Angewandte Chemie International Edition in English

Cover image for Vol. 36 Issue 21

November 14, 1997

Volume 36, Issue 21

Pages 2259–2385

Currently known as: Angewandte Chemie International Edition

    1. Cover Picture (Angew. Chem. Int. Ed. Engl. 21/1997)

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199722571

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      The cover picture shows at the top left corner a space-filling model on an α-cyclodextrin molecule containing a xenon atom in its hydrophobic pocket. By application of optical pumping, a large nuclear-spin polarization of the xenon atom can be achieved, which can be transferred by cross-relaxation to 1H nuclei near xenon binding sites. This process, dubbed “spin polarization induced nuclear overhauser effect” (SPINOE), permits selective enhancement of NMR signals for protons in the interior of the pocket. A section of a SPINOE NMR spectrum of dehydrated α-cyclodextrin after introduction of laser-polarized xenon is shown at the bottom. Read more about this promising method in the contribution from A. Pines et al. on pages 2368–2370.

  1. Reviews

    1. Top of page
    2. Reviews
    3. Highlights
    4. Communications
    5. Book Reviews
    1. The Covalent Chemistry of Higher Fullerenes: C70 and Beyond (pages 2268–2280)

      Dr. Carlo Thilgen, Dr. Andreas Herrmann and Prof. Dr. François Diederich

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199722681

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      The chemistry of higher fullerenes is no longer on the sidelines. Seven years after fullerenes became available on a preparative scale, the functionalization of the higher homologues of buck minsterfullerene C60—in particular C70, but also C76, C78 (a tris-adduct is shown on the right as an example), and C84—has made considerable progress. It has now been reviewed for the first time under particular consideration of the aspects of chirality and some emerging reactivity principles.

    2. Enantioselective Synthesis with Lithium/(−)-Sparteine Carbanion Pairs (pages 2282–2316)

      Prof. Dr. Dieter Hoppe and Dr. Thomas Hense

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199722821

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      No longer on the list of exotic synthons! “Chiral carbanions”, that is, enantiomerically enriched lithium carbanion pairs, have for some time played an important role in asymmetric synthesis. The trick lies in using chiral ligands such as the lupine alkaloid (−)-sparteine 1, which has gained a reputation for its exceptional efficiency and wide applicability.

  2. Highlights

    1. Top of page
    2. Reviews
    3. Highlights
    4. Communications
    5. Book Reviews
    1. Charge Transfer in DNA: A Controversy (pages 2317–2319)

      Dr. Ulf Diederichsen

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199723171

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      Electron transfer over distances of more than 40 Å through a DNA double strand (see schematic representation on the right) still stimulates controversy about mechanism but seems to be proven experimentally. Biochemical processes such as repair of photodimer damage can be initiated by DNA electron transfer. The dependence of electron transport on how nearly perfect a DNA base stack is suggests that conductivity can be used to quantify stacking quality or to recognize a DNA single strand.

    2. How Can One Recognize a Triple Bond between Main Group Elements? (pages 2320–2322)

      Dr. Karl Wilhelm Klinkhammer

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199723201

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      Which formula gives the best representation for the bonding in the “gallyne” 1 (Mes* = 2,4,6-iPr3C6H2) recently reported by Robinson et al., A or B? Is there a Ga[BOND]Ga triple bond, although the classical criteria are not met?

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  3. Communications

    1. Top of page
    2. Reviews
    3. Highlights
    4. Communications
    5. Book Reviews
    1. An Organic Spin-Ladder Molecular Material (pages 2324–2326)

      Dr. Concepció Rovira, Prof. Jaume Veciana, Elisabet Ribera, Judit Tarrés, Prof. Enric Canadell, Dr. Roger Rousseau, Dr. Montserrat Mas, Dr. Elies Molins, Dr. Manuel Almeida, Dr. Rui T. Henriques, Dr. Jorge Morgado, Jean-Philippe Schoeffel and Prof. Jean-Paul Pouget

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199723241

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      Pairs of stacks of organic donors D in the salt [(DT-TTF)2][Au(mnt)2] (DT-TTF = dithiophene-tetrathiafulvalene, mnt = maleonitriledithiolate) form a classical ladder structure due to three close S … S interactions (see picture). Below 225 K the double stack of donor molecules forms a spin ladder with two legs, which arises through localization of unpaired electrons in the (DT-TTF)2 dimers.

