Angewandte Chemie International Edition in English

Cover image for Vol. 36 Issue 6

April 4, 1997

Volume 36, Issue 6

Pages 541–657

Currently known as: Angewandte Chemie International Edition

    1. Cover Picture (Angew. Chem. Int. Ed. Engl. 6/1997)

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199705391

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      The cover picture shows the calculated structure of a 2-silanorbornyl cation and its synthesis by a hydride transfer reaction, both of which show similarities to the structure and synthesis of the carbon analog, the 2-norbornyl cation. The depicted structure emphasizes the intramolecular π complexation of the “siliconium ion”. Electron transfer from the double bond to the positively charged silicon is corroborated by the characteristic, low-field shift of the vinylic 13C signals of the cation (red) relative to those of the starting silane (blue). Efficient intramolecular stabilization of the siliconium ion reduces the tendency to form complexes with solvent molecules or counterions. More details on the synthesis and properties of this novel silyl cation are reported by N. Auner and P. von R. Schleyer et al. on pages 626ff.

  1. Reviews

    1. Top of page
    2. Reviews
    3. Highlights
    4. Communications
    5. Book Reviews
    1. Chiral Recognition in π Complexes of Alkenes, Aldehydes, and Ketones with Transition Metal Lewis Acids; Development of a General Model for Enantioface Binding Selectivities (pages 550–583)

      Prof. Dr. J. A. Gladysz and Brian J. Boone

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199705501

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      A general model for chiral recognition in the complexation of alkenes, aldehydes, and ketones—the most frequently used starting materials in enantioselective organic synthesis—has been formulated. A wealth of supporting data was obtained from studies with the Lewis acidic 16e rhenium complex cation 1. The picture on the right shows the superposition of two alkene complexes of 1.

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  2. Highlights

    1. Top of page
    2. Reviews
    3. Highlights
    4. Communications
    5. Book Reviews
    1. DNA as a Material for Nanotechnology (pages 585–587)

      Dr. Christof M. Niemeyer

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199705851

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      Nanostructured systems and functionalized supramolecular aggregates are accessible by DNA hybridization. The nanocrystalline molecule (see schematic representation below) is constructed from gold clusters (shaded spheres) and oligonucleotides (ladderlike framework) by self-assembly. Complex DNA networks could serve as high-resolution matrices for the production of microchips. DNA technology is thus in the process of expanding to include applications in microelectronics.

    2. Integrin Antagonists and Other Low Molecular Weight Compounds as Inhibitors of Angiogenesis: New Drugs in Cancer Therapy (pages 588–590)

      Priv.-Doz. Dr. Athanassios Giannis and Dr. Frank Rübsam

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199705881

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      Arthritis, rheumatism, and diabetic retinopathy, conditions accompanied by excessive angiogenesis, may be amenable to treatment with the same drugs proposed for cancer therapy. A promising new concept in tumor treatment is the application of integrin antagonists such as 1 and other low molecular weight compounds with antiangiogenic activity. A number of drugs are currently in preclinical and clinical trials.

    3. Deracemization by Enantiodifferentiating Inversion in 1,3-Diols (pages 591–594)

      Prof. Anthony P. Davis

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199705911

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      From a 1:1 mixture of enantiomers to an enantiomerically pure product—the method of “enantiodifferentiating inversion” can be used to convert a complex mixture of diol isomers into a single product, containing a sequence of four asymmetric centers found in several important natural products. In this approach a 1,3-diol with a P and a Σ center reacts to give a diol with two P centers (see reaction on the right).

  3. Communications

    1. Top of page
    2. Reviews
    3. Highlights
    4. Communications
    5. Book Reviews
    1. Chemoselective Polyalkylations of Phosphorus-Containing Dendrimers (pages 596–599)

      Christophe Larré, Dr. Anne-Marie Caminade and Dr. Jean-Pierre Majoral

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199705961

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      At the core, at the core and at the surface, within the cascade structure, or within the cascade structure and at the surface are different ways in which the dendrimers described here can be selectively alkylated. These phosphorus-containing dendrimers have generations of different constitution (example depicted on the right, □ and ▪ are neutral and cationic generations, respectively). Remarkably, even the core of a sixth generation dendrimer is shown to be accessible.

    2. Stability and Conformational Switching in a Mini-Cyclic Oligonucleotide Conjugate (pages 599–601)

      Dr. Mathias K. Herrlein and Dr. Robert L. Letsinger

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199705991

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      A remarkably stable base-stacked structure is shown by the 70-membered ring 2, which possesses only four nucleotide bases and is formed by efficient cyclization of the oligonucleotide conjugate 1. In the presence of alkali, 2 twists to bring the stilbene groups into close proximity, as indicated by an excimer emission upon irradiation.

