Angewandte Chemie International Edition

Cover image for Vol. 46 Issue 25

June 18, 2007

Volume 46, Issue 25

Pages 4587–4797

  1. Cover Picture

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Graphical Abstract
    5. News
    6. Book Review
    7. Highlight
    8. Minireview
    9. Review
    10. Communications
    11. Preview
    1. Cover Picture: Total Synthesis and Revised Structure of Biyouyanagin A (Angew. Chem. Int. Ed. 25/2007) (page 4587)

      K. C. Nicolaou, David Sarlah and David M. Shaw

      Version of Record online: 11 JUN 2007 | DOI: 10.1002/anie.200790112

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      The anti-HIV agent … biyouyanagin A, which was isolated from the leaves of a Hypericum species, such as the one shown in the cover picture, has been synthesized by a photoinduced [2+2] cycloaddition reaction. The convergent 12-step synthesis, as described in the Communication by Nicolaou et al. on page 4708 ff., confirms its structure, renders it available for biological investigation, and also allows for the synthesis of analogues.

  2. Inside Cover

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Graphical Abstract
    5. News
    6. Book Review
    7. Highlight
    8. Minireview
    9. Review
    10. Communications
    11. Preview
    1. Inside Cover: Stepwise Synthesis and Coordination Compound of an Inorganic Cryptand (Angew. Chem. Int. Ed. 25/2007) (page 4588)

      Carsten von Hänisch, Oliver Hampe, Florian Weigend and Sven Stahl

      Version of Record online: 11 JUN 2007 | DOI: 10.1002/anie.200790113

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      On the basis of organic cryptands, an inorganic cryptand was designed by C. von Hänisch and co-workers. The coordination of a lithium atom to this framework supports the analogy to the organic ligands. The picture shows the stepwise formation of the complex, as described in detail in the Communication on page 4775 ff. An aerial photograph of the Forschungszentrum Karlsruhe, which celebrated its 50th anniversary in 2006, is shown in the background.

  3. Graphical Abstract

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

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

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

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Graphical Abstract
    5. News
    6. Book Review
    7. Highlight
    8. Minireview
    9. Review
    10. Communications
    11. Preview
    1. Silicon Analogues of Crown Ethers and Cryptands: A New Chapter in Host–Guest Chemistry? (pages 4610–4613)

      Jamie S. Ritch and Tristram Chivers

      Version of Record online: 1 JUN 2007 | DOI: 10.1002/anie.200701822

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      Crown jewels: The judicious use of weakly coordinating anions has recently led to the first direct syntheses of alkali-metal complexes of siloxane-based crown ethers and cryptands. These findings have implications in the areas of host–guest chemistry, inorganic ring transformations, and ring-opening polymerization.

  7. Minireview

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Graphical Abstract
    5. News
    6. Book Review
    7. Highlight
    8. Minireview
    9. Review
    10. Communications
    11. Preview
    1. The Enantioselective Morita–Baylis–Hillman Reaction and Its Aza Counterpart (pages 4614–4628)

      Géraldine Masson, Christopher Housseman and Jieping Zhu

      Version of Record online: 2 APR 2007 | DOI: 10.1002/anie.200604366

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      Leading the way to highly efficient and generally applicable enantioselective Morita–Baylis–Hillman (MBH) reactions (see scheme; EWG: electron-withdrawing group) is the use of bifunctional organocatalysis. Tethering both Lewis base (LB) and Lewis acid (LA) units to a chiral rigid backbone often generates an efficient catalyst for the MBH reaction. Cinchona alkaloids, binol, and ureas are excellent starting points for further catalyst development.

  8. Review

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Graphical Abstract
    5. News
    6. Book Review
    7. Highlight
    8. Minireview
    9. Review
    10. Communications
    11. Preview
    1. Synthesis of Monodisperse Spherical Nanocrystals (pages 4630–4660)

      Jongnam Park, Jin Joo, Soon Gu Kwon, Youngjin Jang and Taeghwan Hyeon

      Version of Record online: 24 MAY 2007 | DOI: 10.1002/anie.200603148

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      All the same: The synthesis of monodisperse nanocrystals is of key importance for many future applications, because their physical properties depend strongly on their dimensions. Mechanistic studies reveal that monodisperse nanocrystals are produced when a burst of nucleation is combined with a subsequent diffusion-controlled growth process. This Review summarizes recent progress made on the synthesis of monodisperse spherical nanocrystals (TEM image: iron oxide nanoparticles).

