Angewandte Chemie International Edition in English

Cover image for Vol. 31 Issue 6

June 1992

Volume 31, Issue 6

Pages 665–804

Currently known as: Angewandte Chemie International Edition

    1. Cover Picture (Angew. Chem. Int. Ed. Engl. 6/1992)

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199206651

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      The cover picture shows the transition structures for six pericyclic reactions, provided by quantum chemical ab initio calculations, which are the subject of K. N. Houk's review on p. 682 ff. Common to these reactions are the changes in bonding involving six electrons. Examples are found among the most important reactions in preparative organic chemistry including sigmatropic rearrangements, elecrocyclizations, and the ene and Diels–Alder reactions. Calculations reveal interesting aspects—even now 25 years after the formulation of the Woodward–Hoffmann rules—for example, that these very different reactions have features in common and yet a variety of transition structures. Without these postulates organic chemistry would not have been as fruitful. Although by tradition we do not put portraits on the front cover, this issue breaks with editorial policy because Woodward (the right-hand photo) has become a legend and would have celebrated his 75th birthday this year.

  1. Reviews

    1. Top of page
    2. Reviews
    3. Highlights
    4. Communications
    5. Book Reviews
    1. The Enchanting Alkaloids of Yuzuriha (pages 665–681)

      Prof. Clayton H. Heathcock

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199206653

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      A biomimetic synthetic route to complicated natural products can be far superior to a conventional approach in terms of efficiency and elegance as the author of this review article demonstrates. Protodaphniphyllum (1), the postulated parent of the Daphniphyllum alkaloids, can be prepared in only a few steps. The construction of the pentacyclic framework of 1 from an acyclic dialdehyde is achieved in a single step.

    2. Transition Structures of Hydrocarbon Pericyclic Reactions (pages 682–708)

      Prof. Dr. Kendall N. Houk, Dr. Yi Li and Dr. Jeffrey D. Evanseck

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199206821

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      The quantification of the Woodward-Hoffmann rules for pericyclic reactions is a goal of the ab initio studies described here. They revealed some remarkable recurring characteristics for the transition structures (see below). But they also showed that the influence of substituents on reactions that can only proceed concertedly is distinctly different from their influence on a reaction for which a concerted mechanism and a diradical mechanism are energetically comparable.

    3. Synthetic Bilayer Membranes: Molecular Design, Self-Organization, and Application (pages 709–726)

      Prof. Dr. Toyoki Kunitake

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199207091

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      Structural variety and simplicity of molecular design are but two of the characteristics of synthetic bilayer-forming amphiphiles that make them attractive models of bilayer membranes and potential substitutes for biological membranes, as well as useful agents for capturing substrates and directing reactions. In this review the wide spectrum of amphiphilic compounds are introduced with emphasis on the single-, double- (e.g. 1), triple-, and quadruple-chain ammonium compounds and how they self-assemble. The discussion stresses that recognition of the relationship between molecular structure and aggregate properties is essential for the design of compounds with predetermined aggregate characteristics.

  2. Highlights

    1. Top of page
    2. Reviews
    3. Highlights
    4. Communications
    5. Book Reviews
    1. Are Denser Packings of Spheres than Closest Packings Possible? How Many Closest Packings of Spheres Exist? (pages 727–728)

      Prof. Dr. Ulrich Müller

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199207271

      “On the six-cornered snowflake” is the title of a short work by Johannes Kepler from 1611, in which an arrangement of spheres that is known today as cubic closest packing was first described. The modern term is based on the intuition of whole generations of chemists, physicists, and crystallographers. A rigorous mathematical proof that the maximum space-filling is really achieved in this packing was provided in 1991 by W. Y. Hsiang. Central to his proof are the domains of influence of the spheres, which can be described by surrounding polyhedrons and which must completely fill the space.

