Angewandte Chemie International Edition in English

Cover image for Vol. 35 Issue 23‐24

December 1996

Volume 35, Issue 23-24

Pages 2691–2881

Currently known as: Angewandte Chemie International Edition

    1. Cover Picture (Angew. Chem. Int. Ed. Engl. 23/24/1996)

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199626891

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      The cover picture shows the principle of the “Self-Regeneration of Stereocenters (SRS)”, a synthetic method in which a stereogenic center is temporarily destroyed with formation of an intermediate having a trigonal center. A subsequent diastereoselective reaction results in the formation of the stereogenic center once more. The additional center of chirality essential for the diastereoselective reaction is generated by acetalization (with an aldehyde) of the functional groups X and Y in the chiral starting material. The reaction sequence leads to a dissociative, enantioselecitve substitution at a single stereogenic center in a chiral compound without the use of a chiral auxiliary—hence the name “self-regeneration”.

      The general formula of typical glycine derivatives is shown in yellow in the center of the scheme. These are easily prepared in enantiomerically pure form by resolution of the appropriate racemate and have been shown to be particularly useful for the synthesis of α,α-disubstituted amino acids. As these compounds are prepared from chiral starting materials, they also represent the abandonment of the synthetic principle. D. Seebach et al. report more on SRS on p. 2708 ff.

  1. Reviews

    1. Top of page
    2. Reviews
    3. Highlights
    4. Communications
    5. Corrigenda
    1. Self-Regeneration of Stereocenters (SRS)—Applications, Limitations, and Abandonment of a Synthetic Principle (pages 2708–2748)

      Prof. Dr. Dieter Seebach, Dr. Andrea R. Sting and Dipl.-Chem. Matthias Hoffmann

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199627081

      The formation of enantiopure compounds from an achiral starting material has to be one of the greatest challenges in organic synthesis today. One approach has its roots in investigations into the “Self-Regeneration of Stereocenters”. This principle was first realized with compounds containing a stereogenic center (for example the naturally occurring, enantiomerically pure amino acids), but more recently the knowledge gained in this area has been applied to achiral compounds such as glycine, 3-aminopropionic acid, and acetoacetic acid. The resulting procedures have found wide-ranging use in the synthesis of non-proteinogenic and radiolabeled amino acids, and have become particulary valuable in the synthesis of natural products with tertiary C atoms.

    2. Erich Hückel, Pioneer of Organic Quantum Chemistry: Reflections on Theory and Experiment (pages 2750–2764)

      Prof. Jerome A. Berson

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199627501

      The theoretical basis for much of the subsequent application of molecular orbital concepts to important problems of organic chemistry was derived from Erich Hückel's treatment of unsaturated and conjugated compounds in the 1930s. Yet circumstances still not fully understood delayed the recognition that he deserved, and not incidentally, retarded the development of organic chemistry by muffling the impact of his contributions.

  2. Highlights

    1. Top of page
    2. Reviews
    3. Highlights
    4. Communications
    5. Corrigenda
    1. New Carbocations—From Physical Organic Chemistry to Biochemistry (pages 2765–2766)

      Priv.-Doz. Dr. Thomas Laube

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199627651

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      In the first carbotetracation, 1, the charged groups are tetrahedrally arranged on an adamantane cage. Carbocations are no longer a domain of physical organic chemistry. They also play a role in organometallic chemistry and biochemistry, as a new samarocene complex containing a norbornadienyl cation fragment and the newly coined term “Olah enzyme” testify.

    2. The β Turn as a Selectivity Switch: βI or βII′? That Is the Question (pages 2767–2769)

      Dr. Gerhard Müller

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199627671

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      In the design of peptide-based drugs the β turn has been promoted to a design principle in recent years. In research on antiadhesive RGD mimetics, receptor selectivity has been shown to be encoded in the β-turn type within cyclic peptides of type 1 having an identical lead sequence. Switching the turn type from βII′ to βI inverts the selectivity profile so that a compound originally with antithrombotic activity becomes an antimetastatic agent.

