Angewandte Chemie International Edition in English

Cover image for Vol. 31 Issue 4

April 1992

Volume 31, Issue 4

Pages 367–486

Currently known as: Angewandte Chemie International Edition

    1. Cover Picture (Angew. Chem. Int. Ed. Engl. 4/1992)

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199203671

      Thumbnail image of graphical abstract

      The cover picture shows an overlay of ten structures obtained from molecular dynamics simulations of the ligand-free protein FKBP which binds FK506; only the positions of the α-carbon atoms were calculated. Although large sections of the protein are structurally invariant, for example an α-helical portion (red), there are also flexible sections (blue and green) that are important in ligand binding. FK506 and other immunosuppressives are the subject of intense research as they have medical significance. M. K. Rosen and S. L. Schreiber give a summary of this fascinating area which draws on topics from organic chemistry to molecular immunology (p. 384 ff.).

  1. Reviews

    1. Top of page
    2. Reviews
    3. Highlights
    4. Communications
    5. Book Reviews
    1. Multiple Peptide Synthesis Methods and Their Applications. New Synthetic Methods (87) (pages 367–383)

      Prof. Dr. Günther Jung and Dr. Annette G. Beck-Sickinger

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199203673

      Peptide fishing is a new sport in bioorganic and medicinal chemistry–biologically active peptides are identified from an ocean of peptides of various lengths and constitutions. In the last few years new methods have been developed for the synthesis of such peptide collections. Automation is the next step. For example, in immuno-analysis the pin method is very important. Minute amounts of peptide are synthesized on rods (a few hundred simultaneously) and incubated with sera containing antibodies for the analysis. In this way the relevant epitopes, that is, the regions to which the antibodies bind, can be precisely determined and mapped.

    2. Natural Products as Probes of Cellular Function: Studies of Immunophilins (pages 384–400)

      Michael K. Rosen and Prof. Dr. Stuart L. Schreiber

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199203841

      Only through chemistry can we understand the molecular basis for biological phenomena–this is the take-home message of this review. With the help of natural products like the immunosuppressives FK506, rapamycin, and cyclo-sporin A, a new class of receptor proteins, the immunophilins, have been discovered. These proteins proved to be active as complexes with the corresponding immunosuppressive ligands. In subsequent research immunophilin-ligand complexes have been used to probe signal transduction in the cell; the target molecule of these complexes was identified as calcineurin.

    3. On the Influence of Heteroatoms in α- and β-Functionalized Alkyl Transition-Metal Compounds (pages 401–421)

      Doz. Dr. habil. Dirk Steinborn

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199204011

      The structure, stability, and reactivity of alkyl–metal complexes can be critically influenced by the introduction of a hetero atom in the alkyl ligand. Compounds of the type [LxM-(CH2)m-YRn] (m ≥ 1; x,n ≥ 0) provide a series for the investigation of the influence of both the heteroatom and the metal in relation to the length of the alkylene bridge. This interest is not purely academic. Functionalized ethene and ethyl palladium complexes play an important role in the synthesis of acetaldehyde by the Wacker process.

  2. Highlights

    1. Top of page
    2. Reviews
    3. Highlights
    4. Communications
    5. Book Reviews
    1. [4 + 4]-Cycloaddition Reactions in the Total Synthesis of Naturally Occurring Eight-Membered Ring Compounds (pages 422–424)

      Prof. Dr. Gerd Kaupp

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199204221

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      An efficient synthetic method for the construction of highly functionalized polycyclic natural products with a central eight-membered ring such as fusicoccin A and taxol is found in the photochemical [4 + 4] cycloaddition, a reaction previously neglected. Sieburth et al. constructed polycycle 2, a prototypical precursor for taxol, in a single step by irradiation of bis(2-pyridone) 1.

    2. [Ni(PtBu)6]—a Strain on the 18 Electron Rule? (pages 424–425)

      Prof. Dr. Kurt Dehnicke

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199204241

      On first glance a nickel complex with 22 valence electrons is not in keeping with either the well-known 18-electron rule or the electron-counting rules established for cluster molecules by Wade and Mingos. Such a complex is expected to be very unstable. However, [Ni(PtBu)6] prepared by D. Fenske (Angew. Chem. Int. Ed. Engl.1992, 31, 323) is stable at room temperature, diamagnetic, and decomposes only slowly in solution. This highlight tries to show how these facts can be interpreted according to the 18-electron rule.