    2. Oxazaborolidines and Dioxaborolidines in Enantioselective Catalysis (pages 729–730)

      Dr. Braj B. Lohray and Dr. Vidya Bhushan

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199207291

      Enantioselective ketone reductions, allyl additions, and Diels—Alder reactions [for example Eq. (a)] are only a few of the reactions catalyzed by chiral oxazaborolidines and dioxaborolidines, which are sometimes produced in situ. A further application is described by Bringmann and Hartung on p. 761. They used adducts of oxazaborolidines and BH3 for the atropo-enantioselective ring opening of lactones to obtain rotationally hindered biaryls. These are also becoming more and more important as chiral auxiliaries.

    3. Penetrated Ion Pairs: a New Form of Ion Pair (pages 731–732)

      Prof. Dr. Gernot Boche

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199207311

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      Ion pairs whose van der Waals volume is smaller than the sum of the volumes of the single ions were discovered recently. The picture on the right shows an example of these penetrated ion pairs. Here a BFmath image ion penetrates the empty spaces between the alkyl chains of a tetrabutylammonium ion. It has now become possible to study and explain the structures and interactions of ion pairs in solution with NMR techniques.

  3. Communications

    1. Top of page
    2. Reviews
    3. Highlights
    4. Communications
    5. Book Reviews
    1. Self-Assembly of a Cu4 Complex with Coplanar Copper(I) Ions: Synthesis, Structure, and Electrochemical Properties (pages 733–735)

      Dr. Marie-Thérèse Youinou, Dr. Noureddine Rahmouni, Prof. Jean Fischer and Prof. John A. Osborn

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199207331

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      π-Stacking interactions in the nearly parallel 3,6-bis(2-pyridyl)-pyridazine (dppn) ligands probably account for the distortion of the planar Cu4 unit in 1 from a square to a rhombus. Each Cu atom is surrounded in a tetrahedral fashion by two N atoms from pyridine and two N atoms from pyridazine units; the chelate rings themselves are planar. The distance between the pairs of dppn ligands is 3.47 Å.

    2. Alkoxyalkyl-Substituted β-Diketonate Complexes of Barium and Copper: Evidence for Inter- and Intramolecular Stabilization (pages 735–737)

      Prof. Dr. William S. Rees Jr., Dr. Celia R. Caballero and Dr. Werner Hesse

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199207351

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      Useful in the synthesis of low-valent barium compounds, the ligand HL is prepared by the Claisen condensation of MeO2C(CH2)OMe with pinacolone. [BaL2], a base-free barium(II) complex, is formed in the reaction of HL with barium metal. This compound is monomeric in solution and a liquid at room temperature. Such compounds are potential sources of barium for the vapor deposition of thin films for electronic materials.

    3. The First Complex with a σ2π4 Triple Bond between Vanadium Atoms in a Ligand Framework of Fourfold Symmetry—[V2{(p-CH3C6H4)NC(H)N(p-C6H4CH3)}4] (pages 737–738)

      Prof. Dr. F. Albert Cotton, Dr. Lee M. Daniels and Prof. Dr. Carlos A. Murillo

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199207371

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      The long quest for a V[BOND]V triple bond has finally met with success, as shown by the synthesis of the title compound 1. A short intermetallic distance and high magnetic anisotropy indicate strong interaction between the vanadium centers. R = p-CH3C6H4.

    4. How High is the Barrier for the Valence Isomerization of Cyclobutadiene? (pages 738–740)

      Prof. Dr. Gunther Maier, Dipl.-Chem. Reinhard Wolf and Dr. Hans-Otto Kalinowski

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199207381

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      The interconversion of the two square forms A and B of tri-tert-butyl-(isopropoxydimethylsilyl)cyclobutadiene has a “classical” barrier of 5.8 ± 0.2 kcalmol−1. A heavy-atom tunneling effect can be discounted in this process.

    5. Origin of the Stabilization of Vinyldiazonium Ions by β-Substitution; First Crystal Structure of an Aliphatic Diazonium Ion: β,β-Diethoxyethene-diazonium Hexachloroantimonate (pages 740–743)

      Prof. Dr. Rainer Glaser, Grace Shiahuy Chen and Dr. Charles L. Barnes

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199207401

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      The considerable contributions of the O-stabilized mesomeric resonance structures III and IV probably account for the extraordinary stability of the cation of the title compound and related systems. This is apparent from comparisons of the bond lengths and angles of the first experimentally determined structure with the results of ab initio studies. The title compound is prepared by alkylation of diazoacetate with triethyloxonium hexachloroantimonate.

