Angewandte Chemie International Edition in English

Cover image for Vol. 33 Issue 11

June 22, 1994

Volume 33, Issue 11

Pages 1123–1198

Currently known as: Angewandte Chemie International Edition

    1. Cover Picture (Angew. Chem. Int. Ed. Engl. 11/1994)

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199411211

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      The cover picture shows a bay boletus. xerocomus badius. The chemical formula of badion A. a dye found in the cap of this mushroom, is superimposed on the right of the photo. The identical partial structures in the formula (highlighted in green and yellow) were identified with the genetic computer algorithm presented by M. Wagener and J. Gastteiger on p. 1189 ff. The steps in this algorithm are shown schematically on the left. This procedure facilitates comparison of structures, a process required for the analysis of biological activity, the elucidation of biosynthetiic routes, or the identifications of appropriate starting materials for a synthesis. (Photography: W. Steglich. Munich)

  1. Reviews

    1. Top of page
    2. Reviews
    3. Highlights
    4. Communications
    5. Book Reviews
    1. Are Polar Organometallic Compounds “Carbanions”? The Gegenion Effect on Structure and Energies of Alkali-Metal Compounds (pages 1129–1140)

      Dr. Christoph Lambert and Prof. Dr. Paul von Ragué Schleyer

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199411291

      The gegenion often exercises a substantial influence on the course of “ionic” organo alkali-metal reactions. The compounds comprising ions of alkali metals and “carbanions” are present in solution as monomeric or aggregated contact ion pairs, or solvent-separated ion pairs. The gegenion thus changes the electronic and spatial structure of the anion by charge-localization and pyramidalization. Only through ab initio calculations can results be obtained without the falsifying influences of solvation and aggregation on the structures of the carbanionoid moiety, which otherwise prevent comparisons within a group of the periodic table.

  2. Highlights

    1. Top of page
    2. Reviews
    3. Highlights
    4. Communications
    5. Book Reviews
    1. Binuclear Metal Complexes as Efficient Intermediaries in Biochemically Relevant Hydrolysis Reactions (pages 1141–1143)

      Dr. Michael W. Göbel

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199411411

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      Rates never before achieved for the hydrolysis of amides are attained by the Cu2(O2) complex 1, which converts dimethylformamide into the formate ion in seconds (half-lives of amides in water are often several years!). The interacting Cu ions play an important role. Such simple model systems can provide insights into the structure–activity relationships of enzymes and even lead to the development of highly active catalysts.

    2. New Total Syntheses of Strychnine (pages 1144–1149)

      Dr. Uwe Beifuss

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199411441

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      Overall yields up to 100000 times greater than that of the first, and for almost 40 years the only, total synthesis of strychnine (1) by Woodward et al. (28 steps) are obtained in four new approaches to the natural product. The strategies and key steps in these routes are discussed in this article. One approach provides strychnine enantioselectively, another reaches the target molecule in only 15 steps.

  3. Communications

    1. Top of page
    2. Reviews
    3. Highlights
    4. Communications
    5. Book Reviews
    1. Tetraoxa[22]porphyrin( Dication and Tetraoxa[24]porphyrinogens( (pages 1151–1153)

      Prof. Dr. Gottfried Märkl, Heinrich Sauer, Dr. Peter Kreitmeier, Dr. Thomas Burgemeister, Fritz Kastner, Georg Adolin, Prof. Dr. Heinrich Nöth and Dr. Kurt Polborn

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199411511

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      Very flexible and antiaromatic versus relatively rigid and aromatic—that is the difference between [24]porphyrinogen 1 and its oxidation product [22]porphyrin dication 2. Although both compounds occur in the cis, trans, cis, trans configuration, the protons along the inner perimeter of 2 are shifted roughly 20.5 ppm upfield, and the outer protons are shifted approximately 8.4 ppm downfield relative to the corresponding protons in 1.

    2. 3H-Indole (pages 1153–1156)

      Dr. Ivo G. Gut and Prof. Dr. Jakob Wirz

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199411531

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      Remarkable stability is shown by the recently observed 3H isomer 1 of indole (2) (τ ≅ 100 s at pH ≅ 9 and 25°C). The equilibrium constant pKT of the tautomerization of 2 to 1 is 5.8 ± 0.2; in other words, the equilibrium concentration of 1 lies in the range of 1 to 2 ppm. The tautomerization is catalyzed by acid and—less efficiently—by base.

    3. Synthesis, Structures, and Reactions of Two Bis(diaminostannylene)s and a Bis(diaminogermylene) Containing a Central C6 Ring (pages 1156–1158)

      Dr. Holger Braunschweig, Dr. Peter B. Hitchcock, Prof. Michael F. Lappert and Luc J.-M. Pierssens

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199411561

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      Two Sn[N(SiMe3)2] moieties arranged trans, linked by a 1,4-diaminosubstituted cyclohexane or benzene ring describes the first heteroleptic bis(stannylene)s 1 and 2 (R = SiMe3), respectively; the bis(germylene) is isomorphous with 2. The replacement of the N(SiMe3)2 groups for aryloxy groups takes place on addition of Sn(OAr)2 to 1 and 2; surprisingly, the treatment of 2 with SnCl2 affords the redox products 3 and metallic tin.