    3. Spectral Hole Burning at Room Temperature and with a Single Molecule: Two New Perspectives (pages 426–429)

      Prof. Dr. Christoph Bräuchle

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199204261

      En route to real molecular electronics the “spectral hole burners” among physical chemists have come a long way. Two developments which foster these ambitions are discussed herein: 1. For the first time holes with sufficient thermal stability could be burned in experiments at room temperature by using the 4f electron transitions of Sm in substitutionally disordered microcrystals of SrFCl0.5Br0.5 or Mg0.5Sr0.5FCl0.5 doped with Sm2+. 2. The manipulation of single molecules necessary for real molecular electronics was possible on a perylene-doped polyethylene film. At T = 1.5 K, spectral hole burning could be carried out selectively several times in succession with a single perylene molecule.

  3. Communications

    1. Top of page
    2. Reviews
    3. Highlights
    4. Communications
    5. Book Reviews
    1. ‘Bis(oxazolines)’ as Ligands for Self-Assembling Chiral Coordination Polymers— Structure of a Copper(I) Catalyst for the Enantioselective Cyclopropanation of Olefins (pages 430–432)

      Prof. David A. Evans, Keith A. Woerpel and Michael J. Scott

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199204301

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      An efficient CuI catalyst for the highly enantioselective cyclopropanation (>98% ee) of styrene with diazoacetic acid esters is obtained from the reaction of copper(I) trifluoromethanesulfonate with bis(dihydrooxazolyl)propane (1). The CuOTf-1 complex is a helical coordination polymer air-stable in the solid state, whose structure is not retained in solution.

    2. Synthesis and Structure of the First Trinuclear, Half-Sandwich Carboranegadolinium(III) Cluster (pages 432–434)

      Dr. Aderemi R. Oki, Dr. Hongming Zhang and Prof. Dr. Narayan S. Hosmane

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199204321

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      Six C2B4 carborane cages surround the central region of cluster 1, which has approximate C3 symmetry. Six Li atoms make up a trigonal prism here viewed from the top; solid spheres represent atoms of the upper Li3 plane, dotted spheres the (lower). Three Gd atoms (ellipses) cap the rectangular prism faces. In the center of the cluster is a μ-bridged O atom.

    3. The Triolide of (R)-3-Hydroxybutyric acid—Direct Preparation from Polyhydroxybutyrate and Formation of a Crown Estercarbonyl Complex with Na Ions (pages 434–435)

      Prof. Dr. Dieter Seebach, Dipl.-Chem. Hans-Martin Müller, Dipl.-Chem. H. Michael Bürger and Mag. rer. nat. Dietmar A. Plattner

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199204341

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      Ideally oriented to complex a metal ion, the three carbonyl groups of triolide 1 are parallel and pointing in the same direction. Upon complexation with a sodium ion, the ring adjusts by arching inward, tilting the CO groups towards each other. The preparation of triolide 1 from poly(R)-3-hydroxybutanoate is surprisingly simple.

    4. Caro's Acid: Molecular Structure and Association in the Solid State at −130°C (pages 436–437)

      Prof. Dr. Walter Frank and Dr. Birgit Bertsch-Frank

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199204361

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      The controlled reaction of concentrated H2O2 with oleum affords H2SO5/H2SO4 mixtures from which single crystals of H2SO5 (1) precipitate. The X-ray crystal structure analysis contradicts the postulates based on vibrational spectroscopy and shows that 1 occurs as peroxoacid without intramolecular hydrogen bonds (picture right), but is linked in a layer type structure by strong intermolecular O[BOND]H … O hydrogen bonds.

    5. Investigations of the Structure and Reactivity of a Stannaketenimine (pages 437–438)

      Dr. Hansjörg Grützmacher, Stefanie Freitag, Dr. Regine Herbst-Irmer and Prof. Dr. George S. Sheldrick

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199204371

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      A double π donor–acceptor bond is the best description of the Sn–C double bond in stannaketenimine 1. The X-ray crystal structure analysis reveals a bent framework, which points out the analogy between 1 and the distannene 2. Compound 1 dissociates relatively easily (ΔH0 ≈ 30 kJmol−1, ΔS0 ≈ 90 JK−1mol−1) and reacts as R2Sn: and :CNR1. R = 2,4,6-(CF3)3C6H2, R1 = 2,4,6-(CH3)3C6H2, R′ = (Me3Si)2CH.