  3. Communications

    1. Top of page
    2. Reviews
    3. Highlights
    4. Communications
    5. Corrigenda
    1. Unprecedented Conversion of a Compound with Metal–Metal Bonding into a Solvated Molecular Wire (pages 2772–2774)

      Gary M. Finniss, Dr. Enric Canadell, Dr. Charles Campana and Prof. Kim R. Dunbar

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199627721

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      One-electron reduction of the rhodium complex 1 has resulted in the first successful conversion of a discrete metal–metal bonded “dimer” into a one-dimensional polymer (2). The doped material 2 (depicted on the right) differs significantly from the well-known tetracyanoplatinates in that the metal backbone is cationic. In addition, there is the possibility of fine-tuning the material properties by varying the organic group.

      • equation image
    2. E/Z Isomerization in Crystals—Phase Rebuilding on Photolysis with Long-Wavelength Radiation (pages 2774–2777)

      Prof. Dr. Gerd Kaupp and Dipl.-Ing. Michael Haak

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199627741

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      Three solid-state techniques—atomic force microscopy, X-ray structure analysis, and diffuse reflectance spectroscopy—were combined to discover why E/Z isomerizations in the crystal, for example 1 [RIGHTWARDS ARROW] 2, are possible despite their large spatial demands. These studies revealed, for instance, that on irradiation with wavelengths corresponding to the absorption tail of the crystals, anisotropic surface features appear.

    3. Designed Restructuring of Iodine with Microporous SiO2 (pages 2777–2779)

      Dipl.-Ing. Gernot Wirnsberger, Prof. Dr. Harald P. Fritzer, Dr. Alois Popitsch, Dr. Gianpietro van de Goor and Prof. Dr. Peter Behrens

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199627771

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      Templates for the arrangement of guest molecules—that is the role played by microporous crystalline SiO2 modifications in the insertion compounds presented. The electronic interactions between the guest species can be controlled by the dimensionalities of the void systems. When iodine is the guest component, this is directly apparent from the colors of the insertion compounds, which for the host structures shown below range from violet to red-brown.

    4. A Noninterpenetrated Molecular Ladder with Hydrophobic Cavities (pages 2779–2782)

      Dr. Pierre Losier and Prof. Dr. Michael J. Zaworotko

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199627791

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      Not interpenetrated, but filled with solvent molecules, the large cavities of the polymer [Co(NO3)2(4,4′-bpy)1.5]n form different structures depending on the solvent system from which it crystallizes. One of the two possible structures (section of structure shown on the right) exhibits hydrophobic cavities about 11 × 11 Å in size. The solvent molecules can be readily removed, but the process has not yet been proven reversible.

    5. Anion Binding: Self-Assembly of Polypyrrolic Macrocycles (pages 2782–2785)

      Prof. Jonathan L. Sessler, Andrei Andrievsky, Dr. Philip A. Gale and Vincent Lynch

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199627821

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      Anion complexation drives the self-assembly of appropriately designed macrocycles (sapphyrin and/or calix[4]pyrrole) containing pendant carboxylic arms (black in the schematic representation on the right). The self-assembly process can be disrupted by addition of F ions (sapphyrin) or in the case of calix[4]pyrrole, polar solvents.

    6. In Situ Observation of Transient Reaction Phenomena Occurring on Zeolite Catalysts with the Aid of Positron Emission Profiling (pages 2785–2787)

      Prof. Dr. Rutger A. van Santen, Dr. B. G. Anderson, Dr. R. H. Cunningham, Ir. A. V. G. Mangnus, Dr. L. J. van Ijzendoorn and Prof. Dr. M. J. A. de Voigt

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199627851

      The total concentrations of reactants and products within a flow-through reactor can be monitored as a function of both position and time by detecting gamma photons arising from the radioactive positron decay of injected 11C nuclei. The method was demonstrated by directly observing catalyst preconditioning and deactivation of a Pt/H-mordenite catalyst bed during the industrially important hexane hydroisomerization reaction.

