Angewandte Chemie International Edition in English

Cover image for Vol. 32 Issue 4

April 1993

Volume 32, Issue 4

Pages 457–628

Currently known as: Angewandte Chemie International Edition

    1. Cover Picture (Angew. Chem. Int. Ed. Engl. 4/1993)

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199304571

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      The cover picture shows a spectral “landscape” made from the fluorescence excitation spectra of single perylene molecules in a polyethylene film. Each “mountain” represents the fluorescence from one molecule. To paint this landscape the probing laser must scan the frequency (6.1 GHz range, along the axis from the lower right to the upper left) and travel across the sample (23 μm, along the perpendicular axis). This type of picture is one of the results of recent spectacular advances in the characterization of single molecules by optical spectroscopy. Many chemists certainly dream of examining individual molecules each in their specific environment. More of this fascinating area of research is described by W. E. Moerner and T. Basché, p. 457 ff.

  1. Reviews

    1. Top of page
    2. Reviews
    3. Highlights
    4. Correspondences
    5. Communications
    6. Book Reviews
    1. Optical Spectroscopy of Single Impurity Molecules in Solids (pages 457–476)

      Dr. W. E. Moerner and Dr. Thomas Basché

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199304573

      A truly local probe of host–guest interactions is provided by the optical spectroscopy of single impurity molecules in solids. The sensitivity of a single dopant molecule both to its specific local environment and to external perturbations has been exploited recent experiments—most often on the pentacene/ p-terphenyl system—to reveal a wealth of fascinating novel phenomena such as spectral diffusion of single molecules.

    2. Poly(hydroxyalkanoates): A Fifth Class of Physiologically Important Organic Biopolymers? (pages 477–502)

      Dr. Hans-Martin Müller and Prof. Dr. Dieter Seebach

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199304771

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      Ideal storage materials in microorganisms, high molecular weight polyhydroxy acids are the subject of lively interdisciplinary investigations. The most abundant example, poly(R)-3-hydroxybutyric acid P(3-HB), was also found in low molecular weight form in membranes. P(3-HB) is assumed to form an ion channel with Ca ions and a polyphosphate (shown right), which allows the transported of materials through membranes. Biotechnology was used to produce a copolymer from P(3-HB) and hydroxyvaleric acid which is completely biodegradable.

    3. Neural Networks in Chemistry (pages 503–527)

      Prof. Dr. Johann Gasteiger and Prof. Dr. Jure Zupan

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199305031

      The emulation of the elementary functions of the human brain is the goal of artificial neural networks. It is possible, for instance, to recognize similarities in two objects, to classify objects, to derive properties of an object from its other properties, and to transform complex relations into a simpler representation without loss of information. In chemistry neural networks have already been applied for process control, for setting up the relation between structural features and spectra, and for predicting the chemical reactivity and the secondary structure of proteins.

    4. Defect Chemistry: Composition, Transport, and Reactions in the Solid State; Part II: Kinetics (pages 528–542)

      Prof. Dr. Joachim Maier

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199305281

      The equilibrium concentration of point defects has an important dual role in the chemistry of solids: it determines the chemical behavior and departures from the stoichiometric composition in the equilibrium state as shown in the first part of this review, and, together with mobility as a kinetic parameter, it also determines the rate of processes in solids. This is of fundamental importance, since solid-state reactions usually begin at the surface and propagate to the interior by chemical transport. Spatial coordinates are crucial in descriptions of these types of processes.

  2. Highlights

    1. Top of page
    2. Reviews
    3. Highlights
    4. Correspondences
    5. Communications
    6. Book Reviews
    1. Peptoids—A New Approach to the Development of Pharmaceuticals (pages 543–544)

      Prof. Dr. Horst Kessler

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199305431

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      N-substituted oligoglycines, “peptoids”, can be prepared in good yields and high purity without protected monomer building blocks and without deprotection according to Equation (a). This class of compounds should be of great utility in screening for new pharmaceutical lead structures.

    2. Compounds Containing Silicon, Germanium, and Tin Polyhedra: The First Octahedral Tin Cluster (pages 545–546)

      Prof. Dr. Manfred Weidenbruch

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199305451

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      Mostly syntheses with one-pot reaction sequences in which many bonds are broken and remade are required to prepare polyhedral compounds of carbon homologues. The few known examples show a preference for the [n]prismane structure. Clusters of main group elements with octahedral skeletons were previously known only for boron. The synthesis of [Sn6{Cr(CO)5}6]2− (1) by Huttner et al. (Angew. Chem. Int. Ed. Engl.1993, 105, 297) shows that octahedral clusters of elements of the fourth main group can also be stable.

