Angewandte Chemie International Edition

Cover image for Vol. 46 Issue 12

March 12, 2007

Volume 46, Issue 12

Pages 1927–2121

  1. Cover Picture

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Graphical Abstract
    5. Corrigendum
    6. News
    7. Book Reviews
    8. Highlight
    9. Minireview
    10. Review
    11. Communications
    12. Preview
    1. Cover Picture: Interpenetrating Polar and Nonpolar Sublattices in Intermetallics: The NaCd2 Structure (Angew. Chem. Int. Ed. 12/2007) (page 1927)

      Daniel C. Fredrickson, Stephen Lee and Roald Hoffmann

      Article first published online: 2 MAR 2007 | DOI: 10.1002/anie.200790040

      The sun and the moon are not quite equal partners; the two clusters shown in the cover picture are more so. They rise and set in several incredibly complex intermetallic phases, such as NaCd2. As explained by R. Hoffmann and co-workers in their Review on page 1958 ff., an electronic Aufbau based on these clusters generates the full NaCd2 structure in all its glory: the clusters build two interpenetrating networks that strive for the extremes of polarity and nonpolarity. The alchemical image, drawn by Robert Vaughn, is from Elias Ashmole's Theatricum Chemicum Britannicum.

  2. Inside Cover

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Graphical Abstract
    5. Corrigendum
    6. News
    7. Book Reviews
    8. Highlight
    9. Minireview
    10. Review
    11. Communications
    12. Preview
    1. Inside Cover: Bioinspired Design of Nanocages by Self-Assembling Triskelion Peptide Elements (Angew. Chem. Int. Ed. 12/2007) (page 1928)

      Surajit Ghosh, Meital Reches, Ehud Gazit and Sandeep Verma

      Article first published online: 2 MAR 2007 | DOI: 10.1002/anie.200790041

      Inspired by clathrin, a protein that assembles into closed-cage structures as a result of the unique triskelion conformation of its three pendant polypeptide chains, E. Gazit, S. Verma, and co-workers report in their Communication on page 2002 ff. on a synthetic tripodal conjugate with three dipeptide units radiating from a central core. The legs interdigitate to reveal highly spherical structures, as shown in the picture, in which guest molecules such as fluorescent dyes can be trapped and subsequently released.

  3. Graphical Abstract

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

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Graphical Abstract
    5. Corrigendum
    6. News
    7. Book Reviews
    8. Highlight
    9. Minireview
    10. Review
    11. Communications
    12. Preview
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      Water: The Ideal Hydrogen-Atom Source in Free-Radical Chemistry Mediated by TiIII and Other Single-Electron-Transfer Metals? (page 1941)

      Juan M. Cuerva, Araceli G. Campaña, José Justicia, Antonio Rosales, Juan L. Oller-López, Rafael Robles, Diego J. Cárdenas, Elena Buñuel and J. Enrique Oltra

      Article first published online: 2 MAR 2007 | DOI: 10.1002/anie.200790043

      This article corrects:
  5. News

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

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

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Graphical Abstract
    5. Corrigendum
    6. News
    7. Book Reviews
    8. Highlight
    9. Minireview
    10. Review
    11. Communications
    12. Preview
    1. Lithiumboryl—A Synthon for a Nucleophilic Boryl Anion (pages 1946–1948)

      Holger Braunschweig

      Article first published online: 20 FEB 2007 | DOI: 10.1002/anie.200605053

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      B negative: By reduction of a 2-bromo-1,3,2-diazaborole Yamashita, Nozaki, and co-workers have obtained the first three-coordinate boryl anion (see formula), which provides an unprecedented and synthetically highly useful source for a nucleophilic boron species.

  8. Minireview

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Graphical Abstract
    5. Corrigendum
    6. News
    7. Book Reviews
    8. Highlight
    9. Minireview
    10. Review
    11. Communications
    12. Preview
    1. Aryl Calcium Compounds: Syntheses, Structures, Physical Properties, and Chemical Behavior (pages 1950–1956)

      Matthias Westerhausen, Martin Gärtner, Reinald Fischer and Jens Langer

      Article first published online: 30 JAN 2007 | DOI: 10.1002/anie.200604192

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      Calcium supplements for Grignard: The easy access of aryl calcium compounds in high yields now offers the possibility of investigating the properties and chemical behavior of these heavy Grignard reagents (see picture; C black, Ca purple, Cu yellow, O red). The key points are the nature of activation of the metal prior to use and the use of low reaction and handling temperatures to prevent side and decomposition reactions.

