Angewandte Chemie International Edition in English

Cover image for Vol. 29 Issue 6

June 1990

Volume 29, Issue 6

Pages 565–706

Currently known as: Angewandte Chemie International Edition

    1. Cover Picture (Angew. Chem. Int. Ed. Engl. 6/1990)

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199005651

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      The cover illustration shows a ball and stick model of the methylsodium lattice. The sodium atoms are shown in red, the C atoms in gray. The structure contains tetrameric (in the middle and on the right and left sides of the picture) and monomeric NaCH3 units. The ab-initio elucidation of the structure of this still unknown alkali-metal methanide has now been accomplished by combined neutron and synchroton-radiation diffraction studies on NaCD3 powders containing only small amounts of LiCD3. The structure of this real methylsodium—a LiCH3-stabilized form of which was known—is intermediate between the structure of methyllithium and that of methyl compounds of the heavy alkali metals. Further details of this impressive elucidation of the structure of a primary organometallic substance are reported by E. Weiss et al. on p. 650.

  1. Reviews

    1. Top of page
    2. Reviews
    3. Communications
    4. Book Reviews
    1. New Aspects of the Maillard Reaction in Foods and in the Human Body (pages 565–594)

      Prof. Dr. Franz Ledl and Dr. rer. nat. habil. Erwin Schleicher

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199005653

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      The complex reaction between reducing sugars and free amino groups, known as the Maillard reaction, is important, e.g., for the taste and appearance of foodstuffs. It also occurs in the human body, though in this case undesirably: proteins react with glucose to give the compounds 1. Such products of the aging process accumulate in the liver of an individual as a function of time and blood glucose level. Suppression of the Maillard reaction in the body could, e.g., reduce late complications in diabetes and the damaging effects in aging.

    2. The Chemistry of Interstellar Space (pages 595–608)

      Prof. Eric Herbst

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199005951

      Worlds—in the truest sense of the word—lie between chemistry in interstellar space and chemistry in the laboratory. When one thinks: an H atom needs at least a day to meet one of its own kind, even in a dense interstellar cloud! Nevertheless: despite the apparently unfavorable conditions of low temperature and low density, compounds such as OH, CH, SiS, H2O, NH3, cyclo-C3H, C3S, HOCO, H2CO, HCOOH, C2H5OH, and H(C [TRIPLE BOND] C)5CN are formed in the space between the stars. Their formation can be partly simulated by model calculations taking into account the surface of dust particles and ion–molecule reactions.

    3. Stereocontrolled Construction of Complex Cyclic Ketones via Oxy-Cope Rearrangement (pages 609–626)

      Prof. Leo A. Paquette

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199006091

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      The synthetic Potential of the Oxy-Cope rearrangement is far greater than the scheme shown below would suggest. The number of cyclic and polycyclic compounds that can be prepared by this method seems to be limited only by the imagination of the researcher. Regarding, a convergent synthetic strategy, carbonyl regeneration opens up many combinatorial possibilities that assures the excerie of many more options in the future. And, finally, even simultaneous kinectic resolution seems not to be ruled out.

    4. The Coordination Chemistry and Organometallic Chemistry of Tridentate Oxygen Ligands with π-Donor Properties (pages 627–637)

      Prof. Dr. Wolfgang Kläui

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199006271

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      Metal complexes are capable of almost anything, provided they contain the proper metal/ligand combination. A host of essential biochemical transformations, but also a great many industrially important reactions, occur within the coordination spheres of metal ions. The complex CoL2 shown on the right contains two organometallic ligands L with C3v symmetry. Such complexes find exceptionally wide application.

