Angewandte Chemie International Edition

Cover image for Vol. 43 Issue 13

March 19, 2004

Volume 43, Issue 13

Pages 1605–1745

    1. Cover Picture: Chemistry and Biology of Terpene Trilactones from Ginkgo Biloba (Angew. Chem. Int. Ed. 13/2004) (page 1605)

      Kristian Strømgaard and Koji Nakanishi

      Version of Record online: 17 MAR 2004 | DOI: 10.1002/anie.200490035

      Terpene trilactones from the ginkgo tree (Ginkgo biloba) are at least partly responsible for the neuromodulatory effects of G. biloba extracts. The cover picture shows a young ginkgo tree, with its characteristic fan-shaped leaves, growing out of a human brain. Superimposed are the X-ray crystal structures of bilobalide and ginkgolide B. K. Strømgaard and K. Nakanishi discuss the current status of bilobalide and ginkgolides in their Review on page 1640 ff., with a particular focus on chemical and biological studies.

    2. Chemistry in Motion—Unidirectional Rotating Molecular Motors (pages 1622–1624)

      Christian P. Mandl and Burkhard König

      Version of Record online: 17 MAR 2004 | DOI: 10.1002/anie.200301697

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      Clockwise or counterclockwise? On the molecular level this is determined by kinetic control of the competing routes to the new energetically minimized structure. Three recent examples show how this can be achieved. The picture shows a molecular rotor whose large macrocycle contains three binding sites between which the small macrocycle moves.

    3. Bigger DNA: New Double Helix with Expanded Size (pages 1625–1626)

      Andreas Marx and Daniel Summerer

      Version of Record online: 17 MAR 2004 | DOI: 10.1002/anie.200301737

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      Outsized nucleosides inside: A recent report described the rational design of an artificial DNA double helix (xDNA) with increased diameter. The pairing system is based on nucleobase analogues which maintain the natural Watson–Crick binding sites but have extended aromatic surfaces (see picture, view along DNA and xDNA helices).

    4. Nanocatalysis: Mature Science Revisited or Something Really New? (pages 1628–1637)

      Robert Schlögl and Sharifah Bee Abd Hamid

      Version of Record online: 17 MAR 2004 | DOI: 10.1002/anie.200301684

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      Heterogeneous catalysis requires nanosized solids to enable dynamical interactions with substrates. Current techniques give chemically complex materials with poorly defined properties. An alternative approach yields “nanocatalysts” in the form of inorganic polymers whose building blocks are active sites with minimial chemical complexity (the picture shows nanoplatelets of MoO3 hydrate consisting of corner-sharing octahedra).

    5. Chemistry and Biology of Terpene Trilactones from Ginkgo Biloba (pages 1640–1658)

      Kristian Strømgaard and Koji Nakanishi

      Version of Record online: 17 MAR 2004 | DOI: 10.1002/anie.200300601

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      Barking up the right tree: The pharmacological effects of extracts of Ginkgo biloba, the ginkgo tree, are attributed to the structurally unique components, the ginkgolides (see structure, R=H or OH) and bilobalide. The biosynthesis, synthesis, structure–activity relationship studies, and pharmacological effects of these terpene trilactones are described.

    6. Proton-Assisted Ethylene Hydration in Aqueous Solution (pages 1660–1662)

      Titus S. van Erp and Evert Jan Meijer

      Version of Record online: 27 FEB 2004 | DOI: 10.1002/anie.200353103

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      Specific coordination structures like those shown are crucial for inducing reactive events in the proton-assisted hydration of ethylene in aqueous solution as well as in the reverse reaction. An atomistic description of the solvation of the reacting species was possible in this ab initio molecular dynamics study.