  9. Review

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Graphical Abstract
    5. Corrigendum
    6. News
    7. Book Reviews
    8. Highlight
    9. Minireview
    10. Review
    11. Communications
    12. Preview
    1. Interpenetrating Polar and Nonpolar Sublattices in Intermetallics: The NaCd2 Structure (pages 1958–1976)

      Daniel C. Fredrickson, Stephen Lee and Roald Hoffmann

      Article first published online: 8 FEB 2007 | DOI: 10.1002/anie.200601678

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      Inorganic, and yet more complex than an enzyme? The giant unit cells of Mg2Al3, NaCd2, and Cu4Cd3 have challenged geometers of nature—so many beautiful polyhedra and networks to choose from. Could quantum mechanics help pick among alternative patterns? Indeed, simple calculations highlight building blocks derived from the MgCu2 structure type, which pack together in interpenetrating regions of polar and nonpolar bonding (see scheme for NaCd2).

  10. Communications

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Graphical Abstract
    5. Corrigendum
    6. News
    7. Book Reviews
    8. Highlight
    9. Minireview
    10. Review
    11. Communications
    12. Preview
    1. Photopatterned Arrays of Fluorescent Organic Nanoparticles (pages 1978–1982)

      Byeong-Kwan An, Soon-Ki Kwon and Soo Young Park

      Article first published online: 16 JAN 2007 | DOI: 10.1002/anie.200604209

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      Bottom-up and top-down nanofabrication: A fluorescent organic molecule bearing a self-assembly modulator was assembled in situ through a vapor-driven self-assembly process into strongly fluorescent spherical nanoparticles (about 30 nm in diameter) in the photochemically delineated regions of a polymer matrix (see picture; PAG: photoacid generator).

    2. Enantioselective Organocatalytic Conjugate Addition of N Heterocycles to α,β-Unsaturated Aldehydes (pages 1983–1987)

      Peter Dinér, Martin Nielsen, Mauro Marigo and Karl Anker Jørgensen

      Article first published online: 8 FEB 2007 | DOI: 10.1002/anie.200604854

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      Must love cats.! Chiral amines catalyze the enantioselective addition of N-heterocyclic compounds to α,β-unsaturated compounds in high yields and with enantioselectivities of up to 94 % ee (see scheme; TMS=trimethylsilyl). The intermediates and transition states for the catalytic cycle were identified by performing DFT calculations.

    3. Selective Crystal Growth of the Anhydrous and Monohydrate Forms of Theophylline on Self-Assembled Monolayers (pages 1988–1991)

      Jason R. Cox, Marta Dabros, Jeanne A. Shaffer and Venkat R. Thalladi

      Article first published online: 9 FEB 2007 | DOI: 10.1002/anie.200604674

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      SAMs in charge: The monohydrate and anhydrous forms of theophylline crystallize concomitantly from ethanol solutions, but hydrophilic thiol self-assembled monolayers (SAMs) promote the selective growth of the anhydrous form (see picture; C gray, H yellow, N blue, O red). This selectivity is a result of interfacial hydrogen bonding and geometric epitaxy.

    4. Redox Potentiometry Studies of Particulate Methane Monooxygenase: Support for a Trinuclear Copper Cluster Active Site (pages 1992–1994)

      Sunney I. Chan, Vincent C.-C. Wang, Jeff C.-H. Lai, Steve S.-F. Yu, Peter P.-Y. Chen, Kelvin H.-C. Chen, Chang-Li Chen and Michael K. Chan

      Article first published online: 2 FEB 2007 | DOI: 10.1002/anie.200604647

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      A pocketful of coppers: Redox potentiometry and EPR experiments have confirmed that the active site of the particulate methane monooxygenase (pMMO), a membrane-bound enzyme that hydroxylates methane to methanol under ambient conditions, consists of one trinuclear copper cluster (see picture) and one type 2 copper site, in addition to the dinuclear copper cluster revealed previously by X-ray crystallography.

