Angewandte Chemie International Edition in English

Cover image for Vol. 33 Issue 21

November 17, 1994

Volume 33, Issue 21

Pages 2123–2228

Currently known as: Angewandte Chemie International Edition

    1. Cover Picture (Angew. Chem. Int. Ed. Engl. 21/1994)

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199421211

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      The cover picture shows probably the most densely oxygenated complex fragment of a natural product yet synthesized—C10H12O11! The central triol–triacid “core” (space-filling model at the top)of the fungal metabolite zaragozic acid A/squalestatin S1(structural formula and space-filling model at the bottom) is depicted. Showing unprecedented promise as a medicinally usefull inhibitor of squalene synthase (the enzyme controlling the first committed step in the biosynthesis of cholesterol), zaragozic acid A has attracted much attention in biological and chemical cirles. The synthesis of the central core and tthe first total synthesis of zaragozic acid A/squalestatin S1–another race is over—are described by K. C. Nicolaou et al. on p. 2184ff, 2190ff. (Red: oxygen, black: carbon, white: hydrogen; photograph: L. Gomez-Paloma, The Scripps Research Institute)

  1. Reviews

    1. Top of page
    2. Reviews
    3. Highlights
    4. Communications
    5. Book Reviews
    1. The Kinetics of Heterogeneous Electron Transfer Reaction in Polar Solvents (pages 2131–2143)

      Professor William Ronald Fawcett and Dr. Marcin Opallo

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199421311

      Not exactly easy to describe are electron transfer (ET) reactions in which both the oxidized and the reduced form of a compound are present simultaneously; only one electron is transferred, and no chemical bonds are broken or formed during the reaction. What powerful models are available for such “simple” reactions? Which experimental methods can be used, in particular for the very fast ET reactions? What influence do the solvent, reactant, and double layer exert on the thermodynamic and kinetic parameters? Critical answers are provided by Fawcett and Opallo in this review.

    2. Otto Roelen, Pioneer in Industrial Homogeneous Catalysis (pages 2144–2163)

      Prof. Dr. Boy Cornils, Prof. Dr. Wolfgang A. Herrmann and Dr. Manfred Rasch

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199421441

      Despite wartime hardships research was still well documented. This article on Otto Roelen and the discovery and development of the oxo synthesis [Eq. (a)] describes the infancy of industrial homogeneous catalysis with organometallic complexes. The authors try to understand why a collaboration between the industrial chemist Otto Roelen and Professor Walter Hieber never came to be. If they had combined efforts, the oxo synthesis might have been recognized much earlier as a homogeneously catalyzed reaction.

      A unique opportunity for academic and industrial chemists to engage in a goal-oriented collaborative effort with respect to an important new synthetic method was missed in this case, however–missed less as a consequence of events of the day than because of the differing mentalities of two difficult personalities. In less turbulent times these two unpredictable individuals might well have collaborated. A number of contemporary documents published here for the first time, supplemented by Allied reports related to “hidden reparations,” provide interesting insights into the nature of this particular discovery and its subsequent course of development.

      • equation image
  2. Highlights

    1. Top of page
    2. Reviews
    3. Highlights
    4. Communications
    5. Book Reviews
    1. New Upswing of Organolanthanoid Research: A Very Promising Revival of Organocerium(IV) Chemistry and the First Stable Lanthanoid(II/III)–Carbene Complexes (pages 2165–2168)

      Prof. Dr. R. Dieter Fischer

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199421651

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      Less conventional oxidation states of the lanthanoids become important in complexes in which ligands such as trimethylsilyl-substituted cyclooctatetraene anions or imidazol-2-ylidenes coordinate to the metal ion. These types of Lnn+ complexes (n ≠ 3), which were still ignored ten years ago, may have sandwich or even oligodecker structures (see, for example, picture on the right) or contain carbene-like η1-bound ligands.

