Angewandte Chemie International Edition

Cover image for Vol. 43 Issue 18

April 26, 2004

Volume 43, Issue 18

Pages 2311–2453

    1. Cover Picture: Cationic Gold(I) Complexes: Highly Alkynophilic Catalysts for the exo- and endo-Cyclization of Enynes (Angew. Chem. Int. Ed. 18/2004) (page 2311)

      Cristina Nieto-Oberhuber, M. Paz Muñoz, Elena Buñuel, Cristina Nevado, Diego J. Cárdenas and Antonio M. Echavarren

      Version of Record online: 22 APR 2004 | DOI: 10.1002/anie.200490051

      Lauding the rings in the realm of metal-catalyzed cyclizations, where many mechanistic shadows lie: Gold is master, particularly in reactions that proceed through metal cyclopropylcarbene intermediates. In their Communication on page 2402 ff., A. M. Echavarren and co-workers report on their quest to discover cationic gold(I) complexes that selectively promote skeletal rearrangements and other enyne cyclizations under mild conditions.

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      Excess Electron Transfer Driven DNA Does Not Depend on the Transfer Direction (page 2321)

      Clemens Haas, Katja Kräling, Michaela Cichon, Nicole Rahe and Thomas Carell

      Version of Record online: 22 APR 2004 | DOI: 10.1002/anie.200490053

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      Denitrogenation of Transportation Fuels by Zeolites at Ambient Temperature and Pressure (page 2321)

      Arturo J. Hernández-Maldonado and Ralph T. Yang

      Version of Record online: 22 APR 2004 | DOI: 10.1002/anie.200490055

    4. Tateshina Conference on Organic Chemistry (pages 2322–2323)

      Junzo Otera

      Version of Record online: 22 APR 2004 | DOI: 10.1002/anie.200420083

    5. Molecular Peapods as Supramolecular Carbon Allotropes (pages 2326–2329)

      Otto Vostrowsky and Andreas Hirsch

      Version of Record online: 22 APR 2004 | DOI: 10.1002/anie.200301749

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      A high-tech alternative to diamond and graphite: Supramolecular carbon allotropes are formed when single-walled carbon nanotubes are filled with C60 molecules. Similar “molecular peapods“ are also obtained by insertion of endohedral fullerenes and metallocenes into carbon nanotubes. Supramolecular nanotubes built up from porphyrins can also encapsulate C60 peas.

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      Chemical Safety in a Vulnerable World—A Manifesto (pages 2330–2332)

      Carl Djerassi

      Version of Record online: 22 APR 2004 | DOI: 10.1002/anie.200330079

      An unconventional suggestion to promote an understanding in industrialized countries for the problems of developing countries, especially in terms of handling chemicals in a responsible and environmentally aware manner, is proposed in this Essay: A Chemical Social Services Corps consisting of PhD students, postdoctoral researchers, and advanced graduate students from industrialized countries collaborating with colleagues in less-developed countries.

    7. Functional Porous Coordination Polymers (pages 2334–2375)

      Susumu Kitagawa, Ryo Kitaura and Shin-ichiro Noro

      Version of Record online: 22 APR 2004 | DOI: 10.1002/anie.200300610

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      Nanospace laboratories: The chemistry of the coordination polymers (see picture) has developed extensively, affording new porous compounds and realizing not only applications, such as separation, storage, and heterogeneous catalysis but also unique nanosized vessels for low-dimensional ordered arrays. This Review summarizes the current state of research on the functionalization of porous coordination polymers.

    8. Stereoisomeric Discrimination in DNA Compaction (pages 2378–2381)

      Anatoly A. Zinchenko, Vladimir G. Sergeyev, Victor A. Kabanov, Shizuaki Murata and Kenichi Yoshikawa

      Version of Record online: 22 APR 2004 | DOI: 10.1002/anie.200453774

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      The conformational change of T4 DNA from an elongated coil into a compact globule in the presence of the SS, RR, and meso stereoisomeric dications shown was monitored by fluorescence microscopy. The SS and RR isomers were found to have very different compaction activities but similar DNA-binding potentials. Thus, the DNA compaction process itself appears to show chiral discrimination.

