Angewandte Chemie International Edition

Cover image for Vol. 44 Issue 42

October 28, 2005

Volume 44, Issue 42

Pages 6789–6965

    1. Cover Picture: Two-Component Graded Deposition of Biomolecules with a Double-Barreled Nanopipette (Angew. Chem. Int. Ed. 42/2005) (page 6789)

      Kit T. Rodolfa, Andreas Bruckbauer, Dejian Zhou, Yuri E. Korchev and David Klenerman

      Article first published online: 25 OCT 2005 | DOI: 10.1002/anie.200590140

      The persistence of Edgar Degas is illustrated in the formation of highly complex, graded, ‘two-color’ images on the submicron scale. Two species can be delivered independently from a single pipette through the use of scanning ion-conductance distance control. The cover picture shows biological molecules being delivered in air through a liquid meniscus at the tip of a double-barreled nanopipette (Salvador Dali, not to scale, is shown painting the Degas Dancers with a nanopipette) as described by D. Klenerman et al. in their Communication on page 6854 ff.

    2. Charge Densities Come of Age (pages 6810–6811)

      Philip Coppens

      Article first published online: 27 SEP 2005 | DOI: 10.1002/anie.200501734

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      To be or not to be (a bond, that is)? Recent progress in X-ray charge-density analysis is discussed with emphasis on the characterization of unusual bonding situations, such as the recently reported C[BOND]C “bonding” interaction in a [1.1.1]propellane (see structure).

    3. Catalytic Asymmetric Esterification of Ketenes (pages 6812–6814)

      Thomas T. Tidwell

      Article first published online: 14 SEP 2005 | DOI: 10.1002/anie.200501849

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      Ketene esterification after 100 years: In the latest advance in the esterification of ketenes, Schaefer and Fu described the catalytic asymmetric conversion of 2-tolyl(ethyl)ketene (1) and diphenylacetaldehyde to give the enol ester 2 in 99 % yield and 98 % ee (see scheme).

    4. Supramolecular Approaches to Generate Libraries of Chelating Bidentate Ligands for Homogeneous Catalysis (pages 6816–6825)

      Bernhard Breit

      Article first published online: 11 OCT 2005 | DOI: 10.1002/anie.200501798

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      Ligands scoot together: Noncovalent attractive interactions between ligands in the coordination sphere of a metal center lead to a situation typical for complexes with classical bidentate ligands (see picture). In tests with catalyzed reactions these self-assembled systems gave results comparable to those obtained with complexes having classical bidentate ligands.

    5. The Impact of Bacterial Genomics on Natural Product Research (pages 6828–6846)

      Helge B. Bode and Rolf Müller

      Article first published online: 25 OCT 2005 | DOI: 10.1002/anie.200501080

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      Increasing genomic information together with new tools in molecular microbiology have led to powerful and rational applications in natural product research (see picture). Today, it is possible to produce novel and altered secondary metabolites with biological activity.

    6. Nanosized [Pd52(CO)36(PEt3)14] and [Pd66(CO)45(PEt3)16] Clusters Based on a Hypothetical Pd38 Vertex-Truncated ν3 Octahedron (pages 6848–6854)

      Evgueni G. Mednikov, Sergei A. Ivanov, Irina V. Slovokhotova and Lawrence F. Dahl

      Article first published online: 25 OCT 2005 | DOI: 10.1002/anie.200502307

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      Room for one more? The structures of nanosized Pd52 and Pd66 clusters that are based upon a common Pd38 vertex-truncated ν-octahedral kernel have been determined. The 45 CO ligands in the Pd66 cluster (see core structure), [Pd66(CO)45(PEt3)16], are described in terms of one extra and 44 normal ligands, two of which undergo rearrangement to accommodate the 45th CO ligand without causing any substantial changes to the architecture of the metal core.

    7. You have free access to this content
      Two-Component Graded Deposition of Biomolecules with a Double-Barreled Nanopipette (pages 6854–6859)

      Kit T. Rodolfa, Andreas Bruckbauer, Dejian Zhou, Yuri E. Korchev and David Klenerman

      Article first published online: 25 OCT 2005 | DOI: 10.1002/anie.200502338

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      Pretty as a picture: The printing of highly complex graded images with two different species (see picture) has been developed through the use of double-barreled pipettes. This method of submicron deposition of biomolecules eliminates registry problems that are inherent to other deposition techniques.