  9. Communications

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Graphical Abstract
    5. News
    6. Book Review
    7. Highlight
    8. Minireview
    9. Review
    10. Communications
    11. Preview
    1. Sodium-Mediated Manganation: Direct Mono- and Dimanganation of Benzene and Synthesis of a Transition-Metal Inverse-Crown Complex (pages 4662–4666)

      Luca M. Carrella, William Clegg, David V. Graham, Lorna M. Hogg, Alan R. Kennedy, Jan Klett, Robert E. Mulvey, Eva Rentschler and Luca Russo

      Version of Record online: 21 MAY 2007 | DOI: 10.1002/anie.200700965

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      Inside out approach: Twofold deprotonation of benzene by a sodium monoalkyl bisamido manganate(II) reagent derived from BuNa, 2,2,6,6-tetramethylpiperidine, and Mn(CH2SiMe3)2 has produced the first inverse-crown complex in which the transition-metal atoms are incorporated in the host (see X-ray structure, blue N, green Na, purple Mn). Variable-temperature magnetization measurements show that the complex is antiferromagnetic.

    2. Signal-Amplifying Conjugated Polymer–DNA Hybrid Chips (pages 4667–4670)

      Kangwon Lee, Jean-Marie Rouillard, Trinh Pham, Erdogan Gulari and Jinsang Kim

      Version of Record online: 29 MAY 2007 | DOI: 10.1002/anie.200700419

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      Expand on that: Signal-amplifying DNA chips have been fabricated by a light-directed on-chip DNA synthesis on a thin film of a photostable conjugated polyoxadiazole derivative. The fluorescence signal from a hexachlorofluorescein-labeled target DNA was increased by a large amount through efficient Förster energy transfer from the conjugated polymer to the dye after DNA–DNA hybridization when compared with the signal from a control slide.

    3. Isolation of High-Affinity Trypsin Inhibitors from a DNA-Encoded Chemical Library (pages 4671–4674)

      Samu Melkko, Yixin Zhang, Christoph E. Dumelin, Jörg Scheuermann and Dario Neri

      Version of Record online: 11 MAY 2007 | DOI: 10.1002/anie.200700654

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      Maturing is easy to do: Annealing benzamidine–oligonucleotide conjugates with a library of DNA-encoded compounds allows the affinity capture of pharmacophores that are capable of binding to exosites adjacent to the primary substrate-binding pocket of the serine protease trypsin. Selected conjugates show an improvement in IC50 values of several orders of magnitude compared with the starting benzamidine.

    4. A Liquid-Crystalline Bistable [2]Rotaxane (pages 4675–4679)

      Ivan Aprahamian, Takuma Yasuda, Taichi Ikeda, Sourav Saha, William R. Dichtel, Kyosuke Isoda, Takashi Kato and J. Fraser Stoddart

      Version of Record online: 11 MAY 2007 | DOI: 10.1002/anie.200700305

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      Entering a new phase: Mesogenic stoppers (purple) at the ends of the rod section of a switchable donor–acceptor [2]rotaxane induce the formation of a smectic A liquid-crystalline (LC) phase over a wide temperature range. The bistable [2]rotaxane which contains a tetracationic cyclophane (blue), a tetrathiafulvalene unit (green), and a 1,5-dioxynaphthalene unit (red) self-assembles into a LC phase with a layer spacing of about 8 nm (see picture).

    5. A Liquid-Crystalline [2]Catenane and Its Copper(I) Complex (pages 4680–4683)

      Etienne D. Baranoff, Julie Voignier, Takuma Yasuda, Valérie Heitz, Jean-Pierre Sauvage and Takashi Kato

      Version of Record online: 2 MAY 2007 | DOI: 10.1002/anie.200700308

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      Getting organized: A free [2]catenane and its copper complex having forklike mesogens form nanosegregated liquid-crystalline (LC) structures over wide temperature ranges. The ordered arrangement of the free [2]catenane in the LC smectic A phase exerts a significant effect on the conformation of the two macrocycles, which is fixed in the ordered assembled state (see picture).