    9. Highly Enantioselective Phase-Transfer-Catalytic Alkylation of 2-Phenyl-2-oxazoline-4-carboxylic Acid tert-Butyl Ester for the Asymmetric Synthesis of α-Alkyl Serines (pages 2382–2385)

      Sang-sup Jew, Yeon-Ju Lee, Jihye Lee, Myoung Joo Kang, Byeong-Seon Jeong, Jeong-Hee Lee, Mi-Sook Yoo, Mi-Jeong Kim, Sea-hoon Choi, Jin-Mo Ku and Hyeung-geun Park

      Version of Record online: 22 APR 2004 | DOI: 10.1002/anie.200353496

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      A facile synthesis of chiral α-alkyl serines 3 involves the asymmetric alkylation of substrates 1 with alkyl halides (RX) under phase-transfer catalysis (PTC), followed by acidic hydrolysis of the alkylation products 2. The phenyl oxazoline moiety enhances the acidity of the α proton of the ester and is an excellent protecting group for both the amino and hydroxy functions of the serine ester.

    10. Self-Assembly of Two Distinct Supramolecular Motifs in a Single Crystalline Framework (pages 2385–2388)

      Sara R. Halper and Seth M. Cohen

      Version of Record online: 22 APR 2004 | DOI: 10.1002/anie.200353520

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      Copper(II) complexes based on dipyrromethene ligands self-assemble into molecular hexagons (green) and double-helical coordination polymers (blue and yellow) within the same crystalline lattice organized by the self-segregation of CF3 groups.

    11. Fluorescent Probes for Hydrogen Peroxide Based on a Non-Oxidative Mechanism (pages 2389–2391)

      Hatsuo Maeda, Yuka Fukuyasu, Shoko Yoshida, Masako Fukuda, Kanako Saeki, Hiromi Matsuno, Yuji Yamauchi, Kenji Yoshida, Kazumasa Hirata and Kazuhisa Miyamoto

      Version of Record online: 22 APR 2004 | DOI: 10.1002/anie.200452381

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      Highly selective detection of H2O2 through a non-oxidative mechanism has been achieved by desulfonylation of 1 to the corresponding fluorescein. This approach has been used for the intracellular formation of H2O2 in algal cells by using the acetyl derivatives of 1 as fluorescent probes.

    12. Light-Driven Machine Prototypes Based on Dissociative Excited States: Photoinduced Decoordination and Thermal Recoordination of a Ring in a Ruthenium(II)-Containing [2]Catenane (pages 2392–2395)

      Pierre Mobian, Jean-Marc Kern and Jean-Pierre Sauvage

      Version of Record online: 22 APR 2004 | DOI: 10.1002/anie.200352522

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      A marked difference is observed in the photochemistry of [2]catenanes containing a complexed ruthenium(II) center. The photochemical reactions result in a decoordination process and large amplitude motions through the formation of a strongly dissociative ligand-field excited state (see example, L=CH3CN or Cl), with the rate dependent on the ring size. The back reaction is performed thermally.

    13. Magnetic Relaxation Switch Immunosensors Detect Enantiomeric Impurities (pages 2395–2399)

      Andrew Tsourkas, Oliver Hofstetter, Heike Hofstetter, Ralph Weissleder and Lee Josephson

      Version of Record online: 22 APR 2004 | DOI: 10.1002/anie.200352998

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      Purity check: The self-assembly of magnetic nanoparticle sensors in the presence of stereoselective antibodies causes a decrease in the T2 relaxation time of surrounding protons. The introduction of enantiomeric impurities disrupts the antibody/magnetic-sensor binding and increases the T2 relaxation time, which can be monitored by magnetic resonance imaging (see picture).