    2. The Lithocene Anion and “Open” Calcocene–New Impulses in the Chemistry of Alkali and Alkaline Earth Metallocenes (pages 2168–2171)

      Priv.-Doz. Dr. Dietmar Stalke

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199421681

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      The resurgence of the C5 ligand in main group chemistry: Recently Harder et al. (Angew. Chem. Int. Ed. Engl.1994, 33, 1744) have synthesized and structurally characterized the lithocene anion 1, the simplest sandwich complex, and Hanusa et al. (Angew. Chem. Int. Ed. Engl.1994, 33, 2191) have prepared the “open” calcocene 2, an alkaline-earth metal complex with a remarkable structure. Such compounds are not only of significance for bonding theory, they are also interesting as precursors for important industrial processes.

  3. Communications

    1. Top of page
    2. Reviews
    3. Highlights
    4. Communications
    5. Book Reviews
    1. Construction of a Multiwired Molecular Cable of Micrometer Length by a Self-Assembly Process (pages 2173–2175)

      Cornelus F. van Nostrum, Dr. Stephen J. Picken and Prof. Dr. Roeland J. M. Nolte

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199421731

      Thumbnail image of graphical abstract

      Isolated fibers the thickness of a molecule but more than 104 molecules long are present in the gel formed from a solution of 1 in chloroform. This molecular stack may be seen as a molecular cable containing many wires and constructed from a stack of phthalocyanine units, four stacks of crown ether units, and a surrounding mantel of hydrocarbon chains.

    2. Complexes of Partially Fluorinated Macrocycles with a Metal–Fluorine σ-Donor Bond and Their Suitability as Metal Ion Indicators (pages 2175–2177)

      Dr. Herbert Plenio and Dipl.-Chem. Ralph Diodone

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199421751

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      A shift of up to 9 ppm in the 19F NMR resonance of 1 is observed on complexation of metal ions. This property makes these compounds attractive as sensors for metal ions. The mode of coordination (σ bonding to the fluorine atom or η2 coordination to the C[BOND]F bond) in this type of system is also of interest.

    3. Synthesis of a GPI Anchor of Yeast (Saccharomyces cerevisiae) (pages 2177–2181)

      Dipl.-Chem. Thomas G. Mayer, Dipl.-Chem. Bernd Kratzer and Prof. Dr. Richard R. Schmidt

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199421771

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      The highly convergent and versatile synthesis of the GPI anchor 1 is based on the assembly of four building blocks, which are obtained in high yields from readily accessible starting materials.

    4. A Total Synthesis of ( + )-2′S, 3′R-Zoapatanol (pages 2182–2184)

      Prof. Dr. Barry M. Trost, Dr. Paul D. Greenspan, Dr. Holger Geissler, Dr. Jung H. Kim and Dr. Nicholas Greeves

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199421821

      Thumbnail image of graphical abstract

      Three palladium-catalyzed steps (allyl alkylation, Wacker oxidation, and carbonylative cross-coupling) characterize the first asymmetric total synthesis of 1, a component of plant extracts used as contraceptives.

    5. Zaragozic Acid A/Squalestatin S1: Synthetic and Retrosynthetic Studies (pages 2184–2187)

      Prof. Kyriacos C. Nicolaou, Eddy W. Yue, Yoshimitsu Naniwa, Francesco De Riccardis, Alan Nadin, James E. Leresche, Susan La Greca and Zhen Yang

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199421841

      Thumbnail image of graphical abstract

      Step by step the first total synthesis was approached: of the zaragozic acids/ squalestatins showing potential therapeutic value for lowering the serum cholesterol concentration, zaragozic acid A/squalestatin SI (1), the most abundant member of a new class of naturally occurring products, has now been synthesized via the key intermediates 2 and 3. Initially the projected final sequence (2 [RIGHTWARDS ARROW] 1) was achieved, and the side chains attached to C1 and C6 were prepared through efficient asymmetric syntheses. The first synthesis of the highly oxygenated “core”, which is characteristic of this class of natural products, was achieved from a simple prochiral diene via intermediate 3. Finally the synthetic route 3 [RIGHTWARDS ARROW] 2 was developed to successfully complete the total synthesis. Bn [DOUBLE BOND] benzyl, PMB [DOUBLE BOND] para-methoxybenzyl, TMS [DOUBLE BOND] trimethylsilyl.