    3. Palladium-Catalyzed, Enantioselective Allylic Substitutions (pages 547–549)

      Dr. Oliver Reiser

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199305471

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      Are the days of C2 symmetric ligands as chiral inductors numbered? Reports of the record selectivities achieved with the ligands 1 and 2 in Pd-catalyzed allylic substitutions (A. Pfaltz et al., this issue, p. 566) could lead to this conclusion. Their results indicate that not only steric but also stereoelectronic effects are important for these reactions.

  3. Correspondences

    1. Top of page
    2. Reviews
    3. Highlights
    4. Correspondences
    5. Communications
    6. Book Reviews
    1. Concerning “An Opinion on the Heterogeneous Photoreduction of N2 with H2O”: First Letter (page 550)

      Prof. Vincenzo Augugliaro and Prof. Javier Soria

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199305501

      The synthesis of ammonia from nitrogen and water by irradiation in the presence of certain metal oxide powders as catalysts has been published a number of times since 1977 but was called into question last year by Edwards et al. (Angew. Chem. Int. Ed. Engl.1992, 31, 480). Criticism of those arguments and the authors' reply should allow our readers to draw their own conclusions. This discussion is welcome in view of the importance of the reaction, whose apparently simple stoichiometry is even open to debate.

    2. Concerning “An Opinion on the Heterogeneous Photoreduction of N2 with H2O”: Second Letter (page 551)

      Prof. Leonardo Palmisano, Prof. Mario Schiavello and Prof. Antonino Sclafani

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199305511

      The synthesis of ammonia from nitrogen and water by irradiation in the presence of certain metal oxide powders as catalysts has been published a number of times since 1977 but was called into question last year by Edwards et al. (Angew. Chem. Int. Ed. Engl.1992, 31, 480). Criticism of those arguments and the authors' reply should allow our readers to draw their own conclusions. This discussion is welcome in view of the importance of the reaction, whose apparently simple stoichiometry is even open to debate.

    3. Reply: Standards of Demonstration for the Heterogeneous Photoreactions of N2 with H2O (pages 552–553)

      Prof. Julian A. Davies and Prof. Jimmie G. Edwards

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199305521

      The synthesis of ammonia from nitrogen and water by irradiation in the presence of certain metal oxide powders as catalysts has been published a number of times since 1977 but was called into question last year by Edwards et al. (Angew. Chem. Int. Ed. Engl.1992, 31, 480). Criticism of those arguments and the authors' reply should allow our readers to draw their own conclusions. This discussion is welcome in view of the importance of the reaction, whose apparently simple stoichiometry is even open to debate.

  4. Communications

    1. Top of page
    2. Reviews
    3. Highlights
    4. Correspondences
    5. Communications
    6. Book Reviews
    1. TiIV Complexes with Bridging Ylide Ligands: Double Oxophiles in Reactions with Aldehydes (pages 554–555)

      Karin A. Hughes, Pablo G. Dopico, Dr. Michal Sabat and Prof. M. G. Finn

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199305541

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      As compounds with characteristics of Wittig and Tebbe reagents, titanacycles 1 (X = Cl, NMe2) can function as synthetic equivalents of carbon atoms because of the oxophilicity of the P and Ti centers. In fact, complexes 1 react with electron-rich aromatic aldehydes (Ar = 4-MeC6H4, 4-MeOC6H4) to give the allenes 2.

    2. The Incorporation of C60 in Molecular Sieves (pages 556–557)

      Dipl.-Chem. Andreas Gügel, Prof. Dr. Klaus Müllen, Dipl.-Chem. Horst Reichert, Dipl.-Chem. Wolfgang Schmidt, Prof. Dr. Günter Schön, Dr. Ferdi Schüth, Jochen Spickermann, Dr. Jeremy Titman and Prof. Dr. Klaus Unger

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199305561

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      By loading from the gas phase C60 can be incorporated into molecular sieves. C60 uptake in the micropore system of the aluminophosphates VPI-5 (picture on the right) and AlPO4-8 was proven by combined thermogravimetry and differential thermal analysis, IR spectroscopy, and sorption measurements. The preliminary NMR results give indications that the free isotropic rotation of C60 in these compounds is restricted.