    7. Responsive Cyclohexane-Based Low-Molecular-Weight Hydrogelators with Modular Architecture (pages 1663–1667)

      Kjeld J. C. van Bommel, Cornelia van der Pol, Inouk Muizebelt, Arianna Friggeri, André Heeres, Auke Meetsma, Ben L. Feringa and Jan van Esch

      Version of Record online: 17 MAR 2004 | DOI: 10.1002/anie.200352396

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      pH-sensitive gels: By using a cyclohexane-based scaffold to which various amino acid based substituents can be connected, low-molecular-weight compounds were obtained that can gelate water at very low concentrations. Their modular design (see picture: AA=amino acid(s), X=hydrophilic substituent, dark purple=hydrophobic region, light purple=hydrophilic region), allows tuning of the thermally and pH-induced reversible gel-to-sol transition of their gels.

    8. An Electrochemically Controlled Molecular Shuttle (pages 1668–1672)

      Bohdan Korybut-Daszkiewicz, Agnieszka Wiȩckowska, Renata Bilewicz, Sławomir Domagała and Krzysztof Woźniak

      Version of Record online: 17 MAR 2004 | DOI: 10.1002/anie.200352528

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      Usurping the crown: A controlled intramolecular motion of the crown moiety from around the Ni to the Cu center takes place in a transition-metal hetero-dinuclear [2]catenane in response to an applied potential (see picture).

    9. Methotrexate Conjugates: A Molecular In Vivo Protein Tag (pages 1672–1675)

      Lawrence W. Miller, Julia Sable, Philip Goelet, Michael P. Sheetz and Virginia W. Cornish

      Version of Record online: 17 MAR 2004 | DOI: 10.1002/anie.200352852

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      The labeling of proteins in living cells with fluorescent substituents is critical to the study of cell biology. A ligand–receptor approach based on the interaction between dihydrofolate reductase (DHFR) and methotrexate (Mtx) serves as a general method for labeling proteins with fluorescent or otherwise functional small molecules in vivo (see figure).

    10. Targeted Enzyme-Responsive Drug Carriers: Studies on the Delivery of a Combination of Drugs (pages 1675–1678)

      Myung-Ryul Lee, Kyung-Hwa Baek, Hui Juan Jin, Yong-Gyu Jung and Injae Shin

      Version of Record online: 17 MAR 2004 | DOI: 10.1002/anie.200353204

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      Double whammy: Effective and selective killing of E. coli cells containing a specific enzyme was achieved by using targeted enzyme-responsive drug carriers (see picture) that release free drugs in a stringently controlled manner. The carrier lowered the effective concentration of drug needed to kill the bacteria. The system could also be modified to deliver a combination of two drugs.

    11. Copper(II)-Catalyzed Highly Enantioselective Addition of Enamides to Imines: The Use of Enamides as Nucleophiles in Asymmetric Catalysis (pages 1679–1681)

      Ryosuke Matsubara, Yoshitaka Nakamura and Shū Kobayashi

      Version of Record online: 17 MAR 2004 | DOI: 10.1002/anie.200353237

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      High-yielding efficient routes to optically active amino acid and 1,3-diamine derivatives have been achieved by the catalytic enantioselective addition of enamides to imines using a chiral copper catalyst (see scheme). This reaction demonstrates the utility of enamides as nucleophiles. The reaction mechanism and the structure of the chiral catalyst are also discussed.

    12. Synthetic Strategy toward Skeletal Diversity via Solid-Supported, Otherwise Unstable Reactive Intermediates (pages 1681–1685)

      Steven J. Taylor, Alexander M. Taylor and Stuart L. Schreiber

      Version of Record online: 17 MAR 2004 | DOI: 10.1002/anie.200353466

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      Solid supports lend stability: Skeletally diverse alkaloid-like compounds were obtained in only three steps from simple starting materials through a strategy based on dihydropyridine and dihydroisoquinoline intermediates supported on macrobeads (see picture). The otherwise unstable enamine double bond present in the intermediates can undergo a variety of transformations, including cycloadditions, selective reductions, and alkylations.

