Angewandte Chemie International Edition

Cover image for Vol. 46 Issue 24

June 11, 2007

Volume 46, Issue 24

Pages 4405–4585

  1. Cover Picture

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Graphical Abstract
    5. News
    6. Book Reviews
    7. Highlight
    8. Minireview
    9. Review
    10. Communications
    11. Preview
    1. Cover Picture: Tracking the Chiral Recognition of Adsorbed Dipeptides at the Single-Molecule Level (Angew. Chem. Int. Ed. 24/2007) (page 4405)

      Magalí Lingenfelder, Giulia Tomba, Giovanni Costantini, Lucio Colombi Ciacchi, Alessandro De Vita and Klaus Kern

      Version of Record online: 31 MAY 2007 | DOI: 10.1002/anie.200790107

      Thumbnail image of graphical abstract

      As for a couple of tango dancers, mutual conformational changes in homochiral pairs of molecules (in foreground) induce an optimal fit during interaction, but in order not to be lonely (molecule in background) a partner of appropriate chirality must be found. As described in the Communication on page 4492 ff., M. Lingenfelder and co-workers have followed the chiral recognition and discrimination among individual dipeptides with STM movies and have rationalized the process using first-principles and classical molecular-dynamics simulations.

  2. Inside Cover

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Graphical Abstract
    5. News
    6. Book Reviews
    7. Highlight
    8. Minireview
    9. Review
    10. Communications
    11. Preview
    1. Inside Cover: Helical Arrangement of Interstrand Stacked Pyrenes in a DNA Framework (Angew. Chem. Int. Ed. 24/2007) (page 4406)

      Vladimir L. Malinovskii, Florent Samain and Robert Häner

      Version of Record online: 31 MAY 2007 | DOI: 10.1002/anie.200790108

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      A self-organizing system composed of two oligopyrene strands that leads to the formation of an interstrand helical stack embedded in a double strand of DNA is reported by R. Häner and co-workers in their Communication on page 4464 ff. Fluorescence and CD spectroscopy show that helical organization takes place in a hybrid containing 14 consecutive achiral pyrene building blocks but not within the respective single strands nor in hybrids containing 6 or less pyrene residues.

  3. Graphical Abstract

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Graphical Abstract
    5. News
    6. Book Reviews
    7. Highlight
    8. Minireview
    9. Review
    10. Communications
    11. Preview
  4. News

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Graphical Abstract
    5. News
    6. Book Reviews
    7. Highlight
    8. Minireview
    9. Review
    10. Communications
    11. Preview
  5. Book Reviews

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Graphical Abstract
    5. News
    6. Book Reviews
    7. Highlight
    8. Minireview
    9. Review
    10. Communications
    11. Preview
  6. Highlight

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Graphical Abstract
    5. News
    6. Book Reviews
    7. Highlight
    8. Minireview
    9. Review
    10. Communications
    11. Preview
    1. Molecular Self-Assembly across Multiple Length Scales (pages 4428–4432)

      Vincenzo Palermo and Paolo Samorì

      Version of Record online: 11 MAY 2007 | DOI: 10.1002/anie.200700416

      Thumbnail image of graphical abstract

      When enemies become friends: Hierarchical self-assembly, through the concerted use of different forces that dominate on distinct length scales, allows the generation of functional supramolecular architectures with a high degree of order on both the nano- and macroscopic scales, paving the way towards their application in electronics, catalysis, and medicine.

  7. Minireview

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Graphical Abstract
    5. News
    6. Book Reviews
    7. Highlight
    8. Minireview
    9. Review
    10. Communications
    11. Preview
    1. From Glycerol to Value-Added Products (pages 4434–4440)

      Mario Pagliaro, Rosaria Ciriminna, Hiroshi Kimura, Michele Rossi and Cristina Della Pina

      Version of Record online: 30 APR 2007 | DOI: 10.1002/anie.200604694

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      Getting value from glycerol: Over the past 60 years, glycerol (1,2,3-propanetriol) has gone from being a key industrial chemical that faced shortage to a by-product that is formed in surplus during biodiesel production. Recent developments in its applications and its conversion into value-added chemicals highlight the importance of glycerol as a key raw material in biorefineries of the future.