    6. Cyclohexadienyl-Type Cationic Intermediates in the Friedel–Crafts Alkylation of Benzene Derivatives with the 9-Fluorenyl Cation—Observation by Laser Flash Photolysis (pages 743–745)

      Frances Cozens, Jianhui Li, Prof. Dr. Robert A. McClelland and Prof. Dr. Steen Steenken

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199207431

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      Direct detection of both types of cationic intermediates in an electrophilic aromatic substitution is possible by laser flash photolysis of 9-fluorenol (1) in the presence of arenes like mesitylene (2). The reactions are fast, yet products are formed with selectivities suggestive of a transition state resembling the intermediate cyclohexadienyl cation (“σ complex”) and not a “π complex”.

    7. Selective Binding of Sugar to β-Cyclodextrin: A Prototype for Sugar–Sugar Interactions in Water (pages 745–747)

      Prof. Dr. Yasuhiro Aoyama, Yoshiro Nagai, Jun-ichi Otsuki, Dr. Kenji Kobayashi and Dr. Hiroo Toi

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199207451

      Not only the hydrophobicity of the sugar to be complexed determines the strength of its bond to β-cyclodextrin. Steric factors also play a large role. In water, aldopentoses are bound better as their hydrophobicity increases, but aldohexoses do not form complexes with β-cyclodextrin even though some are clearly more hydrophobic than all the pentoses studied. This is the first example of a selective oligosugar–sugar interaction in water.

    8. Assistance by Electrophiles in Photoinduced Alkylidyne–Carbonyl Coupling (pages 747–749)

      Prof. Andreas Mayr, Dr. Cecilia M. Bastos, Richard T. Chang, John X. Haberman, Katrina S. Robinson and Deirdre A. Belle-Oudry

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199207471

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      A one-step synthesis of metal-coordinated ynols and ynol derivatives is possible by irradiation of the alkylidyne–carbonyl–tungsten complexes 1 and entrapment of the resulting ketenyl ligands with the electrophile E. Complexes 2 are obtained in good yields. R = Me, Ph; E = H, C(O)CMe3, Si(CMe3)2Ph.

    9. Ion-Selective Hydrazone–Azine Tautomerism of a 14-Membered Macrocylic Ligand (pages 749–751)

      Prof. Thomas W. Bell and Andrew T. Papoulis

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199207491

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      A distinct change in the absorption characteristics of the hexaaza macrocycle 1 is observed upon complexation of alkali- and alkaline-earth-metal ions. This effect, which is due to the tautomerization of the hydrazone form (left) to the azine form (right) during complexation, is especially pronounced for complexes of Li, Mg, and Ca. 1 is thus targeted as a possible component of ion-selective optical sensors.

    10. Synthesis, Structure, and Thermolysis of an Unusual Azaphosphasiliridine (pages 751–753)

      Dr. Matthias Driess and Dr. Hans Pritzkow

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199207511

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      A π complex of a phosphasilene with the nitrene form of diphenyldiazomethane is the formal description of the azaphosphasiliridine 1 suggested by the X-ray structure analysis. Compound 1 is the first product of the [2 + 1] cycloaddition of a diazomethane to a (p–p) π bond of heavy main-group elements whose structure could be completely characterized. Despite its bulky substituents, 1 rearranges by a thermal elimination of N2, in which 2 and 3 are intermediates. Surprisingly, it is not the phosphasilirane 3, but the isomer 4 that is the final product of the thermolysis. Is = 2,4,6-iPr3C6H2

    11. Estradiols Modified by Metal Carbonyl Clusters as Suicide Substrates for the Study of Receptor Proteins: Application to the Estradiol Receptor (pages 753–755)

      Dr. Anne Vessières, Dr. Siden Top, Dr. Colette Vaillant, Prof. Dr. Domenico Osella, Prof. Dr. Jean-Paul Mornon and Prof. Dr. Gérard Jaouen

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199207531

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      Derivatizing biomolecules with transition-metal fragments can be a useful approach to some biochemical problems, for example in labeling hormone receptors. The estradiol derivatives 1–4 deactivate the estradiol receptor to varying degrees, allowing conclusions to be drawn concerning the chemical environment of the binding site.

