Angewandte Chemie International Edition in English

Cover image for Vol. 34 Issue 16

September 1, 1995

Volume 34, Issue 16

Pages 1661–1773

Currently known as: Angewandte Chemie International Edition

    1. Cover Picture (Angew. Chem. Int. Ed. Engl. 16/1995)

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199516591

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      The cover picture shows the key palladium-catalyzed steps in total syntheses of the natural products taxol and dynemicin A, which have fascinated syntheic chemists the past few years. The success of the total synthesis of taxol hinged on a Pd-catalyzed heck reaction, and that of dynemicin A relied on the Pd-induced cross-coupling of a bis(iodoethynyl) intermediate with (Z)-bis(trimetylstannyl)ethene. Although these were not the first total syntheses of the targets, the strategies and tactics of the “Danishefsky syntheses” are certainly worth a close look (see p. 1721 ff). The era of natural products synthesis appears not to have reached its zenith yet!

  1. Reviews

    1. Top of page
    2. Reviews
    3. Highlights
    4. Communications
    5. Book Reviews
    1. Scalar Coupling Constants—Their Analysis and Their Application for the Elucidation of Structures (pages 1671–1695)

      Dr. Matthias Eberstadt, Dr. Gerd Gemmecker, Prof. Dr. Dale F. Mierke and Prof. Dr. Horst Kessler

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199516711

      The renaissance of NMR coupling constants in the last few years is well founded: modern techniques have made more accurate values more readily available even in difficult cases, and their application in conformational analysis by NMR spectroscopy has increased dramatically thanks to the rapid developments in the field of isotopic labeling of biopolymers and in comoputing. This review focuses on the large number of new measurement techniques and computational methods developed recently for the determination and evaluation of coupling constants.

    2. Thermotropic Liquid Crystals Formed by Intermolecular Hydrogen Bonding Interactions (pages 1696–1711)

      Dr. Constantinos M. Paleos and Dr. Dimitris Tsiourvas

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199516961

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      Molecular recognition can be seen on the macroscopic level when amphiphiles with complementary groups form liquid-crystalline phases (illustrated schematically below for the formation of a columnar mesomorphic structure). The pairing of nucleobases in DNA through hydrogen bonding serves as a model for this type of association. Various classes of compounds can form liquid crystals, for example, the two-component complexes of pyridines with carboxylic acids, and self-assembled complexes of polyhydroxy compounds. A complete understanding of the structures of the mesogenic complexes is needed before the phase behavior can be controlled.

  2. Highlights

    1. Top of page
    2. Reviews
    3. Highlights
    4. Communications
    5. Book Reviews
    1. Two at One Blow: The New Chemical Elements 110 and 111 (pages 1713–1717)

      Prof. Dr. Günter Herrmann

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199517131

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      Superheavy platinum and gold—the elements 110 and 111—were generated by nuclear fusion of nickel with lead or bismuth in November/December 1994 at the Darmstadt heavy-ion accelerator and were unequivocally identified from their α-decay into known atomic nuclei. The picture shows this explored end of the nuclide chart. Unexpectedly high production rates and sufficiently long half-lives suggest that still heavier elements can be created and detected.

    2. Catalytic Asymmetric Carbonyl–Ene Reactions (pages 1717–1719)

      Dr. David J. Berrisford and Prof. Dr. Carsten Bolm

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199517171

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      Practical options for catalytic and enantioselective C[BOND]C bond formation have been extended by recent developments reported by the Carreira and Mikami groups in reactions of aldehydes with alkenes containing an allylic H atom [Eq. (a)]. These studies link two fascinating and topical areas of organic synthesis—carbonyl–ene chemistry and the use chiral Lewis acids.

  3. Communications

    1. Top of page
    2. Reviews
    3. Highlights
    4. Communications
    5. Book Reviews
    1. Total Synthesis of (±)-Dynemicin A (pages 1721–1723)

      Matthew D. Shair, Tae-young Yoon and Prof. Samuel J. Danishefsky

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199517211

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      Pivotal steps in the total synthesis of the enediyne antibiotic dynemicin A are (1) a palladium-mediated double cross-coupling reaction to construct the enediyne array, and (2) cycloaddition of a quinone imine with the anion of a suitably protected homophthalic anhydride followed by oxidation in air to fashion the anthraquinone moiety.