    7. The Titanium(IV)-Catalyzed Epoxidation of Alkenes by tert-Alkyl Hydroperoxides (pages 2787–2790)

      Dr. Richard D. Oldroyd, Prof. John Meurig Thomas, Dr. Thomas Maschmeyer, Philip A. MacFaul, Darren W. Snelgrove, Dr. Keith U. Ingold and Dr. Danial D. M. Wayner

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199627871

      A high catalytic activity towards alkene epoxidation is shown by titanium-modified MCM41 mesoporous silicas if 2-methyl-1-phenyl-2-propyl hydroperoxide (MPPH) is used as oxidant. This first example in which MPPH has been used as an efficient two-electron oxidizing agent demonstrates that it is a competent replacement for tert-butyl hydroperoxide (TBHP) in metal-catalyzed, nonradical hydrocarbon oxidations and that the Ti-MCM41 catalyzed epoxidation of alkenes proceeds by a nonradical mechanism.

    8. Amide Backbones with Conformationally Restricted Furanose Rings: Highly Improved Affinity of the Modified Oligonucleotides for Their RNA Complements (pages 2790–2794)

      Dr. Alain De Mesmaeker, Dr. Catherine Lesueur, Dr. Marc-Olivier Bévièrre, Dr. Adrian Waldner, Dr. Valérie Fritsch and Dr. Romain M. Wolf

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199627901

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      An increased stability of duplexes between amide-modified oligonucleotides (depicted on the right) and RNA was achieved by the introduction of 2′-OMe groups. Since the modified oligonucleotides display a very high affinity for their RNA complement and are more stable towards nucleases, they can be considered as promising antisense agents. X = H, OH, OMe; Y = H, OMe.

    9. Synthesis and Enzymatic Degradation of Dendrimers from (R)-3-Hydroxybutanoic Acid and Trimesic Acid (pages 2795–2797)

      Prof. Dr. Dieter Seebach, Dr. Guido F. Herrmann, Dr. Urs D. Lengweiler, dipl.-phil. II Beat M. Bachmann and Dr. Walter Amrein

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199627951

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      Monodisperse, chiral dendrimers from trimesic acid and (R)-3-hydroxybutanoic acid were synthesized and characterized. Preliminary investigations have shown that these biodegradable dendrimers (depicted on the right) are substrates for hydrolases.

    10. Synthesis and a Preliminary DNA Binding Study of Hybrids of the Carbohydrate Domain of Calicheamicin γmath image and the Aglycone of Daunorubicin: Calichearubicins A and B (pages 2797–2801)

      Kristopher M. Depew, Steven M. Zeman, Serge H. Boyer, Derek J. Denhart, Norihiro Ikemoto, Samuel J. Danishefsky and Prof. Donald M. Crothers

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199627971

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      In calichearubicin B (1) the aglycon of daunorubicin and the carbohydrate domain of calicheamicin γmath image are linked by a spacer (calichearubicin A lacks this spacer). The aglycone serves as an anthracycline-like intercalator, while the carbohydrate portion binds to the minor groove of DNA. Thus calichearubicin B exhibits properties of both parent compounds.

    11. Total Synthesis of (–)-Epothilone A (pages 2801–2803)

      Dr. Aaron Balog, Dongfang Meng, Dr. Ted Kamenecka, Dr. Peter Bertinato, Dr. Dai-Shi Su, Dr. Erik J. Sorensen and Prof. Samuel J. Danishefsky

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199628011

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      An audacious macroaldolization is the key step in the first total synthesis of the cytotoxic epothilone A, which starts with the units 1, 2, and 3. This condensation closes the ring to form the macrolide, whose structure was determined and published (also in Angewandte Chemie) as recently as July 1996.

    12. A Molecularly Defined, Grafted Olefin Metathesis Catalyst from Tris(neopentyl)-nitridomolybdenum(VI) (pages 2803–2805)

      Prof. Dr. Wolfgang A. Herrmann, Dr. Andreas W. Stumpf, Thomas Priermeier, Dr. Sandra Bogdanović, Veronique Dufaud and Prof. Dr. Jean-Marie Basset

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199628031

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      1,2-Addition of the surface silanol groups on SiO2 to the nitridomolybdenum fragment of the title compound and subsequent α-elimination of neopentane forms the catalytically active surface species I. This is the first case in which an alkylated complex is converted into a heterogeneous catalyst in a well-defined way. The immobilized compound is significantly more active in ring-opening metathesis polymerization than the molecular precursor.