    12. “Kinetically Enhanced Metalation”— How Substituents Direct ortho Lithiation (pages 755–758)

      Dr. Nicolaas J. R. van Eikema Hommes and Prof. Dr. Paul von Ragué Schleyer

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199207551

      Not the complexation of the ground state but rather of the transition state explains the directing and activating effect of electronegative ortho substituents in the lithiation of aromatic compounds. Ab initio calculations show that the ground state of a C6H5F[BOND]LiH complex for para metalation (complexation by the benzene ring) is energetically more favorable than that for ortho metalation (complexation by F), by −12.8 vs. −12.4 kcalmol−1. In the transition state, however, the tables are turned; the respective activation barriers are +17.9 and + 6.5 kcalmol−1. This is in accord with the experimental findings that only orhto-fluorolithiobenzene is formed.

    13. A New, High-Yield Synthesis of Tetraphosphacubanes (pages 758–759)

      Dr. Thomas Wettling, Dipl.-Chem. Bernhard Geissler, Dr. Ronald Schneider, Dipl.-Chem. Stefan Barth, Prof. Dr. Paul Binger and Prof. Dr. Manfred Regitz

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199207581

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      Cp2Zr complexes of type 1 of phosphaalkyne dimmers, readily available from [Cp2ZrCl2], RC[TRIPLE BOND]P (R = t-Bu, CMe2Et, 1-adamantyl), and nBuLi, are the starting materials for the tetraphosphacubanes 2. When 1 is treated with hexachloroethane as a halogenating agent, its undergoes a novel dimerization with elimination of [Cp2ZrCl2] producing 2 in quite high yields (for R = tBu, 50% overall).

    14. Photolithographic Immobilization of Biopolymers on Solid Supports (pages 759–761)

      Lawrence F. Rozsnyai, David R. Benson, Dr. Stephen P. A. Fodor and Prof. Peter G. Schultz

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199207591

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      The new technique of site-specific immobilization of biomolecules, for example antibodies, may contribute to the development of biosensors and ligand-binding assays. (The key step is shown schematically here.) A benzophenone-derivatized surface is treated with a solution of the antibody (Ig) and then irradiated through a mask with a checkerboard pattern of transparent and opaque fields. The Ig molecules are bound covalently only in areas which were exposed to light. This was proved by epifluorescence microscopy after the surface was washed free of unbound Ig.

    15. First Atropo-Enantioselective Ring Opening of Achiral Biaryls Containing Lactone Bridges with Chiral Hydride-Transfer Reagents Derived from Borane (pages 761–762)

      Prof. Dr. Gerhard Bringmann and Dipl.-Chem. Thomas Hartung

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199207611

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      An impressive example of the directed “twisting” of bridged, configuratively labile biaryls with chiral H-nucleophiles is seen in the atropo-enantioselective, ring-opening reduction of lactone 1 to alcohol 2 with borane THF in the presence of the chiral oxazaborolidine 3. After one recrystallization 2 is enantiomerically pure.

    16. Matrix-Assisted Laser Desorption Mass Spectrometry of Lignins** (pages 762–764)

      Prof. Dr. Jürgen O. Metzger, Dipl.-Chem. Christine Bicke, Priv.-Doz. Dr. Oskar Faix, Dr. Wilfried Tuszynski, Dipl.-Phys. Raimond Angermann, Dr. Michael Karas and Kerstin Strupat

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199207621

      The matrix-supported laser desorption technique proved to be quick, sensitive, and informative in the characterization of lignins. The technique yields the molecular weight distribution directly (for birch lignin up to about 16000 Da), while the well-resolved fine structure of the spectrum confirms the existence of oligomers from trimers through to nonamers. The hyperfine structure reflects the complicated structure of lignin, constructed of monomeric units that are linked to one another through various types of bonds.