  2. Communications

    1. Top of page
    2. Reviews
    3. Communications
    4. Book Reviews
    1. Synthesis, Structure, and Gas-Phase Decomposition of [Cd(EC6H2tBu3)2]2 (E[DOUBLE BOND]S, Se): First Examples of Low-Coordinate Volatile Cadmium Chalcogenolato Complexes (pages 638–639)

      Dr. Manfred Bochmann, Kevin Webb, Dr. Mary Harman and Prof. Michael B. Hursthouse

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199006381

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      Volatile chalcogenolato complexes of cadmium with stertically demanding thio- and selenophenolato ligands can easily be prepared. In the solid state, the complexes 1 are dimeric with trigonal-planar coordinated cadmium, whereas in solution they dissociate to monomers. They sublime at high temperatures and can be used as starting substances for the deposition of CdS and CdSe films respectively from the gas phase.

    2. Structural Characterization of the Pseudoenantiomeric cis-Dioxo Osmium(VI) Esters of Chiral Diols with Cinchona Alkaloid Ligands (pages 639–641)

      Dr. Ronald M. Pearlstein, Dr. Brent K. Blackburn, Dr. William M. Davis and Prof. K. Barry Sharpless

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199006391

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      Starting point for the development of structure/activity correlations for the asymmetric dihydroxylation of olefins with OsO4 in the presence of chiral amines could be the structures of an osmate ester and its pseudoenantiomer. The esters were obtained from two related trans-disubstituted olefins, OsO4 and the isomeric alkaloids 1 and 2 (R′ = p-C1C6H4CO. aryl = 4-(6-methoxyquinolyl)). Particularly remarkable are the cis-dioxo coordination and the spatial proximity of the equatorial diolate oxygen atom and CO2 group of the chlorobenzoyl moiety.

    3. Synthesis of Cyclosilanylethynes (pages 641–643)

      Prof. Dr. Edwin Hengge, Alfred Baumegger, Markus Eibl, Erhard Hohenester and Doz. Dr. Christoph Kratky

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199006411

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      No σ-π interaction takes place between the Si skeleton and C[BOND]C triple bond in cyclosilanylethynes such as cyclo-Si6Me11-C[TRIPLE BOND]C-cyclo-Si6Me11 and 1. This follows from the NMR and IR spectroscopic data, as well as from the C[BOND]C bond length (121.2pm) and C[BOND]C[BOND]Si angle (177°) in the case of the former. The compounds were prepared from cyclosilanyl (di)halides, acetylene and Na/K alloy.

    4. 4,7-Dimethyl-4,7-dihydro[1,2,5]thiadiazolo-[3,4-b]pyrazine, a Novel Electron Donor with a 12π-Electron Ring System (pages 643–645)

      Prof. Dr. Yoshiro Yamashita, Junko Eguchi, Dr. Takanori Suzuki, Dr. Chizuko Kabuto, Prof. Dr. Tsutomu Miyashi and Dr. Shoji Tanaka

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199006431

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      A very low first oxidation potential (0.15 V vs SCE) characterizes the 12π-electron title compound 1, which is formed by reduction of the corresponding 14π-electron system with potassium and trapping of the dianion with methyl iodide. Reaction of 1 with the electron acceptor 2 affords conducting charge-transfer complexes (σ = 5.6 × 10−2 S cm−1).

    5. Asymmetric Heterodinuclear [L′Ru(μ-O)(μ-CH3CO2)2ML]2⊕ Complexes (M [DOUBLE BOND] Fe, Mn, V): Electronic Structure and Magnetic Properties (pages 645–647)

      Dipl.-Chem. Rainer Hotzelmann, Prof. Dr. Karl Wieghardt, Dr. Ulrich Flörke and Prof. Dr. Hans-Jürgen Haupt

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199006451

      Strong antiferromagnetic coupling or intramolecular electron transfer is found in the products of the reactions of L′RuIIICl3 with LMIIICl3 in aqueous, acetate-containing solution. Electronic and ESR spectra, susceptibility measurements, as well as the results of X-ray structure analyses are consistent with the formulation of 1 and 2 as RuIIIMIII complexes with s = 2 and 3/2, respectively, and of 3 as RuIIVIV complex with S = 1/2. L = 1,4,7-triazacyclononane, L′ = N,N′N″-trimethyl-1,4,7-triazacyclononane.