    13. Chiral Heterocylic Carbenes in Asymmetric Homogeneous Catalysis (pages 2805–2807)

      Prof. Dr. Wolfgang A. Herrmann, Lukas J. Goossen, Christian Köcher and Dr. Georg R. J. Artus

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199628051

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      The ee values of the hydrosilylation of acetophenone with the rhodium catalyst 1 are only small; nevertheless, the robustness of the catalyst is impressive: The chiral carbene ligand, which is readily available and can be easily varied, remains bound to the metal in solution to over 100°C. Thus, no excess of ligand is necessary in the catalytic reactions.

    14. Supramolecular Host–Guest Compounds with Tripod–Metal Templates as Building Blocks at the Corners (pages 2808–2809)

      Susanne Mann, Prof. Dr. Gottfried Huttner, Dr. Laszlo Zsolnai and Katja Heinze

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199628081

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      In a one-pot reaction from 15 components, a tetra-hedral host-guest compound forms by self-assembly. Its tripod–iron(II) groups are the corners of a tetrahedron (depicted on the right). The edges of the tetrahedron are bridged by 1,2-dinitrile ligands, and a BFmath image ion is encapsulated in the tetrahedral cavity.

    15. Smaller Substituents on Nitrogen Facilitate the Osmium-Catalyzed Asymmetric Aminohydroxylation (pages 2810–2813)

      Dr. Joachim Rudolph, Dr. Peter C. Sennhenn, Dr. Cornelis P. Vlaar and Prof. Dr. K. Barry Sharpless

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199628101

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      All of the selectivity criteria for catalytic asymmetric aminohydroxylation with sulfonamides “Eq. (a)” are improved when the original nitrogen source, Chloramine-T, is replaced by its methyl analogue, Chloramine-M (1). This newly introduced reagent exhibits substantially higher ligand dependence, and for most substrates the desirable phenomenon of ligand-accelerated catalysis was observed. DHQ-H = dihydroquinine, PHAL = 1,3-phthalazinediyl.

    16. N-Halocarbamate Salts Lead to More Efficient Catalytic Asymmetric Aminohydroxylation (pages 2813–2817)

      Dr. Guigen Li, Dr. Hubert H. Angert and Prof. K. Barry Sharpless

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199628131

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      Better enantioselectivities and convenient deprotection make the sodium salts of N-chlorocarbamates the oxidant/nitrogen source of choice for the osmium/cinchona alkaloid catalyzed asymmetric aminohydroxylation (AA) of olefins [e.g. Eq. (a)]. This methodology simplifies the synthesis of a vast array of compounds such as unnatural amino acids and other pharmacologically important compounds. DHQH = dihydroquinine, PHAL = 1,3-phthalazinediyl, Z = benzyloxycarbonyl.

    17. Theory Rules Out a [2 + 2] Addition of Osmium Tetroxide to Olefins as Initial Step of the Dihydroxylation Reaction (pages 2817–2820)

      Dipl.-Chem. Ulrich Pidun, Christian Boehme and Prof. Dr. Gernot Frenking

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199628171

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      A difference of at least 35 kcalmol−1 between the activation barriers results from ab initio calculations for the competing [2 + 2] and [3 + 2] additions of OsO4 to ethylene, clearly favoring the latter pathway (the two transition state structures are pictured on the right). The relative barrier heights for the proposed reaction paths hardly change in the presence of NH3, used to model the base-catalyzed reaction. These theoretical findings on asymmetric dihydroxylation contradict the conclusions drawn from kinetic studies by Sharpless et al., but support the recent kinetic investigations by Corey et al.

    18. 5-exo or 6-endo? Exploring Transition State Structures in Cyclizations of 4-Penten-1-oxyl Radicals (pages 2820–2823)

      Dr. Jens Hartung, Dipl.-Chem. Ralf Stowasser, Dipl.-Chem. Daniel Vitt and Prof. Dr. Gerhard Bringmann

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199628201

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      An exo:endo ratio of 98:2! Thermochemistry would have predicted the opposite, but in the rearrangements of 5-hexenyl radicals the exo pathway is preferred due to kinetic reaction control. Selected ab initio methods are able to properly describe cyclizations of the 4-penten-1-oxyl radical (see sketch).

