Angewandte Chemie International Edition

Cover image for Vol. 45 Issue 30

July 24, 2006

Volume 45, Issue 30

Pages 4875–5025

  1. Cover Picture

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    1. Cover Picture: A Ferromagnetically Coupled Mn19 Aggregate with a Record S=83/2 Ground Spin State (Angew. Chem. Int. Ed. 30/2006) (page 4875)

      Ayuk M. Ako, Ian J. Hewitt, Valeriu Mereacre, Rodolphe Clérac, Wolfgang Wernsdorfer, Christopher E. Anson and Annie K. Powell

      Version of Record online: 20 JUL 2006 | DOI: 10.1002/anie.200690103

      King of the spins is provided by the mixed-valent Mn19 aggregate as reported by A. K. Powell et al. in their Communication on page 4926 ff. The use of bridging azido ligands leads to a completely ferromagnetically coupled system with a record ground spin state of 83/2. This remarkable molecule has been investigated and characterized by scientists from three laboratories working together in the European Network of Excellence “MAGMANet”, the logo of which provides the background to the cover picture.

  2. Graphical Abstract

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  3. News

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  4. Book Reviews

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    1. Drug Discovery Handbook. Edited by Shayne C. Gad. (page 4891)

      Günter Hölzemann

      Version of Record online: 20 JUL 2006 | DOI: 10.1002/anie.200585360

  5. Highlights

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    1. Surface Reactions On Demand: Electrochemical Control of SAM-Based Reactions (pages 4894–4897)

      Insung S. Choi and Young Shik Chi

      Version of Record online: 20 JUL 2006 | DOI: 10.1002/anie.200601502

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      Controlled exterior: Electrochemically induced, SAM-based reactions have a potential in the site-selective functionalization of surfaces. A recent study shows that a reaction, Sharpless click chemistry, can be site-selectively performed at microelectrodes by electrochemically controlling the activity of a catalyst for the reaction.

  6. Reviews

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    1. Biologically Active Molecules with a “Light Switch” (pages 4900–4921)

      Günter Mayer and Alexander Heckel

      Version of Record online: 7 JUL 2006 | DOI: 10.1002/anie.200600387

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      A trick of the light: Photolabile protecting groups, attached to a defined position of a molecule, can be used to gain spatiotemporal control over the concentration of the active form of a molecule. Such “caged compounds” can be applied for the analysis of biological phenomena. Together with synthesis strategies of biomolecules the caging strategy enables the characterization of single molecules in cells.

  7. Communications

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    1. Formation of Crystalline SrAl2O4 Nanotubes by a Roll-Up and Post-Annealing Approach (pages 4922–4926)

      Changhui Ye, Yoshio Bando, Guozhen Shen and Dmitri Golberg

      Version of Record online: 3 JUL 2006 | DOI: 10.1002/anie.200601320

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      On a roll: Nanotubes of SrAl2O4, an important phosphorescent host material, are prepared. Nanoscrolls are first formed through the roll-up of an artificial lamellar precursor in solution. The layer interfaces are then removed by high-temperature annealing, resulting in single-crystalline nanotubes.

    2. A Ferromagnetically Coupled Mn19 Aggregate with a Record S=83/2 Ground Spin State (pages 4926–4929)

      Ayuk M. Ako, Ian J. Hewitt, Valeriu Mereacre, Rodolphe Clérac, Wolfgang Wernsdorfer, Christopher E. Anson and Annie K. Powell

      Version of Record online: 4 JUL 2006 | DOI: 10.1002/anie.200601467

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      Mixing it up: A ground spin state of S=83/2 is found in the mixed-valent manganese aggregate [MnIII12MnII74-O)831-N3)8(HL)12(MeCN)6]2+ (H3L=2,6-bis(hydroxymethyl)-4-methylphenol; see polyhedral representation of the core) and arises through ferromagnetic coupling of all the metal centers.

    3. Efficient Construction of the Clerodane Decalin Core by an Asymmetric Morita–Baylis–Hillman Reaction/Lewis Acid Promoted Annulation Strategy (pages 4929–4932)

      Stacy A. Rodgen and Scott E. Schaus

      Version of Record online: 27 JUN 2006 | DOI: 10.1002/anie.200601076

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      Linking rings: A general route toward the clerodane diterpene core using an asymmetric Morita-Baylis-Hillman (MBH)/Lewis acid mediated ring-annulation process has been developed. The scope of the asymmetric Brønsted acid catalyzed MBH reaction has been expanded to include silane-containing aldehydes, which are elaborated into the trans decalin core in high diastereo- and enantioselectivities.