    6. Synthesis of the First Fully Functionalized Core of the Zaragozic Acids/Squalestatins (pages 2187–2190)

      Prof. Kyriacos C. Nicolaou, Alan Nadin, James E. Leresche, Susan La Greca, Tatsuo Tsuri, Eddy W. Yue and Zhen Yang

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199421871

      Thumbnail image of graphical abstract

      Step by step the first total synthesis was approached: of the zaragozic acids/ squalestatins showing potential therapeutic value for lowering the serum cholesterol concentration, zaragozic acid A/squalestatin SI (1), the most abundant member of a new class of naturally occurring products, has now been synthesized via the key intermediates 2 and 3. Initially the projected final sequence (2 [RIGHTWARDS ARROW] 1) was achieved, and the side chains attached to C1 and C6 were prepared through efficient asymmetric syntheses. The first synthesis of the highly oxygenated “core”, which is characteristic of this class of natural products, was achieved from a simple prochiral diene via intermediate 3. Finally the synthetic route 3 [RIGHTWARDS ARROW] 2 was developed to successfully complete the total synthesis. Bn [DOUBLE BOND] benzyl, PMB [DOUBLE BOND] para-methoxybenzyl, TMS [DOUBLE BOND] trimethylsilyl.

    7. Total Synthesis of Zaragozic Acid A/Squalestatin S1 (pages 2190–2191)

      Prof. Dr. Kyriacos C. Nicolaou, Alan Nadin, James E. Leresche, Eddy W. Yue and Susan La Greca

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199421901

      Thumbnail image of graphical abstract

      Step by step the first total synthesis was approached: of the zaragozic acids/ squalestatins showing potential therapeutic value for lowering the serum cholesterol concentration, zaragozic acid A/squalestatin SI (1), the most abundant member of a new class of naturally occurring products, has now been synthesized via the key intermediates 2 and 3. Initially the projected final sequence (2 [RIGHTWARDS ARROW] 1) was achieved, and the side chains attached to C1 and C6 were prepared through efficient asymmetric syntheses. The first synthesis of the highly oxygenated “core”, which is characteristic of this class of natural products, was achieved from a simple prochiral diene via intermediate 3. Finally the synthetic route 3 [RIGHTWARDS ARROW] 2 was developed to successfully complete the total synthesis. Bn [DOUBLE BOND] benzyl, PMB [DOUBLE BOND] para-methoxybenzyl, TMS [DOUBLE BOND] trimethylsilyl.

    8. Synthesis and Crystal Structure of the “Open” Calcocene [(tBu2C5H5)2Ca · thf] (pages 2191–2193)

      Jason S. Overby and Prof. Timothy P. Hanusa

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199421911

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      Calcium behaves more like a transition metal than a main-group element when it forms an “open” metallocene with the 2,4-di-tert-butylpentadienyl ligand. Like most transition metal pentadienyl complexes, the title compound 1 (shown C on the right) contains pentahapto- rather than monohapto-bound ligands. Unlike its transition metal counterparts, however, the metal–carbon bonds in 1 are noticeably longer than those in the analogous cyclopentadienyl complexes. Furthermore, the pentadienyl ligands in 1 have an anti-eclipsed arrangement, which is unprecedented for open metallocenes.

    9. [Ru3CO651-C5H4)3]: The First Six Membered Ru3C3 Ring Formed by Insertion of C5H4 Units into Metal–Metal Bonds of [Ru3(CO)12] (pages 2193–2195)

      Dr. Alejandro J. Arce, Ysaura De Sanctis, Prof. Jorge Manzur and Dr. Mario V. Capparelli

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199421931

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      A cyclic ruthenium trimer without metal-metal bonding, the highly symmetrical trinuclear complex 1 is formed under mild conditions by the reaction of [Ru3(CO)12] and diazocyclopentadiene. Insertion of cyclopentadienyl units into Ru[BOND]Ru bonds also leads to the formation of [Ru3(CO)10(C5H4)] and the dimer [Ru2(CO)4(C5H4)2].

