Angewandte Chemie International Edition

Cover image for Vol. 42 Issue 47

December 8, 2003

Volume 42, Issue 47

Pages 5777–5907

    1. Cover Picture: Breaking Down Barriers: The Liaison Between Sigmatropic Shifts, Electrocyclic Reactions, and Three-Center Cations (Angew. Chem. Int. Ed. 47/2003) (page 5777)

      Roald Hoffmann and Dean J. Tantillo

      Article first published online: 8 DEC 2003 | DOI: 10.1002/anie.200390626

      Orbital-symmetry control was initially explored almost 40 years ago. However, new principles can still be discovered: There is a striking congruence in the geometries of the transition states (not reactants and products) of electrocyclic reactions and sigmatropic shifts related by a proton. A link between these reactions and three-center hydride transfers in a cation is forged, and the idea of a transition-state proton affinity is reintroduced by R. Hoffmann and D. J. Tantillo in their Communication on page 5877 ff.

    2. News: Angew. Chem. Int. Ed. 47/2003 (page 5790)

      Article first published online: 8 DEC 2003 | DOI: 10.1002/anie.200390628

    3. Synthetic Routes towards Enantiomerically Pure β-Amino Acids (pages 5794–5795)

      Norbert Sewald

      Article first published online: 8 DEC 2003 | DOI: 10.1002/anie.200301692

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      Unusual representatives of the synthetically attractive β-amino acids can be accessed by two novel synthetic routes. The synthesis of β2,3- and β2,3,3-amino acids (A and B, respectively) involves a diastereoselective 1,3-dipolar cycloaddition, whereas β2-amino acids C are obtained by enantioselective CuI-catalyzed conjugate addition of dialkyl zinc compounds to nitroalkenes.

    4. Functional Hybrid Devices of Proteins and Inorganic Nanoparticles (pages 5796–5800)

      Christof M. Niemeyer

      Article first published online: 8 DEC 2003 | DOI: 10.1002/anie.200301703

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      The combination of inorganic nanoparticles with biological functionality, such as the ATP-triggered release of CdS nanoparticles from inclusion complexes with chaperonins (see schematic illustration), opens up innovative approaches to novel hybrid devices applicable in biomedical sensing and the fabrication of advanced functional materials.

    5. Domains and Rafts in Lipid Membranes (pages 5802–5827)

      Wolfgang H. Binder, Veronique Barragan and Fredric M. Menger

      Article first published online: 8 DEC 2003 | DOI: 10.1002/anie.200300586

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      Barriers with function: Domains and rafts play an important role in the amazing behavior of lipid membranes. The phase separation of mixed lipid membranes (see scheme) generates a new hierarchy of membrane organization within lipid and polymer vesicles. The biological impact of this structuring as well as the chemical background is described.

    6. Staudinger Ligation: A New Immobilization Strategy for the Preparation of Small-Molecule Arrays (pages 5830–5834)

      Maja Köhn, Ron Wacker, Carsten Peters, Hendrik Schröder, Laurent Soulère, Rolf Breinbauer, Christof M. Niemeyer and Herbert Waldmann

      Article first published online: 20 OCT 2003 | DOI: 10.1002/anie.200352877

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      Chemoselective coupling: The Staudinger ligation between azide-functionalized small molecules and a phosphane-modified glass surface offers a new immobilization strategy for the preparation of drug arrays through the formation of a thermodynamically stable amide (see scheme).

    7. Electric Current through a Molecular Rod—Relevance of the Position of the Anchor Groups (pages 5834–5838)

      Marcel Mayor, Heiko B. Weber, Joachim Reichert, Mark Elbing, Carsten von Hänisch, Detlef Beckmann and Matthias Fischer

      Article first published online: 8 DEC 2003 | DOI: 10.1002/anie.200352179

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      The electronic resistance of an electrode-molecule-electrode device strongly depends on the relative position of the anchor group in the molecular structure. The molecular rod, immobilized through two sulfur groups in the meta position on a pair of electrodes (see picture), displays a considerably increased resistance compared to the rod with the sulfur groups in the para position.

