Angewandte Chemie International Edition

Cover image for Vol. 45 Issue 4

January 16, 2006

Volume 45, Issue 4

Pages 521–675

    1. Cover Picture: Evidence from NMR and EXAFS Studies of a Dynamically Uniform Mononuclear Single-Site Zeolite-Supported Rhodium Catalyst (Angew. Chem. Int. Ed. 4/2006) (page 521)

      Justin O. Ehresmann, Philip W. Kletnieks, Ann Liang, Vinesh A. Bhirud, Olesya P. Bagatchenko, Eric J. Lee, Meghan Klaric, Bruce C. Gates and James F. Haw

      Article first published online: 11 JAN 2006 | DOI: 10.1002/anie.200690012

      Zeolite-supported transition-metal catalysts are of importance in the petrochemical industry. However, the fabrication and characterization of well-defined systems remains a challenge. In their Communication on page 574 ff., B. C. Gates, J. F. Haw, and co-workers present computational and experimental evidence that the rhodium complex {Rh(C2H4)2} supported on zeolite Y is a single-site catalyst with a uniform structure. The cover picture shows the rotation of the ethylene ligands about the Rh+ center (green sphere).

    2. Graphical Abstract: Angew. Chem. Int. Ed. 4/2006 (pages 524–533)

      Article first published online: 11 JAN 2006 | DOI: 10.1002/anie.200690013

    3. You have free access to this content
      Ruthenium-Catalyzed Asymmetric Propargylic Substitution Reactions of Propargylic Alcohols with Acetone (page 533)

      Youichi Inada, Yoshiaki Nishibayashi and Sakae Uemura

      Article first published online: 11 JAN 2006 | DOI: 10.1002/anie.200690014

      This article corrects:

      Ruthenium-Catalyzed Asymmetric Propargylic Substitution Reactions of Propargylic Alcohols with Acetone1

      Vol. 44, Issue 47, 7715–7717, Article first published online: 27 OCT 2005

    4. Enantioselective α-Fluorination of Carbonyl Compounds: Organocatalysis or Metal Catalysis? (pages 544–547)

      Petri M. Pihko

      Article first published online: 21 DEC 2005 | DOI: 10.1002/anie.200502425

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      Five ground-breaking studies in enantioselective α-fluorination of carbonyl compounds have been disclosed. Four describe the use of amine organocatalysts to promote the asymmetric fluorination of aldehydes, whereas the fifth describes a highly enantioselective fluorination of carbonyl compounds capable of two-point binding (e.g. β-ketoesters). NFSI=N-fluorobenzenesulfonimide.

    5. Hydrophobically Directed Organic Synthesis (pages 548–551)

      Ulf M. Lindström and Fredrik Andersson

      Article first published online: 12 DEC 2005 | DOI: 10.1002/anie.200502882

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      Going with the flow: Nature has perfected the use of hydrophobic interactions in biochemical processes. Some recent work on synthesis has shown that reactions in water may be predisposed to favor transition states that optimize hydrophobic interactions (see picture). Thus, it should in principle be possible to use hydrophobic interactions as a nonbonding element of control for synthetic reactions in water.

    6. Serine Octamers: Cluster Formation, Reactions, and Implications for Biomolecule Homochirality (pages 554–569)

      Sergio C. Nanita and R. Graham Cooks

      Article first published online: 11 JAN 2006 | DOI: 10.1002/anie.200501328

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      A remarkable example of magic-number clustering and chiral recognition in molecular aggregates is shown by serine octamers, which partly explains two essential steps in the origin of homochirality: enantiomeric enrichment and chiral transfer (see picture). Extensive investigations over the past five years have revealed many facts about the structure(s), chemistry, and mechanism of formation of serine octamers.

    7. Toward the Isolation of Functional Organic Nanotubes (pages 570–574)

      Scott J. Dalgarno, Gareth W. V. Cave and Jerry L. Atwood

      Article first published online: 27 DEC 2005 | DOI: 10.1002/anie.200503035

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      The last straw: Sonication of C-hexylpyrogallol[4]arene with pyrene, acetonitrile, and water results in the formation of crystalline organic nanotubes. Alternating pockets of acetonitrile and water are contained within the large internal diameter of the tube formed by the calixarenes (see picture; the tube and solvent molecules are shown as stick and space-filling representations, respectively).

