Angewandte Chemie International Edition

Cover image for Vol. 44 Issue 41

October 21, 2005

Volume 44, Issue 41

Pages 6599–6787

    1. Cover Picture: The Design and Evaluation of Heparin-Binding Foldamers (Angew. Chem. Int. Ed. 41/2005) (page 6599)

      Sungwook Choi, Dylan J. Clements, Vojislava Pophristic, Ivaylo Ivanov, Satyavani Vemparala, Joel S. Bennett, Michael L. Klein, Jeffrey D. Winkler and William F. DeGrado

      Version of Record online: 14 OCT 2005 | DOI: 10.1002/anie.200590137

      Small inhibitors for low-molecular-weight heparin, namely short aryl amide foldamers, were designed with the aid of molecular-dynamics calculations. The cover picture shows that the binding is primarily dominated by electrostatic interactions between a pentasaccharide sequence of heparin and the antagonist. In their Communication on page 6685 ff., W. F. DeGrado and co-workers show that heparin binds and modulates the biological properties of a number of proteins, including antithrombin II and factor Xa.

    2. Metal-Containing Nanostructured Materials through In Situ Polymerization of Reactive Metallomesogens (pages 6618–6621)

      Luis Oriol and José Luis Serrano

      Version of Record online: 27 SEP 2005 | DOI: 10.1002/anie.200501880

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      A challenging strategy for the design of metal-containing polymeric systems with a controlled nanostructure is the introduction of polymerizable groups that are both compatible with the mesomorphic order and reactive in the presence of metals. 1,3-Diene groups have recently been reported to offer such compatibility and reactivity, leading to efficient polymerization (see picture).

    3. Bifunctional Metal–Ligand Catalysis: Hydrogenations and New Reactions within the Metal–(Di)amine Scaffold (pages 6622–6627)

      Kilian Muñiz

      Version of Record online: 27 SEP 2005 | DOI: 10.1002/anie.200501787

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      No metal–substrate interactions: A transition-metal complex of a primary amine can serve as an efficient bifunctional metal–ligand catalyst that functions without direct interaction of the metal and the substrate. The example shows the transition-state structure of the enantioselective reduction of acetophenone at the molecular surface of a ruthenium hydride complex bearing a diamine with one free NH2 group (O red, Ru green, N blue).

    4. Ruthenium-Catalyzed Reactions—A Treasure Trove of Atom-Economic Transformations (pages 6630–6666)

      Barry M. Trost, Mathias U. Frederiksen and Michael T. Rudd

      Version of Record online: 5 OCT 2005 | DOI: 10.1002/anie.200500136

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      Ru complexes emerged from obscurity to become accepted as ideal catalysts for diverse C[BOND]C bond-forming reactions beyond the more-well-known redox and metathesis processes. These reactions are highly selective and atom-economic processes for the synthesis of complex molecules (see scheme). Mechanistic principles provide the basis for the semirational design of new reactions, notably for C[BOND]C coupling.

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      Self-Assembly of Nanoparticles on Live Bacterium: An Avenue to Fabricate Electronic Devices (pages 6668–6673)

      Vikas Berry and Ravi F. Saraf

      Version of Record online: 7 OCT 2005 | DOI: 10.1002/anie.200501711

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      24-Carat bacteria: A bacteria/nanoparticle composite device is operated by applying a bias of 10 V across a bacterial bridge, which is coated with gold nanoparticles and spans two gold electrodes, and measuring the current (see image). A change in humidity from 0 to 20 % causes swelling of the bacteria membrane which results in a 40-fold decrease of the current although the interparticle distance increases less than 0.2 nm.