  8. Review

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Graphical Abstract
    5. News
    6. Book Reviews
    7. Highlight
    8. Minireview
    9. Review
    10. Communications
    11. Preview
    1. Biological Soft Materials (pages 4442–4455)

      Ian W. Hamley and Valeria Castelletto

      Version of Record online: 22 MAY 2007 | DOI: 10.1002/anie.200603922

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      The soft side of life: Recent insights into the self-assembly of biological materials, including proteins, DNA, lipids, and blood cells, are reviewed. The particular focus is on applying concepts from soft-matter physics and chemistry to understand structural self-organization (for example, myelin formation; see image).

  9. Communications

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Graphical Abstract
    5. News
    6. Book Reviews
    7. Highlight
    8. Minireview
    9. Review
    10. Communications
    11. Preview
    1. A Ferromagnetic Mixed-Valent Mn Supertetrahedron: Towards Low-Temperature Magnetic Refrigeration with Molecular Clusters (pages 4456–4460)

      Maria Manoli, Russell D. L. Johnstone, Simon Parsons, Mark Murrie, Marco Affronte, Marco Evangelisti and Euan K. Brechin

      Version of Record online: 18 MAY 2007 | DOI: 10.1002/anie.200701027

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      Fridge magnet: A decametallic mixed-valent Mn supertetrahedron (see picture; M purple, O red, N blue, Br brown, C gray) displays dominant ferromagnetic exchange and a spin ground state of S=22. The magnetic behavior of the cluster makes it suitable for use as a low-temperature magnetic refrigerant.

    2. A Coordination Polymer of Gold(I) with Heterotactic Architecture and a Comparison of the Structures of Isotactic, Syndiotactic, and Heterotactic Isomers (pages 4461–4463)

      Craig A. Wheaton and Richard J. Puddephatt

      Version of Record online: 10 MAY 2007 | DOI: 10.1002/anie.200701325

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      A tactic-al approach: By use of gold chemistry the first organic–inorganic polymer with a heterotactic architecture has been synthesized, and has enabled the first direct structural comparison of coordination polymers with isotactic, syndiotactic, and heterotactic architectures (see picture: naphthyl groups green, 4,4′-bipyridine ligands blue, phenyl gray, Au red, P purple).

    3. Helical Arrangement of Interstrand Stacked Pyrenes in a DNA Framework (pages 4464–4467)

      Vladimir L. Malinovskii, Florent Samain and Robert Häner

      Version of Record online: 18 MAY 2007 | DOI: 10.1002/anie.200700891

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      Getting it together: Helical self-organization between oligopyrene strands with 14 consecutive achiral pyrene building blocks embedded in a DNA strand leads to an artificial double helix (see example, oligopyrene regions are shown in dark colors and the flanking DNA regions in light colors). Helicity within the interstrand-stacked oligopyrenes is evident from the observation of exciton-coupled CD signals originating from the pyrene moieties.

    4. Enhancing Activity and Controlling Stereoselectivity in a Designed PLP-Dependent Aldolase (pages 4468–4470)

      Miguel D. Toscano, Manuel M. Müller and Donald Hilvert

      Version of Record online: 7 MAY 2007 | DOI: 10.1002/anie.200700710

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      Chop and change: Site-directed mutagenesis has been employed to optimize the activity of an engineered pyridoxal phosphate-dependent aldolase and to invert its inherent threo selectivity in the cleavage of D-β-phenylserines. The modification of the active-site residues generates significant retroaldol activity that compares favorably with that of natural enzymes in terms of efficiency and selectivity.

    5. Helix Mimetics as Inhibitors of the Interaction of the Estrogen Receptor with Coactivator Peptides (pages 4471–4473)

      Jorge Becerril and Andrew D. Hamilton

      Version of Record online: 9 MAY 2007 | DOI: 10.1002/anie.200700657

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      The short and curlies: A new α-helix mimetic based on a pyridylpyridone scaffold has been developed to bind to the estrogen receptor (ER) by mimicking the key leucine side chains of coactivator LXXLL boxes (L=leucine, X=any amino acid). These inhibitors compete with coactivator peptides for the surface of the ER and act as small-molecule inhibitors of the ER–coactivator interaction.