    19. Recognition of the Helical Sense of Polypeptides by a Chiral Metalloporphyrin Receptor (pages 2823–2825)

      Dr. Katsuaki Konishi, Shu-ichi Kimata, Kiyoko Yoshida, Masanobu Tanaka and Prof. Takuzo Aida

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199628231

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      The secondary structure is of primary importance! The D and L forms of α-helical poly(glutamic acid) (PGA) are complexed selectively by the (R) and (S) isomers, respectively, of the porphyrin-based, chiral receptor 1, which has a xylylenediamide strap. Helical polypeptides can thus be separated by complexation with enantiomerically pure 1.

    20. (Alkylidyne)tungsten Complexes Anchored to a Planar Tetraoxo Surface: Exhaustive Alkylation of a (Calixarene)tungsten Complex (pages 2825–2827)

      Luca Giannini, Dr. Euro Solari, Dr. Antonio Zanotti-Gerosa, Prof. Dr. Carlo Floriani, Prof. Dr. Angiola Chiesi-Villa and Dr. Corrado Rizzoli

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199628251

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      Anchoring gives stability. The recently synthesized anionic tungsten alkylidynes fixed over a planar tetraoxo surface of calix[4]arene (see picture) can undergo reversible protonation and metalation by carbophilic metals without disturbing the calixarene ligand. R = Ph, nPr, SiMe3.

    21. The First Stable Copper(III) Complex Containing Aliphatic Thiolates as Ligands: Structural and Spectroscopic Evidence for CuII and CuIII Ions in Complexes with Square-Planar CuN2S2 Coordination Environments (pages 2827–2830)

      Jan Hanss and Dr. Hans-Jörg Krüger

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199628271

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      Although it was once deemed a nearly impossible task (since CuII centers are generally readily reduced by thiolates), authentic CuII and CuIII complexes with aliphatic thiolates in the metal coordination sphere have been synthesized. The unusual pair of squareplanar complexes (NEt4)2[Cu(phmi)] · H2O and (PPh4)[Cu(phmi)] (the anion is depicted on the right) displays the lowest known redox potential ever recorded for a CuIII/CuII redox couple and has been completely characterized. H4phmi = N, N′-1,2-phenylenebis(2-mercapto-2-methylpropionamide).

    22. Formal Total Synthesis of (—)-Morphine by Cuprate Conjugate Addition (pages 2830–2832)

      Prof. Dr. Johann Mulzer, Dr. Gerd Dürner and Dipl.-Chem. Dirk Trauner

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199628301

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      Conjugate addition of a vinyl cuprate to the sterically and electronically very demanding enone 1 is the key step of a short asymmetric total synthesis of (—)-dihydro-codeinone (2), an immediate precursor of (-)-morphine.

    23. Pyrazolate “Golden” Rings: Trinuclear Complexes That Form Columnar Mesophases at Room Temperature (pages 2832–2835)

      Dr. Joaquín Barberá, Dr. Anabel Elduque, Raquel Giménez, Prof. Luis A. Oro and Prof. José Luis Serrano

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199628321

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      Trinuclear gold(I) pyrazolate complexes of type 1 show liquid crystalline phases at room temperature. The molecules are arranged in a hexagonal columnar structure. The mesogenic behavior of these compounds is strongly related to the molecular symmetry, which is determined by the substituents R and R′. R = 3,4-(H21C10O)2C6H3, R′ = R, 3,4,5-(H21C10O)3C6H2.

    24. Substrate-Directed Diastereoselective Hydroformylation of Methallylic Alcohols (pages 2835–2837)

      Dr. Bernhard Breit

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199628351

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      A reversibly coordinating auxiliary is the key to the first highly diastereo-selective hydroformylation of acyclic methallylic alcohols (syn:anti up to 96:4; in the representation on the right the auxiliary is shown as a sphere). The reaction can be used for the efficient construction of stereotriades, the central structural units of polyketide natural products. R is, for example, Ph, CO2Me, Me, CH2Ph.

