containing molecules are abundant in natural products, pharmaceuticals, and materials. It is highly desirable to synthesize these molecules and their derivatives by direct C[BOND]H functionalization. The novel title reaction provides a simple and efficient method to construct such molecules by using 1,3-dicarbonyl compounds (see scheme).

    20. Transition Alumina Phases

      Mesostructured Forms of the Transition Phases η- and χ-Al2O3 (pages 7501–7504)

      Zhaorong Zhang and Thomas J. Pinnavaia

      Version of Record online: 20 AUG 2008 | DOI: 10.1002/anie.200802278

      Thumbnail image of graphical abstract

      A surfactant-templated route to mesostructured forms of the transition alumina phases η-Al2O3 and χ-Al2O3 is described. The surface areas and pore-size distributions of these novel forms of alumina are substantially improved with respect to those of conventional forms of these phases. Wormholelike pores are visible in the TEM image shown of mesostructured η-Al2O3.

    21. Synthetic Methods

      Intramolecular Huisgen-Type Cyclization of Platinum-Bound Pyrylium Ions with Alkenes and Subsequent Insertion into a Benzylic C[BOND]H Bond (pages 7505–7507)

      Chang Ho Oh, Ji Ho Lee, Su Jin Lee, Jae Il Kim and Chang Seop Hong

      Version of Record online: 19 AUG 2008 | DOI: 10.1002/anie.200802425

      Thumbnail image of graphical abstract

      Access granted: The platinum-catalyzed cyclization of enynals 1, which contain an additional alkene bond in their side chain, through a [3+2] cycloaddition to give tetracyclic platinum–carbene complexes A was followed by C[BOND]H insertion at the δ position to afford highly complex products 2. These polycyclic compounds and related products of the title transformation are extremely difficult to access by other means.

    22. Efficient Iridium-Catalyzed C[BOND]H Functionalization/Silylation of Heteroarenes (pages 7508–7510)

      Biao Lu and John R. Falck

      Version of Record online: 13 AUG 2008 | DOI: 10.1002/anie.200802456

      Thumbnail image of graphical abstract

      CSi investigation: The efficient iridium-catalyzed C[BOND]H functionalization/silylation of a wide variety of N-, S-, and O-heteroarenes, including N-unsubstituted indoles, is promoted by 2-norbornene and features a high level of regioselectivity (see scheme; Ts=p-toluenesulfonyl, cod=cyclooctadiene).

    23. Stereoretentive Halogenations and Azidations with Titanium(IV) Enabled by Chelating Leaving Groups (pages 7511–7514)

      Salvatore D. Lepore, Deboprosad Mondal, Song Ye Li and Anjan K. Bhunia

      Version of Record online: 19 AUG 2008 | DOI: 10.1002/anie.200802472

      Thumbnail image of graphical abstract

      Titanium does it again! With the help of nucleophile-assisting leaving groups (NALGs), alkyl bromides, iodides, and, for the first time, azides are obtained from sulfonates with complete retention of configuration. Critical to the design of these new titanium(IV) reactions has been the use of NALGs which are thought to chelate the Lewis acid reagent in the transition state promoting an SNi-type mechanism.

    24. Divergent Titanium-Mediated Allylations with Modulation by Nickel or Palladium (pages 7515–7519)

      Araceli G. Campaña, Btissam Bazdi, Noelia Fuentes, Rafael Robles, Juan M. Cuerva, J. Enrique Oltra, Susana Porcel and Antonio M. Echavarren

      Version of Record online: 29 AUG 2008 | DOI: 10.1002/anie.200802520

      Thumbnail image of graphical abstract

      Palladium and nickel are used in conjunction with titanocene(III) complexes to perform selective allylations of carbonyl compounds and alkenes, respectively. Pd/Ti-catalyzed allylation of ketones proceeds diastereoselectively under mild conditions, whereas Ni/Ti-promoted cyclizations provide polyalkyl-substituted carbo- and heterocycles with excellent control over regio- and stereoselectivity.