    6. A Straightforward Synthesis of Nitrilimines; X-Ray Crystal Structure of a Nitrilimine Stabilized by Non-Heteroatom Substituents (pages 439–440)

      Dr. Régis Réau, Guilaine Veneziani, Dr. Françoise Dahan and Dr. Guy Bertrand

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199204391

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      Air-stable crystals of bis(triphenylmethyl)-substituted nitrilimine 3 are produced in 90% yield from the reaction of bis(trimethylstannyl)diazomethane 1 with triphenylmethyl chloride. The stability of 3 can only be explained by steric effects, since the electronic interaction of the Ph3C substituents with the CNN frame is not evident. Compound 3 reacts as a 1,3-dipole.

    7. Preparation, Ligand Exchange Reactions, and Structure of a Diene(aqua)ruthenium Complex [(cod)Ru(H2O)4](OTs)2 (pages 440–442)

      Prof. Dr. Ulrich Kölle, Dipl.-Chem. Gabriele Flunkert, Dipl.-Chem. Ralf Görissen, Dipl.-Chem. Martin U. Schmidt and Dr. Ulli Englert

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199204401

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      The trans effect in organometallic aqua complexes was confirmed in a structure for the first time for the dication 1 of the title compound. Here the metal–oxygen bonds trans to the double bonds of the cyclooctadiene ligands are lengthened significantly, and thus these aqua ligands are particularly labile as is evident in exchange reactions.

    8. The Beilstein Test: An Unintentional Dioxin Source in Analytical and Research Laboratories (pages 443–444)

      Dr. Barbara M. Scholz-Böttcher, Dr. Müfit Bahadir and Prof. Henning Hopf

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199204431

      Hazard: Beilstein test! Just one Beilstein test can expose the analyst to more than the acceptable daily limit of 2,3,7,8-tetrachlorodibenzo-l, 4-dioxin, depending on the analyte. The conditions of this routine test for halogenated organic compounds are comparable to those of the Cu-catalyzed formation of polychlorinated dibenzo-p-dioxins and -furans from organic substances and halogen donors in, for instance, the incineration of waste.

    9. Molecular Machines: Molecular Structure of [(p-Tol3P)10Au13Ag12Cl8](PF7)—a Cluster with a Biicosahedral Rotorlike Metal Core and an Unusual Arrangement of Bridging Ligands (pages 445–447)

      Prof. Boon K. Teo and Hong Zhang

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199204451

      Thumbnail image of graphical abstract

      The construction of a molecular rotor from clusters is the fascinating goal which is now a step closer to realization with the synthesis of the title compound 1. The cation of 1 has an M25 metal framework, composed of two vertex-sharing, Au-centered icosahedra (picture right). Isn't this structure a snapshot of a rotor in motion?

      • equation image
    10. Tris(cyclopentanolato)oxovanadium(V): a Model for the Transition State of Enzymatic Phosphoester Cleavage (pages 447–448)

      Dipl.-Chem. Frank Hillerns, Dipl.-Chem. Falk Olbrich, Prof. Dr. Ulrich Behrens and Prof. Dr. Dieter Rehder

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199204471

      Thumbnail image of graphical abstract

      Vanadium atoms with distorted trigonalbipyrimidal coordination are found in dimer 1; the oxo ligand of one monomeric unit and a bridged O atom of an alkoxy ligand of the second form the apexes of the bipyramid. The enzymatic cleavage of phosphate esters, which is presumed to proceed via a transition state with a pentavalent phosphorus atom, can be inhibited by vanadates. Complexes like 1 may serve as model compounds for this transition state.

      • equation image
    11. Oligo(9,10-anthrylenes), Organic Compounds with Stable High-Spin States (pages 448–451)

      Dr. Martin Baumgarten, Dipl.-Chem. Uwe Müller, Dipl.-Chem. Angelika Bohnen and Prof. Dr. Klaus Müllen

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199204481

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      According to ESR spectroscopy and cyclic voltammetric experiments the soluble oligo (9,10-anthrylenes) 1 are unusual redox systems. Significant for the development of organic ferromagnets is the formation of high-spin states in such ions, which can carry one charge per anthracene unit. Even the heptamer 1 (R = n-hexyl, m = 2) was isolated in 18% yield.