    6. [Co2(ppca)2(H2O)(V4O12)0.5]: A Framework Material Exhibiting Reversible Shrinkage and Expansion through a Single-Crystal-to-Single-Crystal Transformation Involving a Change in the Cobalt Coordination Environment (pages 6673–6677)

      Chun-Long Chen, Andrea M. Goforth, Mark D. Smith, Cheng-Yong Su and Hans-Conrad zur Loye

      Version of Record online: 21 SEP 2005 | DOI: 10.1002/anie.200502309

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      Shrinkage factor: The ligand ppca (4-(pyridin-4-yl)pyridine-2-carboxylic acid) has enabled the synthesis of a new 3D framework material, [{[Co2(ppca)2(H2O)(V4O12)0.5]⋅3.62 H2O}n], which exhibits so-called “dynamic structural changes”. Temperature changes lead to the reversible removal of guest molecules and/or ligands (e.g. H2O) bound to the framework with a concomitant reversible structure change (see scheme).

    7. Hierarchical Assembly of {Fe13} Oxygen-Bridged Clusters into a Close-Packed Superstructure (pages 6678–6682)

      Muralee Murugesu, Rodolphe Clérac, Wolfgang Wernsdorfer, Christopher E. Anson and Annie K. Powell

      Version of Record online: 27 SEP 2005 | DOI: 10.1002/anie.200500208

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      Iron aggregates are arranged into a close-packed structure through coordination bonds to give a material that displays a structural and magnetic hierarchy. The tripodal proligand nitrilotripropionic acid (H3ntp=N(CH2CH2COOH)3) successfully traps {Fe13} aggregates, thus producing a lattice that displays three levels of organization (see picture of its 3D packing arrangement; Fe green; O red; N blue; C black; H white).

    8. Nucleic Acid with Guanidinium Modification Exhibits Efficient Cellular Uptake (pages 6682–6685)

      Tatsuo Ohmichi, Masayasu Kuwahara, Naoko Sasaki, Masatoshi Hasegawa, Takahito Nishikata, Hiroaki Sawai and Naoki Sugimoto

      Version of Record online: 19 SEP 2005 | DOI: 10.1002/anie.200500904

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      Quick on the uptake: A 20-mer DNA oligomer modified with 5-[(6-guanidiniohexylcarbamoyl)methyl]-2′-deoxyuridine (Tg) shows efficient cellular uptake (blue arrow) in HeLa cells without any other reagents. The fluorescence microscopy image reveals FAM-labeled DNA oligomer (green) and stained nuclei (blue). FAM=6-carboxyfluorescein.

    9. The Design and Evaluation of Heparin-Binding Foldamers (pages 6685–6689)

      Sungwook Choi, Dylan J. Clements, Vojislava Pophristic, Ivaylo Ivanov, Satyavani Vemparala, Joel S. Bennett, Michael L. Klein, Jeffrey D. Winkler and William F. DeGrado

      Version of Record online: 11 AUG 2005 | DOI: 10.1002/anie.200501279

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      Controlling blood loss: The synthesis of a series of arylamide oligomers 1, which interact with heparin is described. The heparin–small molecule interaction inhibits the heparin's ability to activate antithrombin. These arylamide oligomers are the first example of low-molecular-weight antagonists that inhibit the anticoagulant function of heparin.

    10. Escape from a Nonporous Solid: Mechanically Coupled Biconcave Molecules (pages 6689–6693)

      Justin A. Riddle, John C. Bollinger and Dongwhan Lee

      Version of Record online: 19 SEP 2005 | DOI: 10.1002/anie.200501888

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      Correlated bond rotations within biconcave molecules that comprise a semirigid C3-symmetric core and pendant m-terphenyl groups (see figure) assist mechanical coupling between the two vertices such that structural changes on one side of the molecule are effectively transmitted to the other side. Self-assembly of one such compound affords a nonporous solid from which entrapped guests can completely escape in the absence of channels that connect interstitial voids.

    11. Sequence Symmetry as a Tool for Designing DNA Nanostructures (pages 6694–6696)

      Yu He, Ye Tian, Yi Chen, Zhaoxiang Deng, Alexander E. Ribbe and Chengde Mao

      Version of Record online: 27 SEP 2005 | DOI: 10.1002/anie.200502193

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      Grand designs: DNA sequence symmetry is explored as a tool for designing DNA nanostructures. The resulting symmetric DNA motifs can self-assemble into two-dimensional arrays as wide as 1 mm (see picture). The DNA arrays can be used as templates to fabricate nanostructures of other materials, such as gold.

