Angewandte Chemie International Edition in English

Cover image for Vol. 33 Issue 8

May 2, 1994

Volume 33, Issue 8

Pages 795–902

Currently known as: Angewandte Chemie International Edition

    1. Cover Picture (Angew. Chem. Int. Ed. Engl. 8/1994)

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199407931

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      The cover picture shows the deflagration of 20 mg of hexaspiro-[2.4.2.4.2.4.2.4.2.4.2.4]dotetraconta-4,6,11,13,18,20,25,27,32,34,39,41-dodecayne—truly an exploding [6]rotane—and the chair-shaped structure of its 30-membered ring with six 1,3-butadiyne and six spirocyclopropane units. The compound is obtained in 39% yield from the oxidative coupling of two open-chain halves and decomposes spontanteously upon heating or impact. The picture was put together electronically from a videotape of the explosion and a representation of the crystal structure (fototeam Hansjürgen Gutzeit GmbH, Göttingen (FRG)). A. de. Meijere et al. report on this and related molecules on p. 869 ff.

  1. Reviews

    1. Top of page
    2. Reviews
    3. Highlights
    4. Communications
    5. Book Reviews
    6. New Books
    1. Cyclodextrins as Building Blocks for Supramolecular Structures and Functional Units (pages 803–822)

      Prof. Dr. Gerhard Wenz

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199408031

      Cyclodextrins are valuable components in supramolecular chemistry, as they are readily available, can be modified selectively, and serve as hosts for diverse guests by means of noncovalent interactions. Fascinating molecular architectures such as catenanes, rotaxanes, and tubes can be constructed. Interesting functions like catalysis, molecular recognition, and molecular transport can be performed. Applications in analysis, food chemistry, and pharmacology should provide motivation for scientists to cross traditional interdisciplinary borders and search for new targets constructed from cyclodextrins.

    2. Determination of Reaction Paths for Pentacoordinate Metal Complexes with the Structure Correlation Method (pages 823–839)

      Dr. Thomas Auf der Heyde

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199408231

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      Methods from group theory and multivariate statistical techniques have turned the structure correlation method developed 20 years ago into an even more powerful instrument for structure-reactivity studies. Thus within the general scheme sketched below for [ML5] complexes, short-lived tetrahedral RhI and IrI complexes have been shown to be plausible intermediates along reaction path C, and doubt has been cast on the common assumption that five-coordinate PtII and PdII compounds undergo intramolecular ligand exchange by a Berry mechanism (path B).

  2. Highlights

    1. Top of page
    2. Reviews
    3. Highlights
    4. Communications
    5. Book Reviews
    6. New Books
    1. X-Ray Structure Analysis of Methane Monooxygenase: An Important Step toward Understanding the Oxidation of Methane in Biological Systems (pages 841–843)

      Prof. Dr. Bernt Krebs and Norbert Sträter

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199408411

      Immense ecological and technical importance is enjoyed by methanotrophic bacteria, which can oxidize hydrocarbons to CO2. The key to understanding the mode of action of the enzyme methane monooxygenase is held by the research groups of S. J. Lippard and P. Nordlund, who unraveled the structure of the active site. The processes in the oxidation of methane by air to form methanol under physiological conditions [Eq. (a)] will perhaps soon be elucidated on a molecular level.

      • equation image
    2. Fullercages without Carbon—Fulleranes, Fullerenes, Space-filler-enes? (pages 843–846)

      Prof. Dr. Reinhard Nesper

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199408431

      Fullerene-type structures in other areas of chemistry? Fullercages are elements in feasible structure descriptions of a series of intermetallic phases. In contrast to the carbon fullerenes, single bonds are proposed in these systems, and rather than isolated cages, endohedral polyhedra and covalently bound adjacent cages are found. As an example, Na96In97Z2, Z = Ni, Pd, Pt, can be described as containing Z@In10@Na39@In74.