    3. Selective Cleavage of a 35-mer Single-Stranded DNA Containing the Initiation Codon of the TAT Gene of HIV-1 by a Tailored Cationic Manganese Porphyrin (pages 557–559)

      Marguerite Pitié, Dr. Christiane Casas, Dr. C. Jeffrey Lacey, Dr. Geneviève Pratviel, Prof. Dr. Jean Bernadou and Dr. Bernard Meunier

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199305571

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      The recognition and cleavage of DNA is highly selective when the cleaver is the conjugate from the chemical nuclease 1 and a 19-mer vector. This is shown on a 35-mer complementary DNA target, which contained the initiation colon of HIV-I TAT. Such reactive antisense oligonucleotides invite further investigation as potential antiviral agents. M = MnIII(H2O), X = O(CH2)4C(O)H, R = N = methylpyridinio.

    4. p-[32.56]Octahedrane, the (CH)12 Hydrocarbon with D3d Symmetry (pages 559–561)

      Dr. Chih-Hung Lee, Dipl.-Chem. Shelue Liang, Dipl.-Chem. Thomas Haumann, Priv.-Doz. Dr. Roland Boese and Prof. Dr. Armin de Meijere

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199305591

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      Highly symmetrical compounds like 1–3 have always fascinated chemists. Dodecahedrane (3) was synthesized over ten years ago for the first time, and now the synthesis and crystal structure of the C12H12 hydrocarbon 1 have been accomplished. It was prepared in four steps from a tetracyclic intermediate known from the synthesis of dodecahedrane. Unusual as regards constitution and point symmetry, the (CH)12 hydrocarbon also promises to have unusual chemical properties. Compound 2 still eludes synthesis.

    5. [MnM(egta)] · 8H2O (M = Mn, Cd): A Novel Type of Two-Dimensional Magnetic Lattice (pages 561–563)

      Dr. Juan J. Borrás-Almenar, Prof. Dr. Eugenio Coronado, Dr. Carlos J. Gómez-Garcia and Dr. Lahcène Ouahab

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199305611

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      Extended layered networks in which [M(egta)]2− is eight-coordinate and Mn2+ six-coordinate are present in the title compounds. In the case of the Mn2 compound this leads to the novel two-dimensional lattice sketched on the right; short range antiferromagnetic exchange interactions between the MnII ions were found. H4egta = ethylenedioxybis(ethylenenitrilo)tetraacetic acid; the circles represent the magnetically nonequivalent MnII ions.

    6. The Seven-Component Reaction** (pages 563–564)

      Dipl.-Chem. Alexander Dömling and Prof. Dr. Ivar Ugi

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199305631

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      Seven at one blow! From seven different compounds, two of which are gases, the functionalized thiazolidines 1 and 2 can each be synthesized in a one-pot process. This is the multicomponent reaction with the highest number of components yet discovered.

    7. Tetranuclear Cuboidal and Hexanuclear Prismatic Iron–Sulfur–Nitrosyl Clusters (pages 564–566)

      Michael J. Scott and Prof. Richard H. Holm

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199305641

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      Reductive desulfurization of [Fe4S4(NO)4] with PPh3 affords cluster 1, which may provide a synthetic entry to model compounds for cofactors of nitrogenase. For example, cluster 1 can be converted into prismatic [Fe6S6(NO)6]2−.

    8. Chiral Phosphinoaryldihydrooxazoles as Ligands in Asymmetric Catalysis: Pd-Catalyzed Allylic Substitution (pages 566–568)

      Dipl.-Chem. Peter von Matt and Prof. Andreas Pfaltz

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199305661

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      Enantioselectivities up to 99% ee and excellent yields under mild reaction conditions could be realized in allylic alkylations [Eq. (a)] with palladium catalysts prepared with the chiral ligands 1. Enantiomerically pure phosphinoaryldihydrooxazoles (1) are readily accessible from commercially available chiral amino alcohols. HNu = H2C(COOMe)2, H2C(COMe)2, HC(NHAc)(COOEt)2.