    12. Hydrogel Stamping of Arrays of Supported Lipid Bilayers with Various Lipid Compositions for the Screening of Drug–Membrane and Protein–Membrane Interactions (pages 6697–6700)

      Sheereen Majd and Michael Mayer

      Version of Record online: 27 SEP 2005 | DOI: 10.1002/anie.200502189

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      Stamping on fat: Agarose gel stamps were used to create ≥100 membrane arrays (see picture) by using only picomolar amounts of lipids. This constitutes a rapid and straightforward method for the fabrication of functional membrane arrays with a variety of lipid compositions which can be used for screening assays, for example, for drug–membrane interactions.

    13. Enantioselective Thiourea-Catalyzed Acyl-Mannich Reactions of Isoquinolines (pages 6700–6704)

      Mark S. Taylor, Norihito Tokunaga and Eric N. Jacobsen

      Version of Record online: 21 SEP 2005 | DOI: 10.1002/anie.200502277

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      Inexpensive aromatic feedstocks are substrates for highly enantioselective acylative Mannich reactions catalyzed by a thiourea chiral hydrogen-bond donor 1. This methodology provides access to useful 1-substituted dihydroisoquinolines (see scheme; TrocCl=2,2,2-trichloroethyl chloroformate, TBS=tert-butyldimethylsilyl), which serve as precursors to enantioenriched 1-substituted tetrahydroisoquinolines.

    14. A Family of Hierarchically Self-Assembling Linear-Dendritic Hybrid Polymers for Highly Efficient Targeted Gene Delivery (pages 6704–6708)

      Kris C. Wood, Steven R. Little, Robert Langer and Paula T. Hammond

      Version of Record online: 20 SEP 2005 | DOI: 10.1002/anie.200502152

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      Modular materials composed of concentric functional “shells” with independently tuneable properties are prepared from the self-assembly of DNA and linear-dendritic hybrid polymers (see scheme; PAMAM=poly(amidoamine), PEG=poly(ethylene glycol)). These ligand-targeted systems demonstrate serum stability, low toxicity, and transfection efficiencies that exceed those of the most efficient commercially available polymer poly(ethylenimine).

    15. Specific Generation of 1-Methylcytosine Radicals in the Gas Phase (pages 6708–6711)

      Chunxiang Yao, Maria L. Cuadrado-Peinado, Miroslav Polášek and František Tureček

      Version of Record online: 27 SEP 2005 | DOI: 10.1002/anie.200502363

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      What a radical target! Two key hydrogen-atom adducts of 1-methylcytosine have been prepared by the targeted chemical generation of cytosine radicals. Femtosecond collisional transfer of electrons to gas-phase tautomers of protonated 1-methylcytosine using molecular electron donors (dimethyl disulfide and trimethylamine) produces stable radical adducts with the hydrogen atoms positioned at N3 and C5 of the cytosine ring, respectively.

    16. Synthesis of CdSe and CdTe Nanocrystals without Precursor Injection (pages 6712–6715)

      Yongan Andrew Yang, Huimeng Wu, Kathryn R. Williams and Y. Charles Cao

      Version of Record online: 27 SEP 2005 | DOI: 10.1002/anie.200502279

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      With high quality and in high yield: The synthesis presented here affords CdSe and CdTe semiconductor nanocrystals without the need of a precursor injection. It allows the detailed control of the size and shape of the nanocrystals, as can be seen from the tetrahedral CdSe nanocrystals that have been prepared (TEM image). The method is suitable for industrial-scale preparations.

