Angewandte Chemie International Edition in English

Cover image for Vol. 34 Issue 21

November 17, 1995

Volume 34, Issue 21

Pages 2301–2421

Currently known as: Angewandte Chemie International Edition

    1. Cover Picture (Angew. Chem. Int. Ed. Engl. 21/1995)

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199522991

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      The cover picture shows not skydivers, but molecules of trimethylisocyanurate linked with CHċO hydrogen bonds in the layered hexagonal crystal structure of the 1:1 complex formed by this substance with 1,3,5-trinitrobenzene. But supramolecular patterns in crystals resemble the aerial patterns formed by skydivers in that properties of the group are distinct from those of the individual constituents. In this sense, a crystal of an organic compound is the perfect supermolecule and crystal engineering, which is the deliberate design of crystal structures of organic compounds, is the supramolecular equivalent of organic synthesis. By defining a “supramolecular synthon” as a building block that incorporates both chemical and geometrical features of sets of intermolecular interactions, the conceptual similarity between crystal engineering and classical organic synthesis is uncovered. This striking parallel is discussed by G. R. Desiraju on pp. 2328.

  1. Reviews

    1. Top of page
    2. Reviews
    3. Highlights
    4. Communications
    5. Book Reviews
    1. Supramolecular Synthons in Crystal Engineering—A New Organic Synthesis (pages 2311–2327)

      Prof. Gautam R. Desiraju

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199523111

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      The synthesis of structurally and functionally complex supramolecular compounds from simple building blocks is a particular challenge. Template-controlled, multistep processes in homogeneous solution (see Scheme) are of great use for this synthesis. The chemistry of, for example, intercalation compounds, silicates with framework structures like zeolites, or polyoxometalates offers ample illustrative material for a blossoming branch of inorganic chemistry.

    2. Supramolecular Inorganic Chemistry: Small Guests in Small and Large Hosts (pages 2328–2361)

      Prof. Dr. Achim Müller, Prof. Dr. Hans Reuter and Dipl.-Chem. Stephan Dillinger

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199523281

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      The retrosynthetic analysis of a crystal structure is the first step towards the design of solid-state targets. The procedure provides supramolecular synthons (for instance, [BOND]NO2ċI[BOND], see scheme below), which should be understood as spatial arrangements of intermolecular interactions. This type of synthon plays the same focusing role in the synthesis of solids as the conventional synthon in classical organic synthesis. Therefore, supramolecular synthons are accessible structural units that can be linked to form the target supermolecule.

  2. Highlights

    1. Top of page
    2. Reviews
    3. Highlights
    4. Communications
    5. Book Reviews
    1. New Brain Lipids that Induce Sleep (pages 2363–2364)

      Dr. Thomas Kolter and Prof. Dr. Konrad Sandhoff

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199523631

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      Amide 1 is not the universal sleep-inducing substance, and no appropriate receptors have been found in the brain, but naturally occuring 1 does induce sleep. Compound 1 was found in the cerebrospinal fluid of sleep-deprived animals. Recent research on this compound and others with similar effects have led to a better understanding of the phenomenon of sleep, at least on a molecular level.

    2. Aligning and Trapping Molecules with Light (pages 2365–2366)

      Dr. Lothar Kador

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199523651

      An alternative to matrix isolation, cold molecules can be trapped and aligned in vacuum by an intense infrared laser field according to theoretical considerations expounded recently. The method is based on the polarization of the molecules by the electric field of the light, which creates an attractive potential. If the polarizability of the molecules is anisotropic, the axis of highest polarizability will be aligned along the polarization direction of the laser.