    9. Asymmetric Synthesis and Highly Diastereoselective ortho-Lithiation of Ferrocenyl Sulfoxides. Application to the Synthesis of Ferrocenyl Derivatives with Planar Chirality (pages 568–570)

      Dr. François Rebière, Dr. Olivier Riant, Dr. Louis Ricard and Prof. Dr. Henri B. Kagan

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199305681

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      Enantiomerically pure sulfoxides with planar chirality (3, R = tBu, p-Tol, X = H) can be prepared by the asymmetric synthesis of sulfoxides 1, and subsequent diastereoselective deprotonation to give 2, X = H. Double deprotonation of 1, R = tBu, provided 2, X = Li, which could be converted into diphosphane 3, X = E = PPh2.

    10. A New Type of Hexanuclear Iron(III) Hydroxo(oxo) Cluster (pages 570–572)

      Dr. Charlie J. Harding, Richard K. Henderson and Dr. Anne K. Powell

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199305701

      Bridging μ3-oxo and μ2-hydroxo ligands characterize the structure of the cluster anion 1, which can be prepared as a highly soluble K or Na salt in water. The structure of 1 can be viewed as two parallel, μ3-oxo-bridged Fe3 triangles joined by μ-hydroxo bridges or as two Fe4 butterfly structures with shared wing tips. Cluster 1 has more short Fe[BOND]Fe separations than all other related compounds, and its effective magnetic moment μeff increases dramatically at low temperatures. This magnetic behavior is not completely understood.

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    11. E/Z Diastereoselective Enzymatic Hydrolysis of Esters and Diesters (pages 572–574)

      Pharmacist Tanja Schirmeister and Prof. Dr. Hans-Hartwig Otto

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199305721

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      With porcine liver esterase the α,β-unsaturated diester 1 can be hydrolyzed selectively at the ester group in the Z position relative to the carbonyl group. The further saponification to give the dicarboxylic acid is achieved with aqueous NaOH. However, even under drastic conditions, 1 cannot be hydrolyzed in one step by either bases or acids with retention of the β-lactam ring.

    12. Reduction of Geminal Dihalocyclopropanes with Lithium 4,4′-Di-tert-butylbiphenyl; Cyclopropyl Derivatives of Dilithiomethane and 1,2-Dilithioethane; Inferences Regarding the Intermediate Carbenoids (pages 574–576)

      Drs. Cornelis P. Vlaar and Prof. Dr. Gerhard W. Klumpp

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199305741

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      The reaction of 7,7-dihalonorcaranes with lithium 4,4′-di-tert-butylbiphenyl at −80 °C leads to mixtures containing primarily 7,7′-dilithiobinorcarane (3) besides 7-lithionorcarane (1) and 7,7′-dilithionorcarane (2). Compound 3, a derivative of cyclopropylmethyllithium, is remarkable stable.

    13. [Tc6X8] Clusters in ternary Technetium Chalcogenides (pages 576–578)

      Prof. Dr. Welf Bronger, Dipl.-Chem. Martin Kanert, Dipl.-Chem. Markus Loevenich, Dr. Dieter Schmitz and Prof. Dr. Klaus Schwochau

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199305761

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      Almost regular Tc6 octahedrons inside cubes constructed of chalcogen atoms X (X = S, Se) form the characteristic structural element in ternary alkali metal technetium chalcogenides. The Tc6X8 units are linked through X or X2 bridges (in the picture on the right the bridging X atoms are included with the central unit) to give three-dimensional frameworks, and the alkali metal ions are inserted into suitable interstices.

    14. Asymmetric Synthesis of α-Amino Acids and N-Protected α-Amino Aldehydes by Addition of Chiral Vinyl Anions to Sulfonylimines (pages 578–580)

      Prof. Dr. Manfred Braun and Dipl.-Chem. Kersten Opdenbusch

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199305781

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      With enantiomeric excesses between 93 and 96%, the N-protected α-amino aldehydes 3, which are useful synthesis building blocks, are obtained by addition of the vinyl anion 2 to N alkylidene sulfonamides 1, after ozonolysis of the olefinic double bond. The aldehydes 3 can be converted under complete chelate control in Mukaiyama–aldol reactions to the esters 4. R for example C6H5, 4-CH3OC6H4; MEM = CH2OCH2CH2OCH3; Ar = 2,4,6-(CH3)3C6H2.

    15. Structures of Classical Reagents in Chemical Synthesis: (nBuLi)6, (tBuLi)4, and the Metastable (tBuLi · Et2O)2 (pages 580–582)

      Thomas Kottke and Dr. Dietmar Stalke

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199305801

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      Crystalline nBuLi is also hexameric; this same degree of oligomerization was determined years ago in solutions of hydrocarbons. Six Li atoms form a distorted octahedron, six of whose triangular faces are capped by nBu groups (see structure depicted). The unusual arrangement of the β-C atoms indicates interactions with the Li atoms. In contrast, tBuLi forms a Td-symmetric tetramer in the solid state.

