Angewandte Chemie International Edition

Cover image for Vol. 42 Issue 27

July 14, 2003

Volume 42, Issue 27

Pages 3053–3187

    1. Cover Picture: A Giant Conjugated Molecular Ring (Angew. Chem. Int. Ed. 27/2003) (page 3053)

      Marcel Mayor and Claudia Didschies

      Version of Record online: 10 JUL 2003 | DOI: 10.1002/anie.200390514

      As a circular path for electrons a giant macrocycle with a periphery consisting of exclusively conjugation-active units has been designed. With a diameter of 12 nm it is probably the largest synthesized, shape-persistent, and monodisperse cyclic structure to date. In addition, the front wheel of a bicycle is shown, the 16-fold symmetry of which inspired the design of the molecule. For more information on this molecule see the Communication by M. Mayor and C. Didschies on page 3176 ff.

    2. Web Site: Evolution of the Ribosome (page 3065)

      Burkhard Luy

      Version of Record online: 10 JUL 2003 | DOI: 10.1002/anie.200390517

    3. Stephacidin B—A New Stage of Complexity within Prenylated Indole Alkaloids from Fungi (pages 3068–3071)

      Franz von Nussbaum

      Version of Record online: 10 JUL 2003 | DOI: 10.1002/anie.200301646

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      With its 15 rings, stephacidin B (see structure) is one of the most complex indole alkaloids to be isolated from fungi. The pseudosymmetric structure indicates that a new type of dimerization takes place at a late stage of the biosynthesis.

    4. Increasing the Local Concentration of Drugs by Hydrogel Formation (pages 3072–3075)

      Joerg C. Tiller

      Version of Record online: 10 JUL 2003 | DOI: 10.1002/anie.200301647

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      Drugs that gel: The first hydrogel-forming drug, a pyrene-derivatized form of the antibiotic vancomycin (see structure), exhibits an 11-fold higher antimicrobial activity than vancomycin itself. A possible mechanism for this effect and its influence on future drug design are discussed.

    5. Chemistry and Biology of Biosynthetic Diels–Alder Reactions (pages 3078–3115)

      Emily M. Stocking and Robert M. Williams

      Version of Record online: 10 JUL 2003 | DOI: 10.1002/anie.200200534

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      Do they or don't they? A Diels–Alder cycloaddition has been assumed to occur in the biosynthesis of numerous natural products, for example, lovastatin (see scheme). The existence of enzymes that catalyze these reactions (Diels–Alderases) was until recently not know for certainty, even when biosynthetic investigations and the biommetic total syntheses in some cases suggested it to be so.

    6. Tethered Neuraminidase Inhibitors That Bind an Influenza Virus: A First Step Towards a Diagnostic Method for Influenza (pages 3118–3121)

      Jennifer L. McKimm-Breschkin, Peter M. Colman, Betty Jin, Guy Y. Krippner, Mandy McDonald, Phillip A. Reece, Simon P. Tucker, Lynne Waddington, Keith G. Watson and Wen-Yang Wu

      Version of Record online: 10 JUL 2003 | DOI: 10.1002/anie.200250402

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      Catching flu: The influenza virus neuraminidase inhibitor zanamivir (red) is functionalized at the 7-position to give derivatives that retain a high affinity for the enzyme. When conjugated to biotin (green) or onto microspheres, such derivatives can be used to capture or aggregate influenza virus particles.

    7. Self-Assembled Monolayers That Transduce Enzymatic Activities to Electrical Signals (pages 3121–3124)

      Woon-Seok Yeo and Milan Mrksich

      Version of Record online: 10 JUL 2003 | DOI: 10.1002/anie.200250862

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      A dynamic substrate that transduces a biological activity into an electrical signal has been developed (see scheme). The enzymatic conversion of a redox-inactive substrate presented at a self-assembled monolayer produced a redox-active product that is monitored electrochemically in real time.

    8. Functionality Propagation by Alkylative Oxidation of Cross-Conjugated Cycloheptadienyl Sulfones (pages 3124–3131)

      Eduardo Torres, Yuzhong Chen, In Chul Kim and P. L. Fuchs

      Version of Record online: 10 JUL 2003 | DOI: 10.1002/anie.200350955

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      Getting the most out of sulfur. Enantiopure epoxyvinyl sulfone 1 is transformed to syn- and anti-dienyl sulfones 2 and 3, respectively, by means of a nucleophilic methylation/sulfenylation/directed elimination reaction sequence. Compound 2 has been converted into termini-differentiated seven-carbon polypropionate segments found in five biologically significant natural products.

    9. Asymmetric Azidoselenenylation of Alkenes: A Key Step for the Synthesis of Enantiomerically Enriched Nitrogen-Containing Compounds (pages 3131–3133)

      Marcello Tiecco, Lorenzo Testaferri, Claudio Santi, Cristina Tomassini, Francesca Marini, Luana Bagnoli and Andrea Temperini

      Version of Record online: 10 JUL 2003 | DOI: 10.1002/anie.200351229

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      Chiral, nonracemic azidoselenides such as 2 are useful intermediates for the synthesis of enantiomerically enriched nitrogen-containing compounds (e.g. 3). The asymmetric electrophilic azidoselenenylation of a variety of alkenes with the sulfur-containing chiral selenenyl triflate 1 and sodium azide occurred with high facial selectivity to provide an array of azidoselenides, which were further elaborated.