    4. Metastable Sorption State of a Metal–Organic Porous Material Determined by In Situ Synchrotron Powder Diffraction (pages 4932–4936)

      Yoshiki Kubota, Masaki Takata, Ryotaro Matsuda, Ryo Kitaura, Susumu Kitagawa and Tatsuo C. Kobayashi

      Version of Record online: 29 JUN 2006 | DOI: 10.1002/anie.200600976

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      Guest-responsive framework: Gas adsorption into a metal–organic porous material was studies in situ. Structure analysis of empty phase I, intermediate phase M as a metastable state of gas adsorption, and saturated phase S showed rearrangement of guest molecules and framework transformation in response to guest size, shape, and amount. The picture shows these changes for the superimposed phases M and S.

    5. HaloTag Protein-Mediated Site-Specific Conjugation of Bioluminescent Proteins to Quantum Dots (pages 4936–4940)

      Yan Zhang, Min-kyung So, Andreas M. Loening, Hequan Yao, Sanjiv S. Gambhir and Jianghong Rao

      Version of Record online: 29 JUN 2006 | DOI: 10.1002/anie.200601197

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      On the dot: A genetically engineered haloalkane dehalogenase was used to conjugate Renilla luciferase to quantum dots (see picture). The quantum dots can emit light through bioluminescence resonance energy transfer (BRET). This specific conjugation occurs upon simple mixing under mild conditions, and may be applied for specific in vivo labeling of proteins with quantum dots for imaging.

    6. Switchable Chiral Architectures Containing PrIII Ions: An Example of Solvent-Induced Adaptive Behavior (pages 4940–4944)

      Olimpia Mamula, Marco Lama, Helen Stoeckli-Evans and Sergiu Shova

      Version of Record online: 4 JUL 2006 | DOI: 10.1002/anie.200601939

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      Triangular or pyramidal? Solvent-induced divergent self-assembly of a chiral ligand and PrIII ions leads diastereoselectively to two distinct but related superstructures, in which the ligands form helical domains attached to triangular (Pr3) or pyramidal (Pr4) metallic scaffolds (Pr green). The two structures are reversibly interconverted simply by varying the amount of water present in the solvent (CH3CN).

    7. A Spiropyran-Based Ensemble for Visual Recognition and Quantification of Cysteine and Homocysteine at Physiological Levels (pages 4944–4948)

      Na Shao, Jian Yu Jin, Sin Man Cheung, Rong Hua Yang, Wing Hong Chan and Tian Mo

      Version of Record online: 29 JUN 2006 | DOI: 10.1002/anie.200600112

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      Isomerization of the ligand, followed by cooperative metal–ligand interactions leads to the ternary ensemble shown on the right, which has potential for the recognition and quantification of cysteine and homocysteine. The free ligand (left) is red-violet in solution, but when metal ions and cysteine or homocysteine are simultaneously introduced, the solution turns yellow.

    8. A Simple Strategy for Prompt Visual Sensing by Gold Nanoparticles: General Applications of Interparticle Hydrogen Bonds (pages 4948–4951)

      Shu-Yi Lin, Sung-Hsun Wu and Chun-hsien Chen

      Version of Record online: 4 JUL 2006 | DOI: 10.1002/anie.200600771

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      Local color: Gold nanoparticles (GNPs) bifunctionalized with a crown ether and thioctic acid can be used for the rapid sensing of a target analyte with the naked eye. A color transformation occurs when the interparticle hydrogen bonds of aggregated GNPs are broken forming a dispersion. For example, the detection of PbII takes only 1 s (see picture).

    9. The Structure of a Designed Diiron(III) Protein: Implications for Cofactor Stabilization and Catalysis (pages 4951–4954)

      Herschel Wade, Steven E. Stayrook and William F. DeGrado

      Version of Record online: 3 JUL 2006 | DOI: 10.1002/anie.200600042

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      A closer look into the function of diiron proteins, such as methane monooxygenase and ribonucleotide reductase, is provided by the crystal structure of a designed diiron protein (the picture shows the Fe environment). Cofactor rigidity may be a factor in O2 reactivity and a possible role of HisCεH⋅⋅⋅O hydrogen bonds in cofactor stabilization is implicated.

