Angewandte Chemie International Edition

Cover image for Vol. 44 Issue 22

May 30, 2005

Volume 44, Issue 22

Pages 3323–3495

    1. Cover Picture: Confined Electron-Transfer Reactions within a Molecular Metal Oxide “Trojan Horse” (Angew. Chem. Int. Ed. 22/2005) (page 3323)

      De-Liang Long, Hamera Abbas, Paul Kögerler and Leroy Cronin

      Version of Record online: 24 MAY 2005 | DOI: 10.1002/anie.200590072

      Upon thermal stimulation the two templating sulfite anions embedded in the “Trojan Horse” polyoxometalate cluster shown in the cover picture release electron “soldiers” to the cluster's surface, turning the cluster from colorless to blue (background). The formation of the mixed-valence cluster shell is commensurate with the oxidation of the sulfite to sulfate anions. More details about this coupled structural and electronic rearrangement are given in the Communication by L. Cronin et al. on page 3415 ff.

    2. Organocatalytic Hydride Transfers: A New Concept in Asymmetric Hydrogenations (pages 3340–3342)

      Hans Adolfsson

      Version of Record online: 2 MAY 2005 | DOI: 10.1002/anie.200500827

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      Nature knows best: Recently developed enantioselective organocatalytic methods for the reduction of olefins under transfer-hydrogenation conditions are discussed (see scheme). The metal-free, amine-catalyzed reductions described have been inspired by the way natural systems perform reduction reactions.

    3. Arthur Eichengrün—Tribute to a Forgotten Chemist, Entrepreneur, and German Jew (pages 3344–3355)

      Elisabeth Vaupel

      Version of Record online: 30 MAR 2005 | DOI: 10.1002/anie.200462959

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      The life and achievements of the Jewish chemist and entrepreneur Arthur Eichengrün, a trailblazer in the German cellulose acetate industry, have been unjustly forgotten as a long-term consequence of National Socialism. Newly examined sources give detailed insight into his tragic biography, which was illustrative of the times.

    4. Cellulose: Fascinating Biopolymer and Sustainable Raw Material (pages 3358–3393)

      Dieter Klemm, Brigitte Heublein, Hans-Peter Fink and Andreas Bohn

      Version of Record online: 28 APR 2005 | DOI: 10.1002/anie.200460587

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      The trend toward renewable resources has led to a global renaissance of cellulose research over the past ten years. This review describes the highlights of the progress made in this area, which has provided a better understanding of the structure of cellulose derivatives, the tailoring of cellulose products, alternative production processes for cellulose regenerates, and new pathways for the formation of supramolecular architectures.

    5. Molecular Dynamics Simulations of Protein G Challenge NMR-Derived Correlated Backbone Motions (pages 3394–3399)

      Oliver F. Lange, Helmut Grubmüller and Bert L. de Groot

      Version of Record online: 24 MAY 2005 | DOI: 10.1002/anie.200462957

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      Correlated motions probed? A recently reported NMR relaxation experiment promised to probe correlated motions in proteins. However, molecular dynamics simulations imply that this is not the case. The simulations agree well with data obtained through two independent and established NMR spectroscopic methods and thus provide an alternative and consistent access to correlated protein motions (see picture) from NMR techniques.

    6. Tuning a Metal's Oxidation State: The Potential of Clathrochelate Systems (pages 3400–3402)

      Yan Z. Voloshin, Oleg A. Varzatskii, Ivan I. Vorontsov and Mikhail Yu. Antipin

      Version of Record online: 21 APR 2005 | DOI: 10.1002/anie.200463070

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      A grip on what's inside: A clathrochelate ligand controls the oxidation state of the encapsulated cobalt ion in complex 1. This complex can be reduced chemically in acetonitrile solution by treatment with silver in the presence of tetraalkylammonium or tetra(dimethylamido)phosphonium halides to the dark-blue reduced complex [(NMe2)4P]-1 in high yield (see scheme).