    6. Isolation and Structure of Platencin: A FabH and FabF Dual Inhibitor with Potent Broad-Spectrum Antibiotic Activity (pages 4684–4688)

      Hiranthi Jayasuriya, Kithsiri B. Herath, Chaowei Zhang, Deborah L. Zink, Angela Basilio, Olga Genilloud, Maria Teresa Diez, Francisca Vicente, Ignacio Gonzalez, Oscar Salazar, Fernando Pelaez, Richard Cummings, Sookhee Ha, Jun Wang and Sheo B. Singh

      Version of Record online: 9 MAY 2007 | DOI: 10.1002/anie.200701058

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      Two birds with one stone: Platencin (1) is a novel and potent broad-spectrum Gram-positive antibiotic. Whereas platensimycin is a selective inhibitor of FabF, platencin exerts its activity by a novel mode of action by dual inhibition of FabH and FabF.

    7. Fabrication of Cellular Multilayers with Nanometer-Sized Extracellular Matrix Films (pages 4689–4692)

      Michiya Matsusaki, Koji Kadowaki, Yoshio Nakahara and Mitsuru Akashi

      Version of Record online: 14 MAY 2007 | DOI: 10.1002/anie.200701089

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      Layer it on: Cellular multilayers were fabricated by preparing nanometer-sized extracellular matrix (ECM) films (6-nm thick) with fibronectin (FN) and gelatin on the surface of each cell layer. The four-layer cellular architecture was well organized and self-standing. Xenogenic human bilayer architectures similar to blood vessels were prepared by fabrication of the nanofilms on cell surfaces.

    8. Total Synthesis of (+)-Azaspiracid-1. Part I: Synthesis of the Fully Elaborated ABCD Aldehyde (pages 4693–4697)

      David A. Evans, Lisbet Kværnø, Jason A. Mulder, Brian Raymer, Travis B. Dunn, André Beauchemin, Edward J. Olhava, Martin Juhl and Katsuji Kagechika

      Version of Record online: 1 JUN 2007 | DOI: 10.1002/anie.200701515

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      Has aspirations: The total synthesis of (+)-azaspiracid-1 has been realized. The ABCD fragment was synthesized in 20 linear steps and 16 % overall yield through the enantioselective syntheses of the AB sulfone and the CD aldehyde, their coupling by a sulfone anion addition, and a thermodynamically controlled bis(spiroketalization) event. The E, FG, and HI ring fragments were synthesized enantioselectively and then coupled by using aldol methodology. Finally, a complex addition of the anion of the anomeric EFGHI sulfone to the ABCD aldehyde completed the synthesis in 26 linear steps and 2.7 % yield.

    9. Total Synthesis of (+)-Azaspiracid-1. Part II: Synthesis of the EFGHI Sulfone and Completion of the Synthesis (pages 4698–4703)

      David A. Evans, Travis B. Dunn, Lisbet Kværnø, André Beauchemin, Brian Raymer, Edward J. Olhava, Jason A. Mulder, Martin Juhl, Katsuji Kagechika and David A. Favor

      Version of Record online: 1 JUN 2007 | DOI: 10.1002/anie.200701520

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    10. Total Synthesis and Stereochemistry of Uncialamycin (pages 4704–4707)

      K. C. Nicolaou, Hongjun Zhang, Jason S. Chen, James J. Crawford and Laxman Pasunoori

      Version of Record online: 11 MAY 2007 | DOI: 10.1002/anie.200700917

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      Unseal the secrets of uncialamycin: The total synthesis of the C26 epimers of the newly discovered enediyne natural product allows its stereochemical assignment and further biological investigations of this potent antibiotic. Key steps involve the addition of an acetylide to a pyridinium species, an intramolecular formation of the enediyne, and Hauser annulation to form the anthraquinone moiety.

    11. Total Synthesis and Revised Structure of Biyouyanagin A (pages 4708–4711)

      K. C. Nicolaou, David Sarlah and David M. Shaw

      Version of Record online: 24 MAY 2007 | DOI: 10.1002/anie.200701552

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      It all adds up: A 12-step total synthesis of biyouyanagin A, an inhibitor of HIV replication, has revealed its structure, rendered it available for biological investigations, and allows the synthesis of analogues. The convergent synthesis involves two cascade sequences and a remarkably selective [2+2] cycloaddition reaction to forge the cyclobutane ring of the target molecule in the ultimate step.