    17. Total Synthesis of (+)-Apiosporamide: Assignment of Relative and Absolute Configuration (pages 6715–6718)

      David R. Williams, David C. Kammler, Andrew F. Donnell and William R. F. Goundry

      Version of Record online: 27 SEP 2005 | DOI: 10.1002/anie.200502015

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      Antipodal relationship: A convergent synthetic pathway leading to 4-hydroxy-2-pyridinones was involved in the synthesis of apiosporamide (1) and YM-215343 (2). Both have an antipodal relationship to the natural metabolites, whose relative and absolute configurations have been established. Activated β-alanine enolate equivalents derived from β-lactams were the key to the synthesis.

    18. Structure Elucidation of the Highly Active Titanosilicate Catalyst Ti-YNU-1 (pages 6719–6723)

      Juanfang Ruan, Peng Wu, Ben Slater and Osamu Terasaki

      Version of Record online: 19 SEP 2005 | DOI: 10.1002/anie.200501939

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      Between the sheets: The structure of the titanosilicate Ti-YNU-1 reveals a much larger spacing along the c axis between the MWW sheets than its lamellar precursor and 3D Ti-MWW (see picture). Formation of twelve-membered rings would explain this cell expansion, which results in increased steric accessibility and may explain the higher catalytic activity of Ti-YNU-1 relative to other titanosilicates.

    19. 17β-Estradiol-Associated Stealth-Liposomal Delivery of Anticancer Gene to Breast Cancer Cells (pages 6723–6727)

      Bathula S. Reddy and Rajkumar Banerjee

      Version of Record online: 27 SEP 2005 | DOI: 10.1002/anie.200501793

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      Killing by stealth: The highly specific mutual affinity of estrogen receptor and 17β-estradiol (ES) allows apoptotic genes to be targeted at primary human breast adenocarcinoma cells through the use of stealth liposomes. Cells are transfected with a cationic lipoplex containing a targeting lipid (see picture; DPPE=1,2-dipalmitoyl-Sn-glycero-phosphatidylethanolamine, PEG=poly(ethylene glycol)).

    20. General Synthetic Route toward Functional Hollow Spheres with Double-Shelled Structures (pages 6727–6730)

      Mu Yang, Jin Ma, Chengliang Zhang, Zhenzhong Yang and Yunfeng Lu

      Version of Record online: 27 SEP 2005 | DOI: 10.1002/anie.200501556

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      Double agent: Controlled sulfonation of polystyrene hollow spheres gives hydrophilic layers with sulfonic acid groups that allow the formation of a wide variety of functional composites. In this way, double-shelled hollow spheres have been prepared in one step by using such sulfonated polystyrene hollow spheres as templates (see TEM image of titania sphere).

    21. Expeditious, Potentially Primordial, Aminoacylation of Nucleotides (pages 6731–6734)

      Jean-Philippe Biron, Alastair L. Parkes, Robert Pascal and John D. Sutherland

      Version of Record online: 27 SEP 2005 | DOI: 10.1002/anie.200501591

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      In the beginning: Mixed carboxylic phosphoric anhydrides 3, formed from 3′-nucleotides 1 and amino acid N-carboxyanhydrides 2, undergo competing rearrangement to 2′-aminoacyl esters 4 and cyclization to 2′,3′-cyclic phosphates 5. The intramolecular aminoacyl transfer is faster than the cyclization despite the ease with which 2′,3′-cyclic phosphates are formed through any other form of phosphate activation.

    22. Formation of a Bowl-Shaped, Pentacyclic Phosphonium Cage by Methylation of a Nucleophilic Phosphinidene (pages 6734–6737)

      Matthias Driess, Nicoleta Muresan, Klaus Merz and Michael Päch

      Version of Record online: 21 SEP 2005 | DOI: 10.1002/anie.200501990

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      Domino-cyclization of two phosphinidene molecules: Methylation of the nucleophilic phosphinidene 1 with MeOTf (OTf=triflate) affords the unusual phosphonium cage 2, which implies the formation of the novel phosphenium ion 3 as a reactive intermediate.