  3. Communications

    1. Top of page
    2. Reviews
    3. Highlights
    4. Communications
    5. Book Reviews
    1. para- and ortho-Quinodimethane Intermediates with Cumulative Double Bonds (pages 2367–2368)

      Prof. Dr. Henning Hopf, Prof. Dr. Peter G. Jones, Dipl.-Chem. Peter Bubenitschek and Christian Werner

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199523671

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      The highly reactive intermediates 1 and 2 with cumulative double bonds in para and ortho positions, respectively, react to give products with isolated triple bonds. Intermolecular dimerization of 1 yields a paracyclophanetetrayne, which assumes two conformations in the crystal. Compound 2 reacts by intramolecular cyclization affording a highly strained cycloocta-3-ene-1,5-diyne derivative.

    2. A Simple Route to the 1-Aza-3-Phosphaallyl System: Structure of a Dimeric Lithium Complex and Protonation to Give the First NH2-Substituted Phosphaalkene (pages 2369–2371)

      Dipl.-Chem. Karin Paasch, Dr. Martin Nieger and Prof. Dr. Edgar Niecke

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199523691

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      Lithium phenyl phosphanide and acetonitrile react readily to give the lithium complex 1. The compound crystallizes as a dimer and can be converted by protonation into the thermally stable phosphaalkene 2. This in turn could be suitable for the synthesis of heteropolyenes.

    3. Metal Complexes of N-Heterocyclic Carbenes—A New Structural Principle for Catalysts in Homogeneous Catalysis (pages 2371–2374)

      Prof. Dr. Wolfgang A. Herrmann, Martina Elison, Jakob Fischer, Christian Köcher and Georg R. J. Artus

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199523711

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      Stabilized by “carbene” donor ligands, the Pd complex 1 catalyzes the Heck olefination of aryl halides unexpectedly efficiently and yet has long-term stability at elevated temperatures. The active Pd0 species can be generated during the Heck reaction or deliberately prepared by reduction of 1 with, for instance, hydrazine or sodium formate. Another similar catalyst can be synthesized in situ from Pd0 complexes and 1,3-dimethyldihydroimidazoline-2-ylidene.

    4. Self-Assembly of Polyanions at a Metal Cation Template: Syntheses and Structures of [{Ag([18]aneS6)}I7]n and [Ag([18]aneS6)]I3 (pages 2374–2376)

      Dr. Alexander J. Blake, Dr. Robert O. Gould, Dr. Simon Parsons, Dr. Christian Radek and Prof. Dr. Martin Schröder

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199523741

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      A distorted cubic lattice of Imath image ions, in whose cavities the complex cations [Ag([18]aneS6)]+ ([18]aneS6 = 1,4,7,10,13,16-hexathiacyclooctadecane) are encapsulated, is formed in the synthesis of 1 (section of structure shown on the right). I ions are positioned at the lattice points; one I2 molecule is located along each edge. The Ag+ ions function as a secondsphere template in the synthesis of the Imath image polyanion.

    5. Alkali Metallocene Anions: Syntheses and Structures (pages 2376–2378)

      Dipl.-Chem. Jens Wessel, Dr. Enno Lork and Prof. Dr. Rüdiger Mews

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199523761

      The breakdown of the polymeric structure of alkali metal cyclopentadienides can be achieved by (Me2N)3S+ Cp [(TAS)Cp]. This leads to the salts TAS+[Cp2M] (M[DOUBLE BOND]Li, Na, K). On the other hand, [TAS2Cp]+[Cp2M] salts are obtained if this reaction is carried out in the molar ratio 2:1, the structure analysis of the Na compound shows that sandwich and inverse sandwich units are present side by side.

    6. Kinetic Selection in the Template-Directed Self-Assembly of [2]Catenanes (pages 2378–2380)

      Dr. David B. Amabilino, Peter R. Ashton, Dr. Lluïsa Pérez-García and Prof. J. Fraser Stoddart

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199523781

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      A kinetic template effect directs selection in competitive self-assembly of tetracationic cyclophanes (represented by a circle) containing meta- or para-linked 4,4′-bipyridinium and/or bis(4-pyridinium)ethylene units in the presence of competing crown ether templates (represented by a square or a triangle). The cyclophane fragments first couple covalently to form an intermediate (represented by an arc), and then the molecular recognition event strings the crown ether before the rate-determining second covalent bond formation closes the ring.