    6. The Structural Basis of Glycosidase Inhibition by Five-Membered Iminocyclitols: The Clan A Glycoside Hydrolase Endoglycoceramidase as a Model System (pages 4474–4476)

      Matthew E. C. Caines, Susan M. Hancock, Chris A. Tarling, Tanja M. Wrodnigg, Robert V. Stick, Arnold E. Stütz, Andrea Vasella, Stephen G. Withers and Natalie C. J. Strynadka

      Version of Record online: 9 MAY 2007 | DOI: 10.1002/anie.200700268

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      Fitting five into six: The crystal structure of a glycosidase-bound, five-membered iminocyclitol inhibitor was determined (see picture), and its binding interactions were compared to those of the classical six-membered iminocyclitol inhibitors isofagomine and glucoimidazole and of the glycosyl–enzyme intermediate. This information may be used to develop more potent and specific therapeutically useful glycosidase inhibitors.

    7. Metal-Oxide-Based Nucleation Process under Confined Conditions: Two Mixed-Valence V6-Type Aggregates Closing the W48 Wheel-Type Cluster Cavities (pages 4477–4480)

      Achim Müller, Michael T. Pope, Ana Maria Todea, Hartmut Bögge, Joris van Slageren, Martin Dressel, Pierre Gouzerh, René Thouvenot, Boris Tsukerblat and Aidan Bell

      Version of Record online: 8 MAY 2007 | DOI: 10.1002/anie.200700441

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      Getting together helps: The wheel-shaped {P8W48} polyoxotungstate (see picture) provides a reaction chamber for the directed assembly of two unprecedented mixed-valence vanadium oxide cavity-capping groups based on linked octahedra and tetrahedra with VIV and VV centers, respectively. The magnetic and electronic properties are controlled by the confined conditions.

    8. From Polynorbornene to the Complementary Polynorbornene by Replication (pages 4481–4485)

      Nai-Ti Lin, Shu-Yi Lin, Shern-Long Lee, Chun-hsien Chen, Chao-Hsiung Hsu, Lian Pin Hwang, Zhen-Yu Xie, Chung-Hsuan Chen, Shou-Ling Huang and Tien-Yau Luh

      Version of Record online: 23 APR 2007 | DOI: 10.1002/anie.200700472

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      In undergoing a DNA-like replication process, the single-stranded polynorbornene acts as a template for norbornene monomer adhesion through ester linkages (see scheme). Polymerization of the adhered monomers affords the corresponding unsymmetric double-stranded polymer, which produces a complementary polynorbornene carboxylic acid after hydrolysis. The overall process involves a pass of information from the template polymer to the daughter polymer.

    9. Functionalization of Potassium Graphite (pages 4486–4488)

      Soma Chakraborty, Jayanta Chattopadhyay, Wenhua Guo and W. Edward Billups

      Version of Record online: 3 MAY 2007 | DOI: 10.1002/anie.200605175

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      PEGged as soluble: Potassium graphite (C8K) is functionalized to yield derivatives that are soluble in either water or organic solvents. For example, treatment of C8K with 5-bromovaleric acid followed by amine-terminated poly(ethylene glycol) leads to water-soluble nanoplatelets (see AFM image).

    10. NMR-Guided Fragment-Based Approach for the Design of tRNALys3 Ligands (pages 4489–4491)

      Florence Chung, Carine Tisné, Thomas Lecourt, Frédéric Dardel and Laurent Micouin

      Version of Record online: 7 MAY 2007 | DOI: 10.1002/anie.200605201

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      Two in one: Two ligands for tRNALys3 that were identified from a compound library by flow-injection NMR spectroscopic screening and found to have millimolar dissociation constants (on the left in the picture) inspired the fragment-based synthesis of a new family of ligands with the general structural features of both initial compounds. Ligand 1 of this family is a selective D-stem binder of tRNALys3 with a micromolar Kd value.