    17. Transition Metal in a Cube—A Discrete Eight-Coordinate [Mn2+ ⊂ [2.2.2]cryptand] as a Body Centered Cube with an N2O6 Donor Set (pages 764–766)

      Prof. Karl S. Hagen

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199207641

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      An eight-coordinate manganese(II) ion is found in dication 1, the first complex between the [2.2.2]cryptand and a transition metal. The O- and N-donor centers take up positions at the corners of an almost perfect cube. The formation of this extremely rare coordination polyhedron for MnII can be attributed to the high structural flexibility of the ligand, which enables it to adjust to very different metal cations.

    18. Titration of C60: A Method for the Synthesis of Organofullerenes (pages 766–768)

      Dr. Andreas Hirsch, Antonio Soi and Dr. Heinrich R. Karfunhel

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199207661

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      Isomerically pure monoadducts of C60 such as C60HEt (only the front aspect shown on the right) were obtained from the titration of C60 with alkyllithium or Grignard reagents, followed by protonation. The nucleophile adds to the fullerene framework at a double bond between two six-rings, as was confirmed by the results of AMI calculations. This method may provide access to organofullerenes C60RR′ and C60R2.

    19. A New Reaction Type in the Conversion of Enamines with 1,4-Diphenyl-2-butene-1,4-dione to Give Cage Compounds (pages 768–770)

      Prof. Dr. Gerd Kaupp, Dipl.-Chem. Uwe Pogodda, Dr. Adnan Atfah, Prof. Dr. Herbert Meier and Anita Vierengel

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199207681

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      Spherical oxygenated heteropolycycles 3, containing stable acetal groups of a hitherto unknown type, can be obtained with surprising ease by the action of simple enamines 1 (n = 1–4) on the diketone 2. An ene addition is followed by a thermal [2 + 2 + 2] cycloaddition of the two carbonyl groups to the enamine double bond. Mor = morpholino.

    20. [(CO)3(PPh3)2OsAg(O2CCF3)]: A Model for an Intermediate on the Reaction Coordinate in Electron Transfer (pages 770–772)

      Lin Song and Prof. William C. Trogler

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199207701

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      The formation of a complex with an osmium-silver bond precedes the actual electron transfer Os [RIGHTWARDS ARROW] Ag in the oxidation of trans-[Os(CO)3 (PPh3)2] with Ag(O2CCF3) as indicated by the results of electrochemical measurements and the X-ray structure analysis of the title complex depicted below (the phenyl groups of the phosphine ligands are not shown). This complex can thus be considered a model for intermediates in the oxidation of organometallic compounds by Ag+.

    21. Reagents with Hypervalent Iodine: Formation of Convenient Chiral Synthetic Intermediates by Fragmentation of Carbohydrate Anomeric Alkoxy Radicals (pages 772–774)

      Dr. Pedro de Armas, Dr. Cosme G. Francisco and Prof. Ernesto Suárez

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199207721

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      Cleavage of the C1[BOND]C2 bond in carbohydrates is achieved via the related alkoxy radicals by adding (diacetoxyiodo)benzene (DIB) to the substrate in the presence of iodine [Eq. (a)]. The course of the reaction is independent of the protecting groups R, the ring size, and the configuration of the substrate at C2. The cleavage products are valuable chiral building blocks.

    22. Enzymatic Oxidation of Methyl Groups on Aromatic Heterocycles: A Versatile Method for the Preparation of Heteroaromatic Carboxylic Acids (pages 774–775)

      Dr. Andreas Kiener

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199207741

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      Heteroarenes such as pyrrole, pyrazole, furan, thiophene, pyridine, and pyrazine substituted by one or more methyl groups can be oxidized to the corresponding monocarboxylic acids by the bacterial strain Pseudomonas putida ATCC 33015 grown on para-xylene. Within 50 h on a 20 L scale, 20 gL−1 of 2,5-dimethyl-pyrazine (1 ) could be converted in quantitative yield to 5-methylpyrazine-2-carboxylic acid (as the sodium salt 2).