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      Trifluoroacetamides from Amino Alcohols as Nucleophilic Trifluoromethylating Reagents (pages 3133–3136)

      Jérôme Joubert, Solveig Roussel, Carole Christophe, Thierry Billard, Bernard R. Langlois and Thierry Vidal

      Version of Record online: 10 JUL 2003 | DOI: 10.1002/anie.200351301

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      Both non-enolizable and enolizable carbonyl compounds underwent nucleophilic trifluoromethylation by a new family of cheap and efficient trifluoroacetamide reagents derived from vic-amino alcohols (see picture). From an ecological and an economic viewpoint these represent a promising alternative to other known trifluoromethylation reagents.

    11. The Inside Story of Fullerene Anions: A 3He NMR Aromaticity Probe (pages 3136–3139)

      Tamar Sternfeld, Martin Saunders, R. James Cross and Mordecai Rabinovitz

      Version of Record online: 10 JUL 2003 | DOI: 10.1002/anie.200351429

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      Fullerene anions with helium atoms contained inside the cage exhibit degrees of aromaticity that can be predicted through the measurement of 3He chemical shifts (see picture). These chemical shifts help to demonstrate that the magnetic properties of fullerenes, and their anions, are not simply related to the number of carbon atoms or the number of electrons in the π system.

    12. Bio-Inspired Optically Controlled Ultrafast Molecular AND Gate (pages 3139–3143)

      Mikael Andersson, Louise E. Sinks, Ryan T. Hayes, Yongyu Zhao and Michael R. Wasielewski

      Version of Record online: 10 JUL 2003 | DOI: 10.1002/anie.200351488

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      A fast switch: A covalent molecular tetrad (see picture), consisting of two electron donor/acceptor pairs acts as a high-speed molecular AND gate when it is sequentially excited using laser pulses having two different wavelengths. This system of using two sequential photodriven electron transfers is analogous to photosystems I and II in green plants which act in series to separate charge for long periods of time.

    13. Enantioselective Synthesis of Cyanohydrin O-Phosphates Mediated by the Bifunctional Catalyst Binolam–AlCl (pages 3143–3146)

      Alejandro Baeza, Jesús Casas, Carmen Nájera, José M. Sansano and José M. Saá

      Version of Record online: 10 JUL 2003 | DOI: 10.1002/anie.200351552

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      (R)- and (S)-binolam–AlCl complexes act as bifunctional catalysts to mediate the enantioselective cyanophosphorylation of aldehydes at room temperature. The resulting chiral cyanohydrin O-phosphates can be reduced to β-aminoalcohols or, when suitably substituted, can be transformed into γ-cyanoallylic alcohols through palladium-catalyzed allylic substitution, without loss of enantiomeric excess (see scheme).

    14. Cubic Mesoporous Silica with Large Controllable Entrance Sizes and Advanced Adsorption Properties (pages 3146–3150)

      Jie Fan, Chengzhong Yu, Feng Gao, Jie Lei, Bozhi Tian, Limin Wang, Qian Luo, Bo Tu, Wuzong Zhou and Dongyuan Zhao

      Version of Record online: 10 JUL 2003 | DOI: 10.1002/anie.200351027

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      Large cavities (≈10–12.3 nm) of cubic (Fm-3m) mesoporous silica without intergrowth are synthesized in the presence of block copolymer templates. The entrance sizes of these cavities can be adjusted in the range of ≈4–9 nm as confirmed by nitrogen sorption studies and an examination of the negative gold replicas. The 3D open mesostructures facilitate the transportation of biomolecules (see picture), as well as the replication of a large-pore (9 nm) cubic mesoporous carbon.

    15. Acetylcholine Recognition by a Deep, Biomimetic Pocket (pages 3150–3153)

      Fraser Hof, Laurent Trembleau, Elke Christine Ullrich and Julius Rebek, Jr.

      Version of Record online: 10 JUL 2003 | DOI: 10.1002/anie.200351174

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      Four negative charges at the entrance of a deep pocket, lined with aromatic residues are the features of a synthetic receptor which shows high affinity for acetylcholine (see picture) and choline in water. The size, shape, and charge recognition elements featured in the natural enzyme acetylcholinesterase are reproduced by the synthetic receptor.

    16. Semi-Automated Synthesis and Screening of a Large Library of Degradable Cationic Polymers for Gene Delivery (pages 3153–3158)

      Daniel G. Anderson, David M. Lynn and Robert Langer

      Version of Record online: 10 JUL 2003 | DOI: 10.1002/anie.200351244

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      Higher delivery efficiency than conventional nonviral systems (such as poly(ethyleneimine)) have been identified in 46 polymers through cell-based screening of a large, 2350-member library by a high-throughput, semi-automated process. The transfection potential of the polymers was assessed by testing their ability to deliver luciferase expressing plasmid and green fluorescent protein plasmid (see picture) to a monkey kidney fibroblast cell line.

