Angewandte Chemie International Edition in English

Cover image for Vol. 34 Issue 19

October 16, 1995

Volume 34, Issue 19

Pages 2069–2169

Currently known as: Angewandte Chemie International Edition

    1. Cover Picture (Angew. Chem. Int. Ed. Engl. 19/1995)

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199520671

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      The cover picture shows a ball-and-stick model of the largest discrete cluster (700 heavy atoms) ever characterized by X-ray structure analysis. This cluster containing 154 molybdenum (blue), 532 oxygen (red), and 14 nitrogen atoms (green) has a relative molecular mass of about 24000. A related cluster is shown as a polyhedral representation in the middle of the cavity of the “big wheel”. Remarkably both clusters were obtained from the same reaction solution, though not as a host-guest compound as the picture may imply. Obvious questions arise regarding template effects, for example, by a fragment of the smaller cluster, and the limits of variability in the self-assembly of materials. Further details on this impressive cluster are given by A. Müller et al. on pages 2122–2124.

  1. Reviews

    1. Top of page
    2. Reviews
    3. Highlights
    4. Communications
    5. Corrigenda
    6. Book Reviews
    1. The Conquest of Taxol (pages 2079–2090)

      Prof. Dr. Kyriacos C. Nicolaou and Rodney K. Guy

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199520791

      Total syntheses of complex natural products frequently take on the spirit of a heated battle. A commander directs his courageous and tenacious troops, discusses strategy and tactics with them, and reevaluates the situation after a setback. When the conquest is finally achieved, the triumphant are rewarded with enormous satisfaction and valuable experience. In this review a general and one of his able assistants describe the thrills and frustrations of the total synthesis of taxol. This is the second part of a trilogy of reviews by Nicolaou. The first article, “The Battle of Calicheamicin γmath image”, appeared in 1993 on p. 1377; the third, “The Odyssey to Brevetoxin”, is planned for the beginning of 1996.

    2. Cytomimetic Organic Chemistry: Early Developments (pages 2091–2106)

      Prof. Fredric M. Menger and Dr. Kurt D. Gabrielson

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199520911

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      “How do you make those cells do that?” Little wonder that a visiting scientist to the authors' laboratory mistook the giant vesicles made from commercially available chemicals for cells, since these vesicles undergo the same biological processes (fusion, fission, etc.) as living cells in response to physical or chemical stimuli. The picture on the right shows a giant vesicle “foraging”, during which it “consumes” smaller vesicles in its proximity. Since the large vesicle disintegrates by sequential ejection of lipid molecules when no further small vesicles are available, birth, growth, and death are all observable.

  2. Highlights

    1. Top of page
    2. Reviews
    3. Highlights
    4. Communications
    5. Corrigenda
    6. Book Reviews
    1. Gold in Chains: Self-Assembly of a Gold(I) Catenane (pages 2107–2109)

      Dr. Andreas Grohmann

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199521071

      Aurophilic interactions play a pivotal role in the preparation of interlocking “rings of gold”, as described recently [Angew. Chem. Int. Ed. Engl.1995, 34, 1894]. Secondary Au…Au bonding thus complements the more traditional tools of supramolecular synthesis, such as van der Waals interactions, charge-transfer interactions, and hydrogen bonding.

    2. From cyclo-Te8 to Temath image Sheets: Are Nonclassical Polytellurides More Classical than We Thought? (pages 2109–2111)

      Prof. Dr. Mercouri G. Kanatzidis

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199521091

      The importance of exploratory synthesis in advancing inorganic chemistry is exemplified by the interesting results that have been obtained in polychalcogenide chemistry. Thus, for example, Te8 rings and planar [Te6]math image layers have been found in the solid-state structure of Cs3Te22 [Angew. Chem.1995, 107, 450]. The counterions, which appear to function as templates, strongly influence the formation and structure of the products. Is this a route to polychalcogenides with defined structural features and material properties?