    13. Heterogeneous Enantioselective Catalyzed Carbonyl- and Imino-Ene Reactions using Copper Bis(Oxazoline) Zeolite Y (pages 1685–1688)

      Neil A. Caplan, Frederick E. Hancock, Philip C. Bulman Page and Graham J. Hutchings

      Version of Record online: 17 MAR 2004 | DOI: 10.1002/anie.200352534

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      A recovery discovery: A simple pathway for the synthesis of α-hydroxy and α-amino carbonyl compounds with good yields and high enantioselection is provided by the first heterogeneously catalyzed enantioselective carbonyl-ene and imino-ene reactions. The catalyst is a bis(oxazoline)-modified CuH zeolite Y (Cu-HY)system (see scheme; Rox=CH3,H; Rbrg=Ph,C(CH3)3), which can easily be recovered and reused.

    14. Enantiomeric Resolution of a Ruffled Porphyrinoid (pages 1688–1691)

      Heather W. Daniell and Christian Brückner

      Version of Record online: 17 MAR 2004 | DOI: 10.1002/anie.200352970

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      Let's twist again: Reaction of a racemic mixture of secochlorinato nickel(ii) with cholesterol generates separable diastereomers of a novel porphyrinic chromophore containing a direct β-to-o-phenyl linkage. Exchange of the cholesteryl side chain for an ethyl group produces the enantiomeric conformers of the ruffled macrocycle (see picture).

    15. HP-RAFT: A Free-Radical Polymerization Technique for Obtaining Living Polymers of Ultrahigh Molecular Weights (pages 1691–1694)

      Javid Rzayev and Jacques Penelle

      Version of Record online: 1 MAR 2004 | DOI: 10.1002/anie.200353025

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      Poly(methyl methacrylate)s of extremely high molecular weights (>106) and narrow molecular weight distributions (w/n<1.2:1) were easily obtained by living/controlled free-radical polymerization under high hydrostatic pressure (5 kbar; see scheme, AIBN=2,2′-azobis(isobutyronitrile)). This technique provides conditions amenable to industrial scale-up.

    16. Let the Best Ring Win: Selective Macrocycle Formation through Pd-Catalyzed or Cu-Mediated Alkyne Homocoupling (pages 1694–1697)

      Jeremiah A. Marsden, Jeremie J. Miller and Michael M. Haley

      Version of Record online: 17 MAR 2004 | DOI: 10.1002/anie.200353043

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      Competition is good: The reported “Pd” homocoupling procedure is now a viable alternative to the traditional Cu-mediated reaction for the formation of diacetylenic macrocycles. From the same starting material, use of Cu(OAc)2 or [PdCl2(dppe)]/I2 (dppe=1,2-bis(diphenylphosphanyl)ethane) leads to selective formation of either the bis[15]- or bis[14]annulenes (see scheme).

    17. High-Throughput Measurement of the Enantiomeric Excess of Chiral Alcohols by Using Two Enzymes (pages 1698–1702)

      Zhi Li, Lukas Bütikofer and Bernard Witholt

      Version of Record online: 17 MAR 2004 | DOI: 10.1002/anie.200353055

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      Rapideedetermination: Enantioselective alcohol dehydrogenases A and B were used to oxidize chiral alcohols in a sensitive, accurate, high-throughput method (see scheme). The reaction rates were determined by monitoring the formation of NAD(P)H by UV spectroscopy. The ee value was calculated from the reaction rates and the kinetic constants of the enzymes.

    18. A Tandem Semipinacol Rearrangement/Alkylation of α-Epoxy Alcohols: An Efficient and Stereoselective Approach to Multifunctional 1,3-Diols (pages 1702–1705)

      Xiang-Dong Hu, Chun-An Fan, Fu-Min Zhang and Yong Qiang Tu

      Version of Record online: 17 MAR 2004 | DOI: 10.1002/anie.200353177

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      Three contiguous stereocenters, two of which are quaternary carbon atoms, were efficiently and stereoselectively constructed by a tandem semipinacol rearrangement/alkylation of α-epoxy alcohols with RB(OH)2 (see scheme).