    5. Meisenheimer Complexes Positively Characterized as Stable Intermediates in the Gas Phase (pages 1995–1998)

      Barbara Chiavarino, Maria Elisa Crestoni, Simonetta Fornarini, Francesco Lanucara, Joel Lemaire and Philippe Maître

      Article first published online: 7 FEB 2007 | DOI: 10.1002/anie.200604630

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      Proof positive: Infrared multiphoton dissociation (IRMPD) spectroscopy, with the tunable IR radiation of a free-electron laser source, provides positive identification of alkoxide adducts of 1,3,5-trinitrobenzene as prototypical anionic σ complexes in the gas phase (see calculated IR spectrum of 1 under the experimental IRMPD spectrum; N blue, O green, C gray, H light gray).

    6. Detecting Force-Induced Molecular Transitions with Fluorescence Resonant Energy Transfer (pages 1999–2001)

      Peter B. Tarsa, Ricardo R. Brau, Mariya Barch, Jorge M. Ferrer, Yelena Freyzon, Paul Matsudaira and Matthew J. Lang

      Article first published online: 6 FEB 2007 | DOI: 10.1002/anie.200604546

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      Don't FRET: The first successful combination of optical-tweezers force microscopy and single-molecule fluorescence resonant energy transfer (FRET) is demonstrated with a force sensor based on a DNA hairpin (see picture). As the hairpin is opened and closed by the optical tweezers, the structural change is simultaneously monitored by the FRET emission from fluorescence labels.

    7. Bioinspired Design of Nanocages by Self-Assembling Triskelion Peptide Elements (pages 2002–2004)

      Surajit Ghosh, Meital Reches, Ehud Gazit and Sandeep Verma

      Article first published online: 8 FEB 2007 | DOI: 10.1002/anie.200604383

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      Winning the three-legged race: Rapid self-organization of a tripodal aromatic dipeptide conjugate on a tris(2-aminoethyl)amine scaffold leads to a vesicular morphology (upper image). The structures can trap a fluorescent dye (lower image) and release it upon acidification, suggesting the use of such stimuli-responsive materials as potential delivery vehicles.

    8. Inhibition of siRNA Binding to a p19 Viral Suppressor of RNA Silencing by Cysteine Alkylation (pages 2005–2009)

      Selena M. Sagan, Roger Koukiekolo, Elisabeth Rodgers, Natalie K. Goto and John Paul Pezacki

      Article first published online: 8 FEB 2007 | DOI: 10.1002/anie.200603284

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      Eukaryotes have evolved complex cellular responses to double-stranded RNA. The quantities of short interfering RNA (siRNA) can be determined rapidly by using 96-well arrays of the carnation Italian ringspot virus (CIRV) p19 protein, which binds double-stranded siRNAs with nanomolar affinity and discriminates siRNA according to length. Two compounds were found to inhibit siRNA binding to CIRV p19 by alkylating active-site cysteine residues (see diagram).

    9. The Crucial Role of the f Electrons in the Bent or Linear Configuration of Uranium Cyanido Metallocenes (pages 2010–2012)

      Jérôme Maynadié, Noémi Barros, Jean-Claude Berthet, Pierre Thuéry, Laurent Maron and Michel Ephritikhine

      Article first published online: 7 FEB 2007 | DOI: 10.1002/anie.200604114

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      What makes it go linear? The synthesis of the first polycyanide compounds of a 5f element (see picture, U green, N blue, C white) supports the idea that the geometry of metallocenes depends on both the metal oxidation state and the size and shape of the equatorial ligands. Theoretical investigations reveal that the stability of these novel linear π-sandwich compounds is determined by the availability of f orbitals.

    10. Highly Selective Na+-Templated Formation of [2]Pseudorotaxanes Exhibiting Significant Optical Outputs (pages 2013–2017)

      Sheng-Yao Hsueh, Chien-Chen Lai, Yi-Hung Liu, Shie-Ming Peng and Sheng-Hsien Chiu

      Article first published online: 7 FEB 2007 | DOI: 10.1002/anie.200604166

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      The chosen one: A molecular cage has been shown to form pseudorotaxane-like complexes with threaded anthraquinone and squaraine units in the presence of templating Na+ ions (see picture). The complexation and decomplexation of the pseudorotaxane complexes in solution occur with significant color changes which allows this ion-specific templating effect to be easily monitored with the naked eye.

    11. Development of a Cy3-Labeled Glucose Bioprobe and Its Application in Bioimaging and Screening for Anticancer Agents (pages 2018–2022)

      Jongmin Park, Hyang Yeon Lee, Myung-Haing Cho and Seung Bum Park

      Article first published online: 7 FEB 2007 | DOI: 10.1002/anie.200604364

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      Tracing glucose uptake: Fluorescent glucose analogues were synthesized, and the importance of stereochemistry for cellular uptake efficiency was demonstrated. The chiral bioprobe 1 showed superior properties as a glucose-uptake tracer. The cellular uptake of 1 was demonstrated under various concentrations of D-glucose. A screening system was developed for the discovery of anticancer agents by the measurement of glucose uptake in cancer cells with 1.