    10. Enhancement of Pt Utilization in Electrocatalysts by Using Gold Nanoparticles (pages 4955–4959)

      Dan Zhao and Bo-Qing Xu

      Version of Record online: 28 JUN 2006 | DOI: 10.1002/anie.200600155

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      Full employment of a Pt catalyst is reached by depositing very small (≤1.0 nm) Pt particles onto Au nanoparticles of about 10 nm in diameter (see picture) then loading the Pt∧Au particles onto a conventional carbon support. Data obtained from the electrooxidation of methanol demonstrate that every Pt atom assumes the function of an active site for electrocatalysis.

    11. Formation of Complex Micelles with Double-Responsive Channels from Self-Assembly of Two Diblock Copolymers (pages 4959–4962)

      Guiying Li, Linqi Shi, Rujiang Ma, Yingli An and Nan Huang

      Version of Record online: 29 JUN 2006 | DOI: 10.1002/anie.200600172

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      Getting to the core of the micelle: Phase separation between the hydrophobic shell and the hydrophilic corona leads to channels in the shells of complex micelles (see picture), through which ions and other small molecules could pass. The size of the channels can be regulated by changing the environmental conditions or by manipulating the composition of the two diblock copolymers that form the micelles.

    12. Ionothermal Materials Synthesis Using Unstable Deep-Eutectic Solvents as Template-Delivery Agents (pages 4962–4966)

      Emily R. Parnham, Ewan A. Drylie, Paul S. Wheatley, Alexandra M. Z. Slawin and Russell E. Morris

      Version of Record online: 3 JUL 2006 | DOI: 10.1002/anie.200600290

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      It came from the deep: Deep-eutectic solvents based on mixtures of derivatized ureas and choline chloride can be used as the reaction media and the source of the organic template in the synthesis of aluminophosphate and organophosphonate materials. The template (red in structural formula) is formed by the decomposition of the derivatized urea.

    13. Organocatalytic Asymmetric Conjugate Addition of 1,3-Dicarbonyl Compounds to Maleimides (pages 4966–4970)

      Giuseppe Bartoli, Marcella Bosco, Armando Carlone, Andrea Cavalli, Manuela Locatelli, Andrea Mazzanti, Paolo Ricci, Letizia Sambri and Paolo Melchiorre

      Version of Record online: 3 JUL 2006 | DOI: 10.1002/anie.200600370

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      Nature, our teacher! The natural alkaloids quinine (Q) and quinidine (QD) serve as efficient bifunctional organocatalysts in the asymmetric conjugate addition of 1,3-dicarbonyl compounds to maleimides (see scheme). Very high selectivity is observed in this one-step construction of highly functionalized compounds with two adjacent stereogenic centers from commercially available precursors. R1,R3=alkyl, aryl, O-alkyl; R2=alkyl, Bn; R4=Bn.

    14. Rhodium-Catalyzed Propargylic Substitution: A Divergent Approach to Propargylic and Allenyl Sulfonamides (pages 4970–4972)

      P. Andrew Evans and Michael J. Lawler

      Version of Record online: 3 JUL 2006 | DOI: 10.1002/anie.200600615

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      Construction work: Rh-catalyzed propargylic amination provides an efficient, versatile method for the preparation of aliphatic propargylic sulfonamides. This Rh-catalyzed variant has a divergent nature, from which aryl-substituted propargylic and allenyl sulfonamides can be constructed. A one-pot two-component Rh-catalyzed propargylic amination/isomerization followed by a [4+2] carbocyclization demonstrates the synthetic utility of this divergent behavior.

    15. Fluorobis(phenylsulfonyl)methane: A Fluoromethide Equivalent and Palladium-Catalyzed Enantioselective Allylic Monofluoromethylation (pages 4973–4977)

      Takeo Fukuzumi, Norio Shibata, Masayoshi Sugiura, Hiroyuki Yasui, Shuichi Nakamura and Takeshi Toru

      Version of Record online: 4 JUL 2006 | DOI: 10.1002/anie.200600625

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      Selective introduction of fluorine: Monofluoromethylation with the fluoromethide equivalent fluorobis(phenylsulfonyl)methane (1) was crucial in the syntheses of the pharmacologically important compounds monofluorinated (S)-ibuprofen ((S)-2) and 5-deoxy-5-fluoro-β-D-carbaribofuranose (3). The key step was a palladium-catalyzed allylic monofluoromethylation reaction.