    11. Tracking the Chiral Recognition of Adsorbed Dipeptides at the Single-Molecule Level (pages 4492–4495)

      Magalí Lingenfelder, Giulia Tomba, Giovanni Costantini, Lucio Colombi Ciacchi, Alessandro De Vita and Klaus Kern

      Version of Record online: 19 APR 2007 | DOI: 10.1002/anie.200700194

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      Lights, camera, action! The general mechanism of biomolecular recognition introduced by Pauling more than 50 years ago has now been brought to the movie screen (see still frame; D: D-Phe-D-Phe, L: L-Phe-L-Phe). With STM movies, the chiral-recognition process of individual adsorbed di-phenylalanine molecules is followed to illustrate the dynamic induced-fit mechanism at the single-molecule level.

    12. Exceptional Negative Thermal Expansion in Isoreticular Metal–Organic Frameworks (pages 4496–4499)

      David Dubbeldam, Krista S. Walton, Donald E. Ellis and Randall Q. Snurr

      Version of Record online: 8 MAY 2007 | DOI: 10.1002/anie.200700218

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      Shrink when heated: A new model for flexible frameworks is used to simulate the structures and adsorption properties of isoreticular metal–organic frameworks (IRMOFs), such as IRMOF-1 (see picture; Zn silver, C cyan, H white, O red). The structural simulations suggest that the IRMOFs have negative thermalexpansion coefficients over their full temperature ranges of stability.

    13. Specific Fluorescent Probe for 8-Oxoguanosine (pages 4500–4503)

      Osamu Nakagawa, Sayaka Ono, Zhichun Li, Akira Tsujimoto and Shigeki Sasaki

      Version of Record online: 10 MAY 2007 | DOI: 10.1002/anie.200700671

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      Marking mutations: Complete discrimination of 8-oxoguanosine (8-oxoG) from other nucleosides has been achieved with a new fluorescent probe, named “8-oxoG-clamp” (see picture). The complex structure between 8-oxoG-clamp and 8-oxoG was confirmed by 1H NMR titration and 2D NMR measurements. A preliminary investigation with use of a detergent for solubilization indicates that 8-oxoG-clamp may be applicable in aqueous media.

      Corrected by:

      Corrigendum: Specific Fluorescent Probe for 8-Oxoguanosine

      Vol. 47, Issue 47, 8983, Version of Record online: 5 NOV 2008

    14. Organocatalytic Asymmetric Hydrophosphination of α,β-Unsaturated Aldehydes (pages 4504–4506)

      Armando Carlone, Giuseppe Bartoli, Marcella Bosco, Letizia Sambri and Paolo Melchiorre

      Version of Record online: 4 MAY 2007 | DOI: 10.1002/anie.200700754

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      Getting round the (periodic) table: A highly chemo- and enantioselective conjugate addition of diphenylphosphine to α,β-unsaturated aldehydes in the presence of a chiral secondary amine C provides a direct route to chiral β-phosphino aldehyde intermediates (see scheme, TMS=trimethylsilyl). The synthetic utility of the strategy was exemplified in a rapid one-pot (two-step) synthesis of highly enantioenriched 3-aminophosphines.

    15. Enantioselective Organocatalytic Hydrophosphination of α,β-Unsaturated Aldehydes (pages 4507–4510)

      Ismail Ibrahem, Ramon Rios, Jan Vesely, Peter Hammar, Lars Eriksson, Fahmi Himo and Armando Córdova

      Version of Record online: 11 MAY 2007 | DOI: 10.1002/anie.200700916

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      Keeping it simple: Optically active phosphine derivatives can be obtained in high yields and in up to 99 % ee by using simple chiral amines to catalyze the hydrophosphination of α,β-unsaturated aldehydes (see scheme, green sphere=chiral group). The synthetic utility of this highly chemo- and enantioselective transformation was exemplified by the one-pot asymmetric synthesis of β-phosphine oxide acids.

    16. Consecutive Insertion of a Silylene into the P4 Tetrahedron: Facile Access to Strained SiP4 and Si2P4 Cage Compounds (pages 4511–4513)

      Yun Xiong, Shenglai Yao, Markus Brym and Matthias Driess

      Version of Record online: 4 MAY 2007 | DOI: 10.1002/anie.200701203

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      Silylene bites twice in the first insertion of a silylene into a P[BOND]P bond of the P4 tetrahedron. Reaction of the silylene 1 (see scheme; R=2,6-diisopropylphenyl) with white phosphorus at ambient temperature gives 2 with a tricyclic SiP4 core. The electronic situation in 2 favors the insertion of a second equivalent of 1 into a P[BOND]P bond of the SiP4 skeleton, affording the novel strained tricyclic silaphosphane 3 with a Si2P4 core.