    19. Infrared Spectra of Indium Hydrides in Solid Hydrogen and of Solid Indane (pages 1706–1709)

      Lester Andrews and Xuefeng Wang

      Version of Record online: 17 MAR 2004 | DOI: 10.1002/anie.200353216

      One little indium: Reactions of laser-ablated indium atoms with pure hydrogen give sharp IR absorptions corresponding to InH intermediate species. Irradiation at 193 nm maximizes further reaction to give the indane monomer InH3. Annealing provides evidence for In2H6 and ultimately the sharp absorption bands are replaced with a broad IR band centered at 1460 cm−1 assigned to solid indane (InH3)n [see Equation].equation image

    20. Synthesis and Crystal Structure of [{nBuMg(μ-TMP)}2] and of a Homometallic Inverse Crown in Tetranuclear [{nBuMg2[μ-N(H)Dipp]23-OnBu)}2] (pages 1709–1712)

      Eva Hevia, Alan R. Kennedy, Robert E. Mulvey and Susan Weatherstone

      Version of Record online: 17 MAR 2004 | DOI: 10.1002/anie.200353286

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      Previous inverse crown amides have been heterometallic compounds that contain a mixture of alkali-metal ions (M+) and magnesium cations. However, the first homometallic (magnesium–magnesium′) inverse crown is unveiled (see picture) by exploiting the isovalent relationship between M+ and (BuMg)+.

    21. Novel [60]Fullerene-Assisted ortho-Phosphanation on a Tetrairidium Butterfly Framework (pages 1712–1714)

      Bo Keun Park, M. Arzu Miah, Gaehang Lee, Youn-Jaung Cho, Kwangyeol Lee, Sangwoo Park, Moon-Gun Choi and Joon T. Park

      Version of Record online: 17 MAR 2004 | DOI: 10.1002/anie.200353290

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      A mono- to di- and triphosphane transformation occurs on treatment of [Ir4(CO)9(PPh3)3] (1) with C60 to successively afford 2 and 3. The noninnocent, multifunctional C60 ligand plays a crucial role in transforming three PPh3 ligands into a μ3-PPh2(o-C6H4)P(o-C6H4)PPh(η1-o-C6H4) triphosphane ligand by a series of ortho-phosphanation and ortho-metalation processes on the Ir4 cluster framework.

    22. A Water-Soluble Tetranuclear ZrIV Compound Supported by the Kläui Tripodal Ligand: A Model of ZrIV in Aqueous Media (pages 1715–1718)

      Qian-Feng Zhang, Tony C. H. Lam, Eddie Y. Y. Chan, Samuel M. F. Lo, Ian D. Williams and Wa-Hung Leung

      Version of Record online: 17 MAR 2004 | DOI: 10.1002/anie.200353298

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      Water soluble and stable: The treatment of zirconyl nitrate with the Kläui tripodal oxygen ligand in dilute nitric acid gives a water-soluble tetranuclear hydroxo-bridged ZrIV compound (depicted, C gray; O red; P purple; Co blue; Zr green), which reacts with a phosphodiester to give a ZrIV phosphate cubane cluster.

    23. Aqueous Supramolecular Polymer Formed from an Amphiphilic Perylene Derivative (pages 1718–1721)

      Alix Arnaud, Joël Belleney, François Boué, Laurent Bouteiller, Géraldine Carrot and Véronique Wintgens

      Version of Record online: 17 MAR 2004 | DOI: 10.1002/anie.200353434

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      Aromatic stacking and hydrophobic interactions are the driving forces for the reversible self-assembly of an amphiphilic perylene derivative in water to form a linear polymer (see schematic representation). The structure of the assemblies has been elucidated by small-angle neutron scattering, and the association strength determined by NMR and fluorescence spectroscopies.