    2. Anion Control in Bipyridylsilver(I) Networks: A Helical Polymeric Array (pages 2327–2329)

      Matthew A. Withersby, Dr. Alexander J. Blake, Dr. Neil R. Champness, Dr. Peter Hubberstey, Dr. Wan-Sheung Li and Prof. Martin Schröder

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199723271

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      A helical staircase structure is observed for the layers made from chains of alternating AgI centers and pytz ligands in [Ag(pytz)(NO3)] (pytz = 3,6-di-(4-pyridyl)-1,2,4,5-tetrazine). Decisive for the formation of this array—a view of the structure along the helical axis is shown on the right—is the anionic ligand NOmath image, as shown by the comparison with the analogous PFmath image and BFmath image compounds. These two show parallel chains of alternating AgI ions and pytz ligands held in pairs through weak Ag[BOND]Ag contacts and π–π interactions between adjacent pytz ligands.

    3. Electronic Structure of Manganese(III) Compounds from High-Frequency EPR Spectra (pages 2329–2331)

      Dr. Anne-Laure Barra, Prof. Dante Gatteschi, Dr. Roberta Sessoli, Gian Luca Abbati, Dr. Andrea Cornia, Prof. Antonio C. Fabretti and Myriam G. Uytterhoeven

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199723291

      The use of high magnetic field and high frequency in an unconventional spectrometer has provided very informative EPR spectra of a manganese(III) octahedral complex for the first time. The parameters of the spin Hamiltonian operator are in fair agreement with those calculated with ligand-field theory. High-frequency EPR is thus a powerful tool for the structural investigation of complexes that contain metal ions with integer spins.

    4. Controlling Microstructure in Polymeric Molecular Shuttles: Solvent-Induced Localization of Macrocycles in Poly(urethane/crown ether) Rotaxanes (pages 2331–2333)

      Caiguo Gong and Prof. Harry W. Gibson

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199723311

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      Localized at the NH group in chloroform, but forced away from the NH group in DMSO: This describes the behaviour of the cyclic units in poly(urethane/crown ether rotaxane)s. The dependency on the solvent results in different microstructures (shown schematically below).

    5. The First Lithiated Phosphane Oxide with Li[BOND]C Bonds: Synthesis and Structure of [{Ph2P(O)CHLiC(H)MeEt}4] (pages 2334–2335)

      Dr. John E. Davies, Robert P. Davies, Lorraine Dunbar, Dr. Paul R. Raithby, Matthew G. Russell, Dr. Ronald Snaith, Dr. Stuart Warren and Andrew E. H. Wheatley

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199723341

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      A cubane-like tetrameric structure with Li[BOND]C bonds and two stereogenic centers per monomeric unit results from lithiation of Ph2P(O)CH2C(H)MeEt in toluene. Retention of the Li[BOND]C bonds on dissolution in [D8]THF is confirmed by 13C NMR spectroscopy. The central framework of this lithiated phosphane oxide is shown on the right.

    6. The Structure of [Zn(bix)2(NO3)2]·4.5 H2O (bix = 1,4-Bis(imidazol-1-ylmethyl)benzene): A New Type of Two-Dimensional Polyrotaxane (pages 2336–2338)

      Dr. Bernard F. Hoskins, Dr. Richard Robson and Damian A. Slizys

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199723361

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      Two independent and interpenetrating two-dimensional networks, whose outstanding structural features are the polyrotaxane columns of the unprecedented type shown on the right, are found in the coordination polymer [Zn(bix)2(NO3)2]·4.5 H2O. This compound is only the third example of a 2-D rotaxane; the other two were just recently reported.

    7. Incorporation of a First Row Element into the Bridge of a Strained Metallocenophane: Synthesis of a Boron-Bridged [1]Ferrocenophane (pages 2338–2340)

      Dr. Holger Braunschweig, Dr. Regain Dirk, Dr. Matthias Müller, Dr. Paul Nguyen, Rui Resendes, Derek P. Gates and Prof. Ian Manners

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199723381

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      A new record tilt angle [32.4(2)°] is present between the planes of the cyclopentadienyl ligands in the [1]boraferrocenophane 1. This compound is the first [1]ferrocenophane containing a first row element in the bridge. Ring-opening polymerization of 1 leads to cyclic oligomers and insoluble polymer 2.

