Angewandte Chemie International Edition

Cover image for Vol. 47 Issue 38

September 8, 2008

Volume 47, Issue 38

Pages 7141–7367

  1. Cover Picture

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Editorial
    5. Graphical Abstract
    6. News
    7. Book Review
    8. Essay
    9. Correspondence
    10. Essay
    11. Review
    12. Communications
    13. Preview
    1. Cover Picture: The Continuing Saga of the Marine Polyether Biotoxins (Angew. Chem. Int. Ed. 38/2008) (page 7141)

      K. C. Nicolaou, Michael O. Frederick and Robert J. Aversa

      Article first published online: 3 SEP 2008 | DOI: 10.1002/anie.200890185

      Thumbnail image of graphical abstract

      An odyssey is described by K. C. Nicolaou et al. in their Review on page 7182 ff.: From the isolation of the first marine biotoxin with a ladder structure, brevetoxin B, in 1981 to the synthesis of maitotoxin molecule domains. Pictured is the dinoflagellate Gambierdiscus toxicus (small circle; courtesy of Steve L. Morton, NOAA), a unicellular marine organism producing maitotoxin, the largest and most toxic, non-proteomic secondary metabolite isolated to date. The surgeonfish (moodboard/Corbis) serves as a carrier of this neurotoxin to humans through the food chain causing ciguatera poisoning.

  2. Inside Cover

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Editorial
    5. Graphical Abstract
    6. News
    7. Book Review
    8. Essay
    9. Correspondence
    10. Essay
    11. Review
    12. Communications
    13. Preview
    1. Inside Cover: Solution-State NMR Spectroscopy of a Seven-Helix Transmembrane Protein Receptor: Backbone Assignment, Secondary Structure, and Dynamics (Angew. Chem. Int. Ed. 38/2008) (page 7142)

      Antoine Gautier, John P. Kirkpatrick and Daniel Nietlispach

      Article first published online: 3 SEP 2008 | DOI: 10.1002/anie.200890186

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      Untangling the structure of a helical membrane protein is intricate work. In their Communication on page 7297 ff. D. Nietlispach and co-workers present a high-resolution solution-state NMR study of the seven-helical transmembrane protein receptor sensory rhodopsin II from Natronomonas pharaonis. They discuss triple-resonance-based sequential assignments, secondary structure, solvent exchange, and backbone dynamics of the detergent-solubilized protein.

  3. Editorial

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Editorial
    5. Graphical Abstract
    6. News
    7. Book Review
    8. Essay
    9. Correspondence
    10. Essay
    11. Review
    12. Communications
    13. Preview
    1. You have free access to this content
      Appeals (pages 7144–7145)

      Peter Gölitz

      Article first published online: 6 AUG 2008 | DOI: 10.1002/anie.200803308

  4. Graphical Abstract

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Editorial
    5. Graphical Abstract
    6. News
    7. Book Review
    8. Essay
    9. Correspondence
    10. Essay
    11. Review
    12. Communications
    13. Preview
    1. Graphical Abstract: Angew. Chem. Int. Ed. 38/2008 (pages 7147–7158)

      Article first published online: 3 SEP 2008 | DOI: 10.1002/anie.200890187

  5. News

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Editorial
    5. Graphical Abstract
    6. News
    7. Book Review
    8. Essay
    9. Correspondence
    10. Essay
    11. Review
    12. Communications
    13. Preview
  6. Book Review

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Editorial
    5. Graphical Abstract
    6. News
    7. Book Review
    8. Essay
    9. Correspondence
    10. Essay
    11. Review
    12. Communications
    13. Preview
  7. Essay

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Editorial
    5. Graphical Abstract
    6. News
    7. Book Review
    8. Essay
    9. Correspondence
    10. Essay
    11. Review
    12. Communications
    13. Preview
    1. Computational Studies

      Predicting Molecules—More Realism, Please! (pages 7164–7167)

      Roald Hoffmann, Paul von Ragué Schleyer and Henry F. Schaefer III

      Article first published online: 6 AUG 2008 | DOI: 10.1002/anie.200801206

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      To be or not to be: The terms “viable” and “fleeting,” rather than the imprecise term “stable,” are proposed to describe hypothetical molecules whose existence has been predicted by computational studies. A number of criteria that a molecule described as viable should fulfill are discussed.