    25. Asymmetric Catalysis

      Vanadium-Catalyzed Enantioselective Desymmetrization of meso Secondary Allylic Alcohols and Homoallylic Alcohols (pages 7520–7522)

      Zhi Li, Wei Zhang and Hisashi Yamamoto

      Version of Record online: 29 AUG 2008 | DOI: 10.1002/anie.200802523

      Thumbnail image of graphical abstract

      Desymmetrization isn't complex: The substrate scope for vanadium-catalyzed epoxidation has been extended. In addition to various allylic alcohols, homoallylic alcohols can also be desymmetrized by using vanadium/bishydroxamic acid complexes (see scheme; CHP=cumene hydroperoxide).

    26. Conjugate Stability

      Hydrolytic Stability of Hydrazones and Oximes (pages 7523–7526)

      Jeet Kalia and Ronald T. Raines

      Version of Record online: 19 AUG 2008 | DOI: 10.1002/anie.200802651

      Thumbnail image of graphical abstract

      Watching C 'n' N: Hydrazones and oximes are common conjugates but are labile to hydrolysis. The hydrolytic stabilities of isostructural hydrazones and one oxime were determined at pD 5.0–9.0. The rate constant for the acid-catalyzed hydrolysis of the oxime was nearly 103-fold lower than those for simple hydrazones, and a trialkylhydrazonium ion (formed after condensation) was even more stable than the oxime.

    27. Cell Adhesion

      Photocontrolled Cell Adhesion on a Surface Functionalized with a Caged Arginine-Glycine-Aspartate Peptide (pages 7527–7529)

      Yuki Ohmuro-Matsuyama and Yoshiro Tatsu

      Version of Record online: 21 AUG 2008 | DOI: 10.1002/anie.200802731

      Thumbnail image of graphical abstract

      Sticking to the time and the place: Cell adhesion can be photocontrolled spatiotemporally on a photoresponsive culture dish functionalized with a caged cell-adhesion motif, namely a nitrobenzyl-substituted argine-glycine-aspartate peptide. Photolysis of the dish cleaves the nitrobenzyl group to produce the active peptide to which HeLa cells can adhere (see micrograph: left half, irradiated).

    28. Cyclic Heteroallenes

      Synthesis and Ligand Properties of a Stable Five-Membered-Ring Vinylidenephosphorane (pages 7530–7533)

      Matthew Asay, Tsuyoshi Kato, Nathalie Saffon-Merceron, Fernando P. Cossío, Antoine Baceiredo and Guy Bertrand

      Version of Record online: 14 AUG 2008 | DOI: 10.1002/anie.200802741

      Thumbnail image of graphical abstract

      Best of both worlds: Related to carbodiphosphoranes and carbodicarbenes (bent allenes), a cyclic vinylidenephosphorane has been isolated and is stable at room temperature (see scheme). It features a very long phosphorus ylide bond, much longer than in the acyclic version, which leaves the carbon lone pair fully available. Accordingly, this species behaves as a strong electron-donating ligand, giving rise to very robust transition-metal complexes.

    29. Gold Catalysis

      The Role of Bent Acyclic Allene Gold Complexes in Axis-to-Center Chirality Transfers (pages 7534–7538)

      Vincent Gandon, Gilles Lemière, Alexandra Hours, Louis Fensterbank and Max Malacria

      Version of Record online: 1 AUG 2008 | DOI: 10.1002/anie.200802332

      Thumbnail image of graphical abstract

      Activation of allenes toward nucleophilic attack by gold complexes ([Au], see scheme) often proceeds with axis-to-center chirality transfer. The stereochemical information is shown to be maintained in not only η2 allene complexes, but also in bent η1 allene complexes.