    7. A Molecular Composite Containing Organic and Inorganic Components—A Complex from β-Cyclodextrin and Hydrated Magnesium Chloride (pages 2381–2383)

      Dr. Ioannis Nicolis, Dr. Anthony W. Coleman, Dr. Pierrette Charpin and Dr. Colette de Rango

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199523811

      Two interlocking substructures–infinite chains of β-cyclodextrin monomers and [Mg(H2O)6]Cl2 building blocks–form the basis of a novel composite. The chains of inorganic components, comprising Mg(H2O)6 octahedra linked through Cl anions and water of crystallization, are threaded through the cavities of the cyclodextrins. The complete structure is stabilized by hydrogen bonds.

    8. Radical Additions to (η6-Arene)(tricarbonyl)-chromium Complexes: Diastereoselective Synthesis of Hydrophenalene and Hydrobenzindene Derivatives by Samarium(II) Iodide Induced Cyclization (pages 2383–2385)

      Prof. Dr. Hans-Günther Schmalz, Dipl.-Chem. Stephan Siegel and Dr. Jan W. Bats

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199523831

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      Yes indeed, radical additions to arene-Cr(CO)3 complexes are possible. Treatment of the chiral complex 1 with SmI2 gives tricycle 2 selectively by a 5-endo-trig radical cyclization; dihydro-1 is converted into the demethoxylated complex 3. In the latter case the ketyl radical adds directly to the complexed arene.

    9. A New Platform for Designing Ligands for Asymmetric Induction in Allylic Alkylations (pages 2386–2388)

      Prof. Barry M. Trost, Bernhard Breit, Stefan Peukert, Jorge Zambrano and Joseph W. Ziller

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199523861

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      Simply inverting the orientation of the amide function as in 1 compared to that of the ligand series derived from 2-diphenylphosphinobenzoic acid affects the enantiomeric discriminating step in the Pd-catalyzed nucleophilic alkylation of meso-1,4-dihydroxy-2-cycloalkenes. In reactions such as this, the bond-making or -breaking event occurs outside the coordination sphere of the metal. The chiral scaffold of the ligand is connected to the metal atom by a linker (here 2-diphenylphosphinoaniline), and the preferred conformation of the catalysts provides “chiral spaces” for the substrate–a conclusion supported by X-ray crystallography.

    10. Peripherally Substituted Cobaloximes; X-ray Crystal Structure Analysis of σ-Hexylbis[1,8-di(N-morpholino)octane-4,5-dioximato]pyridinecobalt(III) (pages 2389–2390)

      Berthold Köhler, Dr. Martin Knauer, Prof. Dr. William Clegg, Dr. Mark R. J. Elsegood, Prof. Dr. Bernard T. Golding and Prof. Dr. János Rétey

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199523891

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      Unexpected eliminations defeated attempts to synthesize alkylcobaloximes substituted with α- and β-heteroatoms. However, synthesis of the γ-substituted alkylcobaloxime 1, a functionalized coenzyme B12 model, was successful in only a few steps. The key step was an acyloin condensation for the preparation of the dioxime ligand.

    11. Synthesis of D-(+)-Biotin through Selective Ring Closure of N-Acyliminium Silyl Enol Ethers (pages 2391–2393)

      Marinus J. Moolenaar, Prof. Dr. W. Nico Speckamp, Dr. Henk Hiemstra, Dr. Eike Poetsch and Dr. Michael Casutt

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199523911

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      Irrespective of the geometry of the double bond the configuration of the newly formed chiral center is established by the existing adjacent stereogenic center in the Lewis acid catalyzed cyclization of the N-acyliminium silyl enol ether intermediate 1. This step is the key transformation in a new, concise total synthesis of D-( + )-biotin. R [DOUBLE BOND] protecting group.