  8. Correspondence

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Editorial
    5. Graphical Abstract
    6. News
    7. Book Review
    8. Essay
    9. Correspondence
    10. Essay
    11. Review
    12. Communications
    13. Preview
    1. Computational Studies

      No Important Suggestions (pages 7168–7169)

      Gernot Frenking

      Article first published online: 6 AUG 2008 | DOI: 10.1002/anie.200802500

    2. Attractive and Convincing (page 7172)

      F. Matthias Bickelhaupt

      Article first published online: 6 AUG 2008 | DOI: 10.1002/anie.200802330

  9. Essay

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Editorial
    5. Graphical Abstract
    6. News
    7. Book Review
    8. Essay
    9. Correspondence
    10. Essay
    11. Review
    12. Communications
    13. Preview
    1. Peer Review

      The Effectiveness of the Peer Review Process: Inter-Referee Agreement and Predictive Validity of Manuscript Refereeing at Angewandte Chemie (pages 7173–7178)

      Lutz Bornmann and Hans-Dieter Daniel

      Article first published online: 25 JUL 2008 | DOI: 10.1002/anie.200800513

      Refereeing the referees: The peer review process of Angewandte Chemie has been examined according to the criteria of reliability (agreement between referees) and predictive validity (correlation between publication decision and citation frequency of the reviewed work). Despite the dramatic increase in submitted manuscripts and significant decline in acceptance rate, the results show the unwavering quality of the peer review at Angewandte Chemie.

  10. Review

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Editorial
    5. Graphical Abstract
    6. News
    7. Book Review
    8. Essay
    9. Correspondence
    10. Essay
    11. Review
    12. Communications
    13. Preview
    1. Natural Products

      The Continuing Saga of the Marine Polyether Biotoxins (pages 7182–7225)

      K. C. Nicolaou, Michael O. Frederick and Robert J. Aversa

      Article first published online: 3 SEP 2008 | DOI: 10.1002/anie.200801696

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      Natural products with cyclic ethers: The discovery of brevetoxin B in 1981 marked the beginning of the marine polyether biotoxins saga that still fascinates chemists and biologists. This Review gives a chronological overview of the developments in this research field, including studies on the isolation, chemical synthesis, and chemical biology of these toxins.

  11. Communications

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Editorial
    5. Graphical Abstract
    6. News
    7. Book Review
    8. Essay
    9. Correspondence
    10. Essay
    11. Review
    12. Communications
    13. Preview
    1. Chiral Resolution

      Attrition-Enhanced Deracemization of an Amino Acid Derivative That Forms an Epitaxial Racemic Conglomerate (pages 7226–7229)

      Bernard Kaptein, Wim L. Noorduin, Hugo Meekes, Willem J. P. van Enckevort, Richard M. Kellogg and Elias Vlieg

      Article first published online: 11 AUG 2008 | DOI: 10.1002/anie.200802468

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      Just bead it! Despite the complication of enantiomeric epitaxial behavior, a derivative of phenylalanine was completely resolved (see picture). Racemization takes place by abrasively grinding crystals of the compound in a saturated solution. By studying the influence of different crystal sizes, it was found that Ostwald ripening plays an important role in this process. DBU=1,8-diazabicyclo[5.4.0]undec-7-ene.

    2. Heterocycles

      Palladium-Catalyzed Oxidative Cyclization of N-Aryl Enamines: From Anilines to Indoles (pages 7230–7233)

      Sebastian Würtz, Souvik Rakshit, Julia J. Neumann, Thomas Dröge and Frank Glorius

      Article first published online: 13 AUG 2008 | DOI: 10.1002/anie.200802482

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      The special advantage of the title reaction to form substituted indoles 2 lies within the broad scope of the transformation: A multitude of N-aryl enaminones 1 can be prepared readily in one step from commercially available anilines. Furthermore, anilines can be converted directly in a one-pot process into the indole products. R1=H, Me, OMe, Cl, F, carbonyl functionality, CN, fused aryl; R2=alkyl, aryl; R3=alkyl, O[BOND]alkyl.