    8. (−)-Daucic Acid: Revision of Configuration, Synthesis, and Biosynthetic Implications (pages 5838–5843)

      Frieder W. Lichtenthaler, Katsumi Nakamura and Jürgen Klotz

      Article first published online: 18 NOV 2003 | DOI: 10.1002/anie.200352718

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      The synthesis of dihydropyrans with the D-xylo (1), D-ribo, L-arabino, and D-lyxo (2) configuration by one-carbon-atom homologation of D-mannose or D-galactose, terminal oxidation, and directed β elimination revealed (−)-daucic acid isolated from carrots to be 2, rather than 1 as previously thought. The identical configuration of 2 and KDO 8-P (3) and available biosynthetic information about chelidonic acid (4) suggest a KDO 8-P based pathway for the generation of 2 and 4 in plants.

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      Binary Tellurium(IV) Azides: Te(N3)4 and [Te(N3)5] (pages 5843–5846)

      Thomas M. Klapötke, Burkhard Krumm, Peter Mayer and Ingo Schwab

      Article first published online: 8 DEC 2003 | DOI: 10.1002/anie.200352656

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      Very sensitive materials: Tellurium tetraazide, Te(N3)4, was prepared directly from TeF4 and Me3SiN3 as an extremely sensitive solid; azidation of a pentafluorotellurate(IV) anion gave the pentaazidotellurate(IV) anion. The crystal structure of the pyridinium salt [pyH][Te(N3)5] consists of [Te(N3)5] units, considerably distorted from ideal square-pyramidal symmetry, that are linked through Te⋅⋅⋅N interactions (see picture).

    10. You have free access to this content
      Polyazide Chemistry: Preparation and Characterization of Te(N3)4 and [P(C6H5)4]2[Te(N3)6] and Evidence for [N(CH3)4][Te(N3)5] (pages 5847–5851)

      Ralf Haiges, Jerry A. Boatz, Ashwani Vij, Michael Gerken, Stefan Schneider, Thorsten Schroer and Karl O. Christe

      Article first published online: 8 DEC 2003 | DOI: 10.1002/anie.200352680

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      Highly explosive Te(N3)4 was prepared by the fluoride-ion-catalyzed reaction of TeF6 and Me3SiN3, and converted to the more stable [P(C6H5)4]2[Te(N3)6] salt by reaction with [P(C6H5)4]N3. The sterically active free valence-electron pair at the Te center strongly distorts the structure of the [Te(N3)6]2− ion from the predicted ideal S6 symmetry (see picture). Evidence for the formation of the [Te(N3)5] ion is also presented.

    11. The Usefulness of Time-Dependent Density Functional Theory to Describe the Electronic Spectra of Ti-Containing Catalysts (pages 5851–5854)

      Victor. A. de la Peña O'Shea, Maricarmen Capel-Sanchez, Gema Blanco-Brieva, Jose M. Campos-Martin and Jose L. G. Fierro

      Article first published online: 8 DEC 2003 | DOI: 10.1002/anie.200351452

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      A good correlation between the experimental UV/Vis spectra of titanium-containing catalysts and the photophysical properties calculated using time-dependent density functional theory (TD-DFT) has been found for a ligand to metal charge transfer (LMCT) from an oxygen atom to a TiIV ion (see scheme). This finding makes the TD-DFT methodology an excellent tool to generate and interpret the electronic spectra of isolated atoms on the surface of heteroatom-containing inorganic substrates.

    12. Intramolecular Organocatalytic [3+2] Dipolar Cycloaddition: Stereospecific Cycloaddition and the Total Synthesis of (±)-Hirsutene (pages 5855–5857)

      Jian-Cheng Wang and Michael J. Krische

      Article first published online: 8 DEC 2003 | DOI: 10.1002/anie.200352218

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      A testing ground for cyclopentannulation strategies: the triquinane natural product hirsutene is obtained through the intramolecular organocatalytic [3+2] cycloaddition of the 1,7-enyne (E)-1 . The cycloaddition is stereospecific: reaction of the corresponding Z isomer provides the epimeric diquinane.

    13. Continuous Glucose Sensing with a Fluorescent Thin-Film Hydrogel (pages 5857–5859)

      Jeff T. Suri, David B. Cordes, Frank E. Cappuccio, Ritchie A. Wessling and Bakthan Singaram

      Article first published online: 8 DEC 2003 | DOI: 10.1002/anie.200352405

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      Sweetness and light: A fluorescent thin-film hydrogel that contains a covalently bound boronic-acid-functional quencher (Q) and a fluorescent dye (F; see Figure) continuously senses glucose under physiological conditions through binding of the sugar (S) to a labeled receptor (R).