    8. Recognition of Anions through NH[BOND]π Hydrogen Bonds in a Bicyclic Cyclophane—Selectivity for Nitrate (pages 2340–2342)

      Dr. Adrian P. Bisson, Dr. Vincent M. Lynch, Mary-Katherine C. Monahan and Prof. Eric V. Anslyn

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199723401

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      A combination of geometric and electrostatic complemetarity explains why nitrate is bound only slightly less strongly than acetate within the bicyclic cyclophane 1, although nitrate is a significantly weaker base. The crystal structure of the acetate complex of 1 depicts the binding of the anion in the host's cavity, as in the case of the analogous chloride complex.

    9. Tetraethylammonium Trichloride: A Versatile Reagent for Chlorinations and Oxidations (pages 2342–2344)

      Thierry Schlama, Kiroubagaranne Gabriel, Dr. Véronique Gouverneur and Dr. Charles Mioskowski

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199723421

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      Applicable to a broad range of substrates and convenient to handle, the titel compound oxidizes saturated alcohols to aldehydes or ketones; in the case of allyl alcohols, chlorination at the double bond is preferred. Especially interesting is the reaction of acetal 1, since other reagents provide α-halogenated acetals and not product 2.

    10. The First Total Synthesis of Tricolorin A (pages 2344–2346)

      Shou-Fu Lu, QinQin O'yang, Zhong-Wu Guo, Dr. Biao Yu and Prof. Yong-Zheng Hui

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199723441

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      A regioselective macrolactonization and a one-pot synthesis are the key steps in the first total synthesis of tricolorin A (1), the principal component of a plant used in traditional Mexican agriculture for weed control. The synthesis of this macrolactone tetrasaccharide, which starts from D-(+)-mannitol, contains 45 steps with a longest linear sequence of 20 steps (overall yield 0.65%).

    11. Fluorous Biphasic Catalysis: Complexation of 1,4,7-[C8F17(CH2)3]3-1,4,7-Triazacyclononane with [M(C8F17(CH2)2CO2)2] (M = Mn, Co) To Provide Perfluoroheptane-Soluble Catalysts for Alkane and Alkene Functionalization in the Presence of t-BuOOH and O2 (pages 2346–2349)

      Dr. Jean-Marc Vincent, Dr. Alain Rabion, Dr. Vittal K. Yachandra and Dr. Richard H. Fish

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199723461

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      An autoxidation mechanism was involved in the oxidation of alkanes and alkenes with tBuOOH and O2 under conditions of fluorous biphasic catalysis. The catalytically active complexes are soluble in perfluoroheptane and form in situ from ligand 1 and the Mn2+ complex 2 with polyfluorinated carboxylate ligands (fluoroponytails).

    12. A 1,3,5-Triphosphinantriium Ion (pages 2349–2350)

      Dr. Ekaterina Gorbunowa, Dr. Gernot Heckmann, Prof. Dr. Ekkehard Fluck, Prof. Dr. Matthias Westerhausen and Prof. Dr. Rudolf Janoschek

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199723491

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      Three neighboring charge carriers are found in close proximity in the six membered ring of the title compound. In the solid state the trication contains two PC units that lie in a plane, and a third unit attached slanted at an angle above the plane (a side view is depicted on the right).

    13. [CH(Me)P(Et)2NSiMe3]—A Carbanion That Functions as a Bridging Ligand (pages 2350–2352)

      Dr. Anita Müller, Priv.-Doz. Dr. Bernhard Neumüller and Prof. Dr. Kurt Dehnicke

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199723501

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      A nearly linear coordination geometry is exhibited by the two metal atoms in the lithium cuprate that is obtained from from the title anion after reaction with CuI. The puckered eight-membered ring in this compound is depicted on the right; reaction of the carbanion with ZnCl2 instead of CuI results in a 24-membered macrocycle.

