Angewandte Chemie International Edition

Cover image for Vol. 42 Issue 40

October 20, 2003

Volume 42, Issue 40

Pages 4837–4977

    1. Cover Picture: Organocatalytic Asymmetric Michael Reaction of Cyclic 1,3-Dicarbonyl Compounds and α,β-Unsaturated Ketones—A Highly Atom-Economic Catalytic One-Step Formation of Optically Active Warfarin Anticoagulant (Angew. Chem. Int. Ed. 40/2003) (page 4837)

      Nis Halland, Tore Hansen and Karl Anker Jørgensen

      Version of Record online: 15 OCT 2003 | DOI: 10.1002/anie.200390597

      Optically active anticoagulants are formed in a new one-step organocatalytic asymmetric Michael reaction. The synthesis of the optically active warfarin from simple starting materials is shown. The background is a CT-scanning image of the lungs, where thrombosis can occur. The other images show a heart with a thrombus (left), and the same heart after surgery and treatment with anticoagulant (right), these images can be seen as films in the Supporting Information. Full details are in the Communication by K. A. Jørgensen et al. on page 4955 ff.

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      6-Amino-3-Pyridinols: Towards Diffusion-Controlled Chain-Breaking Antioxidants (page 4847)

      Maikel Wijtmans, Derek A. Pratt, Luca Valgimigli, Gino A. DiLabio, Gian Franco Pedulli and Ned A. Porter

      Version of Record online: 15 OCT 2003 | DOI: 10.1002/anie.200390599

    3. Alkaloids. Nature's Curse or Blessing? By Manfred Hesse. (pages 4852–4854)

      Franz von Nussbaum

      Version of Record online: 15 OCT 2003 | DOI: 10.1002/anie.200385928

    4. Suzuki Reaction Takes a “Naked Hot Bath”: Coupling in High-Temperature Water without Transition Metals (pages 4856–4858)

      Chao-Jun Li

      Version of Record online: 15 OCT 2003 | DOI: 10.1002/anie.200301672

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      Hot stuff: The Suzuki reaction of arylboronic derivatives with aryl halides is the most important method for generating aryl–aryl coupling products. Now such couplings have become easier and cleaner in hot water without the need of a transition-metal catalyst (see scheme).

    5. Electrochemical and Photochemical Control of Host–Guest Complexation at Surfaces (pages 4860–4870)

      Graeme Cooke

      Version of Record online: 15 OCT 2003 | DOI: 10.1002/anie.200301636

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      Solid progress: The transfer of responsive supramolecular systems from the solution to the solid state by immobilizing their components onto surfaces is an attractive method for developing systems with molecular electronics and device applications (see scheme). The ability to coherently interface these systems with the outside world may pave the way for their implementation as novel components within the emerging advanced materials and nanotechnology industries.

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      Binding Affinities of Host–Guest, Protein–Ligand, and Protein–Transition-State Complexes (pages 4872–4897)

      K. N. Houk, Andrew G. Leach, Susanna P. Kim and Xiyun Zhang

      Version of Record online: 15 OCT 2003 | DOI: 10.1002/anie.200200565

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      Statistically shown: Complexes of enzymes and catalytic antibodies with their substrates and cyclodextrins, synthetic hosts, and albumins with organic molecules all have similar association constants (Ka) of 101–106M−1. Antibody–antigen and enzyme–inhibitor complexes achieve tighter binding (Ka=104–1012M−1) and enzyme–transition-state binding is much stronger (Ka=1010–1020M−1). The origins of these differences, the role of enthalpy/entropy compensation, and the relationships between the size of the buried solvent-accessible surface areas of the guest and binding affinities are analyzed.

    7. Native Electron Capture Dissociation for the Structural Characterization of Noncovalent Interactions in Native Cytochrome c (pages 4900–4904)

      Kathrin Breuker and Fred W. McLafferty

      Version of Record online: 23 SEP 2003 | DOI: 10.1002/anie.200351705

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      Selectively cleaved: Under appropriate experimental conditions, electrospray ionization mass spectrometry produces fragment ions that directly indicate noncovalent protein–heme interaction sites in native Cytochrome c (see picture). The proposed mechanism involves asymmetric charge partitioning in gaseous protein dimer ions, which causes electron transfer and subsequent backbone-cleavage.