    3. Cluster Compounds

      [Sn17{GaCl(ddp)}4]: A High-Nuclearity Metalloid Tin Cluster Trapped by Electrophilic Gallium Ligands (pages 7234–7237)

      Ganesan Prabusankar, Andreas Kempter, Christian Gemel, Marie-Katrin Schröter and Roland A. Fischer

      Article first published online: 20 AUG 2008 | DOI: 10.1002/anie.200802470

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      The reduction of SnCl2 by the low-valent gallium(I) β-diketiminate GaI(ddp) gives the title complex, which is best described as a Zintl-type anionic [Sn17]4− cluster stabilized by an electrophilic shell of gallium ligands. This reaction could represent a new concept for the synthesis of metalloid main-group clusters. ddp=HC(CMeNC6H3-2,6-iPr2)2.

    4. Surface Chemistry

      Micrometer-Scale Protein-Resistance Gradients by Electron-Beam Lithography (pages 7238–7241)

      Tobias Winkler, Nirmalya Ballav, Heidi Thomas, Michael Zharnikov and Andreas Terfort

      Article first published online: 14 AUG 2008 | DOI: 10.1002/anie.200800810

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      Sticky slope: The irradiation-promoted exchange reaction on monolayers using ethylene glycol terminated thiols as ligands provides a useful tool for the adjustment of the bioresistance of surfaces. In conjunction with electron-beam lithography, micrometer-scale gradients of protein adhesivity could be produced (see picture: AFM=atomic force microscopy).

    5. Peptidyltransferases

      Peptide-Bond Synthesis on the Ribosome: No Free Vicinal Hydroxy Group Required on the Terminal Ribose Residue of Peptidyl-tRNA (pages 7242–7245)

      Miriam Koch, Yiwei Huang and Mathias Sprinzl

      Article first published online: 8 AUG 2008 | DOI: 10.1002/anie.200801511

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      OH?—OH no! The generally accepted explanation for peptide transfer in ribosomal peptidyltransferase is that the 2′-OH group of the adenosine residue (Ad) in the P site accepts a proton from the incoming α-amino group and transfers it to the outgoing deacylated tRNA (left). However, it has now been shown that peptide transfer still takes place in the absence of the 2′-hydroxy group (right: proposed alternative mechanism).

    6. Metal–Metal Bonds

      Metal–Metal Distances at the Limit: A Coordination Compound with an Ultrashort Chromium–Chromium Bond (pages 7246–7249)

      Awal Noor, Frank R. Wagner and Rhett Kempe

      Article first published online: 13 AUG 2008 | DOI: 10.1002/anie.200801160

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      Shorter than ever: Reduction of chromium(II/III) chlorides stabilized by amidopyridinato ligands leads to a dichromium complex that has a Cr–Cr bond length of 1.75 Å. This bond is exceptionally short, even for bonding orders higher than four, and is at present the shortest reported metal–metal bond for a stable compound. The experimental results are supported by theoretical calculations.

    7. Quintuple Bonds

      Remarkably Short Metal–Metal Bonds: A Lantern-Type Quintuply Bonded Dichromium(I) Complex (pages 7250–7253)

      Yi-Chou Tsai, Chia-Wei Hsu, Jen-Shiang K. Yu, Gene-Hsiang Lee, Yu Wang and Ting-Shen Kuo

      Article first published online: 6 AUG 2008 | DOI: 10.1002/anie.200801286

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      The shortest metal–metal bond so far is found in complex anion 2 (Cr[BOND]Cr 1.7397(9) Å), which is the one-electron reduction product of thermally stable mixed-valent complex 1 (see scheme). Experimental data unambiguously show that the electronic configuration of 1 is σ2π4δ3, and theoretical studies confirm the presence of a Cr[BOND]Cr quintuple bond in 2. Ar=2,6-C6H3(CH3)2.