    23. A Novel Type of Pentacoordinate Silicon Complexes and Unusual Ligand Coupling by Intramolecular Electron Transfer (pages 6738–6741)

      Matthias Driess, Nicoleta Muresan and Klaus Merz

      Version of Record online: 27 SEP 2005 | DOI: 10.1002/anie.200501997

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      Even the electropositive element silicon initiates electron-transfer processes in amido-bis(enolate) complexes: This is shown by the reactions of halides RSiX3 with HN[CH2C(O)tBu]2 in the presence of a base. While small substituents (R=H, Cl, Br, Ph) furnish the dinuclear pentacoordinate complexes 1, the bulkier tBu3Si group favors formation of the dinuclear tetracoordinate complex 2.

    24. Biosynthesis of TDP-D-Desosamine: Identification of a Strategy for C4 Deoxygenation (pages 6742–6746)

      Ping-hui Szu, Xuemei He, Lishan Zhao and Hung-wen Liu

      Version of Record online: 27 SEP 2005 | DOI: 10.1002/anie.200501998

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      The proteins DesI and DesII are proposed to catalyze a C4 deoxygenation reaction to give the key intermediate 1 in the biosynthesis of D-desosamine. Biochemical characterization of purified DesII showed that it is a member of the S-adenosylmethionine (SAM) family of radical enzymes. The involvement of a SAM radical in the reaction with DesII identifies a new strategy for deoxygenation reactions of sugars.

    25. Experimental Evidence for a Jahn–Teller Distortion in AuCl3 (pages 6746–6750)

      Ian J. Blackmore, Adam J. Bridgeman, Neil Harris, Mark A. Holdaway, John F. Rooms, Emma L. Thompson and Nigel A. Young

      Version of Record online: 27 SEP 2005 | DOI: 10.1002/anie.200502503

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      Matrix-isolation IR, electronic-absorption, and Au L3-edge EXAFS (extended X-ray absorption fine structure) data have provided the first experimental evidence that the ground-state structure of AuCl3 is not D3h symmetric (trigonal-planar), but rather has a Jahn–Teller-distorted T-shaped geometry (see picture).

    26. Systems Chemistry: Kinetic and Computational Analysis of a Nearly Exponential Organic Replicator (pages 6750–6755)

      Maik Kindermann, Insa Stahl, Malte Reimold, Wolf Matthias Pankau and Günter von Kiedrowski

      Version of Record online: 27 SEP 2005 | DOI: 10.1002/anie.200501527

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      Combining kinetic, structural, and computational studies on complex dynamic feedback systems may lead to the field of “systems chemistry”. The approach is exemplified by the analysis of a simple organic self-replicating system that has the potential to express both homochiral autocatalysis and heterochiral cross-catalysis (see picture).

    27. Development of Tungsten-Based Heterogeneous Alkane Metathesis Catalysts Through a Structure–Activity Relationship (pages 6755–6758)

      Erwan Le Roux, Mostafa Taoufik, Christophe Copéret, Aimery de Mallmann, Jean Thivolle-Cazat, Jean-Marie Basset, Barry M. Maunders and Glenn J. Sunley

      Version of Record online: 19 SEP 2005 | DOI: 10.1002/anie.200501382

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      More active and selective catalysts of alkane metathesis (see scheme) that are based on well-defined tungsten carbyne and hydride complexes supported on alumina have been developed through a structure–activity relationship. The improvement of activity on changing from Ta in 2 to W in 1 and the product selectivity show that olefin metathesis is probably the key process in C[BOND]C bond formation in the alkane metathesis reaction.