    17. A Concise Synthesis of Eupomatilones 4, 6, and 7 by Rhodium-Catalyzed Enantioselective Desymmetrization of Cyclic meso Anhydrides with Organozinc Reagents Generated In Situ (pages 4514–4518)

      Jeffrey B. Johnson, Eric A. Bercot, Catherine M. Williams and Tomislav Rovis

      Version of Record online: 11 MAY 2007 | DOI: 10.1002/anie.200700816

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      The wages ofsyn: The development of a phosphoramidite-ligated rhodium catalyst allows the enantioselective desymmetrization of cyclic anhydrides with organozinc nucleophiles formed in situ. This methodology has been utilized for a concise synthesis of eupomatilones 4 and 7 and of the putative structure of eupomatilone 6, each of which is completed in four steps in greater than 50 % overall yield.

    18. Mild Cobalt-Catalyzed Hydrocyanation of Olefins with Tosyl Cyanide (pages 4519–4522)

      Boris Gaspar and Erick M. Carreira

      Version of Record online: 4 MAY 2007 | DOI: 10.1002/anie.200700575

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      Mild-mannered and well-behaved: A conceptually new hydrocyanation reaction for non-activated olefins provides secondary and tertiary nitriles in good yields under mild conditions. Salient features of this process include broad functional-group tolerance, readily available starting materials, and ease of execution.

    19. Mixtures of Chiral Phosphorous Acid Diesters and Achiral P Ligands in the Enantio- and Diastereoselective Hydrogenation of Ketimines (pages 4523–4526)

      Manfred T. Reetz and Oleg Bondarev

      Version of Record online: 8 MAY 2007 | DOI: 10.1002/anie.200700533

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      Try this cocktail! Ligand systems comprising a monodentate phosphorous acid diester derived from binol (La) and an achiral monodentate P ligand (Lb), such as a phosphite, are surprisingly efficient in the stereoselective Ir-catalyzed hydrogenation of ketimines (see scheme).

      Corrected by:

      Corrigendum: Mixtures of Chiral Phosphorous Acid Diesters and Achiral P Ligands in the Enantio- and Diastereoselective Hydrogenation of Ketimines

      Vol. 46, Issue 43, 8107, Version of Record online: 26 OCT 2007

    20. Synthesis and Stereochemical Assignment of FR252921, a Promising Immunosuppressant (pages 4527–4529)

      J. Russell Falck, Anyu He, Hiroki Fukui, Hideyuki Tsutsui and Akella Radha

      Version of Record online: 8 MAY 2007 | DOI: 10.1002/anie.200700321

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      Synthetic detective work: FR252921, an unusual 19-membered lactone–dilactam, and three of its diastereomers were prepared by a versatile, convergent strategy from three key segments (see scheme). Comparison of the synthetic compounds with natural material established conclusively that FR252921 has the configuration 12S,13R,18R.

    21. Persistent Silylium Ions Stabilized by Polyagostic Si[BOND]H⋅⋅⋅Si Interactions (pages 4530–4533)

      Andrey Y. Khalimon, Zi Hua Lin, R. Simionescu, Sergei F. Vyboishchikov and Georgii I. Nikonov

      Version of Record online: 4 MAY 2007 | DOI: 10.1002/anie.200604258

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      Diagnostics for diagostics: The silylium ion 1 (see picture; C orange, Si red, H gray) is highly fluxional at room temperature but at −80 °C exhibits a symmetric structure with a three-center two-electron Si-H-Si bond supported by two additional Si[LEFTWARDS ARROW]H-Si agostic interactions. In the related cation 2, two Si[BOND]H bonds coordinate equivalently to the cationic silicon center to afford a symmetrical pentacoordinate silylium ion.