    8. Evidence from NMR and EXAFS Studies of a Dynamically Uniform Mononuclear Single-Site Zeolite-Supported Rhodium Catalyst (pages 574–576)

      Justin O. Ehresmann, Philip W. Kletnieks, Ann Liang, Vinesh A. Bhirud, Olesya P. Bagatchenko, Eric J. Lee, Meghan Klaric, Bruce C. Gates and James F. Haw

      Article first published online: 27 DEC 2005 | DOI: 10.1002/anie.200502864

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      The proof of the pudding is in the analysis! The mononuclearity of the metal in a zeolite-supported Rh+ catalyst with two exchangeable ethylene ligands (see picture; Rh brown, C black, Al gray, O red, Si blue) was confirmed through EXAFS studies, and its dynamic uniformity was demonstrated through variable-temperature NMR spectroscopic studies.

    9. Carbon Nanotubes as Intracellular Transporters for Proteins and DNA: An Investigation of the Uptake Mechanism and Pathway (pages 577–581)

      Nadine Wong Shi Kam, Zhuang Liu and Hongjie Dai

      Article first published online: 13 DEC 2005 | DOI: 10.1002/anie.200503389

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      Endocytosis or not endocytosis: The pathway of the internalization of single-walled carbon nanotube (SWNT) conjugates into mammalian cells was determined to be energy-dependent endocytosis through clathrin-coated pits.

    10. In Situ Deposition and Patterning of Single-Walled Carbon Nanotubes by Laminar Flow and Controlled Flocculation in Microfluidic Channels (pages 581–585)

      Jang-Ung Park, Matthew. A. Meitl, Seung-Hyun Hur, Monica L. Usrey, Michael S. Strano, Paul J. A. Kenis and John A. Rogers

      Article first published online: 8 DEC 2005 | DOI: 10.1002/anie.200501799

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      Well-defined patterns of single-walled carbon nanotubes (SWNTs) with controlled density and alignment were produced by using controlled flocculation in multistream laminar microfluidic networks (see picture). Complex, well-defined SWNT patterns could be generated by control of flow and substrate conditions.

    11. A Highly Active, Heterogeneous Catalyst for Alkyne Metathesis (pages 585–588)

      Haim Weissman, Kyle N. Plunkett and Jeffrey S. Moore

      Article first published online: 15 DEC 2005 | DOI: 10.1002/anie.200502840

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      An alkylidyne molybdenum amide complex is attached to nontoxic, amorphous silica to form a highly active, recyclable heterogeneous catalyst for alkyne metathesis. The catalyst does not undergo alkyne polymerization, can be utilized at a loading of <1 mol % at room temperature, and has shown unprecedented metathesis activity for the homodimerization of 2-propynylthiophene, a substrate that was previously problematic for alkyne metathesis.

    12. Synthesis and Conformational Study of Water-Soluble, Rigid, Rodlike Oligopiperidines (pages 588–591)

      Vincent Semetey, Demetri Moustakas and George M. Whitesides

      Article first published online: 12 DEC 2005 | DOI: 10.1002/anie.200502991

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      An oligomeric backbone of piperidine rings can be synthesized by solution or solid-phase synthesis. These oligomers adopt well-defined, rodlike structures with all the piperidine residues in chair conformations (see picture) both in solution (D2O, CD3OD) and the solid state.

    13. A Synthetic Small Molecule That Induces Neuronal Differentiation of Adult Hippocampal Neural Progenitor Cells (pages 591–593)

      Masaki Warashina, Kyung Hoon Min, Tomoko Kuwabara, Alexis Huynh, Fred H. Gage, Peter G. Schultz and Sheng Ding

      Article first published online: 2 DEC 2005 | DOI: 10.1002/anie.200503089

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      Brain power: An image-based screen of a chemical library was carried out to identify molecules that regulate the differentiation of adult rat hippocampal neural stem cells. Neuropathiazol (1) induces selective neuronal differentiation and competitively suppresses astrocyte differentiation. This compound should be a useful tool to study the processes that control stem-cell fate both in vitro and in vivo.

    14. Epitope Mapping of the Protective Antigen of B. Anthracis by Using Nanoclusters Presenting Conformational Peptide Epitopes (pages 594–598)

      Aren E. Gerdon, David W. Wright and David E. Cliffel

      Article first published online: 15 DEC 2005 | DOI: 10.1002/anie.200503328

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      Secondary choice: Conformational and linear peptide epitopes from the protective antigen of B. anthracis were presented on the surface of monolayer-protected clusters to produce immunoreactive nanostructures. Quartz crystal microbalance studies of these antigen mimics with antibodies suggested a significant difference between two epitopes with identical primary structure but different secondary structure.