    8. Formation of Water Clusters in a Hydrophobic Solvent (pages 4904–4908)

      Thorsten Köddermann, Frank Schulte, Markus Huelsekopf and Ralf Ludwig

      Version of Record online: 15 OCT 2003 | DOI: 10.1002/anie.200351438

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      And not a drop to drink: Hydrogen-bonded water clusters could be detected in CCl4 by IR spectroscopy. The comparison between measured and calculated frequencies along with the characteristic temperature behavior of band intensities suggests that cyclic clusters are formed up to the tetramer (see picture).

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      Daylight Photocatalysis by Carbon-Modified Titanium Dioxide (pages 4908–4911)

      Shanmugasundaram Sakthivel and Horst Kisch

      Version of Record online: 15 OCT 2003 | DOI: 10.1002/anie.200351577

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      Green titana: Carbon-doped titanium dioxide, supported onto filter paper, photocatalyzes the gas-phase degradation of the atmospheric pollutants benzene (a), acetaldehyde (b) and carbon monoxide (c) in diffuse indoor visible light (see picture).

    10. La2CuS4: A Lanthanum Copper Sulfide with Discrete Anion Triples [S3Cu⋅⋅⋅S[BOND]S⋅⋅⋅CuS3]12− Based on La4[Cu2S6(S2)] (pages 4911–4913)

      Sabine Strobel and Thomas Schleid

      Version of Record online: 15 OCT 2003 | DOI: 10.1002/anie.200351641

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      A unique structure: In the crystalline state the lanthanum copper sulfide La2CuS4 comprises discrete anion triples. These are composed of almost planar triangular [CuS3]5− units, which consist of Cu+ and S2− ions linked through a S[BOND]S-dumbbell to form the [S3Cu⋅⋅⋅S[BOND]S⋅⋅⋅CuS3]12− anion (see picture).

    11. Coupling of Mechanical and Chemical Energy: Proton Affinity as a Function of External Force (pages 4913–4915)

      Martin K. Beyer

      Version of Record online: 15 OCT 2003 | DOI: 10.1002/anie.200351748

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      Small action, large effect: The proton affinity has been defined as a function of an external mechanical force and its applicability as a chemical concept is explored (see scheme). It is shown that forces in the sub-nN to nN range change the proton affinity of small model molecules by values ranging from kT up to several 10 kJ mol−1, which suggests that these affinity changes are chemically significant.

    12. Expressed Enzymatic Ligation for the Semisynthesis of Chemically Modified Proteins (pages 4916–4918)

      Zuzana Machova, Regula von Eggelkraut-Gottanka, Nicole Wehofsky, Frank Bordusa and Annette G. Beck-Sickinger

      Version of Record online: 30 SEP 2003 | DOI: 10.1002/anie.200351774

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      Enzymatic synthesis and expressed protein ligation were combined in a method for protein synthesis in which protein thioesters with specific leaving groups could be used by protease V8 from Staphylococcus aureus to catalyze the formation of peptide bonds. This method was applied to the synthesis of fluorescence-labeled (Fl) analogues of proneuropeptide Y (proNPY; see scheme). CBD=chitin binding domain.

    13. Synthesis and Characterization of Dendritic Necklaces: A Class of Outer-Sphere–Outer-Sphere Connected Dendronized Organoplatinum Polymers (pages 4919–4923)

      Hak-Fun Chow, Cham-Fai Leung, Wei Li, Kai-Wai Wong and Luan Xi

      Version of Record online: 15 OCT 2003 | DOI: 10.1002/anie.200351613

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      Molecular jewelry! Up to 880 dendrimer beads can be joined together with Pt complexes to make a long “necklace” of dendrimers (see picture). The polymerization of dendrimers that contain reactive functional subunits on the dendrimer surface opens a new route to a novel class of dendronized polymers of high molecular weights and in good yields.

    14. Gas-Phase Reduction of Oxides of Nitrogen with CO Catalyzed by Atomic Transition-Metal Cations (pages 4923–4927)

      Voislav Blagojevic, Michael J. Y. Jarvis, Eric Flaim, Gregory K. Koyanagi, Vitali V. Lavrov and Diethard K. Bohme

      Version of Record online: 15 OCT 2003 | DOI: 10.1002/anie.200351628

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      A novel catalytic role for transition-metal cations in the homogeneous conversion of the nitrogen oxides NO2, NO, or N2O and CO into N2 and CO2 is demonstrated by thermodynamic and kinetic studies of gas-phase reactions of 29 transition-metal cations and some of their oxides (see scheme). Fe+, Os+, and Ir+ ions are shown to be most effective. The chemistry identified may have practical applications in new designs of catalytic converters.