    22. Efficient Enantioselective Synthesis of Piperidines through Catalytic Asymmetric Ring-Opening/Cross-Metathesis Reactions (pages 4534–4538)

      G. Alex Cortez, Richard R. Schrock and Amir H. Hoveyda

      Version of Record online: 11 MAY 2007 | DOI: 10.1002/anie.200605130

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      Mo the better! Chiral Mo complexes promote highly efficient asymmetric ring-opening/cross-metathesis reactions that afford functionalized piperidines in high E:Z selectivity and enantiomeric purity (see scheme for example; TBS=tert-butyldimethylsilyl). In most cases, Ru catalysts are ineffective.

    23. Unit-Cell-Level Assembly of Metastable Transition-Metal Oxides by Pulsed-Laser Deposition (pages 4539–4542)

      Lei Yan, Hongjun Niu, Craig A. Bridges, Paul A. Marshall, Joke Hadermann, Gustaav van Tendeloo, Paul R. Chalker and Matthew J. Rosseinsky

      Version of Record online: 10 MAY 2007 | DOI: 10.1002/anie.200700119

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      One layer at a time: The sequential pulsed-laser deposition of CaO rock-salt and CaMnO3 perovskite layers on an SrTiO3 substrate allows the growth of the metastable n=4, 5, and 6 members of the Can+1MnnO3n+1 Ruddlesden–Popper series (see high-resolution TEM image of Ca5Mn4O13). The growth process is monitored using reflection high-energy electron diffraction.

    24. α-Amino Acid Induced Rate Acceleration in Aqueous Biphasic Lewis Acid Catalyzed Michael Addition Reactions (pages 4543–4546)

      Karolina Aplander, Rui Ding, U. Marcus Lindström, Johan Wennerberg and Sara Schultz

      Version of Record online: 4 MAY 2007 | DOI: 10.1002/anie.200700560

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      It's as easy as ABC: α-Amino acids may become very important tools in the development of economical and environmentally friendly aqueous biphasic catalysis. Alanine accelerated an Yb(OTf)3-catalyzed Michael addition by a factor of 138. The solubilizing and stabilizing properties of alanine allowed the metal catalyst to be “heterogenized” in the aqueous phase and recycled multiple times without appreciable loss of activity.

    25. The Preparation of Supported NiO and Co3O4 Nanoparticles by the Nitric Oxide Controlled Thermal Decomposition of Nitrates (pages 4547–4549)

      Jelle R. A. Sietsma, Johannes D. Meeldijk, Johan P. den Breejen, Marjan Versluijs-Helder, A. Jos van Dillen, Petra E. de Jongh and Krijn P. de Jong

      Version of Record online: 3 MAY 2007 | DOI: 10.1002/anie.200700608

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      A need for NO: Moderating the thermal decomposition of supported nitrates with NO (see picture, center) prevents precursor mobility and is a versatile method for the preparation of small NiO (left; compared to the product of the conventional procedure, right) and Co3O4 particles. These materials can be used as heterogeneous catalysts and show good activity in the Fischer–Tropsch synthesis.

    26. CB7: Experimental and Theoretical Evidence against Hypercoordinate Planar Carbon (pages 4550–4553)

      Lei-Ming Wang, Wei Huang, Boris B. Averkiev, Alexander I. Boldyrev and Lai-Sheng Wang

      Version of Record online: 8 MAY 2007 | DOI: 10.1002/anie.200700869

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      Changing the wheel: Replacing one B unit by C in B82− is predicted to yield a CB7 molecular wheel, which has now been produced by laser vaporization. Ab initio calculations show that CB7 has an extremely stable planar C2v structure in which C replaces B at the rim of the B82− molecular wheel (see picture). The D7h structure with a heptacoordinate C atom lies 63 kcal mol−1 above the C2v structure.

    27. Enantioselective Synthesis of Allylsilanes Bearing Tertiary and Quaternary Si-Substituted Carbons through Cu-Catalyzed Allylic Alkylations with Alkylzinc and Arylzinc Reagents (pages 4554–4558)

      Monica A. Kacprzynski, Tricia L. May, Stephanie A. Kazane and Amir H. Hoveyda

      Version of Record online: 8 MAY 2007 | DOI: 10.1002/anie.200700841

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      All sorts of allylsilanes including, for the first time, those that contain a Si-bonded quaternary carbon, were synthesized through efficient and highly enantioselective Cu-catalyzed asymmetric allylic alkylations. Reactions may involve dialkyl- as well as diarylzinc reagents and are promoted by various chiral N-heterocyclic carbene complexes.