    8. Regio- and Chemoselective 6′-N-Derivatization of Aminoglycosides: Bisubstrate Inhibitors as Probes To Study Aminoglycoside 6′-N-Acetyltransferases (pages 6859–6862)

      Feng Gao, Xuxu Yan, Oliver M. Baettig, Albert M. Berghuis and Karine Auclair

      Article first published online: 5 OCT 2005 | DOI: 10.1002/anie.200501399

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      Complex nanomolar inhibitors in one pot: Aminoglycoside–coenzyme A derivatives were prepared through an efficient regioselective 6′-N modification of aminoglycosides (see scheme). These bisubstrates show tight-binding competitive inhibition of aminoglycoside 6′-N-acetyltransferase, an enzyme involved in antibiotic resistance.

    9. Sandwich Immunoassay as a High-Throughput Screening Method for Cross-Coupling Reactions (pages 6863–6866)

      Paola Vicennati, Nicolas Bensel, Alain Wagner, Christophe Créminon and Frédéric Taran

      Article first published online: 7 OCT 2005 | DOI: 10.1002/anie.200501641

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      Catalyst sandwich: An efficient and sensitive high-throughput-screening method that uses sandwich immunoassays was developed and applied to the Sonogashira reaction. This new method is amenable to coupling reactions and allows the screening of more than 1000 catalyst samples per day.

    10. [Re12CS17(CN)6]n (n=6, 8): A Sulfido–Cyanide Rhenium Cluster with an Interstitial Carbon Atom (pages 6867–6871)

      Yuri V. Mironov, Nikolai G. Naumov, Svetlana G. Kozlova, Sung-Jin Kim and Vladimir E. Fedorov

      Article first published online: 5 OCT 2005 | DOI: 10.1002/anie.200501911

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      Cyanide clusters [Re12CS17(CN)6]n (n=8 or 6), which may be used to form polymeric material, have been prepared by treating ReS2 with molten KCN at 750 °C. The cluster unit comprises two {Re6} octahedra connected by three μ2-S bridges and one interstitial μ6-C atom (see picture).

    11. Aqueous FeIV[DOUBLE BOND]O: Spectroscopic Identification and Oxo-Group Exchange (pages 6871–6874)

      Oleg Pestovsky, Sebastian Stoian, Emile L. Bominaar, Xiaopeng Shan, Eckard Münck, Lawrence Que Jr. and Andreja Bakac

      Article first published online: 5 OCT 2005 | DOI: 10.1002/anie.200502686

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      A combination of techniques (Mössbauer and X-ray absorption spectroscopy, H218O exchange experiments, and DFT calculations) has shown that the reaction of [Fe(H2O)6]2+ with ozone generates [(H2O)5FeIV[DOUBLE BOND]O]2+ (see calculated structure). The oxidation of selected substrates with [(H2O)5FeIV[DOUBLE BOND]O]2+ yields unique products that are different from those generated in the Fenton reaction or derived from HO. radicals.

      Corrected by:

      Corrigendum: Aqueous FeIV[DOUBLE BOND]O: Spectroscopic Identification and Oxo-Group Exchange

      Vol. 45, Issue 3, 340, Article first published online: 5 JAN 2006

    12. Holding onto Lots of Hydrogen: A 12-Hydride Rhodium Cluster That Reversibly Adds Two Molecules of H2 (pages 6875–6878)

      Simon K. Brayshaw, Michael J. Ingleson, Jennifer C. Green, Paul R. Raithby, Gabriele Kociok-Köhn, J. Scott McIndoe and Andrew S. Weller

      Article first published online: 5 OCT 2005 | DOI: 10.1002/anie.200502221

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      H Box: The clusters [Rh6(PR3)6H12][BArF4]2 (R=cyclohexyl, iPr; see scheme, pink Rh, orange P) reversibly take up two molecules of H2 under ambient conditions (1 atm H2, 298 K) to give discrete octahedral clusters surrounded by 16 hydride ligands.