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    6. 17O NMR Spectroscopy of Benzoyl Compounds Y[BOND]C6H4[BOND]COX: Sensitivity to Ring Substituents as a Measure of the Electron Demand of the Carbonyl Group (pages 647–648)

      Prof. Dr. Hans Dahn, Dr. Peter Péchy and Dr. Vien Van Toan

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199006471

      Contrary to the consensus of opinion13C-NMR spectroscopy is not suitable for the determination of electron density at the carbonyl C-atom. However, by measurement of the 17O-chemical shift in aromatic carbonyl compounds Y-C6H4-COX, X = CF3, H, CH3, CO2R, Br, Cl, F, OCOAryl, SR, OR, NH2, OH, O, reliable statements could be made about the electrophilicity of the carbonyl C-atom. It is gratifying that the results are in agreement with classical chemical rules. There is much to be said for 17O-NMR spectroscopy being given more attention than hitherto.

    7. Lithium-Ion-Catalyzed Epoxidation by Triplet Dioxygen: An ab initio Study (pages 648–650)

      Dipl.-Chem. Heinz Hofmann and Dr. Timothy Clark

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199006481

      Epoxidation is exothermic with −19.3 kcalmol−1 [Eq. (b)] instead of endothermic with +27.7 kcal mol−1 [Eq. (a)] when carried out in the presence of Li. This emerged from demanding ab-initio calculations for this model system. Since Li-catalysis is largely a result of an electrostatic effect, other metal ions should also be able to act as catalysts for epoxidation.

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    8. Structure Determination of NaCD3 Powders at 1.5 and 300 K by Neutron and Synchrotron–Radiation Diffraction (pages 650–652)

      Prof. Dr. Erwin Weiss, Dipl.-Chem. Siegfried Corbelin, Dr. Jeremy Karl Cockcroft and Dr. Andrew Nicholas Fitch

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199006501

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      Both tetramers (right) as well as isolable ions are present in the structure of NaCH3. It therefore assumes an intermediate position between the structures of methyllithium and methyl compounds of the heavier alkali metals. Elucidation of the structure was accomplished by a combination of neutron and synchroton-radiation diffraction measurements on NaCD3 powders at 1.5 and 300 K. All methanide ions are trigonal-pyramidal and have a C-D distance of 109 pm and a D-C[BOND]D angle of 106° (at 1.5 K).

    9. Optically Active Deltacyclanes and Deltacyclenes by Enantioselective Catalysis (pages 652–653)

      Prof. Dr. Henri Brunner, Manfred Muschiol and Dipl.-Chem. Franz Prester

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199006521

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      The reaction of norbornadiene with phenylacetylene leading to the deltacycles 1 can be controlled enantioselectively with norphos/cobalt catalysts. An optical yield of 98.4 % ee with complete conversion is achieved. The reaction thus ranks as one of the best enantioselective reactions catalyzed by transition metal complexes that have been reported so far.

    10. Reactivity in Intramolecular Radical Reactions: A Comparison of Hydrogen Transfer with Alkene Addition (pages 653–655)

      Corrado Berti, Lebert Grierson, Jean A.-M. Grimes, Prof. M. John Perkins and Bulent Terem

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199006531

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      In ionic reactions, as in radical reactions, the effective molarity EM (=kintra/kinter) for additions generally appears to be very much greater than in the case of hydrogen transfer. Values for radical reactions have been obtained for acyl tert-butyl nitroxides: for the transfer of a benzylic H atom in 1, comparison with the corresponding intermolecular reaction gives an EM value of 44M; for the addition of radicals to alkenes one analogously obtains EM values of ca. 105M.