    7. Iodine-Assisted Assembly of Helical Coordination Polymers of Cucurbituril and Asymmetric Copper(II) Complexes (pages 3402–3407)

      Feng Zhang, Tatsuo Yajima, Yi-Zhi Li, Guo-Zheng Xu, Hui-Lan Chen, Qi-Tao Liu and Osamu Yamauchi

      Version of Record online: 21 APR 2005 | DOI: 10.1002/anie.200463071

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      An anion-exchange strategy was used to prepare two helical structures made up of cucurbituril and asymmetric copper(II) complexes containing 8-hydroxyquinoline-5-sulfonate and 3,5-diiodosalicylate (right half of picture) or 3-iodobenzoate (left half). The shape-matching interactions between cucurbituril and the copper complexes were assisted by the iodo substituents.

    8. Insight into and Practical Application of pH-Controlled Asymmetric Transfer Hydrogenation of Aromatic Ketones in Water (pages 3407–3411)

      Xiaofeng Wu, Xiaoguang Li, Frank King and Jianliang Xiao

      Version of Record online: 25 APR 2005 | DOI: 10.1002/anie.200500023

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      Much faster, more enantioselective, and more-productive catalysis was attained in the asymmetric transfer hydrogenation of aromatic ketones with the Noyori–Ikariya Ru–Ts-dpen catalyst in water under slightly basic conditions (see scheme). At low pH values, the reaction was much less efficient and appears to operate through a different mechanism.

    9. Evidence that Electrostatic Interactions Dictate the Ligand-Induced Arrest of RNA Global Flexibility (pages 3412–3415)

      Stephen W. Pitt, Qi Zhang, Dinshaw J. Patel and Hashim M. Al-Hashimi

      Version of Record online: 28 APR 2005 | DOI: 10.1002/anie.200500075

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      The global dynamics of the TAR RNA from HIV-1 bound to two distinctly charged molecules have been characterized by NMR studies of residual dipolar couplings (see picture). While neomycin B (NeoB: +5) arrests global motions in TAR, the small organic molecule acetylpromazine (AcP: +1) does not. Results indicate that electrostatic interactions are critical for arresting global motions in RNA.

    10. Confined Electron-Transfer Reactions within a Molecular Metal Oxide “Trojan Horse” (pages 3415–3419)

      De-Liang Long, Hamera Abbas, Paul Kögerler and Leroy Cronin

      Version of Record online: 4 MAY 2005 | DOI: 10.1002/anie.200500541

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      Cores and effect: Heating the cluster [W18O56(SO3)2(H2O)2]8− causes an electron transfer from the core sulfite anions to the cluster shell resulting in a color change from colorless to dark blue (see backgrounds). The electron transfer is coupled with a structural reorganization of the cluster shell and oxidation of the sulfite to sulfate anions (see scheme).

    11. AFM-Tip-Integrated Amperometric Microbiosensors: High-Resolution Imaging of Membrane Transport (pages 3419–3422)

      Angelika Kueng, Christine Kranz, Alois Lugstein, Emmerich Bertagnolli and Boris Mizaikoff

      Version of Record online: 28 APR 2005 | DOI: 10.1002/anie.200461556

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      A probing combination: Integration of amperometric microbiosensors into combined tips for AFM–scanning electrochemical microscopy allows specific detection of molecular species independent of the AFM measurement, but correlated in space and time with the surface morphology. The applicability of this multidimensional approach is demonstrated by imaging glucose transport across porous membranes at the nanoscale (see picture).

    12. Heterotrimetallic RuMnMn Species on a Hydrotalcite Surface as Highly Efficient Heterogeneous Catalysts for Liquid-Phase Oxidation of Alcohols with Molecular Oxygen (pages 3423–3426)

      Kohki Ebitani, Ken Motokura, Tomoo Mizugaki and Kiyotomi Kaneda

      Version of Record online: 28 APR 2005 | DOI: 10.1002/anie.200462600

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      Robust and structurally defined on the atomic scale: A heterotrimetallic RuIVMnIVMnIV species coordinated to a hydrotalcite surface is a highly efficient heterogeneous catalyst for the liquid-phase oxidation of various alcohols with 1 atm O2 as the sole oxidant (see scheme).

    13. Synthesis of Luciferyl Coenzyme A: A Bioluminescent Substrate for Firefly Luciferase in the Presence of AMP (pages 3427–3429)

      Hugo Fraga, Rui Fontes and Joaquim C. G. Esteves da Silva

      Version of Record online: 28 APR 2005 | DOI: 10.1002/anie.200462934

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      Shedding light on luciferase: Luciferyl coenzyme A (1) was synthesized and it was found that luciferase catalyzes light production from luciferyl coenzyme A and AMP. The results of this study open perspectives for new bioanalytical methods and are strong evidence for the evolutionary relationship between firefly luciferase and acyl-CoA synthetases.