    16. A Versatile Hexadiene Synthesis by Decarboxylative sp3–sp3 Coupling/Cope Rearrangement (pages 4977–4980)

      Shelli R. Waetzig, Dinesh K. Rayabarapu, Jimmie D. Weaver and Jon A. Tunge

      Version of Record online: 3 JUL 2006 | DOI: 10.1002/anie.200600721

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      Have it both ways: The palladium-catalyzed decarboxylative coupling of esters with two allyl groups results in kinetic allylation at a position α to electron-withdrawing groups. Tandem allylation/Cope rearrangement provides access to γ-coupling products (see scheme). Thus, the desired regioisomer is obtained simply by controlling the temperature of the reaction mixture.

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      Oxygen-Balanced Energetic Ionic Liquid (pages 4981–4984)

      C. Bigler Jones, Ralf Haiges, Thorsten Schroer and Karl O. Christe

      Version of Record online: 3 JUL 2006 | DOI: 10.1002/anie.200600735

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      On the way to the perfect propellant: The energetic oxidizer-balanced ionic liquid 1-ethyl-4,5-dimethyltetrazolium tetranitratoaluminate (see scheme) has been prepared and characterized. Oxidizer-balanced ionic liquids are promising propellants with good performance and no vapor toxicity.

    18. The Heat of Formation of Cyclobutadiene (pages 4984–4988)

      Alireza Fattahi, Lev Lis, Zhixin Tian and Steven R. Kass

      Version of Record online: 3 JUL 2006 | DOI: 10.1002/anie.200600839

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      How unstable can it be? Gas-phase measurements on the 3-cyclobutenyl cation were combined in a thermodynamic cycle to provide the first experimental determination of the heat of formation of cyclobutadiene (see scheme, IP=ionization potential, BDE=bond-dissociation energy). The resulting value of 428±16 kJ mol−1 is in good accord with previous predictions based upon similar energetic determinations of benzo- and phenylcyclobutadiene.

    19. Formation of Seven-Membered Carbocycles by the Use of Cyclopropyl Silyl Ethers as Homoenols (pages 4988–4991)

      Oleg L. Epstein, Sejin Lee and Jin Kun Cha

      Version of Record online: 3 JUL 2006 | DOI: 10.1002/anie.200601011

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      Straightforward ring-closure: An expedient entry to seven-membered carbocycles is achieved by the Kulinkovich cyclopropanation of acetal-tethered esters and the subsequent addition of the resulting cyclopropyl silyl ethers to the oxocarbenium ion intermediates. Of particular note is the effective use of a tert-butylsilylene group for diastereoselective cyclization.

    20. Silver-Catalyzed Hydroamination of Siloxy Alkynes (pages 4991–4993)

      Jianwei Sun and Sergey A. Kozmin

      Version of Record online: 29 JUN 2006 | DOI: 10.1002/anie.200601276

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      New catalytic process: The silver-catalyzed hydroamination of siloxy alkynes with secondary amides furnishes silyl ketene aminals with high efficiency and excellent diastereoselectivity (see scheme), including some that are unavailable by conventional silylation methods. The reaction comprises a fast and reversible silver–alkyne complexation, followed by a rate-determining C[BOND]N bond-forming step.

    21. The Roles of Hydrogen Bonding and Sterics in RNA Interference (pages 4994–4997)

      Alvaro Somoza, Jijumon Chelliserrykattil and Eric T. Kool

      Version of Record online: 27 JUN 2006 | DOI: 10.1002/anie.200601311

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      Better than normal: RNA-interference studies with mismatched target RNA have demonstrated sequence selectivity (at the single-nucleotide level) at many different positions of the RNA strand. The use of rF in place of rU at position 7 appears to enhance sequence selectivity beyond that of the natural base.