    11. A First Step toward the Phosphorus Analogues of Polythiophenes (pages 655–657)

      Dr. Marc-Olivier Bevierre, Dr. François Mercier, Dr. Louis Ricard and Prof. Dr. François Mathey

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199006551

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      Tetramerization with α-thienyl migration to give 2 and subsequent cleavage of the P-P bonds of the dimer with sodium afforded access, starting from 1, to a biphospholyl dianion which is isoelectronic with α-sexithienyl. Its further derivatization yielded a W- and a Mo-complex, whose X-ray structure analyses afforded important information about the electronic structure of the chain.

    12. Solvent and Structure Effects in the Photobromination of Benzyltrimethylsilanes. A Mechanistic Changeover from Hydrogen-Atom Transfer to Electron Transfer (pages 658–659)

      Prof. Dr. Enrico Baciocchi and Dr. Manuela Crescenzi

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199006581

      The mechanistic dichotomy in the reaction of Br with arenas could be demonstrated with the photobromination of aryltrimethylsilanes as example: depending on the solvent, benzyltrimethylsilane 1 reacts with Br with hydrogen atom transfer [CC14 or AcOH; route (a)] or with electron transfer [AcOH/CF3CO2H; route (b)]. Electron donating substituents on the phenyl ring of 1 promote reaction according to route (b) in AcOH.

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    13. Direct Evidence for a Nitrile Imine–Imidoylnitrene Rearrangement: X-Ray Crystal Structure of an Unusual Nitrene Complex (pages 659–661)

      Michel Granier, Dr. Antoine Baceiredo, Dr. Hansjörg Grüzmacher, Dr. Hans Pritzkow and Dr. Guy Bertrand

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199006591

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      Compound 2, which first melts above 300 °C without decomposition, is formed via nitrile imine–imidoylnitrene rearrangement upon reaction of the nitrile imine 1 with tetrachloro-o-benzoquinone. The surprising thermal stability of 2 could be due to the coordination of an oxygen atom to the nitrene nitrogen atom. Whether an isodiazirine, an isomer of diazomethane, is formed as intermediate, has not yet been confirmed (R = NiPr2).

    14. Intramolecular Insertion of Arylcarbenes into C[BOND]Si Bonds (pages 661–662)

      Prof. Dr. Wolfgang Kirmse and Dr. Wolfgang Konrad

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199006611

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      C[BOND]Si bonds are generally inert towards the intermolecular attack of carbenes. In contrast, arylcarbenes of type 1 exhibit intramolecular insertion into C[BOND]Si bonds of the ortho side chain (for route b:Ph > Me, benzyl).

    15. Isolation of Conformational Isomers of α- and β-Ionones by Inclusion Complex Formation (pages 662–664)

      Prof. Fumio Toda, Dr. Koichi Tanaka and Prof. Dr. Takaji Fujiwara

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199006621

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      Complexation with 1 as host molecule allows isolation of S-trans-β-ionone 2a, whereas 3 selectively forms an inclusion compound with the S-cis-isomer 2b. The conformation of the complexed isomers were respectively determined by an X-ray structure analysis and spectroscopically.

    16. Synthesis, Structure, and Reactivity of Aryloxo(imido)titanium Complexes (pages 664–665)

      John E. Hill, Robert D. Profilet, Dr. Phillip E. Fanwick and Prof. Ian P. Rothwell

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199006641

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      The η2-iminotitanium complex 1 reacts with azobenzene in the presence of pyrrolidinopyridine py′ with ligand exchange to give the complex 2, which transforms within several days at 100 °C into the phenylimidotitanium complex 3. The length of the Ti-N bond in 3 is 171.9(3) pm, and the Ti-N-C angle is 173.1(3)°. Unlike imidozirconium compounds, which readily react with C-H activation, 3 is a “dead dog”—no reaction in benzene at 110°C! Ar′= 2,6-iPr2C6H3, R1 = tBu.