    8. Mesoporous Sensors

      A Layered Mesoporous Carbon Sensor Based on Nanopore-Filling Cooperative Adsorption in the Liquid Phase (pages 7254–7257)

      Katsuhiko Ariga, Ajayan Vinu, Qingmin Ji, Osamu Ohmori, Jonathan P. Hill, Somobrata Acharya, Jun Koike and Seimei Shiratori

      Article first published online: 6 AUG 2008 | DOI: 10.1002/anie.200802820

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      Tea or coffee? The layer-by-layer assembly of mesoporous carbon onto a quartz crystal microbalance results in a structure (see picture) that can be used for highly selective in situ measurement of nonionic aqueous guests, such as tea components.

    9. DNA Detection

      Ultrasensitive DNA Detection Using Photonic Crystals (pages 7258–7262)

      Mingzhu Li, Fang He, Qing Liao, Jian Liu, Liang Xu, Lei Jiang, Yanlin Song, Shu Wang and Daoben Zhu

      Article first published online: 8 AUG 2008 | DOI: 10.1002/anie.200801998

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      A strong signal: A fluorescence resonance energy transfer (FRET)-based DNA hybridization detection method uses a photonic crystal to amplify the optical signal (see picture). Single-mismatch selectivity and a sensitivity of about 13.5 fM are achieved.

    10. Hydrogen Storage

      Enhancing H2 Uptake by “Close-Packing” Alignment of Open Copper Sites in Metal–Organic Frameworks (pages 7263–7266)

      Xi-Sen Wang, Shengqian Ma, Paul M. Forster, Daqiang Yuan, Juergen Eckert, Joseph J. López, Brandon J. Murphy, John B. Parise and Hong-Cai Zhou

      Article first published online: 19 AUG 2008 | DOI: 10.1002/anie.200802087

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      Open and close: Inspired by close-packing of spheres, to strengthen the framework–H2 interaction in MOFs (metal-organic frameworks), a strategy is devised to increase the number of nearest neighboring open metal sites of each H2-hosting cage, and to align the open metal sites toward the H2 molecules. Two MOF polymorphs were made, one exhibiting a record high hydrogen uptake of 3.0 wt % at 1 bar and 77 K.

    11. Protein Aggregation

      Identification of Aggregation-Prone Elements by Using Interaction-Energy Matrices (pages 7267–7269)

      Jennifer M. Bui, Andrea Cavalli and Jörg Gsponer

      Article first published online: 8 AUG 2008 | DOI: 10.1002/anie.200802345

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      A number of human pathologies have been linked to the conversion of soluble proteins into amyloid aggregates. A new computational method based on first principles, peptide interaction matrix analyzer, identifies aggregation-prone peptides, which form in-register antiparallel (see picture) or parallel β sheets, and predicts the likelihood of coaggregation within or between proteins.

    12. Biotransistors

      Transistor-Like Behavior of a Fungal Laccase (pages 7270–7274)

      Sergey Shleev and Tautgirdas Ruzgas

      Article first published online: 8 AUG 2008 | DOI: 10.1002/anie.200801364

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      Potential for change: The activity of a fungal laccase on a gold electrode can be modulated by an applied potential. The activity–potential dependence resembles “transistor-like” current–potential characteristics. The applied potential affects the chemical and electronic structure of the T2/T3 copper cluster of the enzyme by a mechanism similar to that of the natural regulation of laccase activity (see scheme; IET: intramolecular electron transfer).

    13. Chiral Hybrid Gelator

      Chiral Strandberg-Type Molybdates [(RPO3)2Mo5O15]2− as Molecular Gelators: Self-Assembled Fibrillar Nanostructures with Enhanced Optical Activity (pages 7275–7279)

      Mauro Carraro, Andrea Sartorel, Gianfranco Scorrano, Chiara Maccato, Michael H. Dickman, Ulrich Kortz and Marcella Bonchio

      Article first published online: 8 AUG 2008 | DOI: 10.1002/anie.200801629

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      Twisted fibers with a helical structure are formed by self-assembly of chiral polyoxomolybdates (POMs) [(R*PO3)2Mo5O15]2− (R=CH3CH(NH3), CH3CH(CH3)CH(NH3)) through H-bonding. High-resolution TEM images of single fibers show an ordered substructure with parallel rows about 2 nm in width, in agreement with the packing of the H-bonded POM subunits in the X-ray structure (see inset).