    30. Organocatalysis

      Organocatalytic Asymmetric Domino Reactions: A Cascade Consisting of a Michael Addition and an Aldehyde α-Alkylation (pages 7539–7542)

      Dieter Enders, Chuan Wang and Jan W. Bats

      Version of Record online: 27 AUG 2008 | DOI: 10.1002/anie.200802532

      Thumbnail image of graphical abstract

      A direct approach to cyclic γ-nitroaldehydes with an all-carbon-substituted quaternary stereocenter is provided by a novel organocatalytic diastereo- and enantioselective cascade consisting of a Michael addition and an aldehyde α-alkylation (see scheme). The corresponding γ-amino acids are available in two steps.

    31. H2 Activation

      Metal-Free Catalytic Hydrogenation of Enamines, Imines, and Conjugated Phosphinoalkenylboranes (pages 7543–7546)

      Patrick Spies, Sina Schwendemann, Stefanie Lange, Gerald Kehr, Roland Fröhlich and Gerhard Erker

      Version of Record online: 25 AUG 2008 | DOI: 10.1002/anie.200801432

      Thumbnail image of graphical abstract

      The metal-free hydrogen activator 1 catalyzes the unique P/B hydrogenation of the frustrated Lewis pair 3, which itself is inactive toward H2 under the applied conditions, to yield the hydrogenation product 4. System 1/2 (5 mol %) also catalyzes the hydrogenation of a bulky ketimine and of enamines under mild conditions (2.5 bar H2, RT) to yield the respective amines.

    32. Solid-State Reactions

      Multilateral Solid-State Metathesis Reactions for the Preparation of Materials with Heteroanions: The [Si(CN2)4]4− Ion (pages 7547–7550)

      Jochen Glaser and H.-Jürgen Meyer

      Version of Record online: 26 AUG 2008 | DOI: 10.1002/anie.200801784

      Thumbnail image of graphical abstract

      Adjustable networks: The tetracyanamidosilicates A(RE)[Si(CN2)4] are formed by solid-state metathesis reactions and contain the novel [Si(CN2)4]4− ion. Depending on the alkali metal ion (A=K or Rb), orthorhombic or tetragonal network structures are formed in which the rare-earth (RE) ions have differently distorted trigonal-dodecahedral environments. The crystal structure of RbLa[Si(CN2)4] is shown (Rb yellow, La red, Si gray, C brown, N blue).

    33. Synthetic Vaccines

      Synthetic Vaccines Consisting of Tumor-Associated MUC1 Glycopeptide Antigens and a T-Cell Epitope for the Induction of a Highly Specific Humoral Immune Response (pages 7551–7556)

      Ulrika Westerlind, Alexandra Hobel, Nikola Gaidzik, Edgar Schmitt and Horst Kunz

      Version of Record online: 14 AUG 2008 | DOI: 10.1002/anie.200802102

      Thumbnail image of graphical abstract

      Selective response: The fully synthetic vaccine shown, which contains a glycopeptide antigen from the tumor-associated mucin MUC1 and an immunostimulating T-cell epitope from ovalbumin, induces a highly specific immune response in mice. The induced antibody reacts with the glycopeptides and analogues that carry additional tumor-associated TN antigen monosaccharides in their sequence.

    34. Natural Product Synthesis

      Concise Stereoselective Synthesis of (−)-Podophyllotoxin by an Intermolecular Iron(III)-Catalyzed Friedel–Crafts Alkylation (pages 7557–7559)

      Daniel Stadler and Thorsten Bach

      Version of Record online: 29 AUG 2008 | DOI: 10.1002/anie.200802611

      Thumbnail image of graphical abstract

      Without further ado, the building blocks 13 were combined in three C[BOND]C bond-forming reactions to provide the enantiomerically pure natural product (−)-podophyllotoxin (4). The stereogenic center at C1 was generated in the key reaction, a diastereoselective iron(III)-catalyzed intermolecular Friedel–Crafts alkylation.

  9. Preview

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

SEARCH

SEARCH BY CITATION