  3. Communications

    1. Top of page
    2. Reviews
    3. Highlights
    4. Communications
    5. Corrigenda
    6. Book Reviews
    1. Condensed RuSn6 Octahedra in Ru3Sn15O14 (pages 2113–2114)

      Doz. Dr. Werner Reichelt, Dipl.-Chem. Tilo Söhnel, Dr. Otto Rademacher, Prof. Dr. Heinrich Oppermann, Prof. Dr. Arndt Simon, Dr. Jürgen Köhler and Dr. Hansjürgen Mattausch

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199521131

      The metal-rich composition of the red-translucent title compound is in itself indicative of unusual bonding. Condensed RuSn6 octahedra are present in the structure, in which in some cases the unusual oxidation state +I can be assigned to the tin. The localization of all the bonding electrons is verified by band structure calculations and interpreted with the 18-electron rule. Accordingly, Ru3Sn15O14 is a solid-state analogue of molecular carbonyl–nitrosyl complexes.

    2. The “Submetalate” Ba17Al3O7: The First Member of a New Class of Compounds (pages 2115–2116)

      Dr. Caroline Röhr and Rita George

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199521151

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      [O7(Al2Ba17)] clusters with dialuminate cores [Al2O7]8−, which are topologically closely related to the [O3Cs11] clusters in the Cs suboxides, lie completely separated in the crystal structure of Ba17Al3O7 (together with “metallic” aluminum). Thus, in analogy to the suboxides, the metal-rich oxide can be regarded as the first member of the “submetalates”.

    3. Synthesis and Properties of First to Third Generation Dendrimers with Doubly and Triply Branched Chiral Building Blocks (pages 2116–2119)

      Dipl.-Chem. Peter Murer and Prof. Dr. Dieter Seebach

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199521161

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      Dendrimers with chiral branch components and chiral central units display remarkable CD effects. An interesting case of diastereoselectivity occurs in the synthesis of these compounds: The branch bromide 1 with (S) configuration at the four nonspecific centers can be coupled with the triol 2; the (R) branch bromide 1, on the other hand, cannot!

    4. A Hexadecanuclear Polyolatometalate of Copper(II) Ions and Multideprotonated D-Sorbitol (pages 2119–2121)

      Prof. Dr. Peter Klüfers and Dipl.-Chem. Jörg Schuhmacher

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199521191

      Unsymmetrical, multiply bridging ligands are suitable building blocks for the construction of large ligand–metal frameworks. The nonpolymeric copper(II) complex 1 containing the most copper centers to date was obtained with D-sorbitol. It contains sixfold and fourfold deprotonated sorbitol. The copper atoms form four groups, within which the atoms are antiferromagnetically coupled even at room temperature.

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    5. [Mo154(NO)14O420(OH)28(H2O)70](25 ± 5)−: A Water-Soluble Big Wheel with More than 700 Atoms and a Relative Molecular Mass of About 24000 (pages 2122–2124)

      Prof. Achim Müller, Erich Krickemeyer, Dipl.-Chem. Jochen Meyer, Dr. Hartmut Bögge, Frank Peters, Dr. Winfried Plass, Dr. Ekkehard Diemann, Dr. Stephan Dillinger, Fritz Nonnenbruch, Dipl.-Chem. Markus Randerath and Dipl.-Chem. Carsten Menke

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199521221

      Complex clusters the size of small proteins can be generated in reduced molybdate solutions by linking defined fragments. An example of this is the giant cluster (NH4)25±5[Mo154(NO)14O420(OH)28(H2O)70]·ca. 350 H2O with a molar mass of more than 30000 gmol−1, the anion of which is shaped like a tire with a nanodimensional cavity more than 20 Å in diameter and has an extremely large inner and outer surface as well as a large number of mobile electrons.

    6. A Self-Assembled Bifunctional Receptor (pages 2124–2126)

      Dr. Dmitry M. Rudkevich, Dr. Alexander N. Shivanyuk, Dr. habil. Zbigniew Brzozka, Dr. Willem Verboom and Prof. Dr. Ir. David N. Reinhoudt

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199521241

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      Complexation of Na+ ion “swithces on” the cation receptor 1, a calixarene that can form hydrogen bonds between its diamidopyridine group and a complementary group like thymine. If the latter is linked in turn to an anion receptor, for example a metalated porphyrin, a noncovalently linked bifunctional receptor results, which can complex simultaneously both the cation and the anion of an inorganic salt such as NaSCN.