    13. Spiraling Steroids: Organic Crystals with Asymmetric Nanometer-Scale Channels (pages 6878–6881)

      Adam L. Sisson, Vicente del Amo Sanchez, Germinal Magro, Alex M. E. Griffin, Shilen Shah, Jonathan P. H. Charmant and Anthony P. Davis

      Article first published online: 7 OCT 2005 | DOI: 10.1002/anie.200502330

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      Crystals with broad robust channels are rare, especially if self-assembled without the aid of metal ions. Three such crystals were prepared based on a common steroid motif. The channels formed are chiral, directional, aligned, and wide enough (>1 nm) to accept a variety of guests (see picture; red: oxygen, blue: nitrogen, green: fluorine).

    14. A Germanate Framework Containing 24-Ring Channels, Ni[BOND]Ge Bonds, and Chiral [Ni@Ge14O24(OH)3] Cluster Motifs Transferred from Chiral Metal Complexes (pages 6881–6884)

      Zhi-En Lin, Jie Zhang, Jing-Tai Zhao, Shou-Tian Zheng, Chun-Yang Pan, Guo-Ming Wang and Guo-Yu Yang

      Article first published online: 5 OCT 2005 | DOI: 10.1002/anie.200502432

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      Microporous: Chiral metal complexes as templates under solvothermal conditions resulted in two novel germanates Ni@Ge14O24(OH)3⋅2 Ni(L)3 (L=ethylenediamine, 1,2-diaminopropane). The chiral Ni@Ge14O24(OH)3 cluster motifs have an unprecedented trigonal-bipyramidal Ni@Ge5 core with Ni[BOND]Ge bonds and are linked to each other to form a 3D germanate framework containing 24-ring channels (see picture).

    15. Redox-Switchable Phase Tags for Recycling of Homogeneous Catalysts (pages 6885–6888)

      Marcus Süßner and Herbert Plenio

      Article first published online: 25 OCT 2005 | DOI: 10.1002/anie.200502182

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      A homogeneous catalytic complex is tagged with two ferrocenyl groups to control its solubility properties by reversible switching between its neutral and dicationic states (see scheme). This approach is carried out on an olefin-metathesis catalyst and is shown to effectively switch its catalytic activity on and off; furthermore, efficient separation of the catalyst from the reaction products and subsequent recycling of the catalyst is possible.

    16. Design of a Mechanism-Based Probe for Neuraminidase To Capture Influenza Viruses (pages 6888–6892)

      Chun-Ping Lu, Chien-Tai Ren, Yi-Ning Lai, Shih-Hsiung Wu, Wei-Man Wang, Jean-Yin Chen and Lee-Chiang Lo

      Article first published online: 7 OCT 2005 | DOI: 10.1002/anie.200501738

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      Getting a grip on the flu: A mechanism-based probe, 1, for neuraminidase was developed. It is capable of forming a biotinylated adduct with neuraminidase (NA) from Arthrobacter ureafaciens. It also displays an inhibitory effect on a number of NA activities. ELISA experiments successfully demonstrated that influenza viruses can be selectively captured with this probe.

    17. Reactions of Gold(III) Oxo Complexes with Cyclic Alkenes (pages 6892–6895)

      Maria A. Cinellu, Giovanni Minghetti, Fabio Cocco, Sergio Stoccoro, Antonio Zucca and Mario Manassero

      Article first published online: 5 OCT 2005 | DOI: 10.1002/anie.200501754

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      An auraoxetane, obtained from the reaction of norbornene with a gold(III) oxo complex, has been isolated and fully characterized (see structure). Action of the olefin leads to elimination of the epoxide from the auraoxetane.

    18. Thiazole Synthesis by Cyclocondensation of 1-Alkynyl(phenyl)-λ3-iodanes with Thioureas and Thioamides (pages 6896–6899)

      Kazunori Miyamoto, Yoshio Nishi and Masahito Ochiai

      Article first published online: 5 OCT 2005 | DOI: 10.1002/anie.200502438

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      The isolation and intramolecular cyclization of (S)-(1-alkynyl)isothiouronium and (S)-(1-alkynyl)thiobenzimidonium salts suggest the mechanism for the one-pot synthesis of 2,4-disubstituted thiazoles (see scheme; Ms=methanesulfonyl): Michael addition of sulfur nucleophiles to hypervalent iodanes followed by the 1,2-rearrangement of sulfenyl groups in the resulting alkylidene carbenes.