    12. Bismuth Alkoxide Dimer Complexes Containing Planar Bi2(μ-OR)2 Cores: Syntheses and Structures of [{Bi[OCH(CF3)2]3(thf)}2] and [{Bi(OC6F5)3(C7H8)}2] · 2C7H8 (pages 451–452)

      Dr. Carolyn M. Jones, Michael D. Burkart and Dr. Kenton H. Whitmire

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199204511

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      A potential precursor for the production of high-temperature superconductors, the loose dimer 1 is bound by two asymmetric alkoxide bridges (a monomeric unit is shown right). The Bi atoms in 1 are surrounded in a distorted pseudo-octahedral fashion by one bridging and two terminal alkoxide ligands and a THF molecule. Each Bi atom also has a stereochemically active lone pair of electrons.

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    13. A Nonaromatic Expanded Porphyrin Derived from Anthracene—A Macrocycle which Unexpectedly Binds Anions (pages 452–455)

      Professor Jonathan L. Sessler, Tarak D. Mody, Debra A. Ford and Dr. Vincent Lynch

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199204521

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      A chloride receptor in the solid state and an efficient fluoride carrier in solution–this describes the anion-binding properties of the diprotonated form of the novel expanded porphyrin 1. This macrocycle is prepared from the condensation of 1,8-diaminoanthracene with the corresponding doubly formyl-substituted tripyrrole. Such macrocycles may serve as models for biological anion-transport systems.

    14. Tetrathienylethylenes, a New Class of Electron Donors—Dications Twisted by 90° Stabilized by Formation of Polymethine Units (pages 455–458)

      Dr. Takanori Suzuki, Hiroaki Shiohara, Masayuki Monobe, Tomoo Sakimura, Dr. Shoji Tanaka, Prof. Dr. Yoshiro Yamashita and Prof. Dr. Tsutomu Miyashi

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199204551

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      With a 90° twist between the two halves, dication 12+ is the first ethylene dication with the maximum distortion possible. The stabilization of the positive charge is achieved in the separate halves of the dication by delocalization over polymethine units. 12+, whose ClOmath image salt melts at about 170°C with decomposition, is obtained from the electrochemical oxidation of 1. The structure of neutral 1 differs substantially from that of its dication.

    15. One-Pot Multifunctionalization of Polymethyl Hydrocarbon π Ligands. Maximum Space Occupancy by Double Branching and Formation of Arboroles (pages 458–460)

      Ing. Françoise Moulines, Dr. Bruno Gloaguen and Prof. Didier Astruc

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199204581

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      Eight, ten, and twelve functional groups can be introduced by the double-branching of the methyl groups in polymethyl hydrocarbon π ligands. The one-pot reaction of [CpFe(η6-1,2,4,5-Me4C6H2)] with allylbromide provides iron complex 1 (75% yield) which can be converted to the analogous octol or cleaved photochemically to liberate the octaallyl ligand. FE = CpFe+

    16. (H2Si)2E2 and (Mes(tBu)Si)2E2 (E = As, P): Incommensurable Systems of Different Stability with Unusually Long E[BOND]E Bonds (pages 460–462)

      Dr. Matthias Driess, Prof. Dr. Rudolf Janoschek and Dr. Hans Pritzkow

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199204601

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      Unexpectedly kinetically stable is exo, endo-1,3-diarsa-2,4-disilabicyclo[1.1.0]-butane (1a) in comparison to its phosphorus homologue 2a. Compound 1a, accessible by the photolysis of the 1,3-dimercurio derivative 3, is converted only slowly into 1b (exo,exo). The most notable feature of 1b is its unusually long As-As bond (2.602(3) Å). Quantum chemical calculations showed that as a result of their bulky substituents 1 and 2 cannot undergo Si inversion like their unsubstituted parent compounds. R1 = tBu, R2 = 2,4,6-C6H2Me3

    17. New Routes to Alkylidyne-Bridged Ditungsten Compounds Supported by Alkoxide or Siloxide Ligands by the Activation of Ethylene (pages 462–464)