    10. A Short and Highly Stereoselective Synthesis of the 1,10-seco-Eudesmanolide Ivangulin (pages 2195–2197)

      Priv.-Doz. Dr. Peter Metz, Dipl.-Chem. Jörn Stölting, Mechtild Läge and Prof. Dr. Bernt Krebs

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199421951

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      Three key steps characterize the highly stereoselective synthesis of the title compound 1: a thermodynamically controlled intramolecular Diels—Alder reaction of the vinylsulfonate of 3, the radical cyclization of a derivative of 2, and a reductive sultone cleavage. Thus, this synthesis starting from 2-acetylfuran requires only 15 steps.

    11. Increase in the Enantioselectivity of Asymmetric Hydrogenation in Water Influenced by Surfactants or Polymerized Micelles (pages 2197–2199)

      Dr. Arvind Kumar, Prof. Dr. Günther Oehme, Prof. Dr. Jean Pierre Roque, Manuela Schwarze and Prof. Dr. Rüdiger Selke

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199421971

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      Micelle-forming substances or polymeric micelles 1 enhance not only the rate of the hydrogenation of esters of (Z)-2-N-acyldehydroamino acids in water, but also its enantioselectivity. A high sensitivity of the optical induction to achiral modifiers is observed for the new precatalyst 2.

    12. Towards One-Dimensional Carbon Wires Connecting Single Metal Centers: A Cumulenic C5 Chain that Mediates Charge Transfer between Rhenium and Manganese Termini (pages 2199–2202)

      Dr. Weiging Weng, Dr. Tamás Bartik and Prof. Dr. John A. Gladysz

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199421991

      Thumbnail image of graphical abstract

      The longest Cn bridge known between two single metal centers is found in the bimetallic complex 1. The structure of 1 is best described by the cumulene resonance form +Re[DOUBLE BOND]C[DOUBLE BOND]C[DOUBLE BOND]C[DOUBLE BOND]C[DOUBLE BOND]C[DOUBLE BOND]Mn. A very intense rhenium-to-manganese charge transfer band at 480 nm (ϵ = 60 500M−1 cm−1) suggests that the C5 ligand acts as a “molecular wire”. Counterion: BFmath image

    13. A Novel Hexamer of ButC [TRIPLE BOND] P: Synthesis, Structure, and Theoretical Studies (pages 2202–2204)

      Vinicius Caliman, Dr. Peter B. Hitchcock, Prof. Dr. John F. Nixon, Dipl.-Chem. Matthias Hofmann and Prof. Paul von Rague Schleyer

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199422021

      Thumbnail image of graphical abstract

      Constructed from six phosphaalkyne units, the organophosphorus compound P6C6tBu6 (1) can be considered to have a structure derived from the corresponding tetraphosphacubane in which two opposite carbon corners have been replaced by CCP rings. The hexamer 1 therefore has the same structure as the D3d symmetric (CH)12 hydrocarbon p-[32.56]octahedrane and the hypothetical P12.

    14. Tetraaza[14]annulenezirconium(IV) Complexes with Butadiene Ligands and their Relationship with Bis(cyclopentadienyl)zirconium(IV) Complexes (pages 2204–2206)

      Luca Giannini, Dr. Euro Solari, Prof. Dr. Carlo Floriani, Prof. Angiola Chiesi-Villa and Dr. Corrado Rizzoli

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199422041

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      The reversible binding of pyridine in complex 1 can be considered as a model reaction for the incorporation of a reactive substrate in the coordination sphere of a metal complex. Compound 1 is the first example of a complex with a macrocyclic ligand that contains a metal-butadiene functionality.

      • equation image
    15. A Glucose-Selective Molecular Fluorescence Sensor (pages 2207–2209)

      Dr. Tony D. James, Dr. K. R. A. Samankumara Sandanayake and Prof. Seiji Shinkai

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199422071

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      Low concentrations of D-fructose and D-galactose do not hinder the detection of D-glucose with the fluorescence sensor 1. The diboronic acid 1 is easy to synthesize and forms a cleft structure in which monosaccharides bind with differing selectivity. The saccharide-diboronic acid 1:1 complexes are readily detected by their fluorescence.