    12. siRNA Delivery into Human T Cells and Primary Cells with Carbon-Nanotube Transporters (pages 2023–2027)

      Zhuang Liu, Mark Winters, Mark Holodniy and Hongjie Dai

      Article first published online: 9 FEB 2007 | DOI: 10.1002/anie.200604295

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      Special delivery: Functionalized single-walled nanotubes (SWNT) can be used as molecular transporters to shuttle short interfering RNA (siRNA) into human T cells and primary cells and silence the expression of HIV-specific cell-surface receptors and coreceptors (see picture; scale bars 40 μm). This silencing effect, known to block HIV viral entry and reduce infection, is superior to that observed with conventional liposome-based nonviral delivery agents.

    13. In Vitro and Intracellular Production of Peptide-Encapsulated Fluorescent Silver Nanoclusters (pages 2028–2030)

      Junhua Yu, Sandeep A. Patel and Robert M. Dickson

      Article first published online: 7 FEB 2007 | DOI: 10.1002/anie.200604253

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      Every nucleolus has a silver lining: Formation of silver nanoclusters by fluorescence photoactivation was used for the staining of cells at low silver nitrate concentrations and ambient temperature. The picture shows picosecond lifetime images of peptide-encapsulated silver nanoclusters within NIH 3T3 cells.

    14. Chiroptical Sensing of Asymmetric Hydrocarbons Using a Homochiral Supramolecular Box from a Bismetalloporphyrin Rotamer (pages 2031–2035)

      Junko Aimi, Kazumasa Oya, Akihiko Tsuda and Takuzo Aida

      Article first published online: 9 FEB 2007 | DOI: 10.1002/anie.200604330

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      The surrounding shapes the box: The zinc porphyrin dimer 1 bearing pyridyl groups can chiroptically sense an asymmetric hydrocarbon, such as limonene, by forming the homochiral box-shaped tetrameric assembly BOX. As the BOX formed is enantiomerically enriched, the optical purity as well as the absolute configuration of the solvent limonene can be determined.

    15. pH-Switchable Silver Nanoprism Growth Pathways (pages 2036–2038)

      Can Xue and Chad A. Mirkin

      Article first published online: 13 FEB 2007 | DOI: 10.1002/anie.200604637

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      A pHunction of pH: The silver nanoprism fusion process can be turned on and off as a function of the pH value during photochemical synthesis. With appropriate pH regulation (see TEM images, middle and right), one can achieve excellent control over the nanoprism edge length with a fixed 10-nm thickness and the corresponding plasmon bands, which span the visible and NIR range (see extinction spectra, left).

    16. Structure and Total Synthesis of Lysobactin (Katanosin B) (pages 2039–2042)

      Franz von Nussbaum, Sonja Anlauf, Jordi Benet-Buchholz, Dieter Häbich, Johannes Köbberling, László Musza, Joachim Telser, Helga Rübsamen-Waigmann and Nina A. Brunner

      Article first published online: 9 JAN 2007 | DOI: 10.1002/anie.200604232

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      Tackle-resistant bacteria: Determination of the 3D structure of the antibiotic lysobactin has led to its total synthesis and resulted in a high-yielding macrolactamization step. The minimal use of protecting groups allowed preorganization of the side chains to steer the cyclization. Thus, a new chemical route has been developed in the search for innovative antibiotic lead structures.

    17. Cationic Terminal Aminoborylene Complexes: Controlled Stepwise Insertion into M[DOUBLE BOND]B and B[DOUBLE BOND]N Double Bonds (pages 2043–2046)

      Glesni A. Pierce, Simon Aldridge, Cameron Jones, Timo Gans-Eichler, Andreas Stasch, Natalie D. Coombs and David J. Willock

      Article first published online: 14 FEB 2007 | DOI: 10.1002/anie.200604838

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      One thing leads to another: Reactions of the cationic BN vinylidene analogues 1-[BArF4] (R=Cy, iPr; ArF=3,5-(CF3)2C6H3) towards dicyclohexylcarbodiimide proceed by unprecedented insertion chemistry for terminal borylene complexes. Controlled, stepwise insertion into the Fe[DOUBLE BOND]B and B[DOUBLE BOND]N bonds is demonstrated, sequentially forming four-membered rings linked at a spirocyclic boronium center.