      Stephanie T. Chacon, Prof. Malcolm H. Chisholm, Cindy M. Cook, Prof. Mark J. Hampden-Smith and Dr. William E. Streib

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199204621

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      The signals of six nonequivalent siloxy ligands in the NMR spectrum confirm among other things the existence of one hydrido and one bridging 2-butenylidene ligand in complex 1. It is very likely that the hydrido ligand is terminally bonded to W2, even though there is also evidence of an exchange process between the siloxy and hydrido ligands. Complex 1, whose central framework is shown here, was also characterized by X-ray crystallography.

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    18. [(Ph3PAu)6Mn(CO)3]+, a Cluster with Pentagonal-Bipyramidal Structure (pages 464–466)

      Dipl.-Chem. Jörg Mielcke and Prof. Dr. Joachim Strähle

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199204641

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      Despite having the same total number of electrons the manganese complex 1 has a different structure than the heteronuclear gold cluster 2. The MnAu6 cluster 1 is obtained from the photolysis of a mixture of [Ph3PAuMn(CO)5], [Ph3PAuNCO], and [Ph3PAuN3] in THF. With regard to structure and bonding, 1 is a remarkable analogue of the cyclopentadienyl complex [CpMn(CO)3]. The cluster frameworks of 1 and 2 are depicted right as Mn- and V-centered icosahedral fragments.

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    19. The First Structural Characterization of a Metal–Enterobactin Complex: [V(enterobactin)]2− (pages 466–468)

      Timothy B. Karpishin and Prof. Dr. Kenneth N. Raymond

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199204661

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      Enterobactin, the most important siderophore, is the most powerful known chelater of FeIII, yet the exact structure of this complex is still not known. The structure of the vanadium(IV) analogue (depicted right), a Δ-configured trischelate complex, now allows well-founded, detailed conclusions to be drawn concerning the stereospecific formation of the iron complex and its extreme stability.

    20. α-Hydroxyaldehyde Derivatives Arising from Oxidation of Plasmalogens (pages 468–470)

      Claudia Meyer, Dr. Arnulf Lutz and Prof. Dr. Gerhard Spiteller

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199204681

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      Lipids from mammalian tissue were shown to be a source of the mixed acetals 1 after reductive workup and silylation. These masked α-hydroxyaldehydes may arise from the oxidation of plasmalogens and subsequent solvolysis of the methanol extract, as was shown in studies on plasmalogen model compounds. R = SiMe3, R′ = C14H29, C16H31, C16H33.

    21. Catalysis of the Addition of Allyltrimethylsilane to Aldehydes by Silylating Agents. Me3SiB(OTf)4, a New, ‘Supersilylating’ Reagent (pages 470–471)

      Dr. Anthony P. Davis and Marcel Jaspars

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199204701

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      An unusually good source of electrophilic silyl groups, Me3SiB(OTf)4 (Tf = CF3SO2), can be prepared by the addition of Me3SiOTf to B(OTf)3. This compound catalyzes the efficient allylation of aldehydes as outlined in Equation (a) and is four orders of magnitude more reactive than Me3SiOTf. Further applications for this new reagent will certainly emerge.

    22. The Electronic Structure of [(η5-C5H5)2Co2]: Comment on the Existence of a Complex with an Unsupported Co[BOND]Co Double Bond (pages 471–473)

      Prof. Harmon B. Abrahamson, Gerald P. Niccolai, Prof. D. Michael Heinekey, Prof. Charles P. Casey and Prof. Bruce E. Bursten

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199204711

      Bridging hydrido ligands possibly cause the magnetic behavior of the Cp*Co dimer formulated by Schneider et al. as Cp*Co[DOUBLE BOND]CoCp* (Angew. Chem. Int. Ed.1992, 30, 1124). This would agree with the calculated electron structures of the model compound CpCo[DOUBLE BOND]CoCp and the hydrido complexes derived from them. Also the lack of reactivity of the dimer's “naked” Co[BOND]Co double bond toward CO and ethylene can be explained without difficulty by a stabilizing influence of bridging hydrido ligands. The results of this theoretical study will certainly spark further investigations.