    14. Supramolecular Interactions as Determining Factors of the Geometry of Metallic Building Blocks: Tetracarboxylate Dimanganese Species (pages 3429–3432)

      Abdessamad Grirrane, Antonio Pastor, Agustín Galindo, Diego del Río, Annabella Orlandini, Carlo Mealli, Andrea Ienco, Andrea Caneschi and Javier Fernández Sanz

      Version of Record online: 25 APR 2005 | DOI: 10.1002/anie.200462965

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      Supramolecular structures are generated from manganese thiodiacetate (tda) units and substituted bipyridine (bipy) ligands (see pictures). Analysis of the π-stacking and DFT calculations for isolated binuclear units suggest that, in some cases, the geometry of the building blocks depends ultimately on the strength of noncovalent interactions between the 1D coordination polymers.

    15. Introduction of Multiple Elements of Chirality around an Aromatic Core and an Approach to Enantiomerically Pure C3-Symmetric Ligands (pages 3432–3435)

      M. Paola Castaldi, Susan E. Gibson, Matthew Rudd and Andrew J. P. White

      Version of Record online: 28 APR 2005 | DOI: 10.1002/anie.200500020

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      Chiral-base chemistry has been used to introduce multiple elements of chirality around an (arene)tricarbonylchromium(0) complex. Three stereogenic centers could be installed in one operation to synthesize a nonracemic chiral C3-symmetric triphosphine and a nonracemic chiral C3-symmetric tripyridine (see scheme).

    16. Simultaneous Observation of Green Multiphoton Upconversion and Red and Blue NLO Processes from Polymeric Terbium(III) Complexes (pages 3436–3439)

      Ka-Leung Wong, Ga-Lai Law, Wai-Ming Kwok, Wing-Tak Wong and David Lee Phillips

      Version of Record online: 28 APR 2005 | DOI: 10.1002/anie.200500031

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      Red, green, and blue emissions are observed simultaneously for an organoterbium complex that displays remarkable multiphoton upconversion when excited by a near-infrared light source. The system undergoes two nonlinear optics processes simultaneously: second and third harmonic generation (SHG: red emission; THG: blue), and four-photon upconversion (green) for excitation at λ≈1.26 (see diagram).

    17. Effective Cobalt Mediation of the Radical Polymerization of Vinyl Acetate in Suspension (pages 3439–3442)

      Antoine Debuigne, Jean-Raphaël Caille, Christophe Detrembleur and Robert Jérôme

      Version of Record online: 28 APR 2005 | DOI: 10.1002/anie.200500112

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      A poly(vinyl acetate) macroinitiator, preformed by a cobalt-mediated technique, facilitates controlled radical polymerization of vinyl acetate (VAc) in suspension in water. The molar mass increases with monomer conversion, as demonstrated by size exclusion chromatograms (see picture), and the polydispersity remains low at 1.2–1.4. Moreover, the VAc polymerization rate is much higher in suspension than in the bulk.

    18. Studies toward the Synthesis of Azadirachtin, Part 1: Total Synthesis of a Fully Functionalized ABC Ring Framework and Coupling with a Norbornene Domain (pages 3443–3447)

      K. C. Nicolaou, Pradip K. Sasmal, A. J. Roecker, Xiao-Wen Sun, Sunil Mandal and Antonella Converso

      Version of Record online: 21 APR 2005 | DOI: 10.1002/anie.200500216

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      The advanced decalin intermediate 1 was synthesized and elaborated into the potential azadirachtin precursor 2. The challenging synthesis involved several protecting-group manipulations and coupling of 1 with an appropriate norbornene unit.

    19. Studies toward the Synthesis of Azadirachtin, Part 2: Construction of Fully Functionalized ABCD Ring Frameworks and Unusual Intramolecular Reactions Induced by Close-Proximity Effects (pages 3447–3452)

      K. C. Nicolaou, Pradip K. Sasmal, Theocharis V. Koftis, Antonella Converso, Eriketi Loizidou, Florian Kaiser, A. J. Roecker, Constantinos C. Dellios, Xiao-Wen Sun and Goran Petrovic

      Version of Record online: 22 APR 2005 | DOI: 10.1002/anie.200500217

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      The remarkable antifeedant agent and insecticide, azadirachtin (1), has, to date, escaped a total synthesis. The preparation of an advanced precursor has revealed some of the inner intricacies of this uniquely crowded and highly functionalized molecular architecture.