    14. Hydrogen-Bonded Helices in the Layered Aluminophosphate (C2H8N)2[Al2(HPO4)(PO4)2] (pages 2399–2402)

      Yu Song, Jihong Yu, Yi Li, Guanghua Li and Ruren Xu

      Version of Record online: 22 APR 2004 | DOI: 10.1002/anie.200353118

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      Solvothermal combinatorial chemistry affords the layered aluminophosphate (C2H8N)2[Al2(HPO4)(PO4)2]. The macroanionic layer is based on alternating AlO4 and PO4 tetrahedra linked through vertex oxygen atoms to form 4.8-net sheets, stacked in an ABCD sequence along the c axis. The (CH3)2NH2+ ions between the inorganic layers interact with the terminal P[DOUBLE BOND]O groups to form left- and right-handed helices (see picture) along the b axis.

    15. Cationic Gold(I) Complexes: Highly Alkynophilic Catalysts for the exo- and endo-Cyclization of Enynes (pages 2402–2406)

      Cristina Nieto-Oberhuber, M. Paz Muñoz, Elena Buñuel, Cristina Nevado, Diego J. Cárdenas and Antonio M. Echavarren

      Version of Record online: 16 FEB 2004 | DOI: 10.1002/anie.200353207

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      As good as gold: Alkynophilic cationic gold(I) complexes are very active catalysts for reactions of enynes that proceed exclusively through cyclopropyl carbene complexes as intermediates (see scheme). With such catalysts, the first examples of endocyclic skeletal rearrangements under mild conditions have been observed.

    16. Two-Color Two-Laser DNA Damaging (pages 2406–2409)

      Kiyohiko Kawai, Xichen Cai, Akira Sugimoto, Sachiko Tojo, Mamoru Fujitsuka and Tetsuro Majima

      Version of Record online: 22 APR 2004 | DOI: 10.1002/anie.200353318

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      A combination of two-color pulses allows a high DNA-damaging efficiency. The first laser pulse is applied to produce Sens.− and DNA.+, and the second laser pulse causes the ejection of an electron from Sens.−, thus making the reaction irreversible. Sens=photosensitizer.

    17. A Mixed-Valence Tin–Oxygen Cluster Containing Six Peripheral Ferrocene Units (pages 2409–2411)

      Guo-Li Zheng, Jian-Fang Ma, Zhong-Min Su, Li-Kai Yan, Jin Yang, Yin-Yan Li and Jing-Fu Liu

      Version of Record online: 22 APR 2004 | DOI: 10.1002/anie.200353359

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      Dealkylation ofnBu2SnO with 1,1′-ferrocenedicarboxylic acid gives a mixed-valence Snequation image-Snequation imageO4 cluster. The cubic tin–oxygen core is connected to six ferrocene units through twelve carboxylate bridges in such a way that the iron centers occupy the vertices of a regular octahedron (see structure: Fe Red; C gray; O green; Sn brown).

    18. Origin of Diastereoselection in the Hydrosilylation of Chiral N-Acyliminium Intermediates Derived from Pyroglutamic Acid (pages 2412–2415)

      Makoto Oba, Shinichi Koguchi, Kozaburo Nishiyama, Daisuke Kaneno and Shuji Tomoda

      Version of Record online: 22 APR 2004 | DOI: 10.1002/anie.200353366

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      Explaining an “about-face” in selectivity: Theoretical investigations suggest that steric repulsion (in the top reaction) and attractive interactions between the silicon nucleophile and the side chain of the cyclic iminium intermediate (in the bottom reaction) are responsible for the diastereoselectivities in hydrosilylation of these chiral iminium intermediates.