    23. One-Pot Syntheses of Novel Arene Tricarbonyl Chromium Macrocycles and Macrobicycle: Structure of a Pentanuclear Trichromium(o)-Dicopper(I) Cryptate (pages 775–778)

      Dr. Marie-Thérèse Youinou, Dr. Jean Suffert and Dr. Raymond Ziessel

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199207751

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      Three Cr(CO) 3 units outside and two Cu1 ions inside the cavity are contained in the dicationic cryptate 1, prepared from [Cu(CH3CN) 4]ClO4 and the appropriate macrobicycle. The cryptand is accessible in a one-pot reaction in 74% yield from tere-phthalaldehydetricarbonylchromium and tris-(2-aminoethyl)amine.

    24. 2,2′,5,5′-Tetra-tert-butyl-1,1′-diazaplumbocene— a Stable Azacyclopentadienyl Compound of Lead (pages 778–779)

      Prof. Dr. Norbert Kuhn, Prof. Dr. Gerald Henkel and Dipl.-Chem. Stefan Stubenrauch

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199207781

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      Stable up to 100°, the yellow crystals of the title compound 1 can be obtained in good yields from PbCl2 and the appropriate lithiated pyrrole. Compound 1 shows the bent structure characteristic for metallocenes of elements of Group 14 (the side view is reproduced without tBu substituents) and unlike plumbocene is monomeric in the solid state.

    25. Benzo-1,2,3-triselenolium Trifluoro-methanesulfonate—a C2Se3 Radical Cationic Salt with Unusual Solid-State Structure (pages 779–780)

      Dr. Gotthelf Wolmershäuser and Dipl.-Chem. Gert Heckmann

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199207791

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      A stable 7 π-electron system is present in the radical cation 1 which can be obtained in high yields as 1-Cl, for example, from the reaction of p-C6H4Se2Cl2 and gray selenium. 1-SO3CF3 is accessible by anionic exchange and in the solid state contains dimers comprising rings of 1 superimposed on one another. As a result of cation-anion interactions, the Coulombic repulsion of the cations is reduced.

    26. Investigation of the [1,7] Sigmatropic Hydrogen Shift in a Parent Compound Z,Z-1,3,5-Heptatriene and Its Monodeuterium Analogue (pages 781–783)

      Dr. Mikhail E. Gurskii, Dr. Ilya D. Gridnev, Dr. Yuri V. Il'ichev, Dr. Anatoly V. Ignalenko and Professor Dr. Yuri N. Bubnov

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199207811

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      An experimental confirmation of theoretical predictions is provided by this study of the sigmatropic [1,7] hydrogen shift in 1. Kinetic measurements on the monodeuterium analogue yielded an activation energy of 87 ± 3 kJ mol−1 and a frequency factor of 1.6 × 108 s−1. A comparison of these values with those for (Z)-l,3-pentadiene (152 and 2.8 × 1011, respectively) confirms the prediction that [1,7] hydrogen shifts should have a smaller activation energy and a more negative activation entropy than [1,5] hydrogen shifts.

    27. Synthesis of a Lipophilic Cyclodextrin–[2]-Rotaxane (pages 783–785)

      Dr. Gerhard Wenz, Dr. Eva von der Bey and Dr. Lothar Schmidt

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199207831

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      The complexation of cations by lipophilic cyclodextrins opens new preparative possibilities. This was shown in the first synthesis of a [2]-rotaxane with participation of cyclodextrin. A bipyridinium unit quaternized on one side was complexed by heptakis(3-O-acetyl-2,6-di-O-butyl)-β-cyclo-dextrin and then quaternized at the second N atom. The rotaxane, here shown schematically, was unequivocally identified by mass spectrometry and NMR spectroscopy.