  3. Communications

    1. Top of page
    2. Reviews
    3. Highlights
    4. Communications
    5. Book Reviews
    6. New Books
    1. Organoplatinum Dendrimers Formed by Oxidative Addition (pages 847–849)

      Sudhir Achar and Prof. Dr. Richard J. Puddephatt

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199408471

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      A Pt14 dendrimer is the highest nuclearity complex obtained by the first convergent method for the synthesis of alkyl transition metal dendrimers. The product of the first growth cycle is 1, which forms by oxidative addition of 4,4′-bis(bromomethyl)-2,2′-bi-pyridine to [Me2Pt(tBu2bpy)] and subsequent introduction of a PtII center with [Pt2Me4-(μ-SMe2)].

    2. [Mo57Fe6(NO)6O174(OH)3(H20)24]15−: A Highly Symmetrical Giant Cluster with an Unusual Cavity and the Possibility of Positioning Paramagnetic Centers on Extremely Large Cluster Surfaces (pages 849–851)

      Prof. Dr. Achim Müller, Dr. Winfried Plass, Erich Krickemeyer, Dipl.-Chem. Stephan Dillinger, Dr. Hartmut Bögge, Anja Armatage, Dr. Anna Proust, Christian Beugholt and Ulf Bergmann

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199408491

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      Three hundred and twenty-seven atoms with a combined molecular weight of 9250.9 Da make up the title compound, from which, as a cluster of the mesoscopic range, one can expect unusual material properties. A central O33 polyhedron (shown on the right) defines the unusual cavity of this giant cluster and points to interesting host-guest chemistry. The cluster has been characterized by numerous analytical and spectroscopic methods.

    3. Synthesis and Properties of 2,4,6-Trimethylphenylborane (Mesitylborane), a Stable Alternative to Thexylborane (pages 851–853)

      Prof. Keith Smith, Prof. Andrew Pelter and Zhao Jin

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199408511

      Four advantageous properties characterize mesitylborane MesBH2 as a reagent: (1) It is readily accessible and quite stable. (2) It can be treated with two different 1-alkenes in a stepwise fashion ([RIGHTWARDS ARROW] MesBR1R2). (3) The regioselectivity of each individual step is > 99%. (4) The products MesBR1R2 can be readily transformed via MeOBR1R2 or directly to BR1R2R3. MesBR2 and BR1R2R3 are important precursors for the synthesis of ketones R1R2CO and tertiary alcohols R1R2R3COH, respectively, by the cyanoborate process.

    4. A Concise Total Synthesis of (±)-Mamanuthaquinone by Using an exo-Diels–Alder Reaction (pages 853–855)

      Taeyoung Yoon, Prof. Samuel J. Danishefsky and Susan de Gala

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199408531

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      Only eight steps are required to synthesize the cytotoxic title compound 1 thanks to the unexpectedly high exo selectivity in the key step. This selectivity can most likely be attributed to steric factors; the diene contains a geminal dimethyl group, the dienophile a bulky aryl group.

    5. On the DNA Recognition Role of the Carbohydrate Sector in Calicheamicin: A Comparison of DNA Cleaving Capacity of Enantiomeric Calicheamicinones (pages 855–858)

      Dr. Jayshree Aiyar, Dr. Stephen A. Hitchcock, Dr. Derek Denhart, Dr. Kevin K. C. Liu, Prof. Samuel J. Danishefsky and Prof. Donald M. Crothers

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199408551

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      Surprisingly, the “unnatural” aglycone analogue 1 (R [DOUBLE BOND] Ac) of calicheamicin cleaves double-stranded DNA more effectively than the natural ent-1. If the efficiency of this cleavage for the enediyne effector is determined essentially by its configuration, the sequence selectivity of calicheamicin is rooted in the saccharide recognition sector.

    6. A Convergent Total Synthesis of Calicheamicin γmath image (pages 858–862)

      Dr. Stephen A. Hitchcock, Serge H. Boyer, Margaret Y. Chu-Moyer, Steven H. Olson and Prof. Samuel J. Danishefsky

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199408581

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      Ultimate convergence for the total synthesis of calicheamicin γmath image has been achieved thanks to a remarkable glycosidation between the glycosyl donor 2 and aglycone ent-1 (see preceeding communication; R = SSMe, ketal-protected); after glycosidation the natural product is obtained in two steps.