    18. Crystal Structure of a Spin-Labeled, Channel-Forming Alamethicin Analogue (pages 2047–2050)

      Marco Crisma, Cristina Peggion, Chiara Baldini, Elizabeth J. MacLean, Natascia Vedovato, Giorgio Rispoli and Claudio Toniolo

      Article first published online: 6 FEB 2007 | DOI: 10.1002/anie.200604417

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      Crystal clear: A detailed conformational characterization of a synthetic analogue of the peptide antibiotic alamethicin (see structure; C gray, N blue, O red) has been achieved by X-ray diffraction. The high-resolution structure of this analogue, which incorporates a spin probe, paves the way for a better understanding of the mode of action of alamethicin.

    19. Direct Detection of Nucleic Acids by Tagging Phosphates on Their Backbones with Conductive Nanoparticles (pages 2051–2054)

      Yi Fan, Xiantong Chen, Jinming Kong, Chih-hang Tung and Zhiqiang Gao

      Article first published online: 9 FEB 2007 | DOI: 10.1002/anie.200603605

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      Build a bridge: Strong interactions between zirconium-activated indium tin oxide (ITO) nanoparticles and phosphates are utilized to label nucleic acids with multiple ITO nanoparticles under very mild conditions. The electrically conductive ITO nanoparticle network formed bridges the gap between a pair of interdigitated electrodes, allowing the detection of nucleic acids at subpicomolar levels with high specificity.

    20. Low-Basicity Oxygen Atoms: A Key in the Search for Propylene Epoxidation Catalysts (pages 2055–2058)

      Daniel Torres, Nuria Lopez, Francesc Illas and Richard M. Lambert

      Article first published online: 8 FEB 2007 | DOI: 10.1002/anie.200603803

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      Gotta have copper: DFT studies indicate that the performance of heterogeneous epoxidation catalysts depends on the first step in the reaction between oxygen atoms and propylene molecules coadsorbed on the metal surface (see picture; C yellow, H light blue, O red). The high basicity of oxygen atoms on silver favors allylic hydrogen stripping, whereas the low basicity of oxygen atoms on copper favors metallacycle formation and subsequent epoxidation.

    21. A Thermal Spin Transition in a Nanoporous Iron(II) Coordination Framework Material (pages 2059–2062)

      Suzanne M. Neville, Boujemaa Moubaraki, Keith S. Murray and Cameron J. Kepert

      Article first published online: 15 FEB 2007 | DOI: 10.1002/anie.200603977

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      Influential guests: An abrupt spin-crossover transition is exhibited by a nanoporous framework material that consists of interpenetrated two-dimensional grids linked by hydrogen-bonding interactions. Desorption of guest molecules from the highly robust host lattice occurs by a single-crystal-to-single-crystal transformation and leads to subtle changes in the framework structure and spin-crossover properties.

    22. Synthesis of Cellulose In Vitro by Using a Cellulase/Surfactant Complex in a Nonaqueous Medium (pages 2063–2065)

      Shizuka Egusa, Takuya Kitaoka, Masahiro Goto and Hiroyuki Wariishi

      Article first published online: 9 FEB 2007 | DOI: 10.1002/anie.200603981

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      High and dry: The synthesis in vitro of longer-chain cellulose with more than 100 anhydrous glucopyranose units in the polymer has been performed by a new technique for glycosynthesis. This method uses enzymatic polymerization with enzyme/surfactant complexes that act in nonaqueous organic media.

    23. A Colorimetric Substrate for Poly(ADP-Ribose) Polymerase-1, VPARP, and Tankyrase-1 (pages 2066–2069)

      Amanda C. Nottbohm, Robin S. Dothager, Karson S. Putt, Mirth T. Hoyt and Paul J. Hergenrother

      Article first published online: 14 FEB 2007 | DOI: 10.1002/anie.200603988

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      Color me yellow: Poly(ADP-ribose) polymerases (PARPs) play a major role in cellular survival and maintenance of energy stores after genotoxic insult. The colorimetric PARP substrate ADP-ribose-pNP can be used to monitor PARP activity. By monitoring the production of p-nitrophenolate, the kinetic parameters of PARP-1, tankyrase, and PARP-4 could be evaluated. ADP=adenosine diphosphate, pNP=p-nitrophenoxy.