    4. Toward Polyphospholes: Synthesis and Structure of an α-Linked Quaterphosphole (pages 1158–1161)

      Eliane Deschamps, Dr. Louis Ricard and Prof. Dr. François Mathey

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199411581

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      By simple bromine–lithium exchange a 2,5-dibromophosphole is converted into the corresponding 2-lithio derivative. This opens a new route to difunctionalized biphospholes (which are interesting in their own right as building blocks for synthesis) and to the unprecedented, α-linked quaterphosphole 1.

    5. The Oxenoid Character of Metalated Hydroperoxides O(M)OR: Oxidation of Organometallic Compounds R′M′ to R′OH under Mild Conditions (pages 1161–1163)

      Prof. Dr. Gernot Boche, Ferdinand Bosold and Dr. John C. W. Lohrenz

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199411611

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      The oxygen analogues of carbenoids 1 and nitrenoids 2, namely the lithiated hydroperoxides 3, are more electrophilic than the corresponding nonlithiated derivatives. These “oxenoids” can convert organometallic compounds R′M′, including cuprates, into alcohols under mild conditions.

    6. Sensitive and Selective Coloration of Cryptand-Type Crown Spirobenzopyrans for Alkaline-Earth Metal Cations (pages 1163–1166)

      Dr. Masahiko Inouye, Yoshiyuki Noguchi and Dr. Kakuzo Isagawa

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199411631

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      One equivalent of Ca2+and Sr2+ ions induces the isomerization of the colorless spirobenzopyrans 1a (n = 1) and 1b (n = 2), respectively, to the colored merocyanines 2. Compounds of type 1 thus function as ion-selective chemical sensors.

    7. Novel Optically Active Hydrocarbons in Sediments: Evidence for an Extensive Biological Cyclization of Higher Regular Polyprenols (pages 1166–1169)

      Dr. Philippe Schaeffer, Jacques Poinsot, Véréna Hauke, Dr. Pierre Adam, Patrick Wehrung, Dr. Jean-Michel Trendel, Dr. Pierre Albrecht, Dr. Daniel Dessort and Dr. Jacques Connan

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199411661

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      In sediments and Messel shale, a series of novel hydrocarbons has been identified. They can be considered as the cyclization products of regular all-trans polyprenols (up to C45!). These skeletons have not yet been found in living organisms. One of these “molecular fossils” (C33) is shown on the right.

    8. A Novel Photosystem for Harvesting Visible Light to Drive Photoinduced Electron Transfer (PET) Reductions: β-Activation of α, β-Unsaturated Ketones for Radical Cyclizations (pages 1169–1171)

      Dr. Ganesh Pandey and Saumen Hajra

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199411691

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      Now reductions induced by sunlight are also possible. The photosystem here, which absorbs visible light and transfers electrons from an electron donor D to an electron acceptor A and then to a substrate, is composed of D = Ph3P and A = dicyanoanthracene. Enones 1 were chosed as substrates. After reduction to the radical anion they cyclize to form 2. This conversion is a variant of a cyclization mediated by tin hydride but without toxic side products. R = CN, CO2Et; n = 1, 2.

    9. N-Heteroarene Dianions as Antiaromatic Ligands Bridging two Lanthanocene Moieties (pages 1171–1174)

      Dr. Joachim Scholz, Dipl.-Chem. Annett Scholz, Dr. Roman Weimann, Dr. Christoph Janiak and Prof. Dr. Herbert Schumann

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199411711

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      The quinoxaline and phenazine dianions can each be stabilized by two lanthanocene units, which leads to the novel binuclear rare-earth complexes with short La[BOND]C and La[BOND]N contacts. These La–ligand contacts resemble those in “aromatic alkali-metal amides”. The phenazine complex is shown on the right.

    10. Catalytic Pt+-Mediated Oxidation of Methane by Molecular Oxygen in the Gas Phase (pages 1174–1176)

      Ralf Wesendrup, Dr. Detlef Schröder and Prof. Dr. Helmut Schwarz

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199411741

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      The first catalytic oxidative activation of methane in the gas phase employs high-vacuum conditions and Pt+ ions generated by laser desorption. In the presence of O2 the initially generated Pt+[BOND]CH2 is oxidized to formic acid (65%), formaldehyde (25%), and methanol (10%). The picture on the right shows the most important part of the complicated catalytic cycle.

    11. Increased Selectivity of a Simple Photosensitive Probe in the Presence of Large Proportions of Cholesterol (pages 1176–1178)

      Siw Bodil Fredriksen, Valérie Dollé, Masakuni Yamamoto, Prof. Yoichi Nakatani, Prof. Maurice Goeldner and Prof. Guy Ourisson

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199411761

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      The “half-probe” molecule 1, when a constituent of phospholipid vesicles in the presence of cholesterol in large, but biologically reasonable proportions (over 30 mol%), selectively attacks the middle of the bilayer.