    15. Effective Modular Iminooxazoline (IMOX) Ligands for Asymmetric Catalysis: [Zn(IMOX)]-Promoted Enantioselective Reduction of Ketones by Catecholborane (pages 4928–4930)

      Manuela Locatelli and Pier Giorgio Cozzi

      Version of Record online: 15 OCT 2003 | DOI: 10.1002/anie.200351754

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      Closing the door to nucleophilic attack on one face of the substrate by using a bulky substituent (see schematic formula) was the key to obtaining high enantiomeric excesses in the reduction of methyl ketones by catecholborane with promotion by zinc complexes of new chiral iminooxazoline (IMOX) ligands. The modular nature, simple design, and possibility to produce tailored IMOX ligands could be advantages in designing the next generation of these chiral ligands.

    16. Chloride Transport Across Vesicle and Cell Membranes by Steroid-Based Receptors (pages 4931–4933)

      Atanas V. Koulov, Timothy N. Lambert, Rameshwer Shukla, Mahim Jain, J. Middleton Boon, Bradley D. Smith, Hongyu Li, David N. Sheppard, Jean-Baptiste Joos, John P. Clare and Anthony P. Davis

      Version of Record online: 15 OCT 2003 | DOI: 10.1002/anie.200351957

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      Crossing the barriers: Membrane transport, a well-established phenomenon for neutral cation receptors such as valinomycin, has been demonstrated for the anion-binding “cholapods”. The cholapods promote chloride efflux from vesicles by an antiport mechanism and mediate anion flow through live cells grown as epithelia (see schematic representation).

    17. Label-Free Detection of DNA Hybridization at the Nanoscale: A Highly Sensitive and Selective Approach Using Atomic-Force Microscopy (pages 4934–4937)

      Dejian Zhou, Kumar Sinniah, Chris Abell and Trevor Rayment

      Version of Record online: 15 OCT 2003 | DOI: 10.1002/anie.200352178

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      Less than 10−21mol of label-free probe DNA with high sequence specificity can be quantitatively detected on a surface by using AFM to create nanofeatures of single-stranded DNA and monitor the topographic changes upon exposure to a complimentary DNA (see scheme).

    18. Direct Oxidation of Benzene to Phenol with Hydrogen Peroxide over a Modified Titanium Silicalite (pages 4937–4940)

      Luigi Balducci, Daniele Bianchi, Rossella Bortolo, Rino D'Aloisio, Marco Ricci, Roberto Tassinari and Raffaele Ungarelli

      Version of Record online: 15 OCT 2003 | DOI: 10.1002/anie.200352184

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      Stopping the rot! The selective oxidation of benzene to phenol with hydrogen peroxide is achieved by using a new zeolite catalyst (TS-1B), obtained by the modification of titanium silicalite with NH4HF2 and H2O2 (see scheme). The new catalyst, used in presence of a particular cosolvent (sulfolane) protects the produced phenol from overoxidation and dramatically enhances the selectivity of the reaction.

    19. A 1-Methyl-Phosphininium Compound: Synthesis, X-Ray Crystal Structure, and DFT Calculations (pages 4940–4944)

      Audrey Moores, Louis Ricard and Pascal Le Floch

      Version of Record online: 15 OCT 2003 | DOI: 10.1002/anie.200352230

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      A tetravalent phosphorus atom in an aromatic system! A 1-methylphosphininium tetrachlorogallate is synthesized and fully characterized (see structure). This compound has aromatic properties like those of phosphinine, pyridine, and pyridinium salts. These features were asserted and quantified by DFT calculations. This phosphininium salt reacts easily with an alkyne to yield a phosphabarellenium salt through a Diels–Alder reaction.

    20. Electrochemistry within a Limited Number of Molecules: Delineating the Fringe Between Stochastic and Statistical Behavior (pages 4944–4947)

      Christian Amatore, Frédéric Grün and Emmanuel Maisonhaute

      Version of Record online: 15 OCT 2003 | DOI: 10.1002/anie.200352353

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      The behavior of a limited number of molecules is expected to show a profound stochastic character and therefore to significantly differ from the usual chemical kinetic laws. This dichotomy is investigated theoretically within an electrochemical framework by considering the specific example of the oxidation of a PAMAM redox dendrimer caped by 64 ruthenium bis-terpyridine centers (see picture). Thus the maximum number of adsorbed molecules at which the observation of the intrinsic stochastic nature of the phenomenon should remain observable can be evaluated, either by itself, or when instrumental distortions are involved.