    14. Ligand Design

      Selective Chemical Rescue of a Thyroid-Hormone-Receptor Mutant, TRβ(H435Y), Identified in Pituitary Carcinoma and Resistance to Thyroid Hormone (pages 7280–7283)

      A. Quamrul Hassan and John T. Koh

      Article first published online: 6 AUG 2008 | DOI: 10.1002/anie.200801742

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      Ligand to the rescue! Thyroid hormone receptor (TR) plays a critical role in development and homeostasis. The mutant TRβ(H435Y) was identified in both cancer and resistance to thyroid hormone. A designed synthetic ligand recovered the cellular reporter-gene activity of TRβ(H435Y) with a 5 850-fold improvement in selectivity for the mutant relative to that of the natural hormone T3 (shown in a modeled structure with TRβ(H435Y)).

    15. Biological Imaging

      Micellar Hybrid Nanoparticles for Simultaneous Magnetofluorescent Imaging and Drug Delivery (pages 7284–7288)

      Ji-Ho Park, Geoffrey von Maltzahn, Erkki Ruoslahti, Sangeeta N. Bhatia and Michael J. Sailor

      Article first published online: 11 AUG 2008 | DOI: 10.1002/anie.200801810

      Thumbnail image of graphical abstract

      Multimodal nanoassemblies that contain magnetic nanoparticles, quantum dots, and the anticancer drug doxorubicin within a single PEG–phospholipid micelle were prepared (see scheme; PEG=poly(ethylene glycol)). When equipped with the targeting peptide F3, these nanostructures enable simultaneous targeted drug delivery and dual-mode imaging of tumor tissues by near-infrared fluorescence and NMR spectroscopy.

    16. Protein Detection

      Enantiodifferential Approach for the Detection of the Target Membrane Protein of the Jasmonate Glycoside that Controls the Leaf Movement of Albizzia saman (pages 7289–7292)

      Yoko Nakamura, Ryoji Miyatake and Minoru Ueda

      Article first published online: 6 AUG 2008 | DOI: 10.1002/anie.200801820

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      Pairs of probes with recognition elements of opposite configuration can be used to detect target proteins of biologically active natural products. The diastereomeric probes shown were designed on the basis of structure–activity relationships determined for an endogenous factor that controls leaf opening and closing in the title plant. They revealed that a 38 kDa membrane protein is key to the stereospecific recognition of the natural product.

    17. Supramolecular Chemistry

      A Polymeric Pseudorotaxane Constructed from Cucurbituril and Aniline, and Stabilization of Its Radical Cation (pages 7293–7296)

      Yu Liu, Jun Shi, Yong Chen and Chen-Feng Ke

      Article first published online: 8 AUG 2008 | DOI: 10.1002/anie.200802805

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      Picking up the thread: A polypseudorotaxane 1 with a regular one-dimensional linear structure has been constructed in satisfactory yield from cucurbit[7]uril and polyaniline (PANI). The complexation with cucurbituril not only enhances the water solubility of the PANI (see picture; after 10 h), but also effectively stabilizes its radical cation form, that is, the conductive doped form, as shown by EPR spectroscopy.

    18. Membrane Proteins

      Solution-State NMR Spectroscopy of a Seven-Helix Transmembrane Protein Receptor: Backbone Assignment, Secondary Structure, and Dynamics (pages 7297–7300)

      Antoine Gautier, John P. Kirkpatrick and Daniel Nietlispach

      Article first published online: 1 AUG 2008 | DOI: 10.1002/anie.200802783

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      Protein in motion: A solution-state NMR study on the seven-helix transmembrane protein pSRII (see picture) in a detergent solution focused on the sequential backbone assignment, the characterization of the secondary structure, and the backbone dynamics. The structural integrity of the protein was confirmed, and mobility in the loops (ps–ns timescale) and slower motions in the helical core (μs–ms timescale) were identified.