    28. Titanium-Catalyzed Asymmetric Epoxidation of Non-Activated Olefins with Hydrogen Peroxide (pages 4559–4561)

      Yuji Sawada, Kazuhiro Matsumoto and Tsutomu Katsuki

      Version of Record online: 4 MAY 2007 | DOI: 10.1002/anie.200700949

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      A greener oxidation: A titanium(salalen) complex catalyzes the asymmetric epoxidation of aliphatic (non-activated) olefins using aqueous hydrogen peroxide as the oxidant. Reactions with aliphatic terminal and Z olefins furnish the corresponding epoxides in good yields with high enantioselectivities of up to 97 % ee.

    29. Organocatalytic Enantioselective Reduction of Pyridines (pages 4562–4565)

      Magnus Rueping and Andrey P. Antonchick

      Version of Record online: 11 MAY 2007 | DOI: 10.1002/anie.200701158

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      Metal-free at last! The first enantioselective organocatalytic reduction of pyridine derivatives leads to hexahydrochinolinones and tetrahydropyridines in good yields and with excellent enantioselctivities (up to 92 % ee; see scheme). These compounds are starting materials for the synthesis of various natural products.

    30. From the Alkyllithium Aggregate [{(nBuLi)2⋅PMDTA}2] to Lithiated PMDTA (pages 4566–4569)

      Carsten Strohmann and Viktoria H. Gessner

      Version of Record online: 7 MAY 2007 | DOI: 10.1002/anie.200605105

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      A commonly used deprotonation agent is the combination of n-butyllithium and N,N,N′,N′′,N′′-pentamethyldiethylenetriamine (PMDTA). The highly reactive aggregate [{(nBuLi)2⋅PMDTA}2] crystallizes out of a 2:1 mixture of nBuLi and PMDTA. The molecular structure provides insight into the significant influence of the nBuLi/PMDTA ratio on the course of some deprotonation reactions.

    31. Stereoselective Syntheses and Reactions of Stannylated Peptides (pages 4570–4573)

      Jan Deska and Uli Kazmaier

      Version of Record online: 7 MAY 2007 | DOI: 10.1002/anie.200700759

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      In one fell swoop: Stannylated allyl carbonates allow the highly stereoselective synthesis of metalated peptides, which can be further modified by Stille coupling. Tin–iodine exchange generates iodinated peptides which also can be used for C[BOND]C coupling reactions. Therefore, only one stereoselective reaction is necessary to generate a wide range of different peptides in stereochemically pure form.

    32. Octacyclopropylcubane and Some of Its Isomers (pages 4574–4576)

      Armin de Meijere, Stefan Redlich, Daniel Frank, Jörg Magull, Anja Hofmeister, Henning Menzel, Burkhard König and Jiri Svoboda

      Version of Record online: 4 MAY 2007 | DOI: 10.1002/anie.200605150

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      Decorator rocket fuel? Tricyclooctadiene 1, easily prepared in a single-pot operation from dicyclopropylethyne in 67 % yield, upon irradiation in pentane solution undergoes an intramolecular [2+2] cycloaddition to give octacyclopropylcubane (2) in remarkably good yield (48 %). The new cubane derivative with an overall strain energy of >390 kcal mol−1 displays unique physical and chemical properties.

    33. Solid-Phase Synthesis of Peptide Thioesters with Self-Purification (pages 4577–4580)

      Franziska Mende and Oliver Seitz

      Version of Record online: 3 MAY 2007 | DOI: 10.1002/anie.200700356

      Thumbnail image of graphical abstract

      Separating the wheat from the chaff: A cyclization–thiolysis sequence adds a new property to sulfonamide safety-catch resins. Activation of the sulfonamide is used to introduce a carboxy group for subsequent macrocyclization. Truncation products are noncyclic and hence washed away following thiolytic ring opening. Only the full-length peptide thioesters are detached, usually in pure form, in the final step.

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