    19. The Importance of a β–β Bond for Long-Range Antiferromagnetic Coupling in Directly Linked Copper(II) and Silver(II) Diporphyrins (pages 6899–6901)

      Takahisa Ikeue, Ko Furukawa, Hiroshi Hata, Naoki Aratani, Hiroshi Shinokubo, Tatsuhisa Kato and Atsuhiro Osuka

      Article first published online: 7 OCT 2005 | DOI: 10.1002/anie.200501943

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      Interaction over a distance: Long-range antiferromagnetic interactions between distant copper(II) and silver(II) ions are observed only for triply and singly linked diporphyrins with at least one ββ bond, which underscores the critical importance of this direct bond for antiferromagnetic coupling. These results can be qualitatively accounted for in terms of the spin distribution of copper(II) and silver(II) porphyrins (see picture).

    20. Molecular and Polymeric Hybrids Based on Covalently Linked Polyoxometalates and Transition-Metal Complexes (pages 6902–6905)

      Jeonghee Kang, Bubin Xu, Zhonghua Peng, Xiaodong Zhu, Yongge Wei and Douglas R. Powell

      Article first published online: 5 OCT 2005 | DOI: 10.1002/anie.200501924

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      A rational building-block approach was employed to construct organometallic/polyoxometalate (POM) hybrids in which POM clusters and transition-metal complexes are linked by a π-conjugated bridge. The synthetic strategy for molecular and polymeric hybrids—POM functionalization with iodo-bearing groups, attachment of a terpyridine-type ligand, and metal coordination—is shown schematically in the picture.

      Corrected by:

      Corrigendum: Molecular and Polymeric Hybrids Based on Covalently Linked Polyoxometalates and Transition-Metal Complexes

      Vol. 45, Issue 1, 17, Article first published online: 14 DEC 2005

    21. Perovskite Hollow-Fiber Membranes for the Production of Oxygen-Enriched Air (pages 6906–6909)

      Haihui Wang, Steffen Werth, Thomas Schiestel and Jürgen Caro

      Article first published online: 5 OCT 2005 | DOI: 10.1002/anie.200501914

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      Mixed-ion and electron-conducting perovskite membranes are used to produce oxygen-enriched air (see picture). These membranes are thermally and mechanically stable at high temperatures (>875 °C) over a long period of time, thus making them suitable for industrial processes. Oxygen concentrations of the enriched air typically reach 30–50 vol %.

    22. Allosteric-Controlled Metal Specificity of a Ditopic Ligand (pages 6909–6912)

      Christian J. Baylies, T. Riis-Johannessen, Lindsay P. Harding, John. C. Jeffery, Ryan Moon, Craig R. Rice and Martina Whitehead

      Article first published online: 5 OCT 2005 | DOI: 10.1002/anie.200502571

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      To twist or not to twist? A ditopic ligand, L1, that contains a potentially tetradentate pyridyl–thiazole ligand chain and a “external” crown ether unit is presented. Reaction of L1 with Cu+ or Zn2+ ions results in the formation of a dinuclear double helicate [Cu2(L1)2]2+ or a mononuclear [ZnL1]2+ species. This ditopic system changes its preference for Cu+ or Zn2+ ions on the inclusion of s-block-metal ions at the crown ether binding site (e.g., Sr2+ ions as shown in the scheme).

    23. Recyclable Palladium Catalyst for Highly Selective α Alkylation of Ketones with Alcohols (pages 6913–6915)

      Min Serk Kwon, Namdu Kim, Seong Hyeok Seo, In Soo Park, Ravi Kumar Cheedrala and Jaiwook Park

      Article first published online: 5 OCT 2005 | DOI: 10.1002/anie.200502422

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      An air-stable, heterogeneous, and recyclable catalyst composed of palladium nanoparticles entrapped in aluminum hydroxide was applied to a highly selective α alkylation. A wide range of aliphatic and aromatic ketones and primary alcohols were coupled to prepare enones in an O2 atmosphere and ketones in an argon atmosphere (see scheme).

    24. Water Oxidation Catalyzed by a Dinuclear Mn Complex: A Functional Model for the Oxygen-Evolving Center of Photosystem II (pages 6916–6920)

      Allan K. Poulsen, Annette Rompel and Christine J. McKenzie

      Article first published online: 5 OCT 2005 | DOI: 10.1002/anie.200502114

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      A highly specific and catalytic oxidation of water occurs when using a dinuclear Mn complex of a mononegative carboxylate-containing pentadentate ligand (see scheme). Isotope-labeling experiments coupled with membrane inlet mass spectrometry show that one oxygen atom in the evolved O2 molecule is derived from water and the other from the oxidant.