    16. Enantioselective Catalytic Addition of Functionalized Dialkylzinc Compounds to β-Stannylated Aldehydes: A Convenient Preparation of Chiral β- and γ-Functionalized Secondary Alcohols (pages 582–584)

      Dr. Walter Brieden, Roswitha Ostwald and Prof. Dr. Paul Knochel

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199305821

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      High enantioselectivity is found in the Ti-catalyzed addition of dialkylzinc compounds [R1(CH2)n]2Zn to the β-stannylaldehydes 1 and 2 to give the polyfunctionalized products 3 and 4, respectively. Examples of (CH2)nR1: ethyl, octyl, (CH2)4Cl. R = Me, Bu.

    17. Transfer Hydrogenation and Deuteration of Buckminsterfullerene C60 by 9,10-Dihydroanthracene and 9,9′,10,10′[D4]Dihydroanthracene (pages 584–586)

      Prof. Dr. Christoph Rüchardt, Dipl.-Chem. Matthias Gerst, Jochen Ebenhoch, Dr. Hans-Dieter Beckhaus, Dr. Eleanor E. B. Campbell, Ralf Tellgmann, Prof. Dr. Helmut Schwarz, Dr. Thomas Weiske and Dipl.-Chem. Stephan Pitter

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199305841

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      An efficient and simple method for the synthesis of two uniform buckminsterfullerene hydrogenation products, C60H18 and C60H36, is offered by the title reaction. The picture on the right shows a probable structure of C60H36 obtained from MM2 calculations. These results are an important step on the way to preparative organic chemistry with C60.

    18. Synthesis and Structure of Tetrasilylgermane, Ge(SiH3)4, and Other Sillgermanes (pages 586–587)

      Dipl.-Chem. Thomas Lobreyer, Prof. Dr. Heinz Oberhammer and Prof. Dr. Wolfgang Sundermeyer

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199305861

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      A two-step synthesis provides Ge(SiH3)4, a stable compound that could serve as a process gas for the production of photovoltaic cells from thin films of a-SiGe: H alloy. The unusual 29Si NMR spectrum and an electron diffraction study prove the highly symmetrical molecular structure (shown right).

    19. On the Strength of the C[BOND]H…O Hydrogen Bond and the Eclipsed Arrangement of the Methyl Group in a Tricyclic Orthoamide Trihydrate (pages 588–589)

      Prof. Juan J. Novoa, Pere Constans and Prof. Myung-Hwan Whangbo

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199305881

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      A maximum of 3.0 kcalmol−1 should be the total energy of the three C[BOND]HO hydrogen bonds in the trihydrate of 1 according to the results of the calculations described here. This is substantially less than the energy needed to overcome the rotational barrier of the methyl group, which would thus rationalize the highly unusual eclipsed conformation about the Cmath image[BOND]CH3 bond found in 1·3 H2O experimentally. Further investigations are needed for the complete understanding of this phenomenon.

    20. Structural Variations Observed in the [Bi(O2CCF3)4Ph]2− Anion: Selective Cation–Anion Interactions through Hydrogen Bonds (pages 589–591)

      Steven R. Breeze and Prof. Dr. Suning Wang

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199305891

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      The length of the carbon bridge between the two positively charged nitrogen centers in dication 1 influences the coordination sphere of the Bi center in the title anion. The change from square-pyramidal (n = 3, shown schematically on the right) to pentagonal-pyramidal (n = 2) is attributed to the formation of N[BOND]HO hydrogen bonds.

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    21. Novel Triselenidotantalum Halfsandwich Complexes (pages 591–593)

      Prof. Dr. Kazuyuki Tatsumi, Hiroyuki Kawaguchi and Prof. Dr. Kazuhide Tani

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199305911

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      An almost ideal cube-shaped TaSe3Li3Cl framework is found in complex 1, the first organometallic complex with three monoselenido ligands. The three Li atoms each bridge two Se ligands and together are capped by the Cl atom.