    14. Three/Four/Five-Component Diastereoselective Cyclization of Fischer Carbene Complexes, Lithium Enolates, and Allylmagnesium Bromide (pages 5860–5863)

      José Barluenga, Iván Pérez-Sánchez, Eduardo Rubio and Josefa Flórez

      Article first published online: 8 DEC 2003 | DOI: 10.1002/anie.200352489

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      From three simple starting materials, the diastereoselective synthesis of pentasubstituted cyclopentanols or tetrasubstituted cyclohexane-1,4-diols can be controlled by the appropriate choice of lithium enolate (see scheme). The overall one-pot transformation leads to the formation of up to five new C[BOND]C bonds and up to four contiguous stereogenic centers.

    15. Packing Motifs in Porphyrazine Macrocycles Carrying Peripherally Annulated Thiadiazole Rings: Crystal Growths of Metal-Free and Cobalt Tetrakis(1,2,5-thiadiazole)porphyrazines (pages 5863–5865)

      Masato Fujimori, Yosuke Suzuki, Hirofumi Yoshikawa and Kunio Awaga

      Article first published online: 8 DEC 2003 | DOI: 10.1002/anie.200352571

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      The importance of the thiadiazole ring: While electrostatic interactions between the thiadiazole rings is responsible for the 2D close packing in the solid-state structure of tetrakis(thiadiazole)porphyrazine (TTDPzH2, see X-ray crystal structure), the formation of a coordination bond between the ring and the cobalt ion results in the cobalt derivative TTDPzCo having a chain structure.

    16. Palladium-Catalyzed Equilibrium Addition of Acidic OH Groups across Dienes (pages 5865–5868)

      Masaru Utsunomiya, Motoi Kawatsura and John F. Hartwig

      Article first published online: 8 DEC 2003 | DOI: 10.1002/anie.200352621

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      Mildly acidic O[BOND]H groups undergo transition-metal-catalyzed reversible addition across the C[DOUBLE BOND]C bonds of cyclic and acyclic dienes. For example, the simple complex [Pd(PPh3)4] (1 mol %) effectively catalyzes both the forward addition of phenol across dienes and the reverse elimination of phenol from allylic ethers (see scheme).

    17. Practical Asymmetric Synthesis of Vicinal Diamines through the Catalytic Highly Enantioselective Alkylation of Glycine Amide Derivatives (pages 5868–5870)

      Takashi Ooi, Daiki Sakai, Mifune Takeuchi, Eiji Tayama and Keiji Maruoka

      Article first published online: 8 DEC 2003 | DOI: 10.1002/anie.200352658

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      Phase-transfer catalysis (PTC) by a designer chiral quaternary ammonium bromide facilitated the direct, highly enantioselective introduction of a wide variety of substituents including cycloalkyl side chains at the α position of the prochiral glycine amide derivative 1. A general, practical procedure for the asymmetric synthesis of structurally diverse monosubstituted vicinal diamines of type 2 is presented. Dpm=diphenylmethyl.

    18. Asymmetric Addition of Aryl Boron Reagents to Enones with Rhodium Dicyclophane Imidazolium Carbene Catalysis (pages 5871–5874)

      Yudao Ma, Chun Song, Changqing Ma, Zhijun Sun, Qiang Chai and Merritt B. Andrus

      Article first published online: 8 DEC 2003 | DOI: 10.1002/anie.200352679

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      Chiral N-heterocyclic carbene ligands based on [2.2]paracyclophanes form complexes with rhodium. These catalysts can be used in the high-yielding and enantioselective asymmetric conjugate addition of arylboron compounds to cyclic and acyclic enones (see scheme).

    19. Sulfoxide Covalent Catalysis: Application to Glycosidic Bond Formation (pages 5874–5877)

      Timothy A. Boebel and David Y. Gin

      Article first published online: 8 DEC 2003 | DOI: 10.1002/anie.200352761

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      A versatile glycosylation reaction is used to establish the process of sulfoxide covalent catalysis. Hemiacetals are activated by benzenesulfonic anhydride and a dialkyl sulfoxide catalyst, nBu2SO, for coupling with various nucleophiles (Nu; see scheme, TTBP=2,4,6-tri-tert-butylpyridine). The sulfoxide catalyst functions uniquely in three capacities, first as an O nucleophile, then as a S+ electrophile, and finally as a leaving group to fulfill turnover.

