Angewandte Chemie International Edition in English

Cover image for Vol. 32 Issue 12

December 1993

Volume 32, Issue 12

Pages 1671–1817

Currently known as: Angewandte Chemie International Edition

    1. Cover Picture (Angew. Chem. Int. Ed. Engl. 12/1993)

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199316711

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      The cover picture shows a tennis ball as well as the structure of a dimer generated with the Insight II 2.2.0 program (Biosym Technologies) and optimized by using the Discover force field. The two halves of the structure are held together by hydrogen bonds (yellow dashed lines; C atoms green, N atoms blue, O atoms red, H atoms white). The symmetric monomers have 1,2,4,5-tetramethylenebenzene cores, to which are added two diphenylglycoluril units (the phenyl groups and the H atoms not involved in hydrogen bonds have been omitted for clarity). The two monomers are self complementary and are “interlocked” like the two halves of a tennis ball (in the picture the orientations of the tennis ball and of the dimer are orthogonal to each other). More about this dimer which is even stable in the gas phase is reported by J. Rebek, Jr., J. de Mendoza, and R. Wyler on pages 1699 ff.

    2. Graphical Abstract (Angew. Chem. Int. Ed. Engl. 12/1993)

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199316712

  1. Reviews

    1. Top of page
    2. Reviews
    3. Highlights
    4. Communications
    5. Book Reviews
    6. Subject Index
    1. The Unique Antithrombin III Binding Domain of Heparin: A Lead to New Synthetic Antithrombotics (pages 1671–1690)

      Dr. Constant A. A. van Boeckel and Dr. Maurice Petitou

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199316713

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      A characteristic pentasaccharide domain that specifically binds and activates the protease inhibitor antithrombin III (AT III) is responsible for the biological activity of the anticoagulant drug heparin. In this review the syntheses of the corresponding pentasaccharide 1 and its analogues are described. Studies of the structure–activity relationships of these compounds and molecular modeling are discussed as a means for developing more potent and simplified derivatives. These studies also contribute to our understanding of the recognition between heparin and AT III at the molecular level.

  2. Highlights

    1. Top of page
    2. Reviews
    3. Highlights
    4. Communications
    5. Book Reviews
    6. Subject Index
    1. Got the Flu? Try a Designer Agent Derived from a Sugar (pages 1691–1693)

      Dr. Carlo Unverzagt

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199316911

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      Even in nanomolar concentrations inhibitor 1 halts the replication of the influenza virus and thus introduces an impressive improvement of four orders of magnitude over known inhibitors of influenza sialidase. The design of inhibitor 1 resulted from molecular modeling studies based on the X-ray structure of a sialidase-inhibitor complex. The pharmaceutical industry has lately shown increased interest in drugs derived from sugars.

    2. Electrochemical Production of Zinti Anions: Renaissance of a Synthesis Route** (pages 1693–1695)

      Priv.-Doz. Dr. Brigitte Eisenmann

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199316931

      The catholic reduction of binary compounds—based on Zintl's pioneering work on “polyanionic salts”—is an elegant way to new anions with unusual structures, such as those found by Haushalter et al. Thus, for example, the telluridoantimonates [Sb4Te4]4− and [Sb9Te6]3− are accessible from Sb2Te3 (Angew. Chem. Int. Ed. Engl. 1993, 32, 1646). This electrochemical route is a clever addition to established methods for the production of Zintl anions and appears to hold a great potential.

  3. Communications

    1. Top of page
    2. Reviews
    3. Highlights
    4. Communications
    5. Book Reviews
    6. Subject Index
    1. Regiospecific Alkylation of 6-Chloropurine and 2,6-Dichloropurine at N7 by Transient Protection of N3/N9 by Methylcobaloxime (pages 1696–1697)

      Christine Dalby, Dr. Christine Bleasdale, Prof. Dr. William Clegg, Dr. Mark R. J. Elsegood, Prof. Dr. Bernard T. Golding and Dr. Roger J. Griffin

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199316961

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      Suitable as starting materials for the synthesis of 2- and 6-substituted adenine and guanine derivatives, which are potential enzyme inhibitors, are the 7-alkylpurines 2 (X[DOUBLE BOND]H, Cl; R[DOUBLE BOND]PhCH2, PhCOCH2, CH2[DOUBLE BOND]CHCH2, CH3COCH2). These alkylpurines can be prepared from 1 (X[DOUBLE BOND]H, Cl) regiospecifically according to a process that is based on the elaboration of a reaction discovered by Marzilli et al.