    17. Intramolecular Hetero-Diels–Alder Reactions of Oxadienes: Influence of Substituents of the Tether on the Diastereoselectivity (pages 665–667)

      Lutz F. Tietze, Siegbert Brand, Thomas Brumby and Jens Fennen

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199006651

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      How do substituents on the chain of 1 influence the stereosclectivity of the intramolecular hetero-Diels-Alder reaction? This question was followed up by exact analysis of the product composition of the reactions of 1 a and its methyl analogues 1 be with 2 to give 3ae. It emerged that “steric” and “conformational” effects in the chair-shaped transition structure must be differentiated and that the equatorial position of the methyl group is more strongly favored in the transition structures leading to 3c, d than in methylcyclohexane. R = H (a), α-Me (b), β-Me (c), γ-Me (d), δ-Me (e).

    18. Reductive Scission of a Cyclopropane σ-Bond During the Action of Elemental Lithium on Cyclopropylacetylenes – A cis-1,2-Dilithioalkene as Intermediate (pages 667–669)

      Prof. Dr. Adalbert Maercker and Dipl.-Chem. Ulrich Girreser

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199006671

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      The cis-dilithioalkene 2 a is stable in solution at −30 °C; it is formed as intermediate during the reductive cleavage of a cyclopropane bond in 1 a leading to 3 a. In contrast, in the analogous reaction of 1 b, only the product 3b of ring-opening can be detected, and no intermediate. R = Ph(a), cyclopropyl (b).

    19. Synthesis and Structure of Ph2P(S)N [DOUBLE BOND] TiCl2 · 3C5H5N, the First Imidotitanium Complex (pages 669–670)

      Prof. Dr. Herbert W. Roesky, Heike Voelker, Dr. Michael Witt and Dr. Mathias Noltemeyer

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199006691

      Coordination of electron pair donors at the titanium atom leads to stabilization of imidotitanium complexes, which are of interest as catalysts for C-H activations and polymerizations. Thus, reaction of the thiophosphinic acid amide 1 with TiCl4 and subsequent treatment of the initial product with pyridine enables the synthesis of the orange-red, crystalline title compound 2. The titanium atom exhibits distorted octahedral coordination; the length of the Ti-N bond is 172.0(2) pm.

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    20. Electron Transfer between Covalently Linked Porphyrin and Quinone Units: Synthesis, Magnetic Resonance and Picosecond Fluorescence Spectroscopy (pages 670–672)

      Dipl.-Chem. Jörg von Gersdorff, Dr. Martina Huber, Dipl.-Chem. Heike Schubert, Dipl.-Chem. Dominique Niethammer, Priv.-Doz. Dr. Burkhard Kirste, Dr. Martin Plato, Prof. Dr. Klaus Möbius, Prof. Dr. Harry Kurreck, Dr. Rainer Eichberger, Dr. Reinhard Kietzmann and Prof. Dr. Frank Willig

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199006701

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      Quinones covalently linked with porphyrin like 1 are suitable for investigating light-induced charge separation in the primary process of photosynthesis. The orientation of the ring units was determined by NOE and ENDOR measurements on the Zn-cyclohexylporphyrin and cyclohexylquinone. Detailed MO calculations on Zn-1 and picosecond fluorescence measurements gave satisfactorily consistent rate constants for the electron transfer from the prophyrin to the quinone.

    21. Concanavalin A Binds Pyranosides and Their Tetraacetates Stereoselectively (pages 672–674)

      Jürgen-Hinrich Fuhrhop and Dipl.-Chem. Michael Arlt

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199006721

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      A predominantly planar bonding site for carbohydrate units is deduced for the protein con-canavalin A from the fact that vesicles with pyranoside units such as 1 and their tetraacetates 2 are almost equally well and equally selectively bound.

    22. Synergic Destabilization by Geminal Ester Groups (pages 674–675)

      Dr. Sergej Verevkin, Dr. Barbara Dogan, Dr. Hans-Dieter Beckhaus and Prof. Dr. Christosph Rüchardt

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199006741

      An inverse effect of geminal acceptor substituents should correspond to the anomeric effect of geminal donor substituents. This could be confirmed in the case of the esters 1 and 2 by derivation of group increments: the diesters are destabilized ca. 6 kcal mol−1 compared to monoesters, and the triester is destabilized ca. 6 kcal mol−1 compared to the diesters. The reactivity of these compounds (e.g. their acidity) is seen in a new light with this finding (R = H, Me).