    20. Environmentally Stable Super Water-Repellent Poly(alkylpyrrole) Films (pages 3453–3456)

      Hu Yan, Kazutomo Kurogi, Hiroyuki Mayama and Kaoru Tsujii

      Version of Record online: 28 APR 2005 | DOI: 10.1002/anie.200500266

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      Repellent films: Poly(alkylpyrrole) conductive films with a water contact angle larger than 150° are stable to temperature, organic solvents, and oils and are super water-repellent. The surface of the film is a fractal and consists of an array of perpendicular needle-like structures (see picture; inset: digital camera image of a water droplet on the film).

    21. Quadruple Deprotonation of 2-Aminophenylphosphane with a p-Block-Metal/Alkali-Metal Base (pages 3456–3459)

      Felipe García, Simon M. Humphrey, Richard A. Kowenicki, Eric J. L. McInnes, Christopher M. Pask, Mary McPartlin, Jeremy M. Rawson, Matthew L. Stead, Anthony D. Woods and Dominic S. Wright

      Version of Record online: 28 APR 2005 | DOI: 10.1002/anie.200500340

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      An unusual, paramagnetic SnII-centered cage [{[Sn(L)(NMe2)Li(thf)][Sn(L)Li(thf)3]Sn}2] (see crystal structure) is generated by the treatment of 2-aminophenylphosphane (1-PH2-2-NH2C6H4) with nBuLi and [Sn(NMe2)2]. Remarkable quadruple deprotonation of the ligand results upon use of this mixed system consisting of an alkali-metal base and a p-block dimethylamide.

    22. Selective Meta-Deprotonation of Toluene by Using Alkali-Metal-Mediated Magnesiation (pages 3459–3462)

      Prokopis C. Andrikopoulos, David R. Armstrong, David V. Graham, Eva Hevia, Alan R. Kennedy, Robert E. Mulvey, Charles T. O'Hara and Christine Talmard

      Version of Record online: 21 APR 2005 | DOI: 10.1002/anie.200500379

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      Back to bases: Conventional organometallic bases usually deprotonate toluene at the methyl position to generate resonance-stabilized benzyl anions, but using a new type of bimetallic metalation, sodium-mediated magnesiation, the thermodynamic position for deprotonation can be switched to the aromatic ring (see picture).

    23. Concise and Practical Synthesis of Latrunculin A by Ring-Closing Enyne–Yne Metathesis (pages 3462–3466)

      Alois Fürstner and Laurent Turet

      Version of Record online: 21 APR 2005 | DOI: 10.1002/anie.200500390

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      Selective actin-binding is the most prominent biochemical property of the scarce marine natural product latrunculin A (see formula). Modern metal-catalyzed C[BOND]C bond-formation reactions, including a ring-closing enyne–yne metathesis (shown in red), now open a convenient, flexible, and productive entry to this important probe molecule for chemical biology.

    24. Aminolysis Route to Monodisperse Titania Nanorods with Tunable Aspect Ratio (pages 3466–3470)

      Zhihua Zhang, Xinhua Zhong, Shuhua Liu, Dongfei Li and Mingyong Han

      Version of Record online: 25 APR 2005 | DOI: 10.1002/anie.200500410

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      High-temperature nonhydrolytic aminolysis has been developed as an approach to monodisperse titania nanocrystals by exploiting the chemical modification of reactive titanium isopropoxide with oleic acid as the chelating ligand. Its capabilities for the anisotropic growth of highly crystalline anatase titania nanocrystals (see picture) with controlled size and shape have been demonstrated.