    2. A Novel Complex with Boat-Shaped, Synfacially Bound η33-Benzene Bridges and the First μ3222-Arenetrirhodium Complex (pages 1697–1699)

      Prof. Dr. Jörn Müller, Dr. Petra Escarpa Gaede and Dipl.-Chem. Ke Qiao

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199316971

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      Successive complexation of photolytically generated [CpRh] fragments to benzene affords complexes 1 and 2. The novel structural characteristic of 1 is the bonding of the benzene bridge. It coordinates as two enyl ligand systems, each attached to a different Rh center. Complex 2 is the first example of a face-capping arrangement of an arene in Rh complexes.

    3. A Synthetic Cavity Assembles Through Self-Complementary Hydrogen Bonds (pages 1699–1701)

      Dr. René Wyler, Prof. Javier de Mendoza and Prof. Julius Rebek Jr.

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199316991

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      The occurrence of identical subunits in many biological systems suggests that selfcomplementarily is both useful and advantageous for the organization of these units. This notion is applied to the synthesis of molecules of 1 that dimerize reversibly. The dimer—which resembles a tennis ball held together by hydrogen bonds along the seam—appears capable of encapsulating smaller solvent molecules.

    4. A Hexanuclear Organogallium Fluoride Oxide (pages 1701–1702)

      Dr. Bernhard Neumüller and Dr. Frank Gahlmann

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199317011

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      A distorted gallium octahedron, whose eight faces are capped by fluorine and oxygen atoms, is a description of the structure of Mes6Ga6F4O4 (1) (see picture in which only the ipso C atoms of the mesityl groups are shown); 1 is accessible from [Mes2GaF]2 and H2O. The bulky organo substituents shield the central GaFO framework from further hydrolysis.

    5. Dicyanononasulfane S9(CN)2—An Unbranched Chain of Thirteen Atoms (pages 1702–1703)

      Prof. Dr. Ralf Steudel, Dipl.-Chem. Klaus Bergemann, Dr. Jürgen Buschmann and Prof. Dr. Peter Luger

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199317021

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      Coiled molecules and not the anticipated helical structures are formed by S9(CN)2 (see picture), the acyclic polysulfane containing the longest Sn chain that could be crystallized and characterized by X-ray crystallography. The structure resembling cyclo-S12 can be considered a model for the polysulfanes such as SnCl2 or SnMe2.

    6. Lipophilic 5′,5′-O-Dinucleoside-α-hydroxybenzylphosphonic Acid Esters as Potential Prodrugs of 2′,3′-Dideoxythymidine (ddT) (pages 1704–1706)

      Dr. Chris Meier

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199317041

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      Phosphonylated and phosphonylated derivatives of the antiviral active nucleoside analogue 2′,3′-dideoxythymidine (ddT) can be released from the dinucleoside-α-hydroxybenzylphosphonic acid esters (1). Depending on the substituents at the aryl group, phosphonate–phosphate rearrangement or direct cleavage was observed. Consequently, compounds of type 1 can, in principle, serve as prodrugs of phosphorylated or phosphonylated nucleosides. Ar[DOUBLE BOND]aryl.

    7. Tricyclo[6.2.0.03,6]deca-1,3,6,8-tetraene: A Remarkably Stable para-Quinodimethane from a Novel Rearrangement Reaction (pages 1706–1709)

      Dr. Jan-Dirk van Loon, Paul Seiler and Prof. François Diederich

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199317061

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      Surprisingly, heating a solution of eyelobutane 1 in toluene afforded selectively the (R,S) stereoisomer of compound 2. A cascade of pericyclic reactions is proposed to explain the formation of this remarkably stable para-quinodimethane, which was characterized by X-ray crystallography.