    12. Synthesis and Characterization of Thiolato Complexes with Two-Coordinate Iron(II) (pages 1178–1180)

      Jeffrey J. Ellison, Dr. Karin Ruhlandt-Senge and Prof. Philip P. Power

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199411781

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      Coordination number two, ten valence electrons, and highly bent ligands owing to the weak secondary interactions with ortho mesityl substituents—these characteristic features are present in one (shown on the right) of the first two thiolato complexes with a two-coordinate FeII center. Low coordinate iron centers of this kind bound to sulfur are of particular interest in light of the crystal structure of the FeMo cofactor of nitrogenase.

    13. A Convergent Synthesis of 2,5-trans-Linked Oligo (tetrahydrofuran)s: Potential Building Blocks for a Polyether Helix with Ion Channel Activity (pages 1180–1182)

      Dr. Ulrich Koert, Dipl.-Chem. Matthias Stein and Dr. Klaus Harms

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199411801

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      The C2-symmetric tetrahydrofuran pentamer 1 was prepared in enantiomerically pure form by a convergent synthesis. Compounds of this type are of interest for the construction of synthetic ion channels from polyether helices. TBDPS = tBuPh2Si.

    14. A Reagent for Determining Optical Purities of Diols by Formation of Diastereomeric Arylboronate Esters (pages 1182–1184)

      Dr. Kevin Burgess and Alexander M. Porte

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199411821

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      A remarkably simple arylboronic acid reagent for derivatization of diols enables the determination of the optical purity of diols by 1H NMR spectroscopy by the formation of the corresponding esters 1. This procedure could be particularly valuable as enantioselective bishydroxylations become more widely used for asymmetric syntheses.

    15. Structural and Magnetic Characterization of a Novel Heptanuclear Hydroxo-Bridged Copper(II) Cluster of the Corner-Sharing Dicubane Type (pages 1184–1186)

      Dr. José Antonio Real, Prof. Giovanni De Munno, Rosaria Chiappetta, Prof. Miguel Julve, Dr. Francesc Lloret, Dr. Yves Journaux, Jean-Christophe Colin and Dr. Geneviève Blondin

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199411841

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      An energetically low-lying octet ground state and ferromagnetic exchange interactions between seven CuII ions characterize the magnetic behavior of the complex cation in 1, whose novel Cu7(OH)8 framework is shown on the right, bpym = 2,2′-bypyrimidine.

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    16. The First Zwitterionic, Optically Active Disilicate with Pentacoordinate Silicon (pages 1186–1188)

      Prof. Dr. Reinhold Tacke, Dipl.-Chem. Mathias Mühleisen and Prof. Dr. Peter G. Jones

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199411861

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      Stereospecifically and with surprising ease, the first zwitterionic λ5Si,λ5Si′-disilicate ( + )-1 was prepared from (EtO)3SiCH2NH2 and (R,R)-(+)-tartaric acid in aqueous solution. The binuclear complex is optically active owing to the two chiral equation image units and the tetradentate tartrato ligands.

    17. [Zr3Cp2(O2CNiPr2)6(μ-O)(μ-CCO)], the First Crystallographically Established Ketenylidene Complex; A Model for CO Reductive Cleavage on Metal Surfaces (pages 1188–1189)

      Prof. Fausto Calderazzo, Dr. Ulli Englert, Dr. Alessandro Guarini, Dr. Fabio Marchetti, Prof. Guido Pampaloni and Dr. Annalaura Segre

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199411881

      By reductive coupling of coordinated CO without external reducing agents the μ2-ketenylidene and μ3-oxo ligands are generated simultaneously in the reaction of [Cp2Zr(CO)2] with [Zr(O2CNR2)4] (R = Et, iPr) to form 1. Deoxygenation of carbon dioxide and acetone by 1 occurs readily and leads to the substitution of the ketenylidene ligand for a μ2-O ligand.

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    18. The Determination of Maximum Common Substructures by a Genetic Algorithm: Application in Synthesis Design and for the Structural Analysis of Biological Activity (pages 1189–1192)

      Dr. Markus Wagener and Prof. Dr. Johann Gasteiger

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199411891

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      With a genetic algorithm, a computer-based optimization method that imitates the adaptation methods of nature, the maximum substructure common to two molecules can be found. Appropriate starting materials for the target of a synthesis can thus be found with this method. In an analogous procedure the largest substructure contained twice in a single molecule can be identified so that synthesis precursors can be used several times in a synthetic pathway, as exemplified with badion A (1).

    19. s-Indacene: A Delocalized, Formally Antiaromatic 12 π Electron System (pages 1192–1194)

      Dipl.-Chem. Roland H. Hertwig, Dipl.-Chem. Max C. Holthausen, Prof. Dr. Wolfram Koch and Prof. Dr. Zvonimir B. Maksić

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199411921

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      A D2h-symmetric structure with a delocalized π electron system describes the ground state of s-indacene (1), although it is a formally antiaromatic system. These results, obtained by both high-level ab initio MO methods and calculations based on density functional theory, are in agreement with the known structure of 1,3,5,7-tetra-tert-butyl-s-indacene.

  4. Book Reviews

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