    7. Porous Solids by Design: [Zn(4,4′-bpy)2(SiF6)]n·xDMF, a Single Framework Octahedral Coordination Polymer with Large Square Channels (pages 2127–2129)

      Dr. S. Subramanian and Prof. Dr. Michael J. Zaworotko

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199521271

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      Square channels with an effective cross-sectional area of 8 × 8 Å are present in the colorless crystals of [Zn(4,4′-bpy)2(SiF6)], which selfassemble from ZnSiF6 and 4,4′-bipyridine in DMF. This compound is a neutral octahedral coordination polymer, whose channels are filled with disordered DMF molecules. The picture on the right shows a section of the crystal structure.

    8. Rational Design of Orthogonal Receptor–Ligand Combinations (pages 2129–2132)

      Peter J. Belshaw, Dr. Joseph G. Schoepfer, Karen-Qianye Liu, Kim L. Morrison and Prof. Stuart L. Schreiber

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199521291

      A novel approach to understanding protein–ligand interactions is illustrated using the immunophilin receptor human cyclophilin A and its immunosuppressive ligand cyclosporin A. Synthetic chemistry is used to place “bumps” on the ligand, while site-directed mutagenesis is used to create compensatory “holes” in the receptor. These novel receptor–ligand combinations can have an affinity even greater than that of the natural system, and are expected to facilitate the inducible dimerization of target proteins, and thus the activation of signaling proteins, in transgenic animals.

    9. Strong Binding of Paraquat and Polymeric Paraquat Derivatives by Basket-Shaped Hosts (pages 2132–2134)

      Dipl.-Chem. Albertus P. H. J. Schenning, Dipl.-Chem. Bas de Bruin, Dr. Alan E. Rowan, Dr. Huub Kooijman, Dr. Anthony L. Spek and Prof. Dr. Roeland J. M. Nolte

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199521321

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      Exceptionally high binding constants Ka of up to 57000math image have been determined for the binding of paraquat and polymeric paraquat derivatives 2 in the cavities of basket-shaped host molecules 1. Host–guest complexations of this kind are of interest with respect to the modification of the physical properties of electroactive polymers, which are potential molecular switches.

    10. Formation of a “meso-Helicate” by Self-Assembly of Three Bis(catecholate) Ligands and Two Titanium(IV) Ions (pages 2134–2137)

      Dr. Markus Albrecht and Dr. Sirpa Kotila

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199521341

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      Not a chiral helicate but an achiral meso-helicate assembles from six catecholate units—bound pairwise by (CH2)3 chains—and two Ti4+ as well as four Na+ or K+ ions. NMR spectroscopic investigations at several temperatures allow the direct observation of the inversion of configuration of the chiral metal centers of the potassium salt.

    11. Radical C[BOND]C Bond Formation by Photoinduced Electron Transfer Addition of α-Silyl Carbamates to Acceptor-Substituted Alkenes (pages 2137–2139)

      Eric Meggers, Prof. Dr. Eberhard Steckhan and Prof. Dr. Siegfried Blechert

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199521371

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      α-Silyl carbamates are suitable precursors for carbon radicals. The silyl group is cleaved by photosensitized oxidative fragmentation, and the resulting radicals can add to alkenes. Equation (a) shows one example. A = acceptor, Tms = trimethylsilyl.

    12. Synthesis of the First Adducts of the Dimetallofullerenes La2@C80 and Sc2@C84 by Addition of a Disilirane (pages 2139–2141)

      Prof. Takeshi Akasaka, Prof. Shigeru Nagase, Kaoru Kobayashi, Dr. Toshiyasu Suzuki, Prof. Tatsuhisa Kato, Prof. Koichi Kikuchi, Prof. Yohji Achiba, Dr. Kazunori Yamamoto, Dr. Hideyuki Funasaka and Dr. Takeshi Takahashi

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199521391

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      Either photochemical or thermal conditions can be used to functionalize dimetallofullerene La2@C80 with a disilirane [schematic representation in Eq. (a)]. In contrast, addition of the disilirane to Sc2@C84, like the analogous addition to empty fullerenes, proceeds only photochemically. The thermal reactivity of La2@C80 is attributed to its excellent electron-acceptor properties. M = La, Sc; ○ = fullerene; Ar = 2,4,6-(CH3)3C6H2.