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    23. Some Valenes of Benzannelated Five-Membered Heteroarenes – Synthesis and NMR Spectra (pages 675–677)

      Manfred Christl, Stefan Krimm and Arno Kraft

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199006751

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      1,3-Dipolar cycloadditions to 3-benzvalenyI phenyl sulfones and elimination of phenylsulfinic acid afforded access to valenes such as 1 and 2. With a synthesis according to Paal and an Aldol condensation according to Hinsberg the benz-valene-annelated thiophenes 3 were obtained. The different formal arrangement of the double bonds in 1, on the one hand, and in 2, 3 on the other, give rise to clearly different 13C-NMR chemical shifts of the bicyclobutane bridgehead atoms.

    24. Nitrogen Triiodide (pages 677–679)

      Inis Tornieporth-Oetting and Thomas Klapötke

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199006771

      Deep-red, adduct-free NI3 can be isolated from the reaction of boron nitride with iodine monofluoride at −30°C by sublimation at low temperature. Its low-temperature Raman spectrum is consistent with a C3v molecular symmetry.

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    25. Doubly Stereodifferentiating Hiyama Addition with Mismatched Reactants; Enantio- and Diastereo-controlled Synthesis of Dihydrocanadensolide (pages 679–680)

      Prof. Dr. Johann Mulzer and Dipl.-Chem. Lars Kattner

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199006791

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      Carbon skeleton, functionalization pattern, and chirality centers of the target molecule are formed at once in the key step of the synthesis of 1, a metabolite of Penicillium canadense. This key step is the highly steroselective Hiyama reaction of a chiral allyl bromide derivative with an α-chiral aldehyde in the mismatched combination with predominance of the allyl components.

    26. Synthesis of Enantiomerically Pure (−)-Hypnophilin (pages 680–682)

      Klaus Weinges, Uwe Dietz, Thomas Oeser and Hermann Irngartinger

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199006801

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      Enantiomerically pure (—)-hypnophilin 2 can be prepared on a 100 mg scale in a simple reaction from catalpol 1. The stereoselectivity of the individual steps was demonstrated by X-ray structure analyses of two important intermediate products.

    27. An Allene-analogous Boranylidenephosphane with B[DOUBLE BOND]P Double Bond: 1,1-Diethylpropyl(2,2,6,6-tetramethylpiperidino)-boranylidenephosphane-P-pentacarbonylchromium (pages 682–684)

      Dr. Gerald Linti, Prof. Dr. Heinrich Nöth, Dr. Kurt Polborn and Prof. Dr. R. T. Paine

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199006821

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      Cleavage of the B2P2 ring in 1 with [(CO)5Cr(thf)] affords access to the hetero-allene system 2 in 86% yield. Characteristic for 2 are the extremely short B[BOND]P distance of 1.743(5) Å and the orthogonal arrangement of the N- and P-sub-stituents.

    28. Measuring the Optical Activity of Chiral Imprints in Insoluble Highly Cross-linked Polymers (pages 684–686)

      Prof. Dr. Günter Wulff and Dr. Günter Kirstein

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199006841

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      Polymers such as Pl-□ with chiral imprints are of interest, inter alia, for racemate separation. Because of the insolubility of these polymers there are no methods available for the direct investigation of the chiral voids in the polymer. Measurement of the optical rotation of the polymers in suspension has now been accomplished; it is therefore possible to determine the influence of chiral side groups, incorporated chiral templates, and the structure of chiral voids on the optical rotation.