    25. Non-C2-Symmetric, Chirally Economical, and Readily Tunable Linked-binols: Design and Application in a Direct Catalytic Asymmetric Mannich-Type Reaction (pages 3470–3474)

      Takamasa Yoshida, Hiroyuki Morimoto, Naoya Kumagai, Shigeki Matsunaga and Masakatsu Shibasaki

      Version of Record online: 28 APR 2005 | DOI: 10.1002/anie.200500425

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      An achiral unit is shown to be better than a chiral unit in promoting an asymmetric reaction. Non-C2-symmetric linked-binols 1 with one chiral 1,1′-bi-2-naphthol unit and one flexible achiral unit are employed as ligands in direct catalytic asymmetric Mannich-type reactions (see scheme; TON=turnover number). With as little as 0.01 mol % of ligand 1 a and 0.04 mol % of Et2Zn, the reaction proceeded smoothly to give the product in 98 % ee.

    26. Organometallic Chemistry Inside the Pore Walls of Mesostructured Silica Materials (pages 3475–3477)

      Véronique Dufaud, France Beauchesne and Laurent Bonneviot

      Version of Record online: 28 APR 2005 | DOI: 10.1002/anie.200500454

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      Covalently imprisoned within pore walls of mesostructured porous silica, organophosphanyl transition-metal complexes (Z, see picture) are still able to effect heterogeneous hydrogenation catalysis. The key to the synthetic protocol that leads to the well-defined metal sites lies in silylation of the material prior to extraction of the surfactant template. TEOS=tetraethylorthosilicate.

    27. Catalytic Enantioselective Total Syntheses of Bisorbicillinolide, Bisorbicillinol, and Bisorbibutenolide (pages 3478–3481)

      Ran Hong, Yonggang Chen and Li Deng

      Version of Record online: 28 APR 2005 | DOI: 10.1002/anie.200500480

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      A modified cinchona alkaloid catalyzed ketone cyanosilylation reaction is used as the stereochemistry-defining step in the total synthesis of sorbicillinol derivatives (a protected derivative is shown (PMB=para-methoxybenzyl)). These enantioselective total syntheses were accomplished in 10/11 steps and 12–19 % overall yields. Furthermore, the chemical conversion of bisorbicillinol into bisorbicillinolide provides insight into the biosynthesis of bisorbicillinolide.

    28. Total Synthesis of 2-(5,6-Epoxyisoprostane A2)phosphorylcholine and Elucidation of the Relative Configuration of the Isoprostane Moiety (pages 3481–3484)

      Hukum P. Acharya and Yuichi Kobayashi

      Version of Record online: 28 APR 2005 | DOI: 10.1002/anie.200500534

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      The two possible diastereomers of 5,6-epoxyisoprostane A2 were synthesized efficiently through aldol condensations of a substituted cyclopentenone and the corresponding epoxyaldehydes (see picture). The relative configurations of the products were assigned by comparing their 1H NMR spectra with literature data. Condensation of the epoxyisoprostane A2 with lysophosphorylcholine (lyso-PC) then furnished the title lipid.

    29. Total Synthesis of (+)-Dactylolide through an Efficient Sequential Peterson Olefination and Prins Cyclization Reaction (pages 3485–3488)

      Danielle L. Aubele, Shuangyi Wan and Paul E. Floreancig

      Version of Record online: 21 APR 2005 | DOI: 10.1002/anie.200500564

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      Key steps in the total synthesis of the macrolide natural product (+)-dactylolide (see formula) include two enantioselective vinylogous Mukaiyama reactions, fragment coupling through acetal formation, a sequential Peterson olefination/Prins cyclization reaction that proceeds under very mild conditions, and a Mislow–Evans rearrangement to effect the transposition of an allylic alcohol.

    30. Regio- and Stereoselective Approach to 1,2-Di- and 1,1,2-Trisilylethenes by Cobalt-Mediated Reaction of Silyl-Substituted Dibromomethanes with Silylmethylmagnesium Reagents (pages 3488–3490)

      Hirohisa Ohmiya, Hideki Yorimitsu and Koichiro Oshima

      Version of Record online: 28 APR 2005 | DOI: 10.1002/anie.200500576

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      Functional ethenes: Treatment of dibromo(silyl)methanes 2 a with silylmethyl Grignard reagents 1 and catalytic CoCl2 affords (E)-1,2-disilylethenes 3 a in excellent yields. Dibromodisilylmethanes 2 b undergo a similar transformation to furnish trisilylethenes 3 b with excellent stereo- and regioselectivity in the presence of a stoichiometric amount of a cobaltate reagent.

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