    8. Organometallic Ferrocenyl Polymers Displaying Tunable Cooperative Interactions between Transition Metal Centers (pages 1709–1711)

      Daniel A. Foucher, Charles H. Honeyman, James M. Nelson, Ben Zhong Tang and Prof. Ian Manners

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199317091

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      Due to a dependency on the element in the spacer and its substituents, the extent of the interactions between the ferrocene units of the polymer backbone of 1 and 2 can be varied. The electrochemical behavior of 3 in which the ferrocene units are separated by C2 bridges shows that the cooperative interactions are much less significant for this polymer.

    9. Phenothiazine–Bipyridinium Oligooxacyclophanes (pages 1711–1714)

      Dr. Christoph Petry, Martina Lang, Prof. Dr. Heinz A. Staab and Prof. Dr. Helmut Bauer

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199317111

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      Surprisingly [11.11]cyclophane 1 (n = 3) shows transannular nuclear Overhauser effects (NOES) in dichloromethane and acetonitrile between the protons of the bipyridinium and those of the phenothiazine unit, indicating an attractive donor-acceptor interaction. In the [20.20]cyclophane 1 (n = 6) complexation with barium ions facilitates the approach of the donor and acceptor units.

    10. Heterolysis of Re2O7: Generation and Stabilization of the Cation [ReO3]+ (pages 1714–1716)

      Prof. Dr. Wolfgang A. Herrmann, Peter W. Roesky, Fritz E. Kühn, Wolfgang Scherer and Matthias Kleine

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199317141

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      No side products and no change in the oxidation state of the metal are observed in the cleavage of Re2O7 into [ReO3]+ and [ReO4], if the cation is generated and stabilized by open-chain or cyclic tridentate donor ligands (X[DOUBLE BOND]NH, NCH3, S in 1). The heterolysis, which is driven by coordination chemistry factors, is set up by an unsymmetric solvation of Re2O7 in donor solvents like THE.

    11. Catalysis of the Hydrolysis of Phosphoric Acid Diesters by Lanthanide Ions and the Influence of Ligands (pages 1716–1719)

      Prof. Dr. Hans-Jörg Schneider, Dipl.-Chem. Jörg Rammo and Dipl.-Chem. Ronald Hettich

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199317161

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      From about 10 000 years to 2 days, the half-life of the hydrolysis of phosphoric acid diphenyl ester 1 can be lowered by lanthanide ions in water at 70°C. Nitrogen-containing ligands barely reduce the catalytic effectiveness and allow such complexes to be fixed, which is essential for many applications. Polyhydroxy ligands further increase the reactivity, which can be explained when an analogy is drawn with the effect of a vicinal hydroxy group in ribophosphates 2.

    12. Palladium-Catalyzed Enantioselective Bis-alkoxycarbonylation of Olefins (pages 1719–1720)

      Dr. Silvia C. A. Nefkens, Dipl.-Chem. Martin Sperrle and Prof. Dr. Giambattista Consiglio

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199317191

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      Styrene, carbon monoxide, and methanol react in the presence of a catalyst precursor of the type [Pd(L[BOND]L)Z2] (L[BOND]L is a chiral bisphosphane ligand, Z is, for example, trifluoromethanesulfonate) and 1,4-benzoquinone to provide optically active succinates 1 [Eq. (a)]. Depending on the ligand, high chemoselectivities and enantiomeric excesses of up to 93% ee are achieved. These results may expect rapid application, since chiral succinates are important as intermediates in the synthesis of drugs and natural products.

    13. Phosphinic Acid-Based C2-Symmetrical Inhibitors of HIV-Protease** (pages 1720–1722)

      Dr. Anusch Peyman, Dr. Karl-Heinz Buidt, Dr. Jörg Spanig and Dr. Dieter Ruppert

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199317201

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      As analogues of the transition state of peptide hydrolysis, phosphinic acid groups can be incorporated in a C2-symmetrical peptide environment based on the geometry of the HIV-protease. This leads to compounds such as 1, potent inhibitors of this key enzyme of the AIDS pathogens. R = 1-naphthyl.