    28. Retro-Inverso Amide Bonds between Trifunctional Amino Acids (pages 785–787)

      Hansjörg Dürr, Prof. Dr. Murray Goodman and Prof. Dr. Günther Jung

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199207851

      In a highly functionalized nonapeptide the amide linkage [BOND]CONH[BOND] between glutamine and arginine was inverted to [BOND]NHCO[DOUBLE BOND]. As an example of this difficult modification to the peptide backbone, a retro-inverso killer-cell epitope was synthesized for the first time with a combination of solution and solid-phase peptide synthesis techniques. The synthetic methods used are of importance for the rational design of drugs based on peptides.

    29. Synthesis and Structure of the Cluster [NaAu12Se8]3−: An Inorganic Cryptand Complex (pages 787–789)

      Song-Ping Huang and Prof. Dr. Mercouri G. Kanatzidis

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199207871

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      A cube with twelve linearly coordinated gold atoms in the middle of the edges and eight trigonally coordinated selenium atoms at the corners is found in the structure of the title compound 1 (see right). A sodium ion is encapsulated in the center of the cube and interacts with the gold atoms. The (Et4N) 3 salt of this inorganic cryptand complex is formed in the reaction of AuCN and Na2Se in the presence of Et4NCl.

    30. Chemical Attachment of Organometallics to Proteins in Reverse Micelles (pages 789–790)

      Prof. Alexander D. Ryabov, Alexey M. Trushkin, Lidia I. Baksheeva, Dr. Raisa K. Gorbatova, Dr. Irina V. Kubrakova, Dr. Vadim V. Mozhaev, Boris B. Gnedenko and Dr. Andrey V. Levashov

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199207891

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      For the construction of new biocatalysts it might be necessary to attach a water-insoluble organometallic residue covalently to a soluble enzyme. Reverse micelles—“microreactors” with a polar center and a nonpolar shell—can achieve this, as shown by the covalent binding of carboxyferrocene (Fc[BOND]COOH) to glucose oxidase (E[BOND]NH2) in the presence of dicyclohexylcarbodiimide/N-hydroxysuccinimide as activating couple [Eq. (a)] in a system containing borate buffer, n-octane, aerosol OT, and acetonitrile.

    31. Anti-Bredt Enol Ethers by Transannular Cyclization of Cycloalkynols (pages 791–792)

      Prof. Dr. Heiner Detert, Dr. Christina Anthony-Mayer and Dr. Herbert Meier

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199207911

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      The thermal cycloalkynol–oxabicycloalkene rearrangement provides a new entry to the hitherto poorly known group of anti-Bredt enol ethers. As an example, above 180°C (!) enol ether 2 is formed quantitatively from 1. This rearrangement is not limited to strained cycloalkynols.

    32. A Binary Quinone Receptor (pages 792–795)

      Dr. Christopher A. Hunter and Duncan H. Purvis

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199207921

      Thumbnail image of graphical abstract

      A small change produces a large effect: The replacement of two of the four isophthaloyl groups in macrocycle 1 with two pyridyl groups induces a vastly different preferred conformation for the macrocycle. Although 1 assumes an open conformation, 2 is folded. The two cavities thus formed in 2 provide binding sites for two p-benzoquinone molecules while 1 cannot bind any. The preferred conformations of 1 and 2 are shown schematically on the right.

    33. 3,4-Dihydroisocoumarins, a New Class of Ant Trail Pheromones (pages 795–796)

      Prof. Dr. Hans Jürgen Bestmann, Dipl.-Biol. Friedrich Kern, Dipl.-Chem. Doris Schäfer and Dipl.-Chem. Matthias Christian Witschel

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199207951

      Thumbnail image of graphical abstract

      The common garden ant, Lasius niger, marks its paths with isocoumarin (R)-1. The structures of other isocoumarins from related ant species were elucidated by synthesis and mass spectrometric studies. The substances were tested for biological activity by means of trail-following tests and electroantennograms.

  4. Book Reviews

    1. Top of page
    2. Reviews
    3. Highlights
    4. Communications
    5. Book Reviews
    1. Book Review: Ion Exchangers. Edited by K. Dorfner (pages 802–803)

      Werner Strüver

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199208022

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