    7. Donor-Stabilized Aluminum(II) Bromide (pages 862–863)

      Dipl.-Chem. Mario Mocker, Prof. Dr. Christian Robl and Prof. Dr. Hansgeorg Schnöckel

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199408621

      Cryochemically prepared AlBr and AlBr3 react in anisole to form donor-stabilized AlBr2, which precipitates in the form of yellow needles with the composition Al2Br4 · 2 anisole. In the solid state the compound is stable at room temperature with regard to disproportionation into Al and Al‴ species. The Al-Al distance in the adduct (252.7pm) is roughly as short as that in the radical anion [Al2R4].− (R[DOUBLE BOND]CH(SiMe3)2), which contains an AL[BOND]AL a bond (253 pm) strengthened by π bond contributions.

    8. 3,6-Diazaxanthylium Salts: Dyes with a New Chromophore (pages 863–866)

      Dipl.-Chem. Lutz Eggers, Priv.-Doz. Dr. Walter Grahn, Prof. Dr. Wolfgang Lüttke, Dr. Burkhard Knieriem, Prof. Dr. Peter G. Jones and Axel Chrapkowski

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199408631

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      A new tricyclic framework is the characteristic feature of the violet, air-sensitive dyes 1. The phenyl substituent X (X = Ph, 4-CF3-C6H4) is arranged orthogonally to the chromophore both in the crystal and in solution, and the tricycle is bent by about 5° about the axis C9–O10. In comparison to the frequently used rhodamines, compounds 1 absorb at longer wavelengths and fluoresce with lower quantum yields.

    9. Propeller Isomerism of the Triphenylphosphane Ligand in Half-Sandwich RuII Complexes (pages 866–868)

      Prof. Dr. Henri Brunner, Dipl.-Chem. Ralf Oeschey and Dr. Bernd Nuber

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199408661

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      The chirality of the propeller of the triphenylphosphane ligand is the only difference between the two modifications of the organometallic complex salt 1. Thus, in addition to the stereogenic ruthenium and carbon centers, this complex has a further element of chirality not represented in the formula depicted, namely the propeller configuration of the PPh3 ligand.

    10. Hexaspiro[2.4.2.4.2.4.2.4.2.4.2.4]dotetraconta-4,6,11,13,18,20,25,27,32,34,39,41-dodecayne An Exploding [6]Rotane (pages 869–871)

      Prof. Dr. Armin de Meijere, Dr. Sergei Kozhushkov, Dr. Carsten Puls, Dipl.-Chem. Thomas Haumann, Priv.-Doz. Dr. Roland Boese, Mark J. Cooney and Prof. Dr. Lawrence T. Scott

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199408691

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      The oxidative coupling of the acyclic trimer of 1,1 -di-ethynylcyclopropane gives title compound 1 as the main product. X-ray structural analysis of 1 shows that the spirocyclopropane and adjacent butadiyne units have a distinct electronic interaction. A dehydrononamer (C63H36) was also isolated.

    11. Enzymatic Grooming of Organic Thin Films (pages 871–873)

      Prof. James K. Whitesell, Dr. Hye Kyung Chang and Christopher S. Whitesell

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199408711

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      As if with a razor, single polypeptide chains that extend significantly above the bulk layer of polypeptides can be shaved off with ala-nine and leucine aminopeptidases. In the preparation of tightly packed layers of helical peptides, the lengths of the peptide chains cannot be controlled; with the enzymatic grooming process described here subsequent smoothing is possible, which is important for potential applications of these layers as waveguide materials.

    12. An Extremely Long-Lived Triplet Carbene; Reactivity, Optical Absorption Spectrum, and Kinetics of Highly Congested Diarylcarbenes (pages 873–875)

      Prof. Dr. Hideo Tomioka, Hidetsumu Okada, Tetsuya Watanabe and Katsuyuki Hirai

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199408731

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      Half a second in solution at room temperature is the lifetime of didurylcarbene (1). This species is generated thermally and photochemically from the corresponding diazo compound and reacts by dimerization and by intramolecular H abstraction. The ortho methyl groups are key to stabilizing the carbene, and the meta methyl groups exert an additional buttressing effect.