    12. Adamantaplatensimycin: A Bioactive Analogue of Platensimycin (pages 4712–4714)

      K. C. Nicolaou, Troy Lister, Ross M. Denton, Ana Montero and David J. Edmonds

      Version of Record online: 21 MAY 2007 | DOI: 10.1002/anie.200701548

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      Adamantly pursuing the bugs: The syntheses of the two enantiomers of adamantaplatensimycin ((−)-1 and (+)-1), a novel analogue of the newly discovered antibiotic platensimycin, have been achieved. Potent antibacterial action against methicillin-resistant Staphylococcus aureus and vancomycin-resistant Enterococcus faecium has been revealed for the (−) enantiomer.

    13. Construction of the “Left Domain” of Haplophytine (pages 4715–4718)

      K. C. Nicolaou, Utpal Majumder, Stephane Philippe Roche and David Y.-K. Chen

      Version of Record online: 11 JUN 2007 | DOI: 10.1002/anie.200701947

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      Left of the middle: Synthesis of the “left” structural domain (2) of haplophytine (1) features a stereoselective construction of its sterically congested carbon–carbon bond (C9′–C15) and an efficient cascade sequence involving a skeletal rearrangement of a presumed epoxide intermediate.

    14. A Distinctive Organocatalytic Approach to Complex Macromolecular Architectures (pages 4719–4721)

      Olivier Coulembier, Matthew K. Kiesewetter, Andrew Mason, Philippe Dubois, James L. Hedrick and Robert M. Waymouth

      Version of Record online: 15 MAY 2007 | DOI: 10.1002/anie.200700522

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      Branch manager: A one-step approach to branched copolymers is described. Primary amines are found to function as bifunctional initiators for ring-opening polymerization in the presence of 1 to promote the polymerization of two chains, thereby enabling the facile introduction of branch points in block copolymers.

    15. Hydrogen Peroxide Triggered Prochelator Activation, Subsequent Metal Chelation, and Attenuation of the Fenton Reaction (pages 4722–4725)

      Yibin Wei and Maolin Guo

      Version of Record online: 15 MAY 2007 | DOI: 10.1002/anie.200604859

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      Fenton antidote: The prochelator 2-boronobenzaldehyde isonicotinoyl hydrazone (SIH-B) reacts with H2O2 to yield the active chelator salicylaldehyde isonicotinoyl hydrazone (SIH), which sequesters copper and iron ions (see scheme; M=Fe, Cu). This process attenuates both Fe- and Cu-promoted Fenton reactions under physiologically relevant conditions.

      Corrected by:

      Apology: Hydrogen Peroxide Triggered Prochelator Activation, Subsequent Metal Chelation, and Attenuation of the Fenton Reaction

      Vol. 46, Issue 37, 6948, Version of Record online: 11 SEP 2007

    16. Substrate-Controlled Asymmetric Total Synthesis of (+)-Microcladallene B with a Bromination Strategy Based on a Nucleophile-Assisting Leaving Group (pages 4726–4728)

      Janghyun Park, Byungsook Kim, Hyoungsu Kim, Sanghee Kim and Deukjoon Kim

      Version of Record online: 11 MAY 2007 | DOI: 10.1002/anie.200700854

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      The formidable challenge of incorporating a bromine substituent stereoselectively at an sp3 center was met through application of a nucleophile-assisting leaving group (see scheme). A further highlight of the highly stereo-, regio-, and chemoselective synthesis of (+)-microcladallene B was a dianion alkylation to provide the required α,α′-anti substrate for ring-closing metathesis. TBDPS=tert-butyldiphenylsilyl.

    17. Asymmetric Oxidation Catalysis by a Chiral Al(salalen) Complex: Highly Enantioselective Oxidation of Sulfides with Aqueous Hydrogen Peroxide (pages 4729–4731)

      Tetsufumi Yamaguchi, Kazuhiro Matsumoto, Bunnai Saito and Tsutomu Katsuki

      Version of Record online: 11 MAY 2007 | DOI: 10.1002/anie.200700792

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      Not afraid to get wet: Aluminum(salalen) complexes were found to be water compatible and therefore suitable catalysts for asymmetric oxidation with aqueous hydrogen peroxide. A variety of sulfides underwent the title reaction in the presence of the aluminum(salalen) complex shown to the give the desired sulfoxides with high to excellent enantioselectivity (see scheme; Bn=benzyl).