    2. A Total Synthesis of Taxol (pages 1723–1726)

      John J. Masters, J. T. Link, Lawrence B. Snyder, Wendy B. Young and Prof. Samuel J. Danishefsky

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199517231

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      The intramolecular Heck reaction of 1 to 2 is the cornerstone of this total synthesis of taxol (see conversion below). The route starts with the (S)-Wieland Miescher ketone, and the oxetane ring is installed early in the synthesis. Elaboration to a CD ring fragment, addition of an A ring nucleophile, and further manipulations yield the appropriate starting material (1) for the Heck reaction. After this key step yielding 2, the synthesis of baccatin III (and thence taxol) concludes with the cleavage of the exo double bond at C-10 and oxygenation at C-9 and C-13.

    3. Asymmetric Reaction of Arylalkenes with Diselenides (pages 1726–1728)

      Dr. Thomas Wirth

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199517261

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      The diastereoselective functionalization of non-activated arylalkenes can be achieved with simple chiral diselenides 1. In these reactions, diastereoselectivities of up to 88% de were reached. The attractive synthetic building blocks 2 are readily accessible in this way.

    4. New Fluorescent Model Compounds for the Study of Photoinduced Electron Transfer: The Influence of a Molecular Electric Field in the Excited State (pages 1728–1731)

      Dr. A. Prasanna de Silva, Dr. H. Q. Nimal Gunaratne, Dr. Jean-Louis Habib-Jiwan, Dr. Colin P. McCoy, Terence E. Rice and Prof. Jean-Philippe Soumillion

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199517281

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      The location of the “spacer–receptor” unit in a 4-aminonaphthalimide fluorophore, which undergoes internal charge transfer in the excited state, is crucial for the suitability of the compound as a pH sensor. In studies of the pH dependence of the fluorescence of the regioisomers 1 and 2, only 1 displayed desirable properties.

    5. Intramolecular Allylsilane Addition to Chiral Alkylidene-1,3-dicarbonyl Compounds for the Synthesis of Enantiomerically Pure trans-1,2-Disubstituted Cyclopentanes and Cyclohexanes (pages 1731–1733)

      Prof. Dr. Lutz F. Tietze and Dipl.-Chem. Christian Schünke

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199517311

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      Three new stereogenic centers characterize the 1,2-trans-disubstituted cyclopentanes 2a and cyclohexanes 2b, which can be prepared enantiomerically pure with the Lewis acid SnCl4 in a highly selective SnCl4-induced cyclization of the chiral alkylidene malonic acid derivatives 1a and 1b, respectively. The chiral auxiliary can be removed from 2 with LiAlH4.

    6. A Phycocyanobilin Seryliminoester as a New Model for the Chromophore–Protein Interaction in Phytochrome (pages 1733–1735)

      Dipl.-Ing. Ronald Micura and Univ.-Doz. Dr. Karl Grubmayr

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199517331

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      The new phytochrome model compound 1 is characterized by the covalent linkage of a serine side chain with the ring-A lactam of the phycocyanobilin chromophore. The model readily explains the absorption properties, ensures photoreversibility, and offers the possibility for thermal back reaction.

    7. Calculation of the Thermodynamic Properties of Polycyclic Aromatic Hydrocarbons by an Incremental Procedure (pages 1735–1736)

      Dr. Karen Nass, Prof. Dr. Dieter Lenoir and Prof. Dr. Antonius Kettrup

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199517351

      The relationship between molecular structure and vapor pressure was studied for polycyclic aromatic hydrocarbons. The recognition of defined structural features enables the thermodynamic properties to be calculated, and the results agree well with experimental data.

    8. The First Olefin-Substituted Peroxomolybdenum Complex: Insight into a New Mechanism for the Molybdenum-Catalyzed Epoxidation of Olefins (pages 1737–1738)

      Dr. Werner R. Thiel and Dipl.-Chem. Thomas Priermeier

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199517371

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      What is the source of the epoxide oxygen in the Mo-catalyzed epoxidation of olefins? The olefinic side chain [BOND]CH2CH[DOUBLE BOND]CH2[BOND] of the isolated complex 1 (structure shown on the right) is epoxidized only on addition of hydroperoxides. Thus in complex 1, in contrast to previously proposed mechanisms for the title reaction, an oxygen atom from the η2-peroxo ligand is not transferred to the olefin.