    29. Dicobalt Complexes with syn- and anti-Coordinated μ-Cycloheptatriene Bridges (pages 686–688)

      Priv.-Doz. Dr. Hubert Wadepohl, Wolfgang Galm and Dr. Hans Pritzkow

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199006861

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      Despite their similar composition the two cycloheptatriene-bridged dinuclear complexes [(CpCo)2(μ-C7H8)] and [(Cp*Co)2(μ-C7H8] 1, which are accessible in good yields by reaction of [CpCo(η4-C7H8)] and [Cp*Co (η4-C7H8)] with [CpCo(C2H4)2] and [Cp*Co-(C2H4)2] respectively, have very different structures. The Cp complex shows an unsymmetrical syn-bonding (σ2, η23) of the cycloheptatriene to a (CpCo)2 skeleton, whereas in 1 a structure with anti-cycloheptatriene bridge (η4*) is realized for the first time.

    30. The Monofluorooxonium(0) Hexafluorometalate(VI)S H2OFMFmath image (M = As,Sb) (pages 688–689)

      Prof. Dr. Rolf Minkwitz and Dipl.-Chem. Gabriele Nowicki

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199006881

      Oxidative fluorination of H2O with monofluoroxenonium metalates in anhydrous HF [Eq. (a)] afforded access to the monofluorooxonium salts 1, M = As, Sb. The pale red salts can be stored without decomposition for a few weeks at temperatures below 233 K and for up to 2 h at room temperature.

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    31. Ring Closure and Ring Expansion Reactions in Bridged Triarylphosphanes and Triarylarsanes with o-Isopropenyl Substituents. Novel Candidates for Turnstile Geometry (pages 689–692)

      Prof. Dr. Dieter Hellwinkel, Dipl.-Chem. Andreas Wiel, Dr. Gerhard Sattler and Dr. Bernd Nuber

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199006891

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      ortho-Cyclizations to C3r polycycles 1 and novel ring expansions by three ring members takes place on acid treatment of the 2,6-diisopropenylphenyl derivatives 2. The pentacoordinated o-chloranil adduct of 1 (Y = P) does not exhibit ideal turnstile geometry, but a distorted trigonal-bipyramidal structure.

    32. Electrochemical Solid-State Studies on Oligomeric p-Phenylenes as Model Compounds for Conductive Polymers (pages 692–695)

      Dipl.-Chem. Klaus Meerholz and Prof. Dr. Jürgen Heinze

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199006921

      Reversible reductions and oxidations at separated potentials are possible electro-chemically in the solid state up to the tetraanion and tetracation respectively in the case of sexiphenyl. However, at room temperature and depending on the electrode potential the formation of more or less strongly cross-linked polymer chains is observed during the oxidation. In addition, the measurements prove that the characteristic current plateaus in the voltammograms of conductive polymers are attributable to faradaic redox processes.

    33. Zwitterions as Intermediates of the 1,3-Dipolar Cycloaddition of Electrophilic Azides to 5-Alkylidenedihydrotetrazoles – the Other Non-Concerted Limiting Case (pages 695–697)

      Prof. Dr. Helmut Quast, Dipl.-Chem. Dieter Regnat, Eva-Maria Peters, Dr. Karl Peters and Prof. Dr. Hans Georg von Schnering

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199006951

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      The isolable zwitterions 2 and the tetrahydrotetrazines 3 are formed in the 1,3 -dipolar cycloadditions of R3N3 to 1. It has been established X-ray crystallo-graphically that a strong steric hindrance is responsible for ring closure between the very close centers of opposite charge being difficult in 2 (R1 = H, R2 = tBu = Mes). A detailed investigation of the reactions clearly confirms that the zwitterions 2 are actually the intermediates of a non-concerted cycloaddition (R1 = H. Me; R2 = Me, tBu; R3 = (NO2)3C6H2, p-Tos, Mes).

  3. Book Reviews

    1. Top of page
    2. Reviews
    3. Communications
    4. Book Reviews
    1. Book Review: The Elements. By I. Emsiey (page 700)

      Joachim Wachter

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199007001