    14. The Pagodane Route to Dodecahedranes: An Improved Approach to the C20H20 Parent Framework; Partial and Total Functionalizations—Does C20-Fullerene Exist? (pages 1722–1726)

      Dipl.-Chem. Fabian Wahl, Dr. Jürgen Wörth and Prof. Dr. Horst Prinzbach

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199317221

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      Are selective multisubstitutions on the surface of dodecahedrane possible? Can all twenty hydrogen atoms be replaced? When relatively bulky Br substituents are introduced under “mild” conditions vicinal substitution is avoided, but chlorination and bromination under “extreme” conditions gives C20Cl16 and C20Br20 (1) as the respective final products. A fragment ion generated in the mass spectrometer with m/z 240 is presumed to belong to C20-fullerene (2).

    15. Formation of Alkynyltrithiocarbonato Ligands from Alkylidyne Ligands and Carbon Disulfide (pages 1726–1727)

      Prof. Andreas Mayr and Tsung-Yi Lee

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199317261

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      An alkylidyne–thiocarbonyl coupling in intermediates in which a CS ligand has displaced a PMe3 ligand is a plausible explanation for the formation of the tungsten complexes 2 in the reactions of alkylidyne complexes 1 with carbon disulfide. A carbonyl–alkylidyne coupling, which would also be reasonable, is not observed. X = halogen, RS.

    16. Unprecedented Cage-Opening of P4S3 Initiated by an Organometallic Radical: Synthesis and Structure of [Cp4Cr4(CO)9(P4S3)] (pages 1728–1729)

      Prof. Dr. Lai Yoong Goh, Dr. Wei Chen and Richard C. S. Wong

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199317281

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      A CrP4S bicyclo[2.1.11 system is the central unit of the title complex 1 (the Cp ligands are omitted for clarity from the structure shown on the right). Compound 1 forms in the reaction of P4S3 with the 17-electron complex fragment [CpCr(CO)3]; here, the P4S3 cage undergoes multiple bond cleavage without fragmentation, accompanied by structural rearrangement.

    17. A Simple Synthesis of [(Cp*Al)4] and Its Conversion to the Heterocubanes [(Cp*AlSe)4] and [(Cp*AlTe)4] (Cp* = η5-C5(CH3)5) (pages 1729–1731)

      Dipl.-Chem. Stephan Schulz, Prof. Dr. Herbert W. Roesky, Dr. Hans Joachim Koch, Prof. George M. Sheldrick, Dr. Dietmar Stalke and Annja Kuhn

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199317291

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      Al4Se4 and Al4Te4 cubes are the central structural units of the heterocubanes [(Cp*AlSe)4] and [(Cp*AlTe)4] 1 (structure shown on right). These compounds were formed by the reaction of the tetrameric AlI compound [(Cp*Al)4] with elemental selenium and tellurium, respectively. The driving force of this smooth reaction is the conversion from AlI to AlIII. Cp* = η5-C5Me5;

      • equation image

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    18. A Molecular Heterometal Amide with High Molecular Dynamics: Does the Lithium Atom Orbit? (pages 1731–1733)

      Prof. Dr. Michael Veith, Michael Zimmer and Dr. Stefan Müller-Becker

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199317311

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      Temperature-dependent NMR spectroscopy allows the movements of substituents and groups in [Me2Si(NSiMe3)2]2InLi to be followed. These movements finally result in a process in which the lithium atom also migrates with respect to the other heavy atoms. In one of the models the result is a quasi-orbital movement of the lithium atom around the core of the molecule occupied by an indium atom (picture shown on the right).

    19. Palladium-Catalyzed Arylation of Tetrasubstituted Double Bonds: A Simple Synthesis of Annelated Propellanes (pages 1733–1735)

      Dr. Gerald Dyker, Dipl.-Chem. Jutta Körning, Prof. Dr. Peter G. Jones and Dipl.-Chem. Peter Bubenitschek

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199317331

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      Only two steps are required for the synthesis of the symmetric propellane 1 starting from acenaphthylene. In this conversion the reactivity of strained double bonds is used for palladium-catalyzed annelation reactions.