    13. Ether-Solvated Sodium Ions in Salts Containing π-Hydrocarbon Anions: Crystallization, Structures, and Semiempirical Solvation Energies (pages 875–878)

      Prof. Dr. Hans Bock, Dipl.-Chem. Christian Näther, Dr. Zdenek Havlas, Dipl.-Chem. Andreas John and Dipl.-Chem. Claudia Arad

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199408751

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      Optimally solvated Na+ ions form in ethereal solutions when unsaturated hydrocarbons with extended π-systems such as perylene undergo one-electron reduction by sodium and crystallize as solvent-separated radical anion salts. The coordination number of Na+ is 6, 7, or 8 (see 1) depending on the ether used as solvent. From the structural data approximate solvation enthalpies can be calculated, which agree with laboratory experience.

    14. Preparation of Chiral Nitroxide Radicals and Spontaneous Optical Resolution by Recrystallization (pages 878–879)

      Dr. Rui Tamura, Shinsuke Susuki, Dr. Nagao Azuma, Prof. Akira Matsumoto, Prof. Fumio Toda, Dr. Akio Kamimura and Dr. Kenzi Hori

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199408781

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      Conglomerates of enantiomeric single crystals are formed on slow recrystallization of the chiral nitroxide radicals 1, R [DOUBLE BOND] H, Me, obtained according to reaction (a). The unusual arrangement of 1 in the crystal may explain the spontaneous optical resolution.

    15. Cyclotrimerization of Ethyne on the Complex Fragment [(η1-tBu2PCH2PtBu2)Ni0] with Formation of an η6-Benzene-Nickel(0) Complex (pages 879–882)

      Dipl.-Chem. Thomas Nickel, Dr. Richard Goddard, Prof. Dr. Carl Krüger and Priv.-Doz. Dr. Klaus-Richard Pörschke

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199408791

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      The first Ni0 complex with an arene as a six-electron ligand, complex 1 is formed by the displacement of the ethene ligands in [(η1-tBu2PCH2PtBu2)Ni(C2H4)2] by ethyne, which undergoes cyclotrimerization on the phosphane-nickel complex fragment at temperatures below −50 °C (!). The Ni atom in 1 has pseudo-linear coordination to the η1-bound diphosphane ligand and the planar, symmetric benzene ligand.

    16. The Absolute Configuration of (+)-α-1,2,3,4,5,6-Hexachlorocyclohexane, and Its Permeation through the Seal Blood-Brain Barrier (pages 882–884)

      Dipl.-Chem. Kattrin Möller, Cornelia Bretzke, Priv.-Doz. Dr. Heinrich Hühnerfuss, Dr. Roland Kallenborn, Dr. Jochen N. Kinkel, Priv.-Doz. Dr. Jürgen Kopf and Dr. Gerhard Rimkus

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199408821

      Not the result of enzymatic degradation processes, but of the “preferential permeability” of the blood–brain barrier for (+)-α-hexachlorocyclohexane (HCH)—this is the interpretation of the selective accumulation of this enantiomer in seal brain. This conclusion could be drawn only after the α-HCH isomers were successfully separated on a chiral phase by HPLC. The structure of the (+) enantiomer was determined by X-ray crystallography, but the structural elements responsible for the selective transfer are still unknown.

    17. Cellulose in Schweizer's Reagent: A Stable, Polymeric Metal Complex with High Chain Stiffness (pages 884–887)

      Prof. Dr. Walther Burchard, Dr. Norbert Habermann, Prof. Dr. Peter Klüfers, Dipl.-Chem. Bernd Seger and Dr. Ulf Wilhelm

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199408841

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      Doubly deprotonated monomeric units, chelation of Cu2+ ions, and stiffness imparted by strong hydrogen bonds of the type O[BOND]H … O are characteristics of cellulose in Schweizer's reagent (shown on the right). This solubilized form of cellulose discovered in 1857 forms the basis of current technical processes for the preparation of membranes. The new findings were obtained from the combination of coordination chemistry and polymer analysis.