    15. Unusual Lone Pairs in Tellurium and Their Relevance for Superconductivity (pages 599–602)

      Shuiquan Deng, Jürgen Köhler and Arndt Simon

      Article first published online: 19 DEC 2005 | DOI: 10.1002/anie.200502673

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      When pairs break up: Ab initio calculations are used to quantitatively characterize the stability and shape of an unusual type of lone pair in tellurium. By comparing the calculated band structures for tellurium under ambient and high pressure, it is shown that the flat/steep-band condition necessary for superconductivity is created for the high-pressure modification Te-II through the delocalization and breakdown of the lone pairs (see scheme).

    16. Reversible cistrans Isomerization of a Single Azobenzene Molecule (pages 603–606)

      Jörg Henzl, Michael Mehlhorn, Heiko Gawronski, Karl-Heinz Rieder and Karina Morgenstern

      Article first published online: 13 DEC 2005 | DOI: 10.1002/anie.200502229

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      Single working molecule: The controlled cistrans isomerization (see picture; left cis, right trans isomer) of a single molecule of the azobenzene derivative Disperse Orange 3 on a Au(111) metal surface is acccomplished by injection of tunneling electrons at a certain position (cross in left picture) into the molecule.

    17. Functionalized Benzylic Magnesium Reagents through a Sulfur–Magnesium Exchange (pages 606–609)

      Armin H. Stoll, Arkady Krasovskiy and Paul Knochel

      Article first published online: 15 DEC 2005 | DOI: 10.1002/anie.200501882

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      Switch it: Iodobiphenyl thioethers readily undergo an iodine–magnesium exchange followed by, after the addition of tBuOLi, an intramolecular sulfur–magnesium exchange, which provides benzylic magnesium reagents in excellent yield through a fragmentation reaction.

    18. Synthesis of 2,4,6-Trimethylphenylcalcium Iodide and Degradation in THF Solution (pages 609–612)

      Reinald Fischer, Martin Gärtner, Helmar Görls and Matthias Westerhausen

      Article first published online: 19 DEC 2005 | DOI: 10.1002/anie.200503452

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      Heavy Grignard reagent: Despite the low reactivity of the calcium metal and the high reactivity of the resulting Ca[BOND]C bonds, the synthesis of mesitylcalcium iodide (see structure: purple I, orange Ca, red O, gray C) succeeded at very low temperatures. This compound decomposes by ether cleavage and rearrangement to the 3,5-dimethylbenzylcalcium iodide, even at low temperatures.

    19. Biocatalytic Synthesis of Poly(L-Lactide) by Native and Recombinant Forms of the Silicatein Enzymes (pages 613–616)

      Paul Curnow, David Kisailus and Daniel E. Morse

      Article first published online: 19 DEC 2005 | DOI: 10.1002/anie.200502738

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      Enzymatic polymer synthesis is of considerable interest because of the synthetic advantages afforded by biological catalysts. Silicatein enzymes have shown broad synthetic utility for inorganic materials, and recombinant and native silicateins have been applied in the preparation of poly(L-lactide) (PLA). The picture shows native silicatein filaments coated with PLA (scale bar=4 μm).

    20. Separation of Hydrocarbons with a Microporous Metal–Organic Framework (pages 616–619)

      Long Pan, David H. Olson, Lauren R. Ciemnolonski, Ryan Heddy and Jing Li

      Article first published online: 15 DEC 2005 | DOI: 10.1002/anie.200503503

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      Separating the wheat from the chaff: The microporous metal–organic framework (MMOF) of [Cu(hfipbb)(H2hfipbb)0.5] is based on a bimetallic paddle-wheel building block and comprises 1D tubular microchannels formed by the interpenetration of two identical 44 nets. The channels are hydrophobic and have the ideal size and shape to selectively adsorb C2, C3, and n-C4 olefins and alkanes (see picture).

    21. Total Synthesis of (−)- and ent-(+)-Vindorosine: Tandem Intramolecular Diels–Alder/1,3-Dipolar Cycloaddition of 1,3,4-Oxadiazoles (pages 620–622)

      Gregory I. Elliott, Juraj Velcicky, Hayato Ishikawa, YongKai Li and Dale L. Boger

      Article first published online: 15 DEC 2005 | DOI: 10.1002/anie.200503024

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      From tandem to pentacycle: The intramolecular tandem [4+2]/[3+2] cycloaddition cascade of 1,3,4-oxadiazole (Z)-1 to give the pentacyclic skeleton 2 of (−)- and ent-(+)-vindorosine introduces all the requisite substituents and functionality in a single step by which three new rings and four C[BOND]C bonds form and all six key stereocenters are installed.