    19. Nanostructures

      Optical Waveguide Based on Crystalline Organic Microtubes and Microrods (pages 7301–7305)

      Yong Sheng Zhao, Jinjie Xu, Aidong Peng, Hongbing Fu, Ying Ma, Lei Jiang and Jiannian Yao

      Article first published online: 11 AUG 2008 | DOI: 10.1002/anie.200802570

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      Light at the end of the tunnel: Two kinds of 1D microstructures, tubes and rods, were prepared from 9,10-bis(phenylethynyl)anthracene. While both types of 1D microstructures can absorb excitation light and propagate the photoluminescence (PL) emission towards the tips, the air inside the hollow tubes changes the waveguide behavior and helps to reduce the optical loss (see PL images, scale bar: 10 μm).

    20. Copolymerization

      A Highly Active and Recyclable Catalytic System for CO2/Propylene Oxide Copolymerization (pages 7306–7309)

      Sujith S, Jae Ki Min, Jong Eon Seong, Sung Jea Na and Bun Yeoul Lee

      Article first published online: 11 AUG 2008 | DOI: 10.1002/anie.200801852

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      Converting CO2into polymer: A catalytic system that produces a high molecular weight CO2/propylene oxide copolymer with high activity and selectivity is disclosed. After filtration through silica gel, elution of the catalyst leaves a solid phase with a negligible metal residue (see picture). The catalyst can be reused without significant loss of performance.

    21. Natural Products

      Total Synthesis of (+)-Cortistatin A (pages 7310–7313)

      K. C. Nicolaou, Ya-Ping Sun, Xiao-Shui Peng, Damien Polet and David Y.-K. Chen

      Article first published online: 14 AUG 2008 | DOI: 10.1002/anie.200803550

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      Marine engineering: A modular strategy featuring an intramolecular 1,4-addition/aldol/dehydration cascade sequence (see scheme; TBS=tert-butyldimethylsilyl) has enabled the total synthesis of cortistatin A, a potent anti-angiogenic marine natural product. This flexible route offers access to other members of the cortistatin family, both natural and designed.

    22. Natural Product Synthesis

      Synthesis of (−)-(Z)-Deoxypukalide (pages 7314–7316)

      Timothy J. Donohoe, Alan Ironmonger and Neil M. Kershaw

      Article first published online: 8 AUG 2008 | DOI: 10.1002/anie.200802703

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      Closing the deal: A ring-closing metathesis (RCM)/aromatization protocol, followed by a regioselective Negishi cross-coupling reaction and macrolactonization, with subsequent RCM mediate the synthesis of (−)-(Z)-deoxypukalide in 12 linear steps and 15 % overall yield (see retrosynthesis; TBS=tert-butyldimethylsilyl, TIPS=triisopropylsilyl).

    23. Total Synthesis of Theopederin D (pages 7317–7320)

      Michael E. Green, Jason C. Rech and Paul E. Floreancig

      Article first published online: 6 AUG 2008 | DOI: 10.1002/anie.200802548

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      The transformation is complete! The total synthesis of theopederin D (see structure), a potent cytotoxin, has been achieved through oxidative cleavage of a carbon–carbon bond. Other key transformations include an acid-mediated functionalization of a tetrahydrofuranol, a syn-selective glycal epoxide ring-opening, and an asymmetric aldehyde/acid chloride condensation.

    24. Enzyme Models

      Hydrogen Atom Abstraction and Hydride Transfer Reactions by Iron(IV)–Oxo Porphyrins (pages 7321–7324)

      Yu Jin Jeong, Yaeun Kang, Ah-Rim Han, Yong-Min Lee, Hiroaki Kotani, Shunichi Fukuzumi and Wonwoo Nam

      Article first published online: 6 AUG 2008 | DOI: 10.1002/anie.200802346

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      True identity revealed: The C[BOND]H bond activation of alkyl aromatics by synthetic iron(IV)–oxo porphyrin species and the hydride transfer of NADH analogues to them occur through H-atom abstraction and proton-coupled electron-transfer mechanisms, respectively. Mechanistic studies revealed that iron(IV)–oxo porphyrins, not iron(IV)–oxo porphyrin π-radical cations, are the true oxidant.