    18. A Formally Zwitterionic Ruthenium Catalyst Precursor for the Transfer Hydrogenation of Ketones that Does Not Feature an Ancillary Ligand N[BOND]H Functionality (pages 4732–4735)

      Rylan J. Lundgren, Matthew A. Rankin, Robert McDonald, Gabriele Schatte and Mark Stradiotto

      Version of Record online: 16 MAY 2007 | DOI: 10.1002/anie.200700345

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      Fast and furious: Even without the assistance of an N[BOND]H donor ligand, the Ru complex shown in the scheme is a remarkably active precatalyst for the transfer hydrogenation of ketones in basic iPrOH (R,R′=alkyl or aryl), providing near-quantitative yields within minutes and exhibiting consistently high turnover frequencies (104 to 105 h−1) for a diverse range of substrates.

    19. C[BOND]H Bond Activation by Rhodium(I) Hydroxide and Phenoxide Complexes (pages 4736–4738)

      Susan M. Kloek, D. Michael Heinekey and Karen I. Goldberg

      Version of Record online: 10 MAY 2007 | DOI: 10.1002/anie.200700270

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      Rhodium(I) complexes of the form [(PNP)Rh(OR)] (R=H, CH2CF3, C6H5; PNP=2,6-bis[(di-tert-butylphosphino)methyl]pyridine) have been prepared. Upon thermolysis in [D6]benzene, the hydroxide and trifluoroethoxide complexes undergo benzene activation. [(PNP)Rh(OC6H5)] is an active catalyst for the H/D exchange between D2O and benzene and between H2O and [D8]toluene (see scheme), for which exchange occurs selectively at the meta and para positions.

    20. Synthesis and Evaluation of Modified Oligodeoxynucleotides Containing Diphosphodiester Internucleotide Linkages (pages 4739–4743)

      Yousef Ahmadibeni and Keykavous Parang

      Version of Record online: 11 MAY 2007 | DOI: 10.1002/anie.200605029

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      Build a bridge: Oligodeoxynucleotides (ODNs) containing diphosphodiester bridges were synthesized by a solid-phase synthesis strategy. Modified ODNs formed stable duplexes with complementary modified and unmodified nucleic acid sequences. The modified oligomers were resistant to degradation by DNase I and 3′-exonuclease I under conditions in which unmodified ODNs were degraded. B=T, A, G, or C.

    21. PtCl2-Catalyzed Hydrative Cyclization of Trialkyne Functionalities to Form Bicyclic Spiro Ketones (pages 4744–4747)

      Hsu-Kai Chang, Swarup Datta, Arindam Das, Arjan Odedra and Rai-Shung Liu

      Version of Record online: 18 MAY 2007 | DOI: 10.1002/anie.200700022

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      Triple rounds: A regioselective hydrative cyclization of triynes has been developed to give bicyclic β-hydroxy spiro ketones, which undergo subsequent dehydration to give the β,γ-unsaturated ketones (see scheme). Model reactions suggest that this platinum catalysis includes two selective hydrations, an alkyne insertion, and an aldol condensation.

    22. Systematically Probing the Effect of Catalyst Acidity in a Hydrogen-Bond-Catalyzed Enantioselective Reaction (pages 4748–4750)

      Katrina H. Jensen and Matthew S. Sigman

      Version of Record online: 14 MAY 2007 | DOI: 10.1002/anie.200700298

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      Defining the relationship: The effect of catalyst acidity has been systematically probed by using a modular oxazoline catalyst in a hetero-Diels–Alder reaction catalyzed by hydrogen bonding. Linear free energy relationships were observed between the catalyst acidity and both the reaction rate and enantioselectivity (see picture).

    23. Chemoenzymatic Enrichment of Phosphotyrosine-Containing Peptides (pages 4751–4753)

      Shuwei Li and Dexing Zeng

      Version of Record online: 15 MAY 2007 | DOI: 10.1002/anie.200700633

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      Change the Tyr: A tyrosinase-assisted chemoenzymatic method was used to modify and enrich phosphotyrosine-containing peptides from a peptide mixture. This approach could be used to study protein tyrosine phosphorylation, and represents a promising alternative to immunoaffinity purification by using anti-phosphotyrosine antibodies.