    22. Mechanistic Studies on the Conversion of Arylamines into Arylnitro Compounds by Aminopyrrolnitrin Oxygenase: Identification of Intermediates and Kinetic Studies (pages 622–625)

      Jungkul Lee and Huimin Zhao

      Article first published online: 12 DEC 2005 | DOI: 10.1002/anie.200502903

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      Rieske business! The Rieske N-oxygenase, aminopyrrolnitrin oxygenase (PrnD), catalyzes the unusual oxidation of arylamines to arylnitro compounds. Kinetic analysis has confirmed that PrnD catalyzes the conversion of the substrate pABA (4-aminobenzylamine) through at least three consecutive reactions: two monooxygenation steps and one dehydrogenation step (see scheme).

    23. The Importance of Inter- and Intramolecular van der Waals Interactions in Organic Reactions: the Dimerization of Anthracene Revisited (pages 625–629)

      Stefan Grimme, Christian Diedrich and Martin Korth

      Article first published online: 15 DEC 2005 | DOI: 10.1002/anie.200502440

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      A delicate balance between inter- and intramolecular van der Waals effects can significantly influence the thermodynamics of organic reactions. These “weak interactions” are often underestimated but sum up even for the simple example of the dimerization of anthracene to relative effects of about 10–15 kcal mol−1. It is furthermore shown why common density functional theory yields a seemingly right answer for the wrong reason.

    24. A Copper(II)-Catalyzed Aza-Friedel–Crafts Reaction of N-(2-Pyridyl)sulfonyl Aldimines: Synthesis of Unsymmetrical Diaryl Amines and Triaryl Methanes (pages 629–633)

      Jorge Esquivias, Ramón Gómez Arrayás and Juan C. Carretero

      Article first published online: 13 DEC 2005 | DOI: 10.1002/anie.200503305

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      The choice of the (2-pyridyl)sulfonyl moiety as an N-protecting group and Cu(OTf)2/(±)-binap as catalyst system lead to a highly efficient aza-Friedel–Crafts reaction of electron-rich arenes (Ar2-H) and heteroarenes with N-sulfonyl imines. This protocol is also amenable to the synthesis of unsymmetrical triaryl methanes through a second electrophilic aromatic substitution with a different electron-rich arene (Ar3-H; see scheme).

    25. Formation of Cyclic Sulfinates and Sulfinamides through Homolytic Substitution at the Sulfur Atom (pages 633–637)

      Julien Coulomb, Victor Certal, Louis Fensterbank, Emmanuel Lacôte and Max Malacria

      Article first published online: 19 DEC 2005 | DOI: 10.1002/anie.200503369

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      Ring road: Cyclic sulfinates and sulfinamides can be synthesized by homolytic substitution to give alkyl and benzofused families of compounds. The presence of an additional heteroatom in the ring allows the preparation of sulfur-based heterocycles that are useful synthetic intermediates (see scheme). The stereogenic sulfur atom transfers its chirality to prochiral radicals. TTMSS=tris(trimethylsilyl)silane, AIBN=azobisisobutyronitrile.

    26. Fluoromorphic Substrates for Fatty Acid Metabolism: Highly Sensitive Probes for Mammalian Medium-Chain Acyl-CoA Dehydrogenase (pages 637–642)

      Mary K. Froemming and Dalibor Sames

      Article first published online: 19 DEC 2005 | DOI: 10.1002/anie.200502675

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      Not fussy: A systematic study revealed considerable substrate tolerance of medium-chain acyl-CoA dehydrogenase (MCAD), a member of the β-oxidation pathway for the degradation of fatty acids. Three fluorogenic reporter substrates were developed, which in turn allowed for selective, sensitive, and continuous monitoring of MCAD activity in tissue homogenates.

    27. Nonmechanical Protein Can Have Significant Mechanical Stability (pages 642–645)

      Yi Cao, Canaan Lam, Meijia Wang and Hongbin Li

      Article first published online: 13 DEC 2005 | DOI: 10.1002/anie.200502623

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      The unique topology of the B1 immunoglobulin G (IgG) binding domain of streptococcal protein G (GB1) leads to its remarkable mechanical stability. This nonmechanical protein is shown to be mechanically stable and to unfold at about 180 pN (the force-extension curves (right) shown demonstrate the mechanical unraveling of each GB1 domain in the polyprotein which is made of direct tandem repeats of GB1 (left)).