    25. The Ca2+ Ion as a Cofactor for a Novel RNA-Cleaving Deoxyribozyme (pages 2837–2841)

      Dipl.-Chem. Dirk Faulhammer and Priv.-Doz. Dr. Michael Famulok

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199628371

      In vitro selection experiments yield unexpected results. An RNA-cleaving DNA enzyme that was selected in the presence of Mg2+ ions is much more efficient with Ca2+ as the cofactor. The result is even more surprising because of the lower hydrolytic efficiency of Ca2+ itself.

    26. A Planar [15]Metallacrown-5 That Selectively Binds the Uranyl Cation (pages 2841–2843)

      Dr. Ann J. Stemmler, Dr. Jeff W. Kampf and Prof. Vincent L. Pecoraro

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199628411

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      A novel “copper crown” complexes UOmath image preferentially (see picture), as competition experiments with Ca2+ and Cu2+ showed. This ligand thus provides an alternative to expanded porphyrins for the complexation of actinides and lanthanides by high denticity, planar ligands.

    27. First Phenylene Polymers Linked by Sulfonium Groups (pages 2843–2845)

      Prof. Eishun Tsuchida, Dr. Kimihisa Yamamoto, Dr. Kenji Miyatake and Dr. Yukio Nishimura

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199628431

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      Alternating phenylene units and methylsulfonium groups make up polymer 1, which is formed by polymerizing benzene with sodium methanesulfinate. This reaction is conducted in trifluoromethane-sulfonate, and xylene and diphenyl ether are also suitable monomers.

    28. Vinyl Glycosides in Oligosaccharide Synthesis: A Strategy for the Preparation of Trisaccharide Libraries Based on Latent-Active Glycosylation (pages 2845–2847)

      Dr. Geert-Jan Boons, Dr. Barbra Heskamp and Floris Hout

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199628451

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      Many different trisaccharides (theoretically 256) can in principle be constructed from only four protected building blocks by following the strategy described for the synthesis of trisaccharide libraries. The method relies on latent-active glycosylation. The formula below gives an idea of the compounds in these libraries.

    29. Unusual Regioselectivity in the Reaction of Allyl- or Allenylpropargyltitanium Compounds with Carbonyl Compounds: An Efficient Synthesis of Alkylidenecyclopropane Derivatives (pages 2848–2849)

      Dr. Aleksandr Kasatkin and Prof. Dr. Fumie Sato

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199628481

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      Steric strain shifts the equilibrium between the two isomeric allyltitanium compounds and isomeric allenyl- and propargyltitanium compounds containing cyclopropane units. This leads to unusual regioselectivity in their additions to electrophilic carbonyl compounds (shown on the right) and thus provides easy access to alkylidenecyclopropane derivatives.

    30. Diastereoselective Addition of n-Butyllithium to 2-Phenylpropanal: A Reassessment of the Solvent and Temperature Effects (pages 2849–2852)

      Prof. Dr. Gianfranco Cainelli, Dr. Daria Giacomini, P. Galletti and A. Marini

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199628491

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      The length of the linear hydrocarbon chain in the solvent is a key factor in the facial diastereoselectivity of the nucleophilic addition of n-butyllithium to 2-phenyl-propanal [Eq. (a)]. The reaction in these solvents shows inversion temperatures that correlate with the melting point of the solvent.

    31. Synthesis and Structure of the Metalated Zintl Ion[Ge910-Ge)Ni(PPh3)]2− (pages 2852–2854)

      Donna R. Gardner, Dr. James C. Fettinger and Prof. Bryan W. Eichhorn

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199628521

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      The first metalated germanide ion and only the second example of a cluster of the rare nido-10 (iv+iv) structural type, the anion 1, was isolated from the reaction of [Ni(CO)2(PPh3)2], K4Ge9, and “2.2.2”cryptand in ethylenediamine (en). However, the structure of the Ge10Ni cluster (see picture) is distinctly distorted relative to the ideal nido-10 (iv+iv) geometry.

      • equation image
    32. Te6, [Te8Cl18]2−, and [TeCl3]: New Tellurium and Chlorotellurato Ligands in the Re6 Solid-State Cluster Compounds Re6Te16Cl18 and Re6Te16Cl6 (pages 2854–2856)

      Yuri V. Mironov, Michael A. Pell and Prof. James A. Ibers

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199628541

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      Re6 octahedra inside Te8 cubes is a common feature of both title compounds. The picture on the right shows a section of the structure of Re6Te16Cl18, in which the Re6 octahedron and the binding of the cluster to the [Te8Cl18]2− ligand are apparent. Different binding to ligands results in a three-dimensional structure for Re6Te16Cl18, and a two-dimensional structure for Re6Te16Cl6.