    25. Oxidation

      Photooxygenation of Masked o-Benzoquinones: An Efficient Entry into Highly Functionalized Cyclopentenones from 2-Methoxyphenols (pages 7325–7327)

      Tzu-Chiao Kao, Gary Jing Chuang and Chun-Chen Liao

      Article first published online: 8 AUG 2008 | DOI: 10.1002/anie.200802130

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      MOB tactics: A novel oxidation of masked o-benzoquinones (MOBs) 1 occurs by singlet-oxygen-triggered ring contraction to form cyclopentenone derivatives 2 and by [4+2] cycloaddition to give endoperoxides 3. The competing pathways are directed by solvents and allow access to a variety of functionalized cyclopentenes.

    26. Solid-State NMR Spectroscopy

      Rapid Analysis of Organic Compounds by Proton-Detected Heteronuclear Correlation NMR Spectroscopy with 40 kHz Magic-Angle Spinning (pages 7328–7331)

      Donghua H. Zhou and Chad M. Rienstra

      Article first published online: 6 AUG 2008 | DOI: 10.1002/anie.200802108

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      High-sensitivity proton detection enabled acquisition of well-resolved two-dimensional spectra in only 30 minutes for less than 5 mg of organic compounds at natural abundance. Besides faster resonance assignment, rapid analysis of crystal polymorphism, molecular dynamics, and H-bonding is possible. This method is applicable to both pure and dosage forms of solid pharmaceuticals, such as ibuprofen (see picture).

    27. Cell Imaging

      Three-Coordinate Ligand for Physiological Beryllium Imaging by Fluoresence (pages 7332–7334)

      Himashinie V. K. Diyabalanage, Kumkum Ganguly, Deborah S. Ehler, Gavin E. Collis, Brian L. Scott, Anu Chaudhary, Anthony K. Burrell and T. Mark McCleskey

      Article first published online: 6 AUG 2008 | DOI: 10.1002/anie.200801965

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      To Be or not to Be: Be binds strongly to the three-dentate ligand 2,6-bis(2-hydroxyphenyl)pyridine in a 1:1 ratio with no bridging phenolates (see structure; Be green, C gray, H white, O red, N blue). As Be binds and displaces the strong hydrogen bonds, the ligand fluoresces. The fluorescence is very specific for Be and can be used to detect beryllium in cells, as demonstrated with human lung epithelial cells (see picture, right).

    28. Water Oxidation

      Sustained Water Oxidation Photocatalysis by a Bioinspired Manganese Cluster (pages 7335–7338)

      Robin Brimblecombe, Gerhard F. Swiegers, G. Charles Dismukes and Leone Spiccia

      Article first published online: 1 AUG 2008 | DOI: 10.1002/anie.200801132

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      The generation game: A manganese–oxo complex with a cubic {Mn4O4}7+ core catalyzes the electrooxidation of water when suspended within the aqueous channels of a Nafion membrane (see picture). Illumination with visible light under an applied potential of 1.0 V (vs Ag/AgCl) generates current over one thousand turnovers. The catalytically active species arises from photolysis and subsequent dissociation of the manganese complex.

    29. Asymmetric Catalysis

      Enantioselective Hydrogenation with Racemic and Enantiopure Binap in the Presence of a Chiral Ionic Liquid (pages 7339–7341)

      Dianjun Chen, Mike Schmitkamp, Giancarlo Franciò, Jürgen Klankermayer and Walter Leitner

      Article first published online: 6 AUG 2008 | DOI: 10.1002/anie.200801995

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      Racemic but enantioselective: rac-Binap and a chiral ionic liquid (cIL) used for the asymmetric hydrogenation of dimethyl itaconate led to identical ee values as enantiopure binap. The enantiodifferentiation results primarily from a diastereomeric interaction of the binap–Rh unit and the proline ester moiety. For other substrates, enhanced enantioselectivity with inverted absolute configuration was obtained with the enantiopure ligand in the cIL relative to organic solvents.