    28. Heteroditopic Rebek's Imide Directs the Reactivity of Homoditopic Olefins within Desolvated Quaternary Assemblies in the Solid State (pages 646–650)

      Dushyant B. Varshney, Xiuchun Gao, Tomislav Friščić and Leonard R. MacGillivray

      Article first published online: 19 DEC 2005 | DOI: 10.1002/anie.200502294

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      A rare single crystal to single crystal transformation leads to a [2+2] photodimerization of homoditopic olefins (trans-1,2-bis(4-pyridyl)ethylene) assembled and preorganized within hydrogen-bonded quaternary complexes by using Rebek's imide. In this way a rctt-tetrakis(4-pyridyl)cyclobutane (see picture) was obtained stereospecifically in up to 100 % yield.

    29. Ordered Nanostructures from the Self-Assembly of Reactive Coil–Rod–Coil Molecules (pages 650–653)

      Long Yi Jin, Jinyoung Bae, Ja-Hyoung Ryu and Myongsoo Lee

      Article first published online: 15 DEC 2005 | DOI: 10.1002/anie.200502911

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      Keeping in shape: Polymerizable coil–rod–coil molecules self-organize into 2D columnar and 3D bicontinuous liquid crystals whose supramolecular architectures and lattice dimensions are preserved upon photopolymerization (see picture). Nanofibers resulting from the photopolymerization of the 2D structures are utilized as nanoreactors for Suzuki coupling reactions.

    30. Computational Design of a Human Butyrylcholinesterase Mutant for Accelerating Cocaine Hydrolysis Based on the Transition-State Simulation (pages 653–657)

      Daquan Gao, Hoon Cho, Wenchao Yang, Yongmei Pan, Guangfu Yang, Hsin-Hsiung Tai and Chang-Guo Zhan

      Article first published online: 15 DEC 2005 | DOI: 10.1002/anie.200503025

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      Breaking down cocaine: The transition-state simulation predicts a significantly more stable transition-state structure (see model; C: green, O: red, H: gray, N: blue, cocaine atoms: yellow) for the rate-determining first reaction step (TS1) of the (−)-cocaine hydrolysis catalyzed by a mutant of human butyrylcholinesterase (BChE).

    31. Experimental and Theoretical Characterization of Superoxide Complexes [W2O6(O2)] and [W3O9(O2)]: Models for the Interaction of O2 with Reduced W Sites on Tungsten Oxide Surfaces (pages 657–660)

      Xin Huang, Hua-Jin Zhai, Tom Waters, Jun Li and Lai-Sheng Wang

      Article first published online: 13 DEC 2005 | DOI: 10.1002/anie.200503652

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      Photoelectron spectroscopic analysis and DFT calculations of two O-rich tungsten oxide clusters [W2O8] and [W3O11] showed these anions are superoxide complexes [W2O6(O2)] and [W3O9(O2)]. The data suggest that the clusters [W2O6] and [W3O9] can activate O2 through a one-electron transfer to form superoxide, which makes them simple molecular models for the chemisorption of O2 at reduced defect sites on tungsten oxide surfaces.

    32. Derivatives of Octaethynylphenazine and Hexaethynylquinoxaline (pages 661–665)

      Shaobin Miao, Carlito G. Bangcuyo, Mark D. Smith and Uwe H. F. Bunz

      Article first published online: 19 DEC 2005 | DOI: 10.1002/anie.200502067

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      Pocketing metals with alkynes: The spectral responses of the peralkynylated heteroacenes hexaethynylquinoxaline and octaethynylphenazine (see structure; N blue, C red, H yellow) on the presence of metal cations are more-pronounced for the phenazine derivative, demonstrating that the presence of the lateral alkyne substituents improves the metal-ion-binding capability of the pyrazine motif.

    33. Label-Free, Real-Time Glycosyltransferase Assay Based on a Fluorescent Artificial Chemosensor (pages 665–668)

      Jirarut Wongkongkatep, Yoshifumi Miyahara, Akio Ojida and Itaru Hamachi

      Article first published online: 19 DEC 2005 | DOI: 10.1002/anie.200503107

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      Reality check: The fluorescent probe 1 is applied to a real-time glycosyltransferase assay. The fluorescence of 1 increases with the progress of the glycosyl transfer reaction. The high sensitivity and reliable output of the method under multisubstrate enzymatic conditions make it suitable for the high-throughput screening of glycosyltransferase inhibitors.

    34. You have free access to this content
      Preview: Angew. Chem. Int. Ed. 4/2006 (page 675)

      Article first published online: 11 JAN 2006 | DOI: 10.1002/anie.200690015

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