    24. A Novel Reaction of the “Huisgen Zwitterion” with Chalcones and Dienones: An Efficient Strategy for the Synthesis of Pyrazoline and Pyrazolopyridazine Derivatives (pages 2070–2073)

      Vijay Nair, Smitha C. Mathew, Akkattu T. Biju and Eringathodi Suresh

      Article first published online: 8 FEB 2007 | DOI: 10.1002/anie.200604025

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      Two unexpected transformations: The reaction of the Huisgen zwitterion derived from triphenylphosphane and diisopropyl azodicarboxylate (DIAD) with chalcones affords functionalized pyrazolines. In contrast, the reaction with dienones affords pyrazolopyridazines, presumably by Diels–Alder reaction of the initially formed pyrazoline with excess DIAD (see scheme).

    25. Rhodium-Catalyzed Cycloisomerization: Formation of Indoles, Benzofurans, and Enol Lactones (pages 2074–2077)

      Barry M. Trost and Andrew McClory

      Article first published online: 7 FEB 2007 | DOI: 10.1002/anie.200604183

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      Internal affairs: Indoles, benzofurans, and enol lactones are formed chemoselectively from the rhodium-catalyzed cycloisomerization reaction of easily prepared alkynyl aniline substrates (see scheme, cod=cycloocta-1,5-diene, DMF=N,N-dimethylformamide). The reaction may proceed by nucleophilic capture of a vinylidene intermediate. Indoles are formed under mild conditions using low catalyst loadings.

    26. Pd-Catalyzed Cleavage of Benzylic Nitro Bonds: New Opportunities for Asymmetric Synthesis (pages 2078–2081)

      Thomas C. Fessard, Hajime Motoyoshi and Erick M. Carreira

      Article first published online: 15 FEB 2007 | DOI: 10.1002/anie.200604263

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      Without a trace: Benzylic nitroalkanes are reduced to the corresponding parent alkanes in good yields by using a simple procedure involving heterolytic C[BOND]N bond cleavage (see scheme). Traceless removal of the nitro group leaves behind a stereogenic center that may otherwise be difficult to install. This reaction significantly expands the scope of building blocks that can be accessed.

    27. An Enantioselective CpRu-Catalyzed Carroll Rearrangement (pages 2082–2085)

      Samuel Constant, Simone Tortoioli, Jessica Müller and Jérôme Lacour

      Article first published online: 5 FEB 2007 | DOI: 10.1002/anie.200604573

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      Simple ligands, catalyst, and conditions: The combination of readily prepared unsymmetrical pyridine–imine ligands and [CpRu(CH3CN)3][PF6] (Cp=C5H5) affords regio- and enantioselective Carroll rearrangements (see scheme; b/l= branched-to-linear ratio). This reaction represents the first example of Ru-catalyzed enantioselective C[BOND]C bond-forming allylic substitution.

    28. Copper-Catalyzed Cross-Coupling Reaction of Grignard Reagents with Primary-Alkyl Halides: Remarkable Effect of 1-Phenylpropyne (pages 2086–2089)

      Jun Terao, Hirohisa Todo, Shameem Ara Begum, Hitoshi Kuniyasu and Nobuaki Kambe

      Article first published online: 5 FEB 2007 | DOI: 10.1002/anie.200603451

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      A general get-together: The Cu-catalyzed cross-coupling reaction of primary-alkyl halides with primary-, secondary-, and tertiary-alkyl and phenyl Grignard reagents proceeds efficiently in THF under reflux in the presence of 1-phenylpropyne (see scheme). The reaction is also applicable to alkyl mesylates (OMs) and tosylates (OTs). The reactivities of alkyl[BOND]X with a Grignard reagent increase in the order X=Cl<F<OMs<OTs<Br.

    29. Azoporphyrin: The Porphyrin Analogue of Azobenzene (pages 2090–2093)

      Louisa J. Esdaile, Paul Jensen, John C. McMurtrie and Dennis P. Arnold

      Article first published online: 5 FEB 2007 | DOI: 10.1002/anie.200604658

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      Excellent conjugation: The novel azoporphyrins (1,2-bis(porphyrinyl)diazenes) have been prepared by using copper-catalyzed coupling of primary amines. The structure of the azo(triphenylporphyrin) was determined by X-ray crystallography (see picture). The azo linker provides an excellent conjugating pathway for expansion of porphyrin π conjugation.