    33. First Experimental Determination of the Ionization Potentials of Berkelium and Californium (pages 2856–2858)

      Dr. Stefan Köhler, Dipl.-Phys. Nicole Erdmann, Dipl.-Phys. Martin Nunnemann, Prof. Dr. Günter Herrmann, Prof. Dr. Gerhard Huber, Prof. Dr. Jens Volker Kratz, Dr. Gerd Passler and Dr. Norbert Trautmann

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199628561

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      Only 1012 atoms of an element are required for the determination of its first ionization potential by resonance ionization with laser light in the presence of an electric field and subsequent mass spectrometry. The figure on the right shows the ionization thresholds Wth of berkelium and californium and the extrapolation to the external field strength E = 0, which yields the ionization potentials I (49989(2) and 50665(2) cm−1, respectively).

    34. From Pagodanes to Nonpentagonal (Homo)Dodecahedranes—The Undecacyclo-[,20.03,10.04,19.05,9.06,18.07,15.08,13.019,22.016,21]docosane Cage (pages 2858–2861)

      Dr. Veeraraghava Sharma, Dr. Manfred Keller, Dipl.-Chem. Andreas Weiler, Dr. Dieter Hunkler and Prof. Dr. Horst Prinzbach

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199628581

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      Twofold, transannular cyclization of the bis(methylene)bisseco intermediates B, obtained from the pagodane diester A, provides access to the parent nonpentagonal bis(homo)dodecahedrane C and pairwise symmetrically functionalized derivatives. Some of these products are important model compounds for quantifying the factors that determine the transannular electronic interactions in cage compounds of this type.

    35. Aggregation of Modified Zinc Chlorins in Nonpolar Solvents-Bacteriochlorophyll c Mimics with Interchanged Hydroxy and Carbonyl Functions (pages 2861–2863)

      Dipl.-Chem. Aldo Jesorka, Dr. Teodor Silviu Balaban, Prof. Dr. Alfred R. Holzwarth and Prof. Dr. Kurt Schaffner

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199628611

      Thumbnail image of graphical abstract

      Self-assembly of functionally “inverse” zinc chlorins—31-hydroxy and 131keto groups, which are functionally essential in the bacteriochlorophylls c, d, and e, have been interchanged—is possible in nonpolar solvents (see schematic representation below). This result sets structural conditions for the formation of large aggregates similar to those formed by bacteriochlorophylls in vitro and in light-harvesting antenna systems of photosynthetic bacteria.

    36. New Imido-Bridged Transition Metal Clusters: [(C5H5)4Ti4(NSnMe3)4], [Co11(PPh3)3(NPh)12], [Ni11Br6(NtBu)8], and [Li(thf)4]4[Cu24(NPh)14] (pages 2863–2866)

      Dr. Andrea Decker, Prof. Dr. Dieter Fenske and Dr. Klaus Maczek

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199628631

      Thumbnail image of graphical abstract

      Metal halide complexes and functionalized amines react to form imidobridged transition metal clusters. This method can be used to synthesize imido clusters of electron-rich transition metals such as [Li(thf)4]4-“Cu243-NPh)8 μ4-NPh)61 (the structure of the anion of 1 is depicted on the right).

    37. Monitoring the Reaction Progress in Combinatorial Chemistry: 1H MAS NMR Investigations on Single Macro Beads in the Suspended State (pages 2867–2869)

      Dipl.-Chem. Matthias Pursch, Dipl.-Chem. Götz Schlotterbeck, Li-Hong Tseng, Priv.-Doz. Dr. Klaus Albert and Dr. Wolfgang Rapp

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199628671

      Laborious cleavage and isolation steps are avoided! The method of 1H magic angle spinning (MAS) NMR spectroscopy can be used to monitor the course of the synthesis on a single resin particle in a suspended sample in the nanoliter detection range. This extremely useful technique for combinatorial chemistry was tested on a hydantoin reaction sequence.