    12. Lactendiynes: A New Class of Triggered Cyclic Enediynes (pages 2393–2395)

      Dr. Luca Banfi and Prof. Giuseppe Guanti

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199523931

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      A promising prodrug, the stable cyclic enediyne 1, unleashes a reactive, potentially DNA-damaging enediyne when the β-lactam group is hydrolyzed under basic conditions. This intermediate rapidly undergoes cycloaromatization giving a phenylene diradical, which can be trapped by 1,4-cyclohexadiene. R1, R2 [DOUBLE BOND] OMe, H.

    13. Highly Enantioselective Opening of Cyclic meso-Anhydrides to Isopropyl Hemiesters with Diisopropoxytitanium TADDOLates (pages 2395–2396)

      Prof. Dr. Dieter Seebach, Dipl.-Chem. Georg Jaeschke and Dr. Yan Ming Wang

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199523951

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      The Lewis acid mediated transfer of an alkoxide ligand from the chiral ligand sphere of 1 facilitates the highly enantioselective ring-opening of cyclic CS-symmetric anhydrides 2 to the corresponding hemiesters 3 with enantiomer ratios up to 99:1. This ability to transfer ligands could make 1 an organometallic alternative to hydrolytic enzymes, as the differntiation of enantiotopic functional groups in meso compounds and the resolution of racemic substrates should be possible.

    14. Total Synthesis of Natural (+)-SF 2315A and Determination of the Absolute Configuration (pages 2396–2398)

      Kyungjin Kim and Prof. Gary A. Sulikowski

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199523961

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      An angucycline antibiotic with a nonaromatic B ring, (+)-SF 2315A (3), was synthesized enantioselectively for the first time. A key transformation in the 23-step reaction sequence, which starts from (−)-quinic acid, is the stereocontrolled Diels-Alder reaction between diene 1 and bromojuglone 2. TIPS = triisopropylsilyl.

    15. Evidence for a Mechanism Involving Transient Fragmentation in Carbon Skeleton Rearrangements Dependent on Coenzyme B12 (pages 2398–2401)

      Dr. Birgitta Beatrix, Dr. Oskar Zelder, Dr. Friedrich K. Kroll, Gissur Örlygsson, Prof. Dr. Bernard T. Golding and Prof. Dr. Wolfgang Buckel

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199523981

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      Enzyme kinetics and EPR spectroscopy provide evidence that in the reversible rearrangement of (S)-glutamate (1) to (2S, 3S)-3-methylaspartate (2), which is catalyzed by the coenzyme B12 dependent glutamate mutase from Clostridium cochlearium, the substrate 1 fragments into acrylate (3) and glycine radical (4), which recombine to 2. Ado-CH2-Cbl [DOUBLE BOND] 5′-adenosylcobalamin (coenzyme B12).

    16. Asymmetric Pictet–Spengler Reactions Employing N,N-Phthaloyl Amino Acids as Chiral Auxiliary Groups (pages 2402–2403)

      Prof. Dr. Herbert Waldmann, Dipl.-Chem. Gunther Schmidt, Dr. Henning Henke and Dr. Michael Burkard

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199524021

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      Both aromatic and aliphatic Schiff bases 1 can be cyclized asymmetrically in the presence of titanium alkoxides if N,N-phthaloyl-protected amino acids are employed as chiral auxiliaries. The desired heterocycles 3, which are suitable for alkaloid syntheses, are formed with diastereomer ratios of up to 99%. R [DOUBLE BOND] nPr, iPr; R1 [DOUBLE BOND] Me, Et, iPr, Ph, Ar; R2 [DOUBLE BOND] Me, iPr, tBu.