    30. The Triplet State of Indigo (pages 2094–2096)

      J. Sérgio Seixas de Melo, Hugh D. Burrows, Carlos Serpa and Luis G. Arnaut

      Article first published online: 14 FEB 2007 | DOI: 10.1002/anie.200604679

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      The elusive triplet state of indigo (see picture) has been fully characterized by energy-transfer pulse radiolysis and photoacoustic calorimetry. The triplet energy is (1.04±0.10) eV and the singlet-to-triplet intersystem crossing yield in solution is ϕISC=0.0066. Inefficient intersystem crossing, low triplet energy, and fast internal conversion of the singlet state likely contribute to the high stability of indigo.

    31. Chiral Brønsted Acids in the Catalytic Asymmetric Nazarov Cyclization—The First Enantioselective Organocatalytic Electrocyclic Reaction (pages 2097–2100)

      Magnus Rueping, Winai Ieawsuwan, Andrey P. Antonchick and Boris J. Nachtsheim

      Article first published online: 5 FEB 2007 | DOI: 10.1002/anie.200604809

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      Low catalyst loadings, high enantioselectivities, mild conditions, and fast reaction times are the important features of the first enantioselective organocatalytic electrocyclic reaction: a Nazarov cyclization leading to the synthesis of substituted five-membered rings with a chiral Brønsted acid as a catalyst (see scheme). A further advantage of this method is the possible entry to all four diastereomers of the product.

    32. Isolation of a Copper(I) Triazolide: A “Click” Intermediate (pages 2101–2103)

      Christoph Nolte, Peter Mayer and Bernd F. Straub

      Article first published online: 15 FEB 2007 | DOI: 10.1002/anie.200604444

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      Click snapshot: In an aprotic medium, a copper(I) triazolide complex is synthesized from a sterically hindered copper acetylide and an organoazide (see scheme: yellow Cu, blue N, dark gray C, gray H). This result provides direct evidence for such a complex, which had previously been hypothesized.

    33. Dehydroiodination of Iodo- and Diiodomethane by a Transient Phosphinidene Complex (pages 2104–2107)

      Aysel Özbolat, Arif Ali Khan, Gerd von Frantzius, Martin Nieger and Rainer Streubel

      Article first published online: 7 FEB 2007 | DOI: 10.1002/anie.200602617

      Thumbnail image of graphical abstract

      Elimination round: Dehydroiodination occurs when transient phosphinidene complex 1 is treated with iodomethane and diiodomethane, thus formally eliminating CH2 and CHI and giving in both cases complex 2 (see scheme; R=CH(SiMe3)2; R′=CH3, CH2I). The overall reactions represent examples of unprecedented P[BOND]C bond-cleavage reactions, and proceed under unusually mild conditions.

    34. Synthetic Glycopeptides from the E-Selectin Ligand 1 with Varied Sialyl Lewisx Structure as Cell-Adhesion Inhibitors of E-Selectin (pages 2108–2111)

      Christian Filser, Danuta Kowalczyk, Claire Jones, Martin K. Wild, Ute Ipe, Dietmar Vestweber and Horst Kunz

      Article first published online: 13 FEB 2007 | DOI: 10.1002/anie.200604442

      Thumbnail image of graphical abstract

      Cooperation is key: Peptide and saccharide portions cooperate in sialyl Lewisx glycopeptides and their mimetics in the fucose and sialic acid parts (see formula), resulting in up to greater than 100-fold stronger binding to E-selectin. The synthesis provided sialyl Lewisx amino acids in a form sufficiently acid-stable for application in automated solid-phase syntheses of glycopeptides based on acid-sensitive linkers.

    35. Site-Specific DNA Cleavage on a Solid Support: A Method for Mismatch Detection (pages 2112–2114)

      Sandra Thoeni, Christoph J. Kressierer and Bernd Giese

      Article first published online: 5 FEB 2007 | DOI: 10.1002/anie.200603092

      Thumbnail image of graphical abstract

      Game, set, and mismatch: In a new method for the detection of base-pair mismatches, an immobilized DNA strand with a cleavage site (black square) and a detection tag (red circle) is hybridized with the target strand. If the target nucleotide has a mismatch, then the marker is released from the solid phase (see scheme).

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      Preview: Angew. Chem. Int. Ed. 13/2007 (page 2121)

      Article first published online: 2 MAR 2007 | DOI: 10.1002/anie.200790044

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