    38. A Layer Silicate: Synthesis and Structure of the Zeolite Precursor RUB-15—[N(CH3)4]8[Si24O52(OH)4]·20 H2O (pages 2869–2872)

      Dipl.-Min. Uwe Oberhagemann, Dipl.-Min. Parwis Bayat, Dr. Bernd Marler, Prof. Dr. Hermann Gies and Dr. Jordi Rius

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199628691

      Thumbnail image of graphical abstract

      The missing link in the series clathrate hydrates, group silicate hydrates—layer silicate hydrates—porous framework silicas is provided by RUB-15, a new layer silicate hydrate with a three-dimensional bonding network composed of layerlike silicate ions and water molecules linked by hydrogen bonds. A section of the structure of is shown on the right. RUB-15 further illustrates the close relationship between crystalline compounds of water, silica, and mixtures thereof.

    39. Synthesis and Characterization of the Stable Dicarbonyl(cyclopentadienyl)iron Radical [(C5R5)Fe(CO)2] (R [DOUBLE BOND] CHMe2) (pages 2872–2875)

      Dr. Helmut Sitzmann, Dipl.-Chem. Thomas Dezember, Prof. Dr. Wolfgang Kaim, Dipl.-Chem. Frank Baumann, Prof. Dr. Dietmar Stalke, Dipl.-Chem. Joerg Kärcher, Prof. Dr. Elmar Dormann, Dr. Hubert Winter, Dipl.-Phys. Christoph Wachter and Dipl.-Phys. Marc Kelemen

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199628721

      Thumbnail image of graphical abstract

      Monomeric in solution, dimeric in the crystal is the dicarbonyl(pentaisopropyl-cyclopentadienyl)iron(I) radical 2, which is formed from the high-spin iron(II) complex 1 by carbonylation and reduction.

    40. [As2(AlCp*)3]—A Compound with a Polyhedral As2Al3 Framework (pages 2875–2877)

      Carsten K. F. von Hänisch, Christoph Üffing, Markus A. Junker, Achim Ecker, Boris O. Kneisel and Prof. Dr. Hansgeorg Schnöckel

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199628751

      Thumbnail image of graphical abstract

      The bonding in heteropolyhedral compounds of the closo-borane type is discussed for “As2(AlCp*)3” clusters, whose molecular structure has been characterized by X-ray crystallography (framework shown on the right). Quantum chemical calculations on several trigonal-bipyramidal Emath imageEmath image structures revealed the mode of bonding for a variety of ligands (Cp* = C5Me5; EIII: Group 13 element, EV: Group 15 element).

    41. Functionalized Organoimidorhenium(V) Complexes as Potential Radiopharmaceuticals: Syntheses of Glycine Derivatives and the Structure Determination of a Rhenium Analogue of Chlorambucil (pages 2877–2879)

      Prof. Dr. Jeffrey B. Arterburn, Ian M. Fogarty, Dr. Keith A. Hall, Dr. Kevin C. Ott and Dr. Jeffrey C. Bryan

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199628771

      Thumbnail image of graphical abstract

      Two important aspects, the synthesis of imido complexes of radioactive metal isotopes and the diversity that can be incorporated with this ligand, distinguish this communication. The multiply bonded organoimide ligand provides a new and powerful means of conjugating suitable radioisotopes of rhenium to biologically relevant molecules in the design of radiopharmaceuticals. Here stable isotope and 188Re-labeled analogues (1) of the anticancer drug chlorambucil were synthesized.

    42. Solvent-Dependent C[BOND]N Bond Lengths in a Protonated Orthoamide (pages 2879–2881)

      Dr. Randolf D. Köhn, Guido Seifert and Dr. Gabriele Kociok-Köhn

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199628791

      Thumbnail image of graphical abstract

      A bond stretch isomerism predicted over 30 years ago could exist in the organic cations 2+ and 3+, which arise from the protonation of 1 and have been characterized by X-ray crystallography. The two isomeric cations can be interconverted by changing the solvent polarity.

  4. Corrigenda

    1. Top of page
    2. Reviews
    3. Highlights
    4. Communications
    5. Corrigenda
    1. You have free access to this content
      Corrigenda (page 2881)

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199628811