    9. Design of Novel, Nonpeptidic Thrombin Inhibitors and Structure of a Thrombin–Inhibitor Complex (pages 1739–1742)

      Dipl.-Chem. Ulrike Obst, Dr. Volker Gramlich, Prof. François Diederich, Dr. Lutz Weber and Dr. David W. Banner

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199517391

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      A strong inhibition of the serine protease thrombin, important in the blood coagulation process, was achieved through de novo designed inhibitors. The most active compound is shown. The X-ray crystal structure of the thrombin–inhibitor complex showed the binding mode of these compounds and confirmed that only the enantiomer predicted by computer modeling was bound in the active site.

    10. σ Metathesis as a Critical Step for the Transition Metal Catalyzed Formation of Formic Acid from CO2 and H2? An Ab Initio Investigation (pages 1742–1745)

      François Hutschka, Dr. Alain Dedieu and Dr. Walter Leitner

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199517421

      The hydrogenation of CO2 to formic acid catalyzed by three-coordinate d8 hydridorhodium complexes has been studied by ab initio calculations on [HRh(PH3)2] as the model catalyst. A catalytic cycle involving a 2σ + 2σ metathesis reaction between H2 and [Rh(PH3)2(O2CH)], in which rhodium remains in the oxidation state I, is proposed as an alternative to the traditional pathway involving RhI/RhIII oxidation/reduction sequences.

    11. Designed Assemblies in Open Framework Materials Synthesis: An Interrupted Sodalite and An Expanded Sodalite (pages 1745–1747)

      Pingyun Feng, Dr. Xianhui Bu and Prof. Dr. Galen D. Stucky

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199517451

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      Structure-directing hydrogen bonding, the molecular symmetry of the guest, and charge matching between host and guest are used to assemble four-ring units into sodalite-type cage assemblies with the imposition of the molecular symmetry of the template (guest) onto the final framework structure. Variable charge matching with PPZ+ or PPZ2+ (mono- and diprotonated piperazine, respectively) is shown to give interrupted and expanded sodalite-type zincophosphate structures (shown on the right).

    12. Synthesis of dTDP-6-Deoxy-4-ketoglucose and Analogues with Native and Recombinant dTDP-Glucose-4,6-dehydratase (pages 1748–1749)

      Dipl.-Chem. Andreas Stein, Prof. Dr. Maria-Regina Kula, Dr. Lothar Elling, Dipl.-Biol. Stefan Verseck and Dr. Werner Klaffke

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199517481

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      The enzymatic deoxygenation of dTDP-glucose and two 3-deoxy analogues [Eq. (a)] is now possible on a preparative scale with dTDP-D-glucose-4,6-dehydratase. In addition a highly selective HPLC method for the separation of structurally related activated sugars has been developed. This should provide new impetus for structure–function studies of deoxysugars and further elucidation of their biosynthetic pathways. R [DOUBLE BOND] OH, H, N3; dTDP = thymidine-5′-diphosphate.

    13. Estramycins: A New Diyl Precursor Family Derived from Estradiol (pages 1749–1752)

      Dr. Jing Wang and Prof. Dr. Pierre J. De Clercq

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199517491

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      The protected enediyne 1 is the first example of an estramycin, a new family of potential anticancer antibiotics, derived from estradiol. Important for therapeutic applications is the cyclization of the enediyne unit, which proceeds via a diradical intermediate. R1 [DOUBLE BOND] R3 [DOUBLE BOND] Ac; R2 [DOUBLE BOND] SiMe3.

    14. Substituent-Controlled Reactions of Iminophosphoranes with Methyllithium (pages 1752–1755)

      Dr. Alexander Steiner and Priv.-Doz. Dr. Dietmar Stalke

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199517521

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      Totally different reactivity is observed in the reactions of the two isoelectronic iminophosphoranes Py3P [DOUBLE BOND] NSiMe3 (Py = 2-pyridyl) and Ph3P [DOUBLE BOND] NSiMe3 with methyllithium. While the first, even at −78 °C, spontaneously yields a monomeric amide on reduction of phosphorus(V) to phosphorus(III), the triphenyliminophosphorane yields the dimer 1 only after several days at room temperature in a deprotonation reaction of one phenyl ring in the ortho position.