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    22. [Cr(CO)5PCl3]—A P1 Building Block for the Formation of Complexes with cyclo-Px Ligands (x = 3, 5) (pages 593–594)

      Dr. Manfred Scheer, Gabriele Friedrich and Dipl.-Chem. Kay Schuster

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199305931

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      Multiple P[BOND]P bond formation in the coordination sphere of transition metals occurs in reactions of [Cr(CO)5PCl3] with carbonylcyclopentadienylmolybdenates and -ferrates. Complexes with cyclo-P3 and cyclo-P5 ligands (like 1), respectively, result.

    23. Novel VIII Complexes with a Central [V33-S)-(μ-S2)3]+ or [V2(μ-O)(μ-SPh)2]2+ Unit (pages 594–596)

      Norman S. Dean, Dr. Kirsten Folting, Dr. Emil Lobkovsky and Prof. Dr. George Christou

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199305941

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      Positioned in the middle of the V3 triangle in complex 1, whose edges are bridged asymmetrically by three Smath image ligands, is a μ3-sulfido ligand (the central unit of 1 is shown on the right). In addition each V atom is coordinated to a terminal bipyridyl ligand. This structure type is new for vanadium complexes.

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    24. The First Unsolvated Chelate and Cubane-Type Barium Complexes: Effective Compounds for the Sol–Gel Process (pages 596–598)

      Dr. Sushil K. Pandey, Dipl.-Chem. Alexander Steiner, Prof. Dr. Herbert W. Roesky and Dr. Dietmar Stalke

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199305961

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      Unexpectedly good solubility was found for complexes 1 and 2 prepared from barium bis(trimethylsilyl)amide. In the Ba[BOND]N heterocubane 2 (shown on the right, methyl groups are omitted), four of the corners are occupied by imido N atoms of the tri- to pentadentate phosphazene ligands. The coordination numbers of the Ba atoms range from 5 to 7.

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    25. Diastereo- and Enantioselective Synthesis of 2-Substituted 3-Trialkylstannylcyclohexanones by Michael Addition of Trialkylstannyllithium to Cyclohexenone SAMP Hydrazone (pages 598–601)

      Prof. Dr. Dieter Enders, Dipl.-Chem. Klaus-Jürgen Heider and Dr. Gerhard Raabe

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199305981

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      Overall yields of up to 80% are achieved in the Michael addition of trialkylstannyllithium to cyclohexenone SAMP hydrazone (S)-1 (or its R enantiomer) followed by α-alkylation. This tandem reaction provides, after oxidative cleavage of the auxiliary, 2-substituted trans-3-trialkylstannylcyclohexanones (S,S)2 (and the enantiomers (R,R)-2) in high enantiomeric purity (de ≥ 98%, ee 85 to ≥ 96%). R1, R2 are for example, nBu, Me.

    26. Molecular Tweezers with a Hydrocarbon Skeleton and Convergent Carboxyl Groups (pages 601–603)

      Dipl.-Chem. Ralf Güther, Dr. Martin Nieger and Prof. Dr. Fritz Vögtle

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199306011

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      Linked cyclophane units allow the convergent arrangement of carboxyl groups, leading to tweezer compounds like 1 with ideally preorganized functional groups. In investigations of the host–guest chemistry of the new tweezer compounds and diamines, purines, and pyrimidines, high association constants and selectivities were found.

    27. Structure and Symmetry of the Benzene Cation (pages 603–606)

      Dipl.-Phys. Reiner Lindner, Dr. Hiroshi Sekiya, Dipl.-Phys. Bernhard Beyl and Dr. Klaus Müller-Dethlefs

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199306031

      The benzene cation is planar with D6h symmetry in the ground state. This is the conclusion from its first photoelectron spectrum with fully resolved rotational lines (ZEKE photoelectron spectrum). The change in the ring structure on ionization deduced from the rotational parameters is less than predicted by ab initio calculations. The elongation of the ring bonds anticipated for the removal of an electron from a bonding orbital is only about 0.1% and thus approximately five times smaller than assumed from the calculations.

    28. A New Atropisomeric Molecular Structure for Efficient Enantiodifferentiation (pages 606–608)

      Prof. Dr. Edwin Weber, Dr. Konstantinos Skobridis, Dipl.-Chem. Andreas Wierig, Dipl.-Chem. Stavroula Stathi, Prof. Dr. Luigi R. Nassimbeni and Dr. Margaret L. Niven

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199306061

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      Enantioselective clathrate formation and sorption is possible with the enantiomers of the novel atropisomer 1. Racemic 1 is easily accessible from 2,2′-dibromophenyl and fluorenone; the (S)-(+) enantiomer can be obtained pure with (−)-fenchone on formation of the sparingly soluble inclusion complex. Other potential applications are envisaged for these atropisomers in analysis and in asymmetric synthesis.