    19. Desulfurization of Flue Gas: SO2 Absorption by an Ionic Liquid (pages 2415–2417)

      Weize Wu, Buxing Han, Haixiang Gao, Zhimin Liu, Tao Jiang and Jun Huang

      Version of Record online: 22 APR 2004 | DOI: 10.1002/anie.200353437

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      The ionic liquid, (IL) 1,1,3,3-tetramethylguanidinium lactate, can absorb SO2 from simulated flue gas effectively under ambient conditions (see scheme). Absorbed SO2 can be desorbed under vacuum or by heating, and the IL can be reused. This absorption method might be used for cleaning gases that contain SO2.

    20. Direct Evidence for Oxygen-Atom Exchange between Nonheme Oxoiron(IV) Complexes and Isotopically Labeled Water (pages 2417–2420)

      Mi Sook Seo, Jun-Hee In, Sun Ok Kim, Na Young Oh, Jongki Hong, Jinheung Kim, Lawrence Que Jr. and Wonwoo Nam

      Version of Record online: 2 APR 2004 | DOI: 10.1002/anie.200353497

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      Rates of exchange: Evidence that nonheme oxoiron(IV) complexes exchange their oxygen atoms with H218O was obtained for the first time, by monitoring electrospray ionization mass spectral changes of the oxoiron(IV) species. The oxygen-atom exchange depended markedly on the amounts of H218O present and reaction temperatures but not on the presence of trans axial ligand (see scheme).

    21. Synthesis of β-Hydroxyaldehydes with Stereogenic Quaternary Carbon Centers by Direct Organocatalytic Asymmetric Aldol Reactions (pages 2420–2423)

      Nobuyuki Mase, Fujie Tanaka and Carlos F. Barbas III

      Version of Record online: 22 APR 2004 | DOI: 10.1002/anie.200353546

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      A fluorescence detection system was used to identify effective chiral-amine/acid combinations as bifunctional catalysts for asymmetric direct catalytic aldol reactions of α,α-dialkyl aldehydes with aryl aldehydes (see scheme). With the optimized catalyst system, the reaction of isobutyraldehyde with p-nitrobenzaldehyde provided the α,α-dimethyl aldol product in 92 % yield with 96 % ee. R1, R2=alkyl; X=NO2, CN, Br, Cl, OMe, H.

    22. Cascade Carbonylation Methods Leading to β-Diketones and β-Functionalized δ-Diketones (pages 2423–2425)

      Katsukiyo Miura, Mami Tojino, Naoki Fujisawa, Akira Hosomi and Ilhyong Ryu

      Version of Record online: 22 APR 2004 | DOI: 10.1002/anie.200453702

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      A radical combination: An intermolecular cascade reaction involving alkyl halides, CO, electron-deficient alkenes, and stannyl enolates proceeds smoothly by a radical chain pathway to give four-component coupling products in good to high yields (see scheme). A series of 1,5-diketones with a substituent at the 3-position was prepared by this method.

    23. A Highly Effective Phosphoramidite Ligand for Asymmetric Allylic Substitution (pages 2426–2428)

      Karine Tissot-Croset, Damien Polet and Alexandre Alexakis

      Version of Record online: 22 APR 2004 | DOI: 10.1002/anie.200353744

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      Very high enantioselectivity has been achieved both in the copper-catalyzed alkylation of allylic substrates by Grignard and organozinc reagents and in the iridium-catalyzed amination of cinnamyl carbonate by employing a very efficient phosphoramidite ligand (see scheme).

    24. Nickel-Catalyzed Cross-Coupling of Aryl Grignard Reagents with Aromatic Alkyl Ethers: An Efficient Synthesis of Unsymmetrical Biaryls (pages 2428–2432)

      John W. Dankwardt

      Version of Record online: 22 APR 2004 | DOI: 10.1002/anie.200453765

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      New substrates for biaryl synthesis: aromatic ethers undergo nickel-catalyzed cross-coupling with aryl Grignard reagents to give unsymmetrical biaryls in excellent yields (see scheme). Both the nature of the nickel catalyst and the choice of solvent are crucial for reaching high levels of conversion.