    24. IR Spectra of Protonated Carbonic Acid and Its Isomeric H3O+⋅CO2 Complex (pages 4754–4756)

      Horia-Sorin Andrei, Sergey A. Nizkorodov and Otto Dopfer

      Version of Record online: 8 MAY 2007 | DOI: 10.1002/anie.200700750

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      Complex detection: Gas-phase protonated carbonic acid, C(OH)3+ (1), and its isomeric H3O+⋅CO2 complex (2) were spectroscopically identified for the first time by resonant IR photodissociation spectroscopy of their Ar-tagged adducts (see picture). This identification represents an important step toward understanding the precise role of protonated carbonic acid in CO2 hydrolysis and related processes.

      Corrected by:

      Corrigendum: IR Spectra of Protonated Carbonic Acid and Its Isomeric H3O+⋅CO2 Complex

      Vol. 46, Issue 32, 5999, Version of Record online: 3 AUG 2007

    25. Rh-Catalyzed Transannulation of Pyridotriazoles with Alkynes and Nitriles (pages 4757–4759)

      Stepan Chuprakov, Frank W. Hwang and Vladimir Gevorgyan

      Version of Record online: 11 MAY 2007 | DOI: 10.1002/anie.200700804

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      Changing the rings: A variety of N-fused pyrrolo- and imidazopyridines can be readily formed by a direct Rh-catalyzed transannulation of pyridotriazoles with alkynes and nitriles, respectively (see scheme). Substituted pyridotriazoles can also serve as stable precursors for Rh carbenoids, the preparation of which does not require special precautions or slow-addition techniques.

    26. Total Synthesis of the Antibiotic Erypoegin H and Cognates by a PtCl2-Catalyzed Cycloisomerization Reaction (pages 4760–4763)

      Alois Fürstner, Eike K. Heilmann and Paul W. Davies

      Version of Record online: 10 MAY 2007 | DOI: 10.1002/anie.200700895

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      Fighting back: A concise route to the pterocarpene derivative erypoegin H, a natural product endowed with considerable activity against a range of methicillin-resistant Staphyllococcus aureus strains and vancomycin-resistant enterococci, has been developed. The key step in the synthesis is a PtCl2-catalyzed carboalkoxylation reaction of an alkyne (see retrosynthesis; Piv=pivaloyl).

    27. Synthesis of 1,3,4-Trisubstituted Isoquinolines by Iodine-Mediated Electrophilic Cyclization of 2-Alkynyl Benzyl Azides (pages 4764–4766)

      Dirk Fischer, Hisamitsu Tomeba, Nirmal K. Pahadi, Nitin T. Patil and Yoshinori Yamamoto

      Version of Record online: 22 MAY 2007 | DOI: 10.1002/anie.200701392

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      The I's have it: A series of 2-alkynyl benzyl azides have been smoothly converted into 1,3,4-trisubstituted isoquinolines in moderate to excellent yields by an iodonium-mediated synthesis (see scheme). Depending on the structure of the substrate, iodine, Barluenga reagent (Py2IBF4/HBF4), or N-iodosuccinimide has been employed as the I+ source.

    28. Fibrous Aggregation of Magnetite Nanoparticles Induced by a Time-Varied Magnetic Field (pages 4767–4770)

      Jianfei Sun, Yu Zhang, Zhongping Chen, Jie Zhou and Ning Gu

      Version of Record online: 15 MAY 2007 | DOI: 10.1002/anie.200604474

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      In the field: In the presence of a time-varied magnetic field, electrostatically stabilized magnetite nanoparticles aggregate into microsized fibrous suprastructures (see image). The process is irreproducible for sterically stabilized colloids. It is inferred that the phenomenon results from the co-effects of magnetic moment interaction and electrostatic interaction that are connected by the time-varied magnetic field.