    17. A Comparison of Enthalpies of Formation in Solution and Enthalpies for HPLC Retention for Hydrogen-Bonded Host—Guest Complexes (pages 2404–2406)

      Prof. Steven C. Zimmerman and Dr. Wing-Sum Kwan

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199524041

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      From the temperature-dependent HPLC retention of a guest or host on a chemically bonded stationary phase containing the complementary component (as shown schematically on the right), the complexation enthalpies of a series of hydrogen-bonded host-guest complexes can be rapidly and conveniently determined. The ΔH̊ values determined in this way agree within experimental error with the complexation enthalpies measured in free solution by traditional methods.

    18. Phosphorothioates: β-Fragmentation versus β-Silicon Effect (pages 2406–2409)

      Dr. Achim H. Krotz, Patrick Wheeler and Dr. Vasulinga T. Ravikumar

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199524061

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      β-Silylethoxy-protected phosphoramidites are useful reagents for the synthesis of O,O,O-trialkylphosphorothioates of type 1 in solution, which are interesting as building blocks for antisense oligonucleotides. Trialkylsilyl substituents in the β-position promote rapid thiono–thiolo rearrangement through neighboring group participation (β-silicon effect). Selective deprotection under mild conditions through β-fragmentation yields only O,O-dialkylphosphorothioates. T [DOUBLE BOND] N1-thyminyl.

    19. Direct Electrochemical Coupling of Components of the Biological Electron Transfer Chain to Modified Surfaces: Molecular Recognition between Cytochrome c Peroxidase and Cytochrome c (pages 2409–2411)

      Dr. Li Jiang, Dr. Calum J. McNeil and Dr. Jonathan M. Cooper

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199524091

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      Electron transfer between two heme proteins can be readily observed if one of the proteins is immobilized on an electrode. The signal transduction following the molecular recognition occurs at the phase interface, as it does in nature, and can be directly monitored by cyclic voltammetry. The picture shows schematically the course of the reaction for the example of immobilized cytochromec.

    20. Hydrolysis of a Phosphate Diester Doubly Coordinated to a Dinuclear Cobalt(III) Complex: A Novel Mechanism (pages 2412–2414)

      Daphne Wahnon, Anne-Marie Lebuis and Prof. Jik Chin

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199524121

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      Nucleophilic attack of the bridging oxo ligand is the key step in the hydrolysis of the bridging phosphate diester in complex 1. This hydrolysis is 1012 times faster than the hydrolysis of the free phosphate diester. Thus, the phosphate-free Co complex is an interesting model of enzymes having two metal atoms in the active site.

    21. A Framework Containing Ga-O-Ga Links: The Synthesis and Structure of Gallobicchulite Ca8(Ga2SiO6)4(OH)8 (pages 2414–2416)

      Dr. Sandra E. Dann, Philip J. Mead and Prof. Mark T. Weller

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199524141

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      Ca8[Ga2SiO6]4(OH)8 is the first gallosilicate containing Ga-O-Ga links. The gallium-rich compound crystallizes in a sodalite structure, in which the number of Ga-O-Ga links is minimized, according to Löwenstein's rule, by surrounding each SiO4 tetrahedron by four GaO4 tetrahedra. The hydroxide ions present in the sodalite cage are disordered and form weak hydrogen bonds with the framework oxygen atoms (depicted on the right).

    22. The Nonaaquabismuth(III) Cation (pages 2416–2417)

      Prof. Dr. Walter Frank, Dipl.-Chem. Guido J. Reiss and Dipl.-Chem. Jürgen Schneider

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199524161

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      The first aqua complex of an element of group 15, namely the [Bi(H2O)9]3+ ion (shown on the right) in bismuth(III) trifluoromethanesulfonate enneahydrate, has been detected. Hence the last gap in the systematics of aqua complexes of main group metals has been closed. The central Bi3+ ion in the C3h-symmetric coordination polyhedron–a tricapped trigonal prism—shows no recognizable stereochemical activity of the lone pair of electrons in the solid state.

  4. Book Reviews

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