    23. 1,2,4-Cyclohexatriene, an Isobenzene, and Bicyclo[4.4.0]deca-1,3,5,7,8-pentaene, an Isonaphthalene: Generation and Trapping Reactions (pages 473–476)

      Prof. Dr. Manfred Christl, Dr. Martin Braun and Dipl.-Chem. Germar Müller

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199204731

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      The addition of bromofluorocarbene to cyclopentadiene and indene yields stable geminal endo-fluoro, exo-bromocyclopropane derivatives, which when treated with methyllithium lead to isobenzene 1 and isonaphthalene 2, respectively. These cycloallenes can be trapped in cycloaddition reactions, for example with styrene. This reaction sequence can be converted into a one-pot procedure if dibromocarbene is generated at low temperatures from tetrabromomethane and methyllithium and treated in situ for the subsequent reactions.—Because the synthesis of a new isomer of benzene is not reported every day, the experimental study immediately precedes this profile of isobenzene 1 obtained from quantum chemical calculations. These results include data regarding its heart of formation, equilibrium geometry, racemization, diradical character, IR spectrum, and chemoselectivity in its [2 + 2] cycloaddition reaction with styrene.

    24. 1,2,4-Cyclohexatriene, an Isobenzene, and its [2 + 2] Cycloaddition with Styrene: A Theoretical Study (pages 476–478)

      Prof. Rudolf Janoschek

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199204761

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      The addition of bromofluorocarbene to cyclopentadiene and indene yields stable geminal endo-fluoro, exo-bromocyclopropane derivatives, which when treated with methyllithium lead to isobenzene 1 and isonaphthalene 2, respectively. These cycloallenes can be trapped in cycloaddition reactions, for example with styrene. This reaction sequence can be converted into a one-pot procedure if dibromocarbene is generated at low temperatures from tetrabromomethane and methyllithium and treated in situ for the subsequent reactions.–Because the synthesis of a new isomer of benzene is not reported every day, the experimental study immediately precedes this profile of isobenzene 1 obtained from quantum chemical calculations. These results include data regarding its heat of formation, equilibrium geometry, racemization, diradical character, IR spectrum, and chemoselectivity in its [2 + 2] cycloaddition reaction with styrene.

    25. Designing Synthetic Cationic Molecular Receptors for Alcohols (pages 478–480)

      Dr. Luis Méndez, Dr. Raymond Singleton, Alexandra M. Z. Slawin, Prof. J. Fraser Stoddart, Dr. David J. Williams and Dr. M. Kevin Williams

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199204781

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      The monoprotonation of diaza-12-crown-6 derivatives converts these macrocycles to hosts for short-chain alcohols; the association constant Ka is as high as 47 M−1. For the neutral diaza crown ether, on the other hand, Ka is only 1.1 M−1. X-ray structure investigations show that the alcohol (R = Me) is held in place by two hydrogen bonds (see right). R = Me, Et, nPr, nBu; R′ = PhCH2, PhCH2CH2

    26. An Opinion on the Heterogeneous Photoreactions of N2 with H2O (pages 480–482)

      Prof. Jimmie G. Edwards, Prof. Julian A. Davies, Mr. David L. Boucher and Dr. Abdelkader Mennad

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199204801

      The artificial photosynthesis of ammonia, that is, the fixation of N2 and conversion to NH3, is a fascinating research goal about which there are repeated reports of success in the literature. This communication now shows amongst other results why the obvious methods, in particular the heterogeneous catalysis of the reaction of N2 and H2O on the surface of oxidic compounds, are destined to failure.

    27. Synthesis of Octameric Phosphodiesters of [3,3-Bis(hydroxymethyl)cyclobutyl]adenine and -Thymine as well as their Hybridization Properties (pages 482–484)

      Dr. Jean-Michel Henlin, Klaus Jaekel, Dr. Peter Moser, Hans Rink, Erich Spieser and Dr. Gerhard Baschang

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199204821

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      The concept of antisense nucleic acids promises the possibility of specific interventions in the nucleic acid metabolism. Apart from the direct derivatives of ribose and deoxyribose, no structures that pair with RNA in the form of oligomeric phosphodiesters are known so far. The first examples, obtained from the carbanucleoside 1, namely octanucleotides of the type 2 (B = thymine, adenine), are reported here.

  4. Book Reviews

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

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