    22. [Pd(Ar-BIAN)(alkene)]-Catalyzed Highly Chemo-, Regio-, and Stereoselective Semihydrogenation of 1,2-Allenyl Phosphonates and Related Compounds (pages 4997–5000)

      Hao Guo, Zilong Zheng, Fei Yu, Shengming Ma, Alexandre Holuigue, Dorette S. Tromp, Cornelis J. Elsevier and Yihua Yu

      Version of Record online: 29 JUN 2006 | DOI: 10.1002/anie.200601366

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      Often elusive, trisubstituted (Z)-1-alkenyl phosphonates can be prepared by the semihydrogenation of allenyl phosphonates in the presence of Pd complex 1. This reaction, which occurs in high yield with high chemo-, regio-, and stereoselectivity, can be extended to related functionalized allenes and the corresponding Z alkene products (see scheme). R1=H, alkyl, aryl, benzyl; R2,R3=H, alkyl; FG=P(O)(OR)2, P(O)Ph2, SO2Ph, COOEt.

    23. Asymmetric Aza-Wittig Reactions: Enantioselective Synthesis of β-Quaternary Azacycles (pages 5000–5002)

      Duanpen Lertpibulpanya, Stephen P. Marsden, Ignacio Rodriguez-Garcia and Colin A. Kilner

      Version of Record online: 3 JUL 2006 | DOI: 10.1002/anie.200601383

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      A hindrance no more: The direct asymmetric synthesis of nitrogen heterocycles containing β-quaternary stereocenters, widely found for example in alkaloids, is highly challenging. The novel approach shown exploits the desymmetrization of prochiral diketo azides to unmask the asymmetric quaternary center, and represents the first reported examples of the asymmetric aza-Wittig reaction.

    24. Substituted Allyl Diphenylphosphine Oxides as Radical Allylating Agents (pages 5002–5006)

      Gilles Ouvry, Béatrice Quiclet-Sire and Samir Z. Zard

      Version of Record online: 20 JUL 2006 | DOI: 10.1002/anie.200601556

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      Radically useful: The radical addition of dithiocarbonates to branched allyl diphenylphosphine oxides can be followed by elimination of a diphenylphosphinoyl radical, thereby giving rise to allylated products (see scheme; Phth=phthalimido). Highly functionalized structures can thus be rapidly assembled under mild conditions and from cheap and readily available substrates and reagents.

    25. A Surface-Bound DNA Switch Driven by a Chemical Oscillator (pages 5007–5010)

      Tim Liedl, Michael Olapinski and Friedrich C. Simmel

      Version of Record online: 29 JUN 2006 | DOI: 10.1002/anie.200600353

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      Proton control: Chemical oscillations produced in a continuously stirred tank reactor can be used to drive the conformational changes of DNA nanoswitches immobilized on a thin gold film (see scheme). The autonomous switching events of these substrate-bound actuators are characterized in fluorescence measurements by utilizing energy transfer between the fluorophores and gold substrate.

    26. Transition-Metal-Free Homocoupling of Organomagnesium Compounds (pages 5010–5014)

      Arkady Krasovskiy, Alexander Tishkov, Vicente del Amo, Herbert Mayr and Paul Knochel

      Version of Record online: 3 JUL 2006 | DOI: 10.1002/anie.200600772

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      Without palladium or copper: A wide range of functionalized Grignard compounds were coupled by using diphenoquinone 1 as an electron acceptor. The oxidative dimerization of alkenylmagnesium reagents proceeds with complete retention of the stereochemistry (see scheme; TBDMS=tert-butyldimethylsilyl).

    27. Multiple Palladium-Catalyzed Reactions for the Synthesis of Analogues of the Highly Potent Insecticide Spinosyn A (pages 5015–5018)

      Lutz F. Tietze, Gordon Brasche, Christian Stadler, Alexander Grube and Niels Böhnke

      Version of Record online: 3 JUL 2006 | DOI: 10.1002/anie.200601003

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      Resistance is useless? The increasing resistance towards (−)-spinosyns A (1) and D (2) used as plant-protection agents makes new derivatives of these natural products necessary. On the basis of investigations into the structure–activity relationships a convergent approach to the synthesis of novel spinosyn A analogues (3) is developed. A double Heck reaction is the key step in the construction of the basic carbocyclic framework.

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    1. Top of page
    2. Cover Picture
    3. Graphical Abstract
    4. News
    5. Book Reviews
    6. Highlights
    7. Reviews
    8. Communications
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