    29. One-Flask Synthesis of Propargylic Alcohols from Organolithium Reagents, N,N-Disubstituted Amides, and Acetylenes (pages 608–610)

      Prof. Jih Ru Hwu, Prof. Gholam Hosein Hakimelahi, Fung Fuh Wong and Chun Chieh Lin

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199306081

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      Good to excellent yields of propargyl alcohols are obtained in a new one-flask reaction at room temperature [Eq. (a)]. The order of addition of the reagents is very important; the organolithium compound must be added to phenylacetylene and the amide, which also functions as the solvent, otherwise the yields sink drastically.

    30. Vanadium Phosphate Framework Solid Constructed of Octahedra, Square Pyramids, and Tetrahedra with a Cavity Diameter of 18.4 Å (pages 610–612)

      Victoria Soghomonian, Dr. Qin Chen, Dr. Robert C. Haushalter and Prof. Jon Zubieta

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199306101

      Thumbnail image of graphical abstract

      Large cavities with segregated hydrophobic and hydrophilic domains result from the inclusion of inorganic and organic canons in the hydrothermal synthesis of the blue compound 1. Its structure is shown in the picture on the right.

      • equation image
    31. Photochemical Carboxylation of Cubanes (pages 612–613)

      Dr. A. Bashir-Hashemi

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199306121

      Thumbnail image of graphical abstract

      In one step and in 60% yield, the cubane tetracarboxylic acid derivative of 1 could be prepared by irradiation of a mixture of oxalyl chloride and cubane monocarboxylic acid. In this photochemical chlorocarbonylation of cubanes, substitution in the β and γ positions is preferred. A wide range of substituted cubanes not accessible by ortho-metalation may be synthesized in this way.

    32. 2,2′-Bipyrimidineoxalatocopper(II) Complexes: From the Mononuclear Complex to the 2D Sheetlike Polymer (pages 613–615)

      Prof. Giovanni De Munno, Prof. Miguel Julve, Dr. Francesco Nicolo, Dr. Frances Lloret, Prof. Juan Faus, Rafael Ruiz and Prof. Ekkehard Sinn

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199306131

      Thumbnail image of graphical abstract

      An unusual two-dimensional mesh of CuII ions is found in complex 1(see picture); the metal atoms are bridged by oxalato (ox) and bipyrimidine (bpym) ligands to form ringshaped hexamers. Variable-temperature magnetic susceptibility measurements indicate that antiferromagnetic coupling between the Cu atoms occurs.

      • equation image
    33. Reaction Tuning in Zeolites: An in situ MAS NMR Study of Acetaldehyde on HZSM-5 (pages 615–617)

      Eric J. Munson and Prof. Dr. James F. Haw

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199306151

      Coadsorbants tune the reactivity of zeolite catalysts in organic reactions. 13C NMR studies showed that [1,2-13C]acetaldehyde is converted on pure HZSM-5 into a complex product mixture, on HZSM-5 saturated with coadsorbed water into crotonaldehyde, and on HZSM-5 saturated with a mixture of coadsorbed water and oxygen into acetic acid.

    34. Aza- versus Phospha-Substitution in Cyclobutadiene: A Theoretical Evaluation of Bonding Properties (pages 617–619)

      Prof. Dr. Wolfgang W. Schoeller and Thilo Busch

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199306171

      Completely different effects on the stability of cyclobutadiene are found upon replacement of C with N or P. Whereas in the phospha derivatives the cyclobutadiene structure is less stable than the tetrahedrane, and the barrier to valence isomerization is reduced, the exchange of N for C increases this barrier, and the tetrahedranes are prone to fragmentation. According to the results of the ab initio calculations described here, not only the monoaza- and monophosphacyclobutadienes but also their analogues with two heteroatoms should, in principle, be experimentally accessible.

  5. Book Reviews

    1. Top of page
    2. Reviews
    3. Highlights
    4. Correspondences
    5. Communications
    6. Book Reviews
    1. Book Review: Organic Synthesis with Oxidative Enzymes. By H. L. Holland (pages 622–623)

      Karlheinz Drauz and Herbert Waldmann

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199306221

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