    29. Total Synthesis of the Thiazolyl Peptide GE2270 A (pages 4771–4774)

      H. Martin Müller, Oscar Delgado and Thorsten Bach

      Version of Record online: 14 MAY 2007 | DOI: 10.1002/anie.200700684

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      When one door closes, another opens: In the synthesis of the thiazolyl peptide GE2270 A (1), the bonds labeled I and II at the pyridine core were established by two consecutive cross-coupling reactions. Amide bond formation (IV) and subsequent intramolecular Stille reaction (III) were more effective than the originally conceived connection strategy (III before IV). GE2270 A (1) was prepared with an overall yield of 4.8 % in 20 steps along the longest linear sequence.

    30. Stepwise Synthesis and Coordination Compound of an Inorganic Cryptand (pages 4775–4779)

      Carsten von Hänisch, Oliver Hampe, Florian Weigend and Sven Stahl

      Version of Record online: 27 APR 2007 | DOI: 10.1002/anie.200604673

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      Modeled on organics: The inorganic cryptand [P2{O(SiiPr2)2}2{SiMe2(OSiMe2)2}] (see figure; C black, O orange, P red, Si blue) can be synthesized by a stepwise lithiation/silylation process. A first coordination compound of this ligand was obtained from its reaction with Li[Al(ORF)4].

    31. A Highly Enantiomerically Enriched Lithiosilane by Selective Cleavage of a Silicon–Phenyl Bond with Lithium (pages 4780–4782)

      Carsten Strohmann, Christian Däschlein, Marco Kellert and Dominik Auer

      Version of Record online: 22 MAY 2007 | DOI: 10.1002/anie.200604636

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      On the path to chiral polysilanes, the synthesis and first structural characterization of the enantiomerically pure tetrasilane (R)-3 was achieved. A new synthetic strategy was used, by which the cleavage of a silicon–phenyl bond in the substrate (R)-1 generated as intermediate the enantiomerically enriched lithiosilane 2.

    32. Structural Requirements of Jasmonates and Synthetic Analogues as Inducers of Ca2+ Signals in the Nucleus and the Cytosol of Plant Cells (pages 4783–4785)

      Agnes Walter, Christian Mazars, Mathias Maitrejean, Jörn Hopke, Raoul Ranjeva, Wilhelm Boland and Axel Mithöfer

      Version of Record online: 8 MAY 2007 | DOI: 10.1002/anie.200604989

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      A three-class society: Jasmonates, a group of oxylipin phytohormones differentially induce changes in intracellular Ca2+ concentrations in plant cells (see diagram). Structure–activity analysis revealed that jasmonates fall into three distinct classes: 1) compounds inducing Ca2+ changes in both the cytosol and the nucleus 2) compounds inactive on either compartment, and 3) compounds acting selectively on the nucleus.

    33. Direct and Label-Free Detection of Solid-Phase-Bound Compounds by Using Surface-Enhanced Raman Scattering Microspectroscopy (pages 4786–4789)

      Carsten Schmuck, Peter Wich, Bernd Küstner, Wolfgang Kiefer and Sebastian Schlücker

      Version of Record online: 11 MAY 2007 | DOI: 10.1002/anie.200605190

      Thumbnail image of graphical abstract

      Sensitive and specific: By using surface-enhanced Raman scattering (SERS) microspectroscopy, solid-phase-bound compounds can be detected directly and marker-free in a few seconds on a single polystyrene bead. No significant contributions of the matrix are observed, as demonstrated by reference Raman spectra.

    34. Stereospecific Styrene Enchainment at a Titanium Site within a Helical Ligand Framework: Evidence for the Formation of Homochiral Polystyrene (pages 4790–4793)

      Klaus Beckerle, Ramanujachary Manivannan, Bing Lian, Geert-Jan M. Meppelder, Gerhard Raabe, Thomas P. Spaniol, Henner Ebeling, Frederic Pelascini, Rolf Mülhaupt and Jun Okuda

      Version of Record online: 29 MAY 2007 | DOI: 10.1002/anie.200700783

      Thumbnail image of graphical abstract

      Tactful: Titanium catalyst precursors in both optically active, enantiomeric forms have been obtained diastereoselectively, and after activation with methylaluminoxane (MAO) they were used for the stereospecific oligomerization of styrene. The isotactic polystyrenes with a degree of polymerization of up to 45 show measurable optical activity, thus corroborating that enantiomorphic site control is operating in these homogeneous catalysts.

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