    20. Reverse Hydrozirconation Reaction: A Regio- and Diastereospecific Route to New Diphosphanes (pages 1735–1737)

      Dr. Maria Zablocka, Florence Boutonnet, Dr. Alain Igau, Dr. Françoise Dahan, Dr. Jean Pierre Majoral and Dr. K. Michal Pietrusiewicz

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199317351

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      The additional stabilization by the dative P[BOND]Zr bond induces the regio- and diastereospecific formation of the α-zirconated phospholanes 1 on the hydrozirconation of 1-phenyl-2,3-dihydrophosphole. Amazingly, the diphosphanes 3 can be synthesized selectively from the α- (1) as well as the usual α-substituted product 2 on hydrozirconation with the same chlorophosphanes.

    21. Enzyme-Catalyzed Asymmetric Synthesis: Kinetic Resolution of Chiral Hydroperoxides by Enantioselective Reduction to Alcohols with Horseradish Peroxidase (pages 1737–1739)

      Prof. Dr. Waldemar Adam, Lebensmittelchemikerin Ute Hoch, Dr. Chantu R. Saha-Möller and Dr. Peter Schreier

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199317371

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      Highly selective for (R)-hydroperoxides (R)-1, horseradish peroxidase (HRP) is used for the kinetic resolution of racemic 1 furnishing (R)-2 alcohols and enantiomerically pure hydroperoxides, which are difficult to prepare by nonenzymatic means. This transformation carried out in the presence of guaiacol [Eq. (a)] can be conducted on a preparative scale. R1 [DOUBLE BOND] Ph, C([DOUBLE BOND]CH2)CO2Me; R2 [DOUBLE BOND] Me, Et.

    22. Highly Coordinated Lanthanoid–Phosphane Complexes (pages 1739–1742)

      Prof. Dr. Hans H. Karsch, Dr. Gunter Ferazin, Dr. Oliver Steigelmann, Dr. Huub Kooijman and Prof. Dr. Wolfgang Hiller

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199317391

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      More and more lanthanoid–phosphorus bonds and a wide variety of structure variations are found in the complexes prepared from the phosphinomethanide Li[C(PMe2)2(SiMe3)] and lanthanoid triflates. In the homoleptic scandium complex 1, for example, the ligands are bound in a mode intermediate to σ and π coordination.

    23. The Mechanism of Anaerobic, Radical-Induced DNA Strand Scission (pages 1742–1743)

      Prof. Dr. Bernd Giese, Dipl.-Chem. Xenia Beyrich-Graf, Dr. Jutta Burger, Dipl.-Eng. Christoph Kesselheim, Dipl.-Chem. Martin Senn and Dipl.-Eng. Thomas Schäfer

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199317421

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      After selective generation of the mononucleotide radical 1, the formation and reactions of radical cation 2 could be studied. Trapping with allyl alcohol, which is known to trap both cations and radicals, gave primarily the bicyclic product 3. With methanol several intermediates could be trapped, the hydrolysis products of which correspond to DNA cleavage products. 4′-Deoxyribonucleotide radicals are proposed as intermediates in radical-induced DNA strand scission. ℗ [DOUBLE BOND] P(O)(OEt)2, b [DOUBLE BOND] thymine.

    24. A Stable η5-Germacyclopentadienyl Complex: [(η5 C5Me5)Ru{η5-C4Me4GeSi(SiMe3)3}] (pages 1744–1745)

      William P. Freeman, Prof. Dr. T. Don Tilley, Prof. Dr. Arnold L. Rheingold and Dr. Robert L. Ostrander

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199317441

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      A planar five-membered C4Ge ring with a delocalized π system stabilized by a [Cp*Ru] fragment is the key feature of the title compound 1. This compound can be prepared from [(Cp*RuCl)4] and the lithiated germole Li[C4Me4Ge{Si(SiMe3)3}].