    16. Synthesis of a Fully Unsaturated “Molecular Board” (pages 2209–2212)

      Matthias Löffler, Prof. Dr. Arnulf-Dieter Schlüter, Katrin Gessler, Dr. Wolfram Saenger, Dr. Jean-Marc Toussaint and Prof. Dr. Jean-Luc Brédas

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199422091

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      A regular sequence of naphthalene and anthracene units form the basis of the backbone of the polymer 1. This “molecular board” is obtained by dehydration of the appropriate O-bridged unsaturated precursors and should be of interest in areas such as nonlinear optics and electroluminescence.

    17. Dimesityldioxirane—A Dioxirane Stable in the Solid State (pages 2212–2214)

      Dipl.-Chem. Andreas Kirschfeld, Dr. Sengodagounder Muthusamy and Prof. Dr. Wolfram Sander

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199422121

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      On a preparative scale of 10 mg per batch the dioxirane 2 can be synthesized from the diazomethane 1. Compound 2 is the first dioxirane that is stable in the solid state at room temperature. An intermediate, probably the carbonyl oxide, can also be kept for several hours in solution at –78°C.

    18. Platinum(II) Complexes with Porphyrin Ligands—Additive Cytotoxic and Photodynamic Effect (pages 2214–2215)

      Prof. Dr. Henri Brunner and Dr. Herbert Obermeier

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199422141

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      Tumoral destruction increases from 0% to 37% in the dark, and from 19% to 62% with subsequent IR irradiation, when instead of the free ligand 1 its platinum complex 2 is employed against tumor cells.

    19. Free Acid Porphyrin and Its Conjugated Monoanion (pages 2215–2217)

      Dr. Jürgen Braun, Dipl.-Chem. Christian Hasenfratz, Priv.-Doz. Dr. Reinhard Schwesinger and Prof. Dr. Hans-Heinrich Limbach

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199422151

      Thumbnail image of graphical abstract

      An absolute pKa value of about 36 in acetonitrile is obtained for porphyrin from its reaction with phosphazene bases. The monoanion 1 is stable in aprotic solvents and was characterized by NMR and UV/ Vis spectroscopy. The remaining central proton in the monoanion migrates between the four nitrogen atoms much faster than the two protons in the parent compound.

    20. A Carbene–Iron Chelate Complex as a Source of a Ferraborane Derivative (pages 2218–2219)

      Dr. Sylvain Nlate, Dr. Pierre Guénot, Dr. Sourisak Sinbandhit, Dr. Loic Toupet, Dr. Claude Lapinte and Dr. Véronique Guerchais

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199422181

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      Insertion of a BH3 molecule with simultaneous reduction is observed in the reaction of 1 with NaBH4. The lability of the methoxy group in the chelate ligand is thought to favor formation of the unusual product 2.

    21. Bridgehead Functionalization of Non-Enolizable Ketones: The First Preparatively Useful Methods (pages 2220–2222)

      Dr. Urs P. Spitz and Prof. Philip E. Eaton

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199422201

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      cis,cis-1,2,4-Cyclopentanetriol (2) is introduced as an auxiliary to assist removal of an α bridgehead hydrogen in non-enolizable ketones 1. Bridgehead functionalization of 3 to yield 4 can then be achieved by directed metalation or radical substitution. Examples of 1 include homocubanone and adamantanone.

    22. Toward Unified Enantioselective Chromatography with a Single Capillary Column Coated with Chirasil-Dex (pages 2222–2223)

      Prof. Dr. Volker Schurig, Dr. Martin Jung, Dr. Sabine Mayer, Dipl.-Ing. Simona Negura, Dipl.-Chem. Markus Fluck and Dipl.-Chem. Hansjörg Jakubetz

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199422221

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      Irrespective of what mobile phase is used the enantiomers of hexobarbital (1) can be separated chromatographically on a fused silica capillary column coated with Chirasil-Dex. This is shown by their separation with gas chromatography, supercritical fluid chromatography, open tubular liquid chromatography, and capillary electrochromatography.

  4. Book Reviews

    1. Top of page
    2. Reviews
    3. Highlights
    4. Communications
    5. Book Reviews
    1. Book Review: Chemical Bonding. By M. J. Winter (pages 2225–2226)

      Burkhard König

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199422252

    2. Book Review: Four Books on Fullerenes (page 2227)

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199422271

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