    18. A Mixed-Valent, Unsymmetrical FeIIFeIII Complex with a Terminal Phenolato Ligand as a Model for the Active Site of Purple Acid Phosphatases (pages 887–889)

      Elisabeth Bernard, Dr. William Moneta, Jean Laugier, Dr. Sylvie Chardon-Noblat, Dr. Alain Deronzier, Prof. Jean-Pierre Tuchagues and Dr. Jean-Marc Latour

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199408871

      The structure and the magnetic and electrochemical properties of the active center of purple acid phosphatases are modeled by a complex that mimics the terminal coordination of the tyrosine residue and was prepared with a new heptadentate phenola-to ligand system. The instability of the reduced FeIIFeII state of the enzyme may be attributed to the terminal ligand, since the phenolato ligand in the model is a destabilizing factor.

    19. Porphyrins with Biconcave Frameworks (pages 889–891)

      Dr. Yvan Ramondenc, Mag. Reinhold Schwenninger, Dipl.-Ing. Thao Phan, Mag. Karl Gruber, Doz. Dr. Christoph Kratky and Prof. Dr. Bernhard Kräutler

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199408891

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      New, “three-dimensionally structured” porphyrins were prepared in very few steps from β,β′-disubstituted pyrroles. In the corresponding biconcave metalloporphyrins (shown on the right) the peripheral groups on both sides of the porphyrin plane limit axial access to the metal center. For this reason selective interactions with guest molecules and interesting catalyst properties can be expected.

    20. Electrostatic Activation of Hypervalent Organo-Iodine Compounds: Bis(onio)-Substituted Aryliodine(III) Salts (pages 891–893)

      Prof. Dr. Robert Weiss and Dipl.-Chem. Jörg Seubert

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199408911

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      A new class of compounds, for example 2, synthesized from 1 or iodosobenzene, are the title compounds in this article. The oxidation potential of 1 is increased considerably by bis(onio) substitution; thus, these new systems can be used as potent oxidants. Applications include dehydrogenations of monohydrazones to give diazo compounds and of 1,2-bishydrazones to give alkynes.

    21. Concerning the Mechanism of α-Elimination: Hypervalent Ion Pairing in an Iodocarbenium Iodide (pages 893–895)

      Prof. Dr. Robert Weiss, Dipl.-Chem. Michael Rechinger and Dipl.-Chem. Frank Hampel

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199408931

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      The first crystalline iodocarbenium iodide 1 has an almost linear C[BOND]I[BOND]I sequence, as revealed by the X-ray structure analysis. Thus 1 contains a new hypervalent three-center, four-electron bonding system and marks a characteristic point on the general reaction coordinate of the polar α-di-halogen elimination.

    22. Reductive Disproportionation of NO Mediated by Copper Complexes: Modeling N2O Generation by Copper Proteins and Heterogeneous Catalysts (pages 895–897)

      Christy E. Ruggiero, Susan M. Carrier and Prof. William B. Tolman

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199408951

      Nitrito-O,O-copper complexes and dinitrogen oxide are the products of the reaction of excess NO with the nitrosyl complexes [LCu(NO)] (L = substituted tris(pyrazolyl)hydroborate), a process that models environmentally important transformations carried out by copper ions in proteins and zeolites. According to the results of kinetic studies, the involvement of dimeric copper species in the rate-determining step is ruled out, which suggests that NO coupling occurs at a single metal ion.

    23. Evidence of Room-Temperature Superconductivity in the Bi[BOND]Sr[BOND]Cu[BOND]O System (pages 897–899)

      Richard S. Burrows and Prof. Darl H. McDaniel

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199408971

      A tetragonal phase SrCuO2 possibly causes the superconducting behavior of the samples with the nominal composition Bi2Sr2CuO6 prepared in the sol-gel process. The results of the measurements indicate a critical temperature of 70 °C, and the superconductivity is attributed to a phase present in the sample in less than 0.1%. Eight samples show evidence of room-temperature superconductivity, and an additional fourteen samples show superconductivity between 25 and 110 K.

  4. Book Reviews

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

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

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