    14. Synthesis of Doubly Unsaturated Aldehydes and Ketones by a Novel β-Decarbopalladation (pages 2352–2354)

      Dr. Hiroto Harayama, Toshitsugu Kuroki, Dr. Masanari Kimura, Dr. Shuji Tanaka and Prof. Dr. Yoshinao Tamaru

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199723521

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      Excellent diastereoselectivity is observed for the conversion of cyclic vinyl-substituted carbonates into unsaturated open-chain carbonyl compounds [Eq. (1)]. Decisive for the success of this ring opening is a PD0 complex as the catalyst. Cn = complex, also cyclic substituted carbon chains with n = 0, 1, 2, 4, 8; R, R′ = H, Me.

    15. Efficient Enzymatic Synthesis of the Core Trisaccharide of N-Glycans with a Recombinant β-Mannosyltransferase (pages 2354–2356)

      Dr. Gregory M. Watt, Dr. Leigh Revers, Dr. Matthew C. Webberley, Dr. Iain B. H. Wilson and Dr. Sabine L. Flitsch

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199723541

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      A highly stereo- and regioselective linkage for the β-1,4-mannoside bond of trisaccharide 1 (R/R′ = H/OH) is achieved with a redesigned recombinant biocatalyst: a suitably modified yeast enzyme (ALG1) was expressed in E. coli; the enzyme was then immobilized on a NiII affinity column.

    16. Artificial Phototropism: Reversible Photoseparation of Self-Assembled Interlocking Conjugates (pages 2356–2358)

      Dr. Andrew C. Benniston, Prof. Anthony Harriman and Dr. Dimitri S. Yufit

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199723561

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      Careful balancing of the energy levels permits photoseparation of a closely coupled inclusion complex (see schematic representation below). Diffusive charge recombination gives rise to strong fluorescence upon optical excitation of the transitory (uncomplexed) guest molecule.

    17. Novel Zwitterionic Diallylzirconium Complexes: Synthesis, Structure, Polymerization Activity, and Deactivation Pathways (pages 2358–2361)

      Dr. Gerardo Jiménez Pindado, Dr. Mark Thornton-Pett, Marco Bouwkamp, Dr. Auke Meetsma, Dr. Bart Hessen and Prof. Dr. Manfred Bochmann

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199723581

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      The zwitterionic allyl complex 1 (Rn = 1,3-(SiMe3)2) is a new catalyst type for the polymerization of ethene under mild conditions. The propensity of these and similar zwitterionic complexes for C[BOND]H activation and rearrangements is very sensitive to steric conditions. The reactions provide evidence for a new, surprisingly facile catalyst-deactivation mechanism.

    18. Regio- and Enantioselective Synthesis of α-Fluoroketones by Electrophilic Fluorination of α-Silylketone Enolates with N-Fluorobenzosulfonimide (pages 2362–2364)

      Prof. Dr. Dieter Enders, Dipl.-Chem. Marcus Potthoff, Dr. Gerhard Raabe and Dr. Jan Runsink

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199723621

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      Practically enantiopure α-fluoroketones 3 are accessible for the first time starting from simple ketones 1. Key steps in this new method are the asymmetric electrophilic α-fluorination of α-silylketone enolates with NF reagents and subsequent racemization-free removal of the silyl auxiliary group.

    19. The Use of a Ten-Membered Tetraphosphole Macrocycle to Increase the Lifetime of a Palladium Catalyst (pages 2364–2366)

      Dr. François Mercier, Dr. Frank Laporte, Dr. Louis Ricard, Prof. Dr. François Mathey, Dipl.-Chem. Marc Schröder and Prof. Dr. Manfred Regitz

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199723641

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      No precipitation of palladium occurs when complex 1 is employed in Stille and Heck reactions, even at high temperature. This complex also remains fully active even after more than 48 h. The use of the title compound as a complex ligand is the first application of such phosphole macrocycles.

    20. Asymmetric Catalytic Protonation of Silyl Enol Ethers with Chiral Palladium Complexes (pages 2366–2368)

      Dr. Masaharu Sugiura and Prof. Takeshi Nakai

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199723661

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      Addition of amine is required to convert the chiral cationic palladium complex obtained from a silver salt and [PdCl2{(R)-binap}] into an efficient asymmetric catalyst for the protonation of cyclic silyl enol ethers with water [Eq. (a)]. The effect of the amine is most likely based on selective deactivation of an initially formed Pd–binap comple. The “surviving” Pd species cause a reaction that is slower but proceeds with enhanced enantioselectivity.