    13. The First Dinuclear Low-Valent Samarium Complex with a Short Sm–Sm Contact (pages 2141–2143)

      Jae-Inh Song and Prof. Dr. Sandro Gambarotta

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199521411

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      Transamination of the amidosamarium complex [{(Me3Si)2N}2Sm(tmeda)] with octaethylporphyrinogen (OEPG-H4) gives the dinuclear complex [(OEPG)Sm2(Et2O)2], which has two SmII centers and a short Sm–Sm contact. (In the structure shown on the right the Et2O ligands are omitted for clarity.)

    14. An Yttrium-Based Strong Lewis Acid for the Heterogeneous Catalysis of the Diels–Alder Reaction (pages 2143–2145)

      Alive Keshavaraja, Vishnumurthy R. Hegde, Dr. Bipin Pandey, Dr. Arumugamangalam V. Ramaswamy, Dr. Pradeep Kumar and Dr. T. Ravindranathan

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199521431

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      Excellent endo:exo selectivities can be achieved in heterogeneously catalyzed Diels-Alder reactions, even in the case of dienophiles such as 1-3 with cyclopentadiene. The key to the success is a new yttrium-based, strong Lewis acid catalyst, whose synthesis and characterization is described.

    15. Enantioselective Reduction of Ketones with Sodium Borohydride, Catalyzed by Optically Active (β-Oxoaldiminato)cobalt(II) Complexes (pages 2145–2147)

      Takushi Nagata, Dr. Kiyotaka Yorozu, Dr. Tohru Yamada and Prof. Dr. Teruaki Mukaiyama

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199521451

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      Asymmetric reduction of prochiral ketones with sodium borohydride proceeds in the presence of catalytic amounts of optically active β-oxoaldiminatocobalt(II) complexes 1 to the corresponding optically active secondary alcohols in high chemical yields with high enantioselectivities (68–94% ee).

    16. Octacationic Cyclophanes: Binding of ATP and Other Anionic Guests in Water (pages 2147–2150)

      Prof. Fredric M. Menger and Dr. Kelly K. Catlin

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199521471

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      Macrocyclic host molecule 1 with eight quaternary nitrogen atoms within the ring can bind anionic guests (including ATP) in aqueous media. X-ray structure analyses and NMR studies show that the guests do not enter the cavity; instead they associate with the host externally through a surprisingly efficient ion-exchange mechanism.

    17. Temperature and Solvent Effect on the Nucleophilic Addition of n-Butyllithium to the N-(Trimethylsilyl)imine of (2S)-Lactal (pages 2150–2152)

      Prof. Dr. Gianfranco Cainelli, Dr. Daria Giacomini and Dr. Martin Walzl

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199521501

      Are the Felkin–Ahn and Cram chelate models reliable? These models predict asymmetric induction without consideration of solvent and temperature. However, the addition of n-butyllithium to the N-(trimethylsily)imine of (2S)-lactal leads to syn/anti ratios between 98:2 and 28:72 when performed in different solvents and at different temperatures. The reaction appears to be the first example of nucleophilic addition that follows the isoinversion principle (isoinversion temperature Ti = −21 °C). This indicates a stepwise process with at least two diastereoselective steps that are affected differently by temperature and solvent.

    18. Influence of Lewis Base Complexation and the Degree of Aggregation of Alkyllithium Compounds on the Ration in Which They Form Addition Products and Enolates with Ketones (pages 2152–2153)

      Dr. Ing. Hendrikus Luitjes, Dr. Marius Schakel, Robert F. Schmitz and Prof. Dr. Gerhard W. Klumpp

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199521521

      The difference between 1 and 2 lies only in the number of nitrogen atoms and not in the carbanionic unit. Since 1, which is a tetramer, reacts with ketones to form adducts almost exclusively, but 2 virtually only enolates, the type of product formed is linked to the degree of aggregation, which in turn depends on the Lewis base.