    15. Reaction of (Butadiene)zirconocene with Tris(pentafluorophenyl)borane—A Novel Way of Generating Methylalumoxane-Free Homogeneous Ziegler-Type Catalysts (pages 1755–1757)

      Dr. Bodo Temme, Prof. Dr. Gerhard Erker, Dipl.-Chem. Jörn Karl, Dr. Heinrich Luftmann, Dr. Roland Fröhlich and Dr. Sirpa Kotila

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199517551

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      An active catalyst for α-olefin polymerization without addition of activator components has been discovered in the betain 2, which is formed in the title reaction shown below. Laser desorption mass spectrometry shows that B(C6F5)3-containing polymers with a molecular weight distribution typical of Ziegler catalysts are formed.

    16. The Preparation of Salts of [Pd2(μ-Se2N2)Cl6]2−, the First Adducts of Diselenium Dinitride (pages 1758–1759)

      Dr. Paul F. Kelly and Alexandra M. Z. Slawin

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199517581

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      An Se2N2 ring bridges two PdCl3 units (structure shown on the right) in the title compounds, which are formed in the reaction of appropriate salts of [Pd2Cl6]2− with Se4N4. Unlike Se4N4, these Se2N2 adducts are not explosive.

    17. Rhodium-Catalyzed Hydroformylation of Internal Alkynes to α,β-Unsaturated Aldehydes (pages 1760–1761)

      Dr. John R. Johnson, Dr. Gregory D. Cuny and Prof. Dr. Stephen L. Buchwald

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199517601

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      Under mild conditions—1 atm syngas and room temperature—symmetric internal alkynes are selectively converted into α,β-unsaturated aldehydes in good yields [Eq. (a)].

    18. (Sr6N)[Ga5] and (Ba6N)[Ga5]: Compounds with Discrete (M6N) Octahedra and [Ga5] Clusters (pages 1761–1763)

      Dr. Gerhard Cordier, Dipl.-Ing. Matthias Ludwig, Dr. Dagmar Stahl, Prof. Dr. Peter C. Schmidt and Prof. Dr. Rüdiger Kniep

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199517611

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      [Ga5]7− trigonal bipyramids and (M6N)9+ octahedra are present in the crystal structures of the isotypic title compounds. The charge in these phases is balanced by two electrons in metallic states: {(M6N)9+[Ga5]7− · 2e}. This simple model of the chemical bonding is supported by band structure calculations. A section of the hexagonal crystal structure together with a pseudo-cubic unit cell is shown on the right.

    19. Solid-Phase Synthesis of Vinylogous Sulfonyl Peptides (pages 1763–1765)

      Prof. Dr. Cesare Gennari, Dr. H. Peter Nestler, Barbara Salom and Prof. Dr. W. Clark Still

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199517631

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      Now available for combinatorial compound libraries, vinylogous sulfonyl peptides like 1 may have potential as components of enzyme inhibitors. Newly developed solid-phase synthesis of these compounds (shown schematically below) opens up these possibilities. • = polyoxyethylene-grafted crosslinked polystyrene resin.

    20. Synthetic Receptors Based on Vinylogous Sulfonyl Peptides (pages 1765–1768)

      Prof. Dr. Cesare Gennari, Dr. H. Peter Nestler, Barbara Salom and Prof. Dr. W. Clark Still

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199517651

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      The tripeptide sequence (L-Pro)-(D-Val)-(D-Pro) is recognized by a tweezerlike molecular receptor constructed from vinylogous sulfonyl peptides (see diagram on the right). The screening of this tweezer molecule against a combinatorial tripeptide library reveals interesting sequence specifities for this new class of receptors. DR = dye molecule (Disperse Red 1), • = polystyrene support.

  4. Book Reviews

    1. Top of page
    2. Reviews
    3. Highlights
    4. Communications
    5. Book Reviews
    1. Book Review: Chemische Kabinettstücke. By H. W. Roesky and K. Möckel (pages 1769–1770)

      Hans Georg von Schnering

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199517693

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