    21. Selective Enhancement of NMR Signals for α-Cyclodextrin with Laser-Polarized Xenon (pages 2368–2370)

      Yi-Qiao Song, Boyd M. Goodson, Rebecca E. Taylor, David D. Laws, Prof. Gil Navon and Prof. Alexander Pines

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199723681

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      “Lighting up” the nuclear magnetic resonance of molecules with laser-polarized xenon could be a valuable new source of structural information. The 1H NMR signals of protons near the xenon binding site in α-cyclodextrin (shown schematically on the right) are selectively enhanced through couplings that are sensitive to 129Xe[BOND]1H internuclear distances.

    22. Reducible Nanoscale Molecular Rods Based on Diacetylene-Linked Poly(phenylthio)-Substituted Benzenes (pages 2370–2372)

      Dr. Marcel Mayor, Prof. Dr. Jean-Marie Lehn, Dr. Katharina M. Fromm and Prof. Dr. Dieter Fenske

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199723701

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      More positive reduction potentials with increasing molecular length characterize the title compounds (see drawing below, n = 0,1). Their physical and chemical properties, in particular the facile reduction that was investigated with cyclic voltammetry, make them promising candidates for the development of molecular electronic and photonic devices.

    23. Synthesis, Structure, and Coordination Chemistry of Diisocyanomethane (pages 2372–2374)

      Dr. Jürgen Buschmann, Thilo Bartolmäs, Priv.-Doz. Dr. Dieter Lentz, Prof. Dr. Peter Luger, Ingo Neubert and Matthias Röttger

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199723721

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      Unstable even in solution is how Neidlein described diisocyanomethane, which has been known for over 30 years. Now this compound, the only geminal diisocyanide known (crystal structure depicted on the right), has been isolated by fractional condensation. The compound can be stabilized by coordination to transition metal complex fragments.

    24. Catalytic Conversion of Methane into Aromatic Hydrocarbons over Iron Oxide Loaded ZSM-5 Zeolites (pages 2374–2376)

      Dr. Bert M. Weckhuysen, Dr. Dingjun Wang, Prof. Michael P. Rosynek and Prof. Jack H. Lunsford

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199723741

      Without an oxidant like O2, Fe/H-ZSM-5 catalysts are able to convert methane selectively into benzene, toluene, and naphthalene. Methane is activated on iron oxide clusters, and the primary product ethylene undergoes subsequent oligomerization and cyclization reactions on Brønsted acidic sites to form the aromatic products.

    25. Carbene Complex Modified Glycals: Synthesis and Reactivity (pages 2376–2378)

      Prof. Karl Heinz Dötz, Dr. Richard Ehlenz and Dipl.-Chem. Daphne Paetsch

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199723761

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      New opportunities in the functionalization of carbohydrates arise from carbene complex modified glycals. They undergo a chromium-induced benzannulation to give benzoglycals 1 and allow a C2-homologization to 2 with retention of the metal–carbene bond by a diastereoselective insertion of ynol ethers.

    26. Stabilization of the (π-Indenyl)–Lead Bond: The First Structurally Authenticated Bis(η5-indenyl) Complex of a Post-Transition Element, [Pb{1,3-(SiMe3)2C9H5}2] (pages 2378–2379)

      Jason S. Overby, Prof. Timothy P. Hanusa and Dr. Paul D. Boyle

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199723781

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      Where are all the bis(π-indenyl) complexes of the “post-transition elements”? The first example of this type of complex with a Group 14 element has now been synthesized and characterized. [Pb{1,3-(SiMe3)2C9H5}2] is unstable in solution, but forms thermally stable crystals that reveal a sandwich geometry with nearly parallel, η5-coordinated C5 rings of the indenyl ligand (see structure on the right).

    27. New Insights into the Mechanism of the McMurry Reaction (pages 2380–2382)

      Dr. Claude Villiers and Dr. Michel Ephritikhine

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199723801

      Not only pinacolate intermediates appear in McMurry reactions of aliphatic ketones R2CO (R = Me, Et, iPr) with MCl4Li(Hg) (M = Ti, U) [Eq. (1)]. Rather, carbenoid species must also be considered. This conclusion was drawn from an exact analysis of the reaction products as well as control experiments with pinacol derivatives.

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  4. Book Reviews

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