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    19. A Concise Synthetic Route to Cyclopentenes by [3 + 2] Cycloaddition of Dipolar Trimethylenemethane to Alkynes (pages 2154–2156)

      Dr. Shigeru Yamago, Satoshi Ejiri and Prof. Eiichi Nakamura

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199521541

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      A purely thermal reaction under neutral conditions, the trimethylene compound 2 is generated in situ from 1 and transformed with an alkyne into the cyclopentene derivatives 3. EWG [DOUBLE BOND] CO2Me, CO2iPr.

    20. N-Hydroxypyridinethiones as Photochemical Hydroxyl Radical Sources for Oxidative DNA Damage (pages 2156–2158)

      Prof. Dr. Waldemar Adam, Dipl.-Chem. Daniel Ballmaier, Prof. Dr. Bernd Epe, Dipl.-Chem. Günther N. Grimm and Dr. Chantu R. Saha-Möller

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199521561

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      On irradiation with UV light (λ = 350 nm) the N-hydroxypridinethiones 1 and 2 generate hydroxyl radicals, which cause single-strand breaks and base modifications in calf thymus DNA and superhelical PM2 DNA. The para isomer 2 is significantly more genotoxic than the known antibacterial and fungicidal reagent pyridinethione 1.

    21. Generation of Enantiomerically Enriched Lithium Indenides by Means of (–)-Sparteine: Structure, Stereoselective Substitution, and Solvent Effects (pages 2158–2160)

      Dr. Inga Hoppe, Michael Marsch, Dr. Klaus Harms, Prof. Dr. Gernot Boche and Prof. Dr. Dieter Hoppe

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199521581

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      The thermodynamically controlled equilibration of the configurationally labile diastereomeric lithium 1-alkylindenide/(–)-sparteine complexes in diethyl ether/hexane combined with the crystallization of the diastereomer shown (1; R = Me, nBu) results in a stereoselective addition of these complexes to carbonyl compounds with enantiofacial differentiation at the indenide moiety. In THF/hexane, however, the solvent displaces the chiral ligand and leads to complete racemization of the products.

    22. Additions of Carbanions to a Cationic Cyclopentadienyl(naphthalene)iron Complex (pages 2161–2163)

      Prof. Dr. Ernst Peter Kündig, Dr. Patrick Jeger and Dr. Gérald Bernardinelli

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199521611

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      A simple change in the substitution pattern of the naphthalene ligand can effectively alter the reaction pathway: the reaction of [Cp(naphthalene)Fe]PF6 with carbon nucleophiles results in reduction of the Fe center, but complex 1 reacts with PhLi by nucleophilic addition at the condensed arene. When tBuLi is used as the nucleophile, addition to the Cp ring of 1 giving 2 is observed instead.

    23. Highly Effective Hydrogen-Bonding Receptors for Guanine Derivatives (pages 2163–2165)

      Prof. Thomas W. Bell, Zheng Hou, Prof. Steven C. Zimmerman and Paul A. Thiessen

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199521631

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      In the complexation of neutral organic molecules, preorganization of the receptors can play a crucial role, as studies on a new series of hydrogen-bonding receptors demonstrate. The receptor shown in the complex on the right binds guanine derivatives in [D6]DMSO/CDCl3 (1/4) with a stability constant (Ka) greater than 1.9 × 105M−1. In comparison, a complex with a more flexible host and the same number of primary hydrogen-bonding sites is at least 4.1 kcalmol−1 less stable.

  4. Corrigenda

    1. Top of page
    2. Reviews
    3. Highlights
    4. Communications
    5. Corrigenda
    6. Book Reviews
    1. You have free access to this content
      Corrigendum (page 2165)

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199521651

  5. Book Reviews

    1. Top of page
    2. Reviews
    3. Highlights
    4. Communications
    5. Corrigenda
    6. Book Reviews