    21. The Two Main DNA Lesions 8-Oxo-7,8-dihydroguanine and 2,6-Diamino-5-formamido-4-hydroxypyrimidine Exhibit Strongly Different Pairing Properties (pages 4947–4951)

      Matthias Ober, Uwe Linne, Johannes Gierlich and Thomas Carell

      Version of Record online: 15 OCT 2003 | DOI: 10.1002/anie.200351287

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      A stable analogue (cFapydGuo) of the major oxidative DNA lesion FapydGuo was prepared. The direct comparison of the pairing properties of the oxidative lesion β-8-oxodGuo and β-cFapydGuo (see formulae) revealed significant differences in base pairing, indicative of unexpected mutagenic differences.

    22. A Ruthenium Pterin Complex Showing Proton-Coupled Electron Transfer: Synthesis and Characterization (pages 4951–4954)

      Takahiko Kojima, Taisuke Sakamoto, Yoshihisa Matsuda, Kei Ohkubo and Shunichi Fukuzumi

      Version of Record online: 15 OCT 2003 | DOI: 10.1002/anie.200352111

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      Coupled to coenzymes: Ruthenium(II) complexes having a pterin as a ligand, which is a redox-active heteroaromatic coenzyme, are synthesized and characterized to reveal that the complexes showed reversible proton-dependent redox behavior (see scheme). The pterin ligand undergoes proton-coupled electron transfer to form a ruthenium(II)-coordinated monohydropterin radical upon one-electron reduction.

    23. Organocatalytic Asymmetric Michael Reaction of Cyclic 1,3-Dicarbonyl Compounds and α,β-Unsaturated Ketones—A Highly Atom-Economic Catalytic One-Step Formation of Optically Active Warfarin Anticoagulant (pages 4955–4957)

      Nis Halland, Tore Hansen and Karl Anker Jørgensen

      Version of Record online: 29 SEP 2003 | DOI: 10.1002/anie.200352136

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      A broad range of Michael adducts 3 were obtained by the organocatalytic asymmetric Michael addition of cyclic 1,3-dicarbonyl compounds 1 to α,β-unsaturated ketones 2. The reaction allows a one-step synthesis of the optically active anticoagulant warfarin and several analogues 3 on a kilogram scale in up to 99 % yield with 88 % ee (>99.9 % ee after a single recrystallization).

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      Amide from Dinitrogen by In Situ Cleavage and Partial Hydrogenation Promoted by a Transient Zero-Valent Thorium Synthon (pages 4958–4961)

      Ilia Korobkov, Sandro Gambarotta and Glenn P. A. Yap

      Version of Record online: 29 SEP 2003 | DOI: 10.1002/anie.200352205

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      Reduction through cleavage: The reduction of a tetravalent thorium–bisdiaryloxide complex 1 with [K(naphthalenide)] leads to the cleavage of dinitrogen and partial hydrogenation via the probable formation of a zero-valent thorium–amide synthon (2; see scheme).

    25. A Concise and Flexible Total Synthesis of (−)-Diazonamide A (pages 4961–4966)

      Anthony W. G. Burgett, Qingyi Li, Qi Wei and Patrick G. Harran

      Version of Record online: 30 SEP 2003 | DOI: 10.1002/anie.200352577

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      The remarkable action of an IIIIspecies on a tripeptide containing acyclic tyrosine/tryptophan is the key step in a total synthesis of (−)-diazonamide A. The completed preparation of this new antimitotic is concise, multiply convergent, and amenable to diversification of intermediates.

    26. Exceptional Redox and Photophysical Properties of a Triply Fused Diporphyrin–C60 Conjugate: Novel Scaffolds for Multicharge Storage in Molecular Scale Electronics (pages 4966–4970)

      Davide Bonifazi, Markus Scholl, Fayi Song, Luis Echegoyen, Gianluca Accorsi, Nicola Armaroli and François Diederich

      Version of Record online: 15 OCT 2003 | DOI: 10.1002/anie.200352265

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      Up to fifteen electrons are reversibly accommodated in a triply fused porphyrin dimer conjugated to two [60]fullerene moieties. Its photophysical properties differ completely from those of the many known porphyrin–fullerene dyads: Photoexcitation of the C60 moieties results in quantitative sensitization of the low-lying (about 1 eV) and very short lived lowest singlet level of the porphyrin sheet (see scheme).

    27. Preview: Angew. Chem. Int. Ed. 40/2003 (page 4977)

      Version of Record online: 15 OCT 2003 | DOI: 10.1002/anie.200390601

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