    20. Breaking Down Barriers: The Liaison Between Sigmatropic Shifts, Electrocyclic Reactions, and Three-Center Cations (pages 5877–5882)

      Roald Hoffmann and Dean J. Tantillo

      Article first published online: 19 NOV 2003 | DOI: 10.1002/anie.200352853

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      Almost indistinguishable transition-state (TS) geometries, which differ only by the presence or absence of a simple proton, were found for electrocyclic and sigmatropic rearrangements with the same electron count (see picture).

    21. Synthesis and Characterization of Oligonucleotides Containing the C4′-Oxidized Abasic Site Produced by Bleomycin and Other DNA Damaging Agents (pages 5882–5885)

      Jaeseung Kim, Jun Mo Gil and Marc M. Greenberg

      Article first published online: 8 DEC 2003 | DOI: 10.1002/anie.200352102

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      Selective introduction of damage: The C4′-position of DNA serves as the site of attack for a number of DNA damaging agents, including bleomycin. The C4′-abasic site is a major product found in damaged DNA following abstraction of the hydrogen atom from this position. The first general method for the synthesis of oligonucleotides 1 containing the C4′-abasic site at defined positions is described (see scheme). This method should facilitate physicochemical, biochemical, and biological studies on this commonly formed DNA lesion.

    22. Entropy-Driven Translational Isomerism: A Tristable Molecular Shuttle (pages 5886–5889)

      Giovanni Bottari, Francois Dehez, David A. Leigh, Phillip J. Nash, Emilio M. Pérez, Jenny K. Y. Wong and Francesco Zerbetto

      Article first published online: 8 DEC 2003 | DOI: 10.1002/anie.200352176

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      Two's company but three's allowed! An entropy-driven tristable molecular shuttle has been developed, where shuttling between two of three stations is brought about through a photochemical isomerization, but a further stable co-conformation is unexpectedly observed simply upon changing the temperature (the picture shows the molecular shuttle in one of the three possible co-conformations).

    23. Towards the Rational Design of Magnetic Resonance Imaging Contrast Agents: Isolation of the Two Coordination Isomers of Lanthanide DOTA-Type Complexes (pages 5889–5892)

      Mark Woods, Zoltan Kovacs, Shanrong Zhang and A. Dean Sherry

      Article first published online: 8 DEC 2003 | DOI: 10.1002/anie.200352234

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      Controlling water exchange: Square antiprism (SAP; left) and twisted square antiprism (TSAP; right) coordination isomers of LnIIIDOTA-type complexes (DOTA=1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid) may be isolated by choosing substituents on the ring and arms with identical chirality for the TSAP isomer, or with opposite chirality for the SAP isomer. The water exchange rates of the complexes differ by an order of magnitude.

    24. Why Does TNA Cross-Pair More Strongly with RNA Than with DNA? An Answer From X-ray Analysis (pages 5893–5895)

      Pradeep S. Pallan, Christopher J. Wilds, Zdzislaw Wawrzak, Ramanarayanan Krishnamurthy, Albert Eschenmoser and Martin Egli

      Article first published online: 8 DEC 2003 | DOI: 10.1002/anie.200352553

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      The TNA twist: L-α-threofuranosyl (3′[RIGHTWARDS ARROW]2′) nucleic acid (TNA) residues adopt a C4′-exo pucker when incorporated into an A- (left) or a B-form DNA duplex (right). The resulting intranucleotide P⋅⋅⋅P distance in TNA is very similar to that in RNA (represented by a C3′-endo puckered adenosine residue; green). The structural data explain earlier observations that TNA hydridizes more stably with RNA than with DNA and that RNA constitutes the better template for ligating TNA fragments.

    25. Ultrafast Dynamics in DNA-Mediated Electron Transfer: Base Gating and the Role of Temperature (pages 5896–5900)

      Melanie A. O'Neill, Hans-Christian Becker, Chaozhi Wan, Jacqueline K. Barton and Ahmed H. Zewail

      Article first published online: 8 DEC 2003 | DOI: 10.1002/anie.200352831

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      The ultrafast dynamics of electron transfer (ET) between bases in DNA have been determined to elucidate the critical role of base-pair gating on the timescale of the electron transport and the temperature dependence of the rates. ET occurs only through DNA duplexes that adopt a specific, well-coupled alignment of bases (ET-active; see picture). Descriptions of ET dynamics must include fluctuations of DNA bases.

    26. Preview: Angew. Chem. Int. Ed. 47/2003 (page 5907)

      Article first published online: 8 DEC 2003 | DOI: 10.1002/anie.200390629