    28. 1,5-Lactamized Sialyl Acceptors for Various Disialoside Syntheses: Novel Method for the Synthesis of Glycan Portions of Hp-s6 and HLG-2 Gangliosides (pages 6759–6763)

      Hiromune Ando, Yusuke Koike, Sachiko Koizumi, Hideharu Ishida and Makoto Kiso

      Version of Record online: 27 SEP 2005 | DOI: 10.1002/anie.200501608

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      A dramatic enhancement of the reactivity of the C4- and C8-hydroxy groups of sialic acid has been demonstrated by 1,5-lactam bridging. Sialyl-α(2[RIGHTWARDS ARROW]4)sialoside and sialyl-α(2[RIGHTWARDS ARROW]8)sialoside were made available in high yields through direct sialylation (see scheme). Furthermore, the glycan parts of the new gangliosides Hp-s6 and HLG-2 were synthesized for the first time.

    29. Synthesis of Corrole Derivatives through Regioselective Ir-Catalyzed Direct Borylation (pages 6763–6766)

      Satoru Hiroto, Ichiro Hisaki, Hiroshi Shinokubo and Atsuhiro Osuka

      Version of Record online: 19 SEP 2005 | DOI: 10.1002/anie.200502335

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      Showdown at the OK corrole: The direct borylation of corroles under iridium catalysis through C[BOND]H activation proceeds with perfect regioselectivity and excellent yields. 2-Borylated corroles allow an easy access (two steps) to directly linked corrole–porphyrin conjugates and other functionalized corroles (see scheme).

    30. Multilocus Binding Increases the Relaxivity of Protein-Bound MRI Contrast Agents (pages 6766–6769)

      Zhaoda Zhang, Matthew T. Greenfield, Marga Spiller, Thomas J. McMurry, Randall B. Lauffer and Peter Caravan

      Version of Record online: 20 SEP 2005 | DOI: 10.1002/anie.200502245

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      Spinning around: The sensitivity of MRI contrast agents can be increased through multilocus binding. This restricts the internal motion and therefore increases the relaxivity of a bound protein multimer (see picture; A) relative to a single binding group (B), whose flexibility and internal motion limits the relaxivity gain. Protein-targeting groups (TG) can be used to anchor the multimer.

    31. Deactivation of Pd Acetoxylation Catalysts: Direct Observations by XPS Investigations (pages 6771–6774)

      Jörg Radnik, Abdulhadi Benhmid, Venkata Narayana Kalevaru, Marga-Martina Pohl, Andreas Martin, Bernhard Lücke and Uwe Dingerdissen

      Version of Record online: 27 SEP 2005 | DOI: 10.1002/anie.200501650

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      Addition of Bi prevents deactivation of Pd–Sb catalysts in the acetoxylation of toluene. The presence of Bi hinders the formation of an inactive Pdδ− state and the blockage of the active Pd sites by carbon species from coke deposits (see the photoelectron spectrum). The modified catalyst displays extremely high selectivity for benzyl acetate (≥95 %) at higher toluene conversions.

    32. Size-Controlled Electrochemical Synthesis of Metal Nanoparticles on Monomolecular Templates (pages 6775–6778)

      Thomas Hirsch, Michael Zharnikov, Andrey Shaporenko, Joachim Stahl, Dieter Weiss, Otto S. Wolfbeis and Vladimir M. Mirsky

      Version of Record online: 27 SEP 2005 | DOI: 10.1002/anie.200500912

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      Reduction on the spot: Planarly adsorbed thiolated porphyrin molecules (purple) incorporated in an insulating alkanethiol monolayer (blue) function as nanoelectrodes for the local reduction of metals (gray). This approach was applied for the in situ synthesis of nanoparticles of a predetermined size.

    33. 1,2-Chirality Transfer in the Synthesis of Cyclopropanes (pages 6778–6781)

      Pablo Wessig and Olaf Mühling

      Version of Record online: 19 SEP 2005 | DOI: 10.1002/anie.200501481

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      Influential neighbors: 1,2-Chirality transfer provides the basis for a novel asymmetric synthesis of cyclopropanes by irradiation of enantiomerically pure alkyl phenyl ketones bearing a leaving group X in the α position. The photochemically excited carbonyl group is able to distinguish between the diastereotopic positions γ and γ′ in terms of a desymmetrization. In some cases the configuration is influenced by the temperature.

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