    17. Preparation of Neutral [60]Fullerene-Based [2]Catenanes and [2]Rotaxanes Bearing an Electron-Deficient Aromatic Diimide Moiety (pages 3158–3162)

      Yosuke Nakamura, Satoshi Minami, Kazuki Iizuka and Jun Nishimura

      Version of Record online: 10 JUL 2003 | DOI: 10.1002/anie.200351411

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      Crowning glory: An unprecedented [2]catenane that exhibits a donor–acceptor–donor–acceptor stacking motif was obtained through intramolecular Bingel reactions of [60]fullerene monoadducts that bear a naphthalenetetracarboxylic diimide moiety, in the presence of 1,5-dinaphtho[38]crown-10 ether at −78 °C (see scheme; DBU=1,8-diazabicyclo[5.4.0]undec-7-ene).

    18. A Highly Configurationally Stable [4]Heterohelicenium Cation (pages 3162–3166)

      Christelle Herse, Delphine Bas, Frederik C. Krebs, Thomas Bürgi, Jacques Weber, Tomasz Wesolowski, Bo W. Laursen and Jérôme Lacour

      Version of Record online: 10 JUL 2003 | DOI: 10.1002/anie.200351443

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      A [4](hetero)helicenium cation was resolved using the hexacoordinated phosphorus-containing binphat anion (see picture: N, blue; O, red; C, gray). Its absolute configuration was determined by vibrational circular dichroism spectroscopy. The barrier of interconversion of its enantiomers is higher than that of [6]helicene.

    19. A Self-Assembled Tetracopper Triple-Stranded Helicate: Towards the Controlled Synthesis of Finite One-Dimensional Magnetic Chains (pages 3166–3169)

      Craig J. Matthews, Stuart T. Onions, Gérald Morata, Lisa J. Davis, Sarah L. Heath and Daniel J. Price

      Version of Record online: 23 JUN 2003 | DOI: 10.1002/anie.200351634

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      Spiraling into control: A finite linear arrangement of four magnetically coupled copper(II) centers has been generated within a triple-stranded helical motif that was formed through a strict self-assembly process between a single octadentate ligand and CuII ions (see picture). This approach opens the way to constructing finite one-dimensional magnetic chains in a controlled manner.

    20. Influence of Cyclodextrin Molecules on the Synthesis and the Thermoresponsive Solution Behavior of N-Isopropylacrylamide Copolymers with Adamantyl Groups in the Side-Chains (pages 3171–3173)

      Helmut Ritter, Oleg Sadowski and Elmar Tepper

      Version of Record online: 10 JUL 2003 | DOI: 10.1002/anie.200250814

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      Parting the clouds: A supramolecular recognition reaction of cyclodexdrins with polymers—adamantyl derivative N-isopropylacrylamide copolymers—with inverse phase behavior is described. The turbidity of the polymer solutions depends upon the cyclodextrin concentration. Competition reactions with potassium-1-adamantylcarboxylate show that the inclusion-complex formation is reversible (see scheme).

    21. N-Glycosyl Amides: Removal of the Anomeric Protecting Group and Conversion into Glycosyl Donors (pages 3174–3176)

      Norbert Pleuss and Horst Kunz

      Version of Record online: 10 JUL 2003 | DOI: 10.1002/anie.200351351

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      Reactivity upon demand: Because of their stability towards acids, bases, and many oxidizing and reducing agents, N-glycosyl amides 1 (see scheme) can be used as anomerically protected carbohydrates. The amide function can be cleaved under mild conditions with Ph3P/CBr4 and the carbohydrate activated for the synthesis of N- and O-glycosides 2. PG=protecting group.

    22. A Giant Conjugated Molecular Ring (pages 3176–3179)

      Marcel Mayor and Claudia Didschies

      Version of Record online: 10 JUL 2003 | DOI: 10.1002/anie.200250763

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      Ever increasing circles? The giant cycle 1 has a diameter of 12 nm making it the largest, shape persistent and monodisperse cyclic molecular structure designed and synthesized to date. A modular approach consisting of a series of subsequent dimerization steps made 1 accessible.

    23. Blue, Green, and Red Upconversion Emission from Lanthanide-Doped LuPO4 and YbPO4 Nanocrystals in a Transparent Colloidal Solution (pages 3179–3182)

      Stephan Heer, Olaf Lehmann, Markus Haase and Hans-Ulrich Güdel

      Version of Record online: 10 JUL 2003 | DOI: 10.1002/anie.200351091

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      Light converter: The emission of visible light (Vis) upon excitation in the near-infrared (NIR) has been observed for the first time in a transparent solution. Excitation at 975 nm (marked red in the picture) of optically clear colloidal solutions of LuPO4:Yb3+, Tm3+, and YbPO4:Er3+ nanocrystals in chloroform leads to visible upconversion luminescence in the blue, green, or red spectral regions.

    24. Preview: Angew. Chem. Int. Ed. 27/2003 (page 3187)

      Version of Record online: 10 JUL 2003 | DOI: 10.1002/anie.200390520

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