    25. Pseudodynamic Combinatorial Libraries: A Receptor-Assisted Approach for Drug Discovery (pages 2432–2436)

      Andrew D. Corbett, Jeremy D. Cheeseman, Romas J. Kazlauskas and James L. Gleason

      Version of Record online: 31 MAR 2004 | DOI: 10.1002/anie.200453769

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      Enzyme protection: An irreversible solid-phase, aqueous peptide coupling resulted in the formation of a library of eight dipeptides, while an irreversible protease-catalyzed hydrolysis destroyed them. Those dipeptides that bound to carbonic anhydrase were protected from destructions. Six cycles of active ester addition produced only the best-binding dipeptide (>100:1) in 29 % yield.

    26. Arylnaphthalene Lignans through Pd-Catalyzed [2+2+2] Cocyclization of Arynes and Diynes: Total Synthesis of Taiwanins C and E (pages 2436–2440)

      Yoshihiro Sato, Takayuki Tamura and Miwako Mori

      Version of Record online: 22 APR 2004 | DOI: 10.1002/anie.200453809

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      3 in 1: A novel method for the synthesis of the arylnaphthalene skeleton by the Pd0-catalyzed [2+2+2] cocyclization of diynes and arynes involves three C[BOND]C bond-forming reactions in a single step (see scheme; R=CON(OCH3)CH3, dba=dibenzylideneacetone). This cocyclization was the key step in the total synthesis of the arylnaphthalene lignans taiwanins C and E.

    27. Synthesis of Amines from Imines in the Coordination Sphere of Silicon—Surprising Photo-Rearrangement of Hexacoordinate Organosilanes (pages 2441–2444)

      Jörg Wagler, Thomas Doert and Gerhard Roewer

      Version of Record online: 22 APR 2004 | DOI: 10.1002/anie.200353267

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      There's room at the top: In the coordination sphere of hexacoordinate organosilanes with O- and N-donor ligands (see picture) the Si[BOND]C bond is elongated and activated. This effect is so strongly pronounced that cleavage of one Si[BOND]C bond and migration of this organo substituent takes place upon irradiation with UV light to give a pentacoordinate silicon complex.

    28. Metallocene-Catalyzed C7-Linkage in the Hydrooligomerization of Norbornene by σ-Bond Metathesis: Insight into the Microstructure of Polynorbornene (pages 2444–2446)

      Christos Karafilidis, Holger Hermann, Anna Rufiñska, Barbara Gabor, Richard J. Mynott, Georg Breitenbruch, Claudia Weidenthaler, Jörg Rust, Werner Joppek, Maurice S. Brookhart, Walter Thiel and Gerhard Fink

      Version of Record online: 22 APR 2004 | DOI: 10.1002/anie.200353454

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      An unusual linkage: The zirconocene-catalyzed hydrooligomerization of norbornene proceeds by σ-bond metathesis to form a 2-exo,7′-syn linkage (as evident in the pentamer shown). The oligomers were characterized by gas chromatography, NMR spectroscopy , X-ray crystallography, and DFT calculations.

    29. Highly Modular Construction of Differently Substituted Dihydrodibenzo[a,c]cycloheptenes: Fast and Efficient Access to Derivatives of 2,2′-Cyclo-7,8′-neolignans (pages 2446–2449)

      Beate Kramer and Siegfried R. Waldvogel

      Version of Record online: 22 APR 2004 | DOI: 10.1002/anie.200353597

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      Tying the knot: Two aryl units are linked in a one-pot reaction. In a subsequent MoCl5-mediated oxidative cyclization dihydrodibenzo[a,c]cycloheptenes are provided in excellent yields and an unusually broad range of functional groups are tolerated (see scheme).

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      Preview: Angew. Chem. Int. Ed. 18/2004 (page 2453)

      Version of Record online: 22 APR 2004 | DOI: 10.1002/anie.200490054