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      Onion-Type Complexation Based on Carbon Nanorings and a Buckminsterfullerene (pages 1722–1724)

      Takeshi Kawase, Kenji Tanaka, Nami Shiono, Yohko Seirai and Masaji Oda

      Version of Record online: 27 FEB 2004 | DOI: 10.1002/anie.200353517

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      2 into 1 will go: Multi-inclusion structures, reminiscent of Russian Matrioshka dolls, have been constructed in nonpolar organic solvents from carbon nanorings and a C60 molecule (see picture). A study of these structures show there is a substantial difference between the electronic properties of planar and curved conjugated systems.

    25. Total Synthesis of Natural Myriaporones (pages 1724–1727)

      Marta Pérez, Carlos del Pozo, Fernando Reyes, Alberto Rodríguez, Andrés Francesch, Antonio M. Echavarren and Carmen Cuevas

      Version of Record online: 17 MAR 2004 | DOI: 10.1002/anie.200353313

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      The relative and absolute configuration of the cytotoxic myriaporones (e.g. 4) was assigned by their total synthesis from aldehyde 1. Key steps included aldol reactions with chiral oxazolidinone 2 and with Weinreb amide 3. TBS=tert-butyldimethylsilyl, PMB=p-methoxybenzyl.

    26. Total Synthesis and Stereochemical Assignment of Myriaporones 1, 3, and 4 (pages 1728–1730)

      Kristen N. Fleming and Richard E. Taylor

      Version of Record online: 17 MAR 2004 | DOI: 10.1002/anie.200353348

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      Two stereoselective aldol reactions, a nitrile oxide cycloaddition, and a stereoselective late-stage epoxidation were key steps in the total synthesis of myriaporones 1, 3, and 4 (see scheme). The synthesis allowed the unambiguous assignment of stereogenic centers not previously assigned for these compounds.

    27. Iron-Containing Nucleoside Analogues with Pronounced Apoptosis-Inducing Activity (pages 1731–1734)

      Daniel Schlawe, André Majdalani, Juraj Velcicky, Erik Heßler, Thomas Wieder, Aram Prokop and Hans-Günther Schmalz

      Version of Record online: 17 MAR 2004 | DOI: 10.1002/anie.200353132

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      Bioactive organometallic compounds: Iron-containing nucleoside analogues, which can be stereoselectively synthesized in a few steps starting from simple carbohydrates, cause tumor cells to undergo apoptosis (programmed cell death; see picture for the typical morphological characteristics of BJAB tumor cells after apoptosis).

    28. Fluorescent Imaging of Citrate and Other Intermediates in the Citric Acid Cycle (pages 1735–1738)

      Zhihong Lin, Meng Wu, Michael Schäferling and Otto S. Wolfbeis

      Version of Record online: 17 MAR 2004 | DOI: 10.1002/anie.200353169

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      Getting the picture: Citrate and other intermediates of the citric acid cycle can be imaged by time-resolved fluorescence with a Eu3+ tetracycline complex as a fluorescent probe (see picture). The time resolution enables discrimination between intermediates, and enzymatic conversions are not needed.

    29. Regio- and Stereoselective Tether-Directed Remote Functionalization of C60 with Derivatives of the Tröger Base (pages 1738–1740)

      Sergey Sergeyev and François Diederich

      Version of Record online: 17 MAR 2004 | DOI: 10.1002/anie.200453743

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      Bringing two fascinating molecules together: Bismalonate derivatives of the Tröger base were used in the high-yielding regio- and diastereoselective preparation of bisadducts of C60 with trans-1, trans-2, and trans-4 addition patterns (e.g. see structure). Moreover, both enantiomers of the inherently chiral trans-2 adduct were prepared from enantiomerically pure tethers.

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      Preview: Angew. Chem. Int. Ed. 13/2004 (page 1745)

      Version of Record online: 17 MAR 2004 | DOI: 10.1002/anie.200490037