    25. Selective Sensing of Zinc Ions with a PARACEST Contrast Agent (pages 6920–6923)

      Robert Trokowski, Jimin Ren, Ferenc Krisztián Kálmán and A. Dean Sherry

      Article first published online: 5 OCT 2005 | DOI: 10.1002/anie.200502173

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      A europium complex capable of selectively binding zinc (see picture) has been developed as a new paramagnetic chemical exchange saturation transfer (PARACEST) imaging agent for use in magnetic resonance imaging (MRI). A hydroxide group on the bound Zn ion increases the rate of water exchange on the Eu ion.

    26. Deracemization of Quaternary Stereocenters by Pd-Catalyzed Enantioconvergent Decarboxylative Allylation of Racemic β-Ketoesters (pages 6924–6927)

      Justin T. Mohr, Douglas C. Behenna, Andrew M. Harned and Brian M. Stoltz

      Article first published online: 5 OCT 2005 | DOI: 10.1002/anie.200502018

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      Stereochemical alchemy! Racemic allyl β-ketoesters allow the regiocontrolled formation of enolates, where the same catalyst is intimately involved in both the stereoablative (C[BOND]C bond-breaking) and stereoselective (C[BOND]C bond-forming) steps. This mechanistic and practical insight led to the formation of multiple quaternary carbon stereocenters in a single cascade reaction (see scheme).

    27. Lattice Expansion of Clathrate Hydrates of Methane Mixtures and Natural Gas (pages 6928–6931)

      Satoshi Takeya, Tsutomu Uchida, Yasushi Kamata, Jiro Nagao, Masato Kida, Hirotsugu Minami, Hirotoshi Sakagami, Akihiro Hachikubo, Nobuo Takahashi, Hitoshi Shoji, Oleg Khlystov, Mikhail Grachev and Valery Soloviev

      Article first published online: 5 OCT 2005 | DOI: 10.1002/anie.200501845

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      Structural transition from type I to type II is accompanied by a large increase in lattice constant a in CH4+C2H6 clathrate hydrates (see picture). In contrast, the lattice constants of CH4+CO2 clathrate hydrates are independent of composition. Data for a natural gas hydrate from the sediments of Lake Baikal are also consistent with these trends.

    28. Ruthenium-Catalyzed Oxidative Cyanation of Tertiary Amines with Hydrogen Peroxide and Sodium Cyanide (pages 6931–6933)

      Shun-Ichi Murahashi, Naruyoshi Komiya and Hiroyuki Terai

      Article first published online: 29 SEP 2005 | DOI: 10.1002/anie.200501496

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      Versatile intermediates for the synthesis of N-aryl-α-amino acids and N,N-disubstituted 1,2-diamines can now be synthesized with high efficiency by the ruthenium-catalyzed oxidative cyanation of tertiary amines. The use of hydrogen peroxide as an oxidant in the presence of NaCN/AcOH or HCN provides the corresponding α-aminonitriles (see reaction).

    29. Bulk Preparation of Si–SiOx Hierarchical Structures: High-Density Radially Oriented Amorphous Silica Nanowires on a Single-Crystal Silicon Nanocore (pages 6934–6937)

      Hui Wang, Xiaohong Zhang, Xiangmin Meng, Shaomin Zhou, Shikang Wu, Wensheng Shi and Shuittong Lee

      Article first published online: 7 OCT 2005 | DOI: 10.1002/anie.200501960

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      Promising building blocks: High-density radially-oriented amorphous silica nanowires standing on a single-crystal Si nanocore were synthesized by simple thermal evaporation of silicon with tin as catalyst. The growth process (see schematic picture) appears to involve concurrent vapor–liquid–solid and oxide-assisted growth mechanisms. Scanning electron micrographs corresponding to 1 and 2 are also shown.