    25. Structures and Reactions of the Oxidation Products of Dimeric Ketenylidene(triphenyl)phosphorane (pages 1746–1747)

      Prof. Dr. Hans Jürgen Bestmann, Dipl.-Chem. Thomas G. Fürst and Dr. Annette Schier

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199317461

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      The neutral cyclobutanetrione 2 is synthesized from dimeric ketenylidene(triphenyl)phosphorane 1 by treatment with two equivalents of N-p-tolylsulfonyl(phenyl)oxaziridine. Oxidation of 1 with one equivalent of the oxaziridine provides compound 3, which like 2 was characterized by X-ray structure analysis. Compound 3 functions as a dienophile in Diels–Alder reactions.

    26. Trimeric Ketenylidene(triphenyl)phosphorane: A Hybrid between an Arene and an Ylide (pages 1747–1750)

      Prof. Dr. Hans Jürgen Bestmann, Dipl.-Chem. Thomas G. Fürst and Dr. Annette Schier

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199317471

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      Bond-length alternation is not found in the six-membered ring of the title compound 1 by X-ray structure analysis. Compound 1 undergoes Wittig reactions and can be oxidized to give the colored quinoid compound 2, which in turn can be oxidized to yield the cyclopentanetrione derivative 3. Compounds 2 and 3 were also characterized by X-ray crystallography. Elimination of three equivalents of triphenylphosphane oxide from 1 could lead to C6 or the products of its subsequent reactions.

    27. [(I6Te2)Nb(Te2)2)Nb(Te2I6)], a Metal Complex with Halochalcogenate Ligands (pages 1751–1752)

      Dipl.-Chem. Astrid Leist and Prof. Dr. Wolfgang Tremel

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199317511

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      One iodotellurate(II) ligand is present in the title compound 1 (structure shown on the right). Compound 1 can be prepared from the elements by reactions at high temperature. Halo anions of chalcogenides were previously only known in the free form and were prepared in solution by disproportionation of the tetrahalides. ○ [DOUBLE BOND] Nb, • [DOUBLE BOND] Te, ○ [DOUBLE BOND] I.

    28. Tetrahedral Coordination of Palladium in Ta2Pd3Te5: A Compound with a “Stuffed” Ta2NiSe5 Structure (pages 1752–1755)

      Prof. Dr. Wolfgang Tremel

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199317521

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      Strong Pd[BOND]Ta interactions stabilize the unusual tetrahedral coordination of palladium in the layer compound Ta2Pd3Te5. This compound is accessible by the reaction of the elements at 850/800°C; the structure illustrated below shows a parallel projection of a layer along [010]. Large, medium, and small circles represent Te, Ta, and Pd, respectively.

    29. Monoclinic and Triclinic Tetraisopropyl-p-phenylenediamine: To what Extent do nN/π Interactions Determine Structures? (pages 1755–1758)

      Prof. Dr. Hans Bock, Dipl.-Chem. Ilka Göbel, Dipl.-Chem. Christian Näther, Dr. Zdenek Havlas, Prof. Dr. Angelo Gavezzotti and Dr. Giuseppe Filippini

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199317551

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      Two conformations-two crystal forms! This is the case for the title compound. The crystal of the conformer with nN/π interactions between the nitrogen lone pairs and the benzene π system (left) is monoclinic, whereas that of the conformer without this interaction (right) is triclinic. The dihedral angles ω (C2N[BOND]C6) are 28 and 74°. According to potential energy surface calculations, the conformers have almost identical enthalpies of formation (ΔHmath image = −46 and −47 kJmol−1).

    30. aci-Nitrodiphenylmethane: A Hydrogen-Bonded Dimer (pages 1758–1760)

      Prof. Dr. Hans Bock, Dipl.-Chem. Rüdiger Dienelt, Dipl.-Chem. Holger Schödel, Dr. Zdenek Havlas, Dr. Eberhardt Herdtweck and Prof. Dr. Wolfgang A. Herrmann

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199317581

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      The first structurally characterized aci-nitromethane, the title compound, was obtained by acidifying its sodium salt. It crystallized as the hydrogen-bonded dimer 1. The eight-membered ring that includes the H bonds has a chair conformation. According to quantum mechanical calculations, the cooperative effect on the formation of the H-bonded dimer is 40%.