    30. Dye-Sensitized Solar Cells

      Multifunctionalized Ruthenium-Based Supersensitizers for Highly Efficient Dye-Sensitized Solar Cells (pages 7342–7345)

      Chia-Yuan Chen, Jian-Ging Chen, Shi-Jhang Wu, Jheng-Ying Li, Chun-Guey Wu and Kuo-Chuan Ho

      Article first published online: 6 AUG 2008 | DOI: 10.1002/anie.200802120

      Thumbnail image of graphical abstract

      The sensitive type: Two new ruthenium-based supersensitizers (CYC-B6S and CYC-B6L) in which a hole-transport moiety and a conjugated segment are connected sequentially to the bipyridine of the ancillary ligand show efficiency in dye-sensitized solar cells (DSCs) of up to 9.72 %. Increasing the conversion efficiency of liquid-state DSCs by connecting a carbazole moiety to the ancillary ligand of the ruthenium-based sensitizer is demonstrated.

    31. Homogeneous Catalysis

      Branched-Regioselective Hydroformylation with Catalytic Amounts of a Reversibly Bound Directing Group (pages 7346–7349)

      Christian U. Grünanger and Bernhard Breit

      Article first published online: 8 AUG 2008 | DOI: 10.1002/anie.200802296

      Thumbnail image of graphical abstract

      Phosphinites do the trick and work as reversibly bound catalyst-directing groups in catalytic amounts to allow for the highly regioselective hydroformylation of homoallylic alcohols with terminal and internal alkene functions in favor of the branched product.

    32. Alkene Synthesis

      Stereoselective Synthesis of Tri- and Tetrasubstituted Alkenes by Iron-Catalyzed Carbometalation Ring-Opening Reactions of Cyclopropenes (pages 7350–7353)

      Yi Wang, Euan A. F. Fordyce, Fung Yan Chen and Hon Wai Lam

      Article first published online: 13 AUG 2008 | DOI: 10.1002/anie.200802391

      Thumbnail image of graphical abstract

      Open sesame: An iron-catalyzed cyclopropene carbometalation ring-opening sequence using trialkylaluminum reagents is described. The reactions proceed with high levels of regio- and stereocontrol to provide a range of multisubstituted alkenes, including trisubstituted vinylsilanes, trisubstituted vinylstannanes, and all-carbon tetrasubstituted alkenes.

    33. Gold Catalysis

      Gold(I)-Catalyzed Tandem Reactions Initiated by 1,2-Indole Migrations (pages 7354–7357)

      Roberto Sanz, Delia Miguel and Félix Rodríguez

      Article first published online: 8 AUG 2008 | DOI: 10.1002/anie.200802660

      Thumbnail image of graphical abstract

      Take your pick! Indene-containing indole scaffolds have been catalytically prepared from C3-propargylated indoles by tandem reactions involving an initial 1,2-indole migration. This unprecedented process generates a gold carbene complex and proceeds through either a formal C[BOND]H insertion or a Nazarov cyclization (see scheme).

    34. Asymmetric Conjugate Additions

      Enantioselective Synthesis of All-Carbon Quaternary Stereogenic Centers by Catalytic Asymmetric Conjugate Additions of Alkyl and Aryl Aluminum Reagents to Five-, Six-, and Seven-Membered-Ring β-Substituted Cyclic Enones (pages 7358–7362)

      Tricia L. May, M. Kevin Brown and Amir H. Hoveyda

      Article first published online: 6 AUG 2008 | DOI: 10.1002/anie.200802910

      Thumbnail image of graphical abstract

      Solution to pesky problems: Effective methods for catalytic asymmetric conjugate additions of alkyl and aryl aluminum reagents with unactivated β-substituted cyclopentenones are now available (see scheme). Transformations, promoted by chiral bidentate N-heterocyclic carbene (NHC) copper complexes derived from 1, give rise to all-carbon quaternary stereogenic centers.

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      Preview: Angew. Chem. Int. Ed. 39/2008 (page 7367)

      Article first published online: 3 SEP 2008 | DOI: 10.1002/anie.200890189

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