    30. Solution-Phase Mixture Synthesis with Double-Separation Tagging: Double Demixing of a Single Mixture Provides a Stereoisomer Library of 16 Individual Murisolins (pages 6938–6940)

      Craig S. Wilcox, Venugopal Gudipati, Hejun Lu, Serhan Turkyilmaz and Dennis P. Curran

      Article first published online: 5 OCT 2005 | DOI: 10.1002/anie.200501989

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      Two tags are better than one: Sixteen individual stereoisomers of murisolin (see scheme) are synthesized together and isolated in pure form with the aid of a double-separation tagging procedure. A strategy for solution-phase stereoisomer synthesis based on double-separation tagging and double demixing is implemented with fluoroalkyl and oligoethylene glycol (OEG, (OCH2CH2)nOCH3) tags.

    31. Bond- and Site-Selective Loss of H Atoms from Nucleobases by Very-Low-Energy Electrons (<3 eV) (pages 6941–6943)

      Sylwia Ptasinska, Stephan Denifl, Paul Scheier, Eugen Illenberger and Tilmann D. Märk

      Article first published online: 5 OCT 2005 | DOI: 10.1002/anie.200502040

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      When excess charge is deposited on thymine and uracil by resonant attachment of low-energy electrons (0–3 eV), H atoms are cleaved exclusively from the N positions. This bond selectivity can be made site selective (N1 vs. N3 position) by properly tuning the electron energy. This conclusion was drawn from experiments with methylated thymine and uracil (see picture) in crossed beam experiments.

    32. Multiple Switching and Photogated Electrochemiluminescence Expressed by a Dihydroazulene/Boron Dipyrromethene Dyad (pages 6943–6947)

      Christian Trieflinger, Holger Röhr, Knut Rurack and Jörg Daub

      Article first published online: 10 OCT 2005 | DOI: 10.1002/anie.200501573

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      Optical control of the photo- and electrochemiluminescence of a brightly fluorescent reporter group is possible by switching between the photochromic units of dyads 1 a and 1 b. Irradiation, that is, writing in information, with UV light converts the highly luminescent dihydroazulene 1 a into the weakly emissive vinylheptafulvene 1 b. Readout of the system can be performed by either electrochemically generated or photogenerated luminescence.

    33. Rhodium-Mediated Formation of Peroxides from Dioxygen: Isolation of Hydroperoxo, Silylperoxo, and Methylperoxo Intermediates (pages 6947–6951)

      Marcel Ahijado, Thomas Braun, Daniel Noveski, Nikolaus Kocher, Beate Neumann, Dietmar Stalke and Hans-Georg Stammler

      Article first published online: 6 OCT 2005 | DOI: 10.1002/anie.200501615

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      Out of thin air, a rhodium complex converts molecular oxygen into hydrogen peroxide, bis(trimethylsilyl) peroxide, and methyl hydroperoxide. Intermediate η1-hydroperoxo and η1-silylperoxo, and η1-methylperoxo complexes have been isolated. Another η1-methylperoxo (see picture) and an η1-hydroperoxo complex have been characterized by X-ray crystallography.

    34. Concise Syntheses of Meridianins by Carbonylative Alkynylation and a Four-Component Pyrimidine Synthesis (pages 6951–6956)

      Alexei S. Karpov, Eugen Merkul, Frank Rominger and Thomas J. J. Müller

      Article first published online: 5 OCT 2005 | DOI: 10.1002/anie.200501703

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      In one go: (Hetero)aryl iodides, alkynes, carbon monoxide, and amidines can be assembled in a consecutive four-component reaction to give pyrimidines by a sequence of carbonylative alkynylation and cyclocondensation. Carbonylative alkynylation also is the key step in the two-step syntheses of meridianins and meridianin derivatives.

    35. Al20equation imageX10 (X=Cl, Br): Snapshots of the Formation of Metalloid Clusters from Polyhedral AlnXm Molecules? (pages 6956–6960)

      Jean Vollet, Ralf Burgert and Hansgeorg Schnöckel

      Article first published online: 10 OCT 2005 | DOI: 10.1002/anie.200500671

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      Polyhedral Al halides: Four halogen atoms directly coordinated to an Al12 icosahedron in two structurally characterized Al20 clusters indicate the mechanism of formation of Al22X20 subhalides. No Al atom is located in the center of the icosahedron in either of these icosahedral compounds!

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      Preview: Angew. Chem. Int. Ed. 42/2005 (page 6965)

      Article first published online: 25 OCT 2005 | DOI: 10.1002/anie.200590142

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