    31. Elimination of the Barrier to Cope Rearrangement in Semibullvalene by Li+ Complexation (pages 1760–1763)

      Dipl.-Chem. Haijun Jiao and Prof. Dr. Paul von Ragué Schleyer

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199317601

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      The coordination of a Li+ ion stabilizes the transition state for the Cope rearrangement of semibullvalene and essentially eliminates the barrier. At 0 K structure 1 is 0.7 kcal mol−1 lower in energy than the semibullvalene–Li+ complex. Ab initio calculations also indicate that both species are homoaromatic.

    32. A Detailed Theoretical Analysis of the 1,7-Sigmatropic Hydrogen Shift: The Möbius Character of the Eight-Electron Transition Structure (pages 1763–1765)

      Dipl.-Chem. Haijun Jiao and Prof. Dr. Paul von Ragué Schleyer

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199317631

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      Pronounced aromatic character is found in the helical transition structure 1 for the 1,7 H shift in (Z,Z)-1,3,5-heptatriene according to ab initio calculations. The C[BOND]C bond lengths are similar to those in benzene, the 1H NMR shifts (IGLO calculations) indicate strong ring current effects, and the energy of concert (roughly 60 kcal mol −1) is the highest reported for any pericyclic reaction.

    33. (R)- and (S)-4-Alkoxy-2-tert-butyl-2,5-dihydroimidazole-1-carboxylates—New Chiral Glycine Derivatives for Amino Acid Synthesis (pages 1765–1766)

      Dr. Stefan Blank and Prof. Dr. Dieter Seebach

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199317651

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      In only a few hours at room temperature and with 0.2 N HCl—these mild conditions can be used to prepare α-amino acid esters by hydrolysis of compounds 3, which are obtained from 1 by the selective reaction of its lithium derivative 2 with electrophiles. Both enantiomeric forms of the new chiral derivatives 1 are available by resolution.

    34. Self Assembly Through Hydrogen Bonding: Preparation of a Supramolecular Aggregate Composed of Ten Molecules (pages 1766–1769)

      Dr. John P. Mathias, Eric E. Simanek, Dr. Christopher T. Seto and Prof. George M. Whitesides

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199317661

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      Fifty-four (!) hydrogen bonds stabilize the single supramolecular aggregate (1) formed from the cooperative selfassembly of ten molecules. Compound 1, designated as Hub-(MMM)3 · 9 neohex(CA) by the authors—conventional nomenclature and even the drawing of structural formulae are overtaxed—, further demonstrates the potential of molecular self assembly as a strategy for the preparation of well-defined chemical nanostructures.

    35. The First Structure of a Lithiated Cyanamide; Synthesis of (PhNCNLi · HMPA)n by Extrusion of N2 and S from 5-Phenylamino-1,2,3,4-thiatriazole with Li Reagents and HMPA (pages 1769–1771)

      Dr. David R. Armstrong, F. Adele Banbury, Ian Cragg-Hine, Matthew G. Davidson, Dr. Francis S. Mair, Ehmke Pohl, Dr. Paul R. Raithby and Dr. Ronald Snaith

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199317691

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      Alternating and orthogonal (LiNCN)2 eight membered rings and (LiO)2 four-membered rings are linked through common Li atoms to form polymeric strands in the crystal structure of the title compound. The Li complex of the anion of PhNH[BOND]C[TRIPLE BOND]N is formed by extrusion of N2 and S from aminothiatriazole 1 with Li bases such as LiOH, MeOLi, and LiNH2 in the presence of hexamethyl phosphoric triamide (HMPA); however, the mechanism for this reaction is not yet clear.

    36. Synthesis and Reactivity of α,α-Dichloroglycyl Peptides (pages 1771–1772)

      Dr. Stefan Jaroch, Dipl.-Chem. Thomas Schwarz, Prof. Dr. Wolfgang Steglich and Dipl.-Chem. Peter Zistler

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199317711

      Thumbnail image of graphical abstract

      Novel peptide derivatives like 1 with an α,α-disubstituted (heteroatom substituents) glycine residue can be prepared from α,α-dichloroglycyl peptides. These compounds, in turn, are obtained from 4,4-di(alkylthio)5(4H)-oxazolones by ring-opening with amino acid esters and subsequent reaction with SO2Cl2.

    37. [(CO)5Cr[DOUBLE BOND]Tl[DOUBLE BOND]Cr(CO)5], the First Complex Containing Linear Twofold-Coordinated Thallium (pages 1772–1774)

      Dipl.-Chem. Berthold Schiemenz and Prof. Dr. Gottfried Huttner

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199317721

      Thumbnail image of graphical abstract

      The first trimetallacumulene containing an element of group 13 as bridging atom, title anion 1 crystallizes as a stable complex [K+[2.2.2]cryptand] · 1 · 0.6 THF; the Cr[DOUBLE BOND]Tl[DOUBLE BOND]Cr unit is linear. Compounds of this type were previously only known with bridging atoms from groups 14 and 15.

    38. The Bis(cyclopentadienyl)thallate(I) Anion Isoelectronic with Stannocene (pages 1774–1776)

      Dr. David R. Armstrong, Dr. Regine Herbst-Irmer, Annja Kuhn, Dr. David Moncrieff, Michael A. Paver, Christopher A. Russell, Priv.-Doz. Dr. Dietmar Stalke, Alexander Steiner and Dr. Dominic S. Wright

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199317741

      A bent thallocene anion is found in complexes 1 and 2, which are prepared by the reaction of [CpTl] and [Cp2Mg] (for 1) or [CpLi] (for 2) and N,N,N′,N′,N″-pentamethyldiethylenediamine (PMDETA). The [(η5-Cp)2Tl] anion is isoelectronic and isostructural with stannocene. Ab initio calculations show that the bent structure with CS symmetry is only marginally more stable than the linear conformer with D5h symmetry.

      • equation image
    39. Conformational Analysis of Model Complexes for Methyl-Coenzyme-M Reductase from Methanogenic Bacteria: A Comparison of Crystal and Solution Structures (pages 1777–1780)

      Prof. Dr. Albrecht Berkessel, Dr. Michael Bolte, Prof. Dr. Christian Griesinger, Prof. Dr. Gottfried Huttner, Dipl.-Chem. Thomas Neumann, Dipl.-Chem. Berthold Schiemenz, Dipl.-Chem. Harald Schwalbe and Dipl.-Chem. Thomas Schwenkreis

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199317771

      Thumbnail image of graphical abstract

      Do predictions based on crystal structure data hold for conformers in solution? This question was asked in studies of the NiII model complexes rac-1rac-3 by NMR spectroscopy and X-ray structure analysis. The result—drastically different distributions of conformers in solution and in the solid state—may contribute to the current understanding of the mechanism of action of the nickel-containing enzyme methyl-coenzyme-M reductase.

    40. Cation Inclusion within the Mixed-Valence Polyanion Cluster [(MoVIO3)4Momath imageO28(OH)12]8−: Syntheses and Structures of (NH4)7[NaMo16(OH)12O40]·4H2O and (Me2NH2)6[H2Mo16(OH)12O40] (pages 1780–1782)

      Dr. M. Ishaque Khan, Prof. Dr. Achim Müller, Dipl.-Chem. Stephan Dillinger, Dr. Hartmut Bögge, Dr. Qin Chen and Prof. Dr. Jon Zubieta

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199317801

      Thumbnail image of graphical abstract

      A flexible ϵ-Keggin (Mo12O40) core that can encapsulate either two protons or a Na+ ion is found in the title compounds. In the Na compound (shown on the right) the Na+ guest has the unusual coordination number of four.

  4. Book Reviews

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

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

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