    3. Chains, Ladders, and Two-Dimensional Sheets with Halogen ċ Halogen and Halogen ċ Hydrogen Interactions (pages 601–603)

      Oshrit Navon, Prof. Joel Bernstein and Vladimir Khodorkovsky

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199706011

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      A recurring motif in a variety of crystal structures is represented by the atomic arrangement I. The participating molecules are stabilized by two intermolecular interactions (dashed lines) into a nonminimal energy conformation. This motif is useful for molecular recognition and the generation of crystal structures.

    4. The First Crystalline Solids in the Ternary Si-C-N System (pages 603–606)

      Prof. Dr. Ralf Riedel, Axel Greiner, Dr. Gerhard Miehe, Dr. Wolfgang Dressler, Dr. Hartmut Fuess, Dr. Joachim Bill and Dr. Fritz Aldinger

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199706031

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      The reaction of SiCl4 with bis(trimethylsilyl)carbodiimide in a 1:2 molar ratio followed by annealing at temperatures above 400 or 900°C provides the first crystalline ternary Si-C-N solids, namely silicon dicarbodiimide (SiC2N4) and silicon (carbodiimide)nitride (Si2CN4), in near quantitative yields. The anti-cuprite type structure of SiC2N4 is shown on the right.

    5. To Couple or Not To Couple: The Dilemma of Acetylide Carbons in [(η5-C5H5)2M(μ-CCR)2M(η5−C5H5)2] Complexes (M [DOUBLE BOND] Ti, Zr)—A Theoretical Study for R [DOUBLE BOND] H, F (pages 606–608)

      Prof. Dr. Eluvathingal D. Jemmis and M.Sc.-Chem. Kalathingal T. Giju

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199706061

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      Substituents on the ethynyl group influence the fate of the title complexes: unusual C[BOND]C coupling and formation of complex type 2 is observed in dimeric bis(η5-cyclopentadienyl)-phenylethynyltitanium (R [DOUBLE BOND] Ph), but not in the zirconium analogue. Theoretical studies of 1 and 2 at the ab initio MO and DFT levels demonstrate that the electron-withdrawing substituent R [DOUBLE BOND] F drives the equilibrium towards 2 for M [DOUBLE BOND] Zr.

    6. Synthesis and Resolution of the Configurationally Stable Tris(tetrachlorobenzenediolato)phosphate(V) Ion (pages 608–610)

      Dr. Jérǒ;me Lacour, Catherine Ginglinger, Chantal Grivet and Dr. Gérald Bernardinelli

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199706081

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      Easily accessible and configurationally stable are words that describe the enantiopure tris(tetrachlorobenzenediolato)phosphate(V) ion (1). These qualities predetermine 1 for use in enantiomeric resolution and asymmetric synthesis. X-ray structure analysis of the cinchonidinium salt of 1 confirmed the octahedral geometry and provided the absolute configuration of the anion.

    7. Oligo(ethylenoxy)oxy-Bridged Stilbenes as Ligands for σ- and π-Coordinated Ag+ and Na+ Ions (pages 611–613)

      Dipl.-Chem. Thomas Futterer, Prof. Dr. Andreas Merz and Dr. Johann Lex

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199706111

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      Four oxygen atoms and a double bond, coordinate to the Ag+ ion in the complex with the stilbene crown ether 1. Surprisingly, the Na+ ion is also complexed by 1 in a similar geometry. The coordinative bond between a Na+ ion and a π bond, which is detected here for the first time, is probably induced and supported by the oligo(ethylenoxy)oxy bridge. M+X [DOUBLE BOND] AgNO3, NaClO4.

    8. Metal-Induced Self-Assembly of Cavitand-Based Cage Molecules (pages 613–615)

      Dr. Paola Jacopozzi and Dr. Enrico Dalcanale

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199706131

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      Opening and closing of the stable, molecular-sized cages 1 (M [DOUBLE BOND] Pd, Pt; L [DOUBLE BOND] 1,3-bis(diphenylphosphino)propane) can be efficiently controlled by ligand exchange. Simply mixing the preorganized cavitand with the appropriate metal complex precursor provides 1 quantitatively in one step. One triflate ion is encapsulated in the self-assembly process.

    9. A μ4-Peroxo Complex of Antimony: Synthesis and Structure of (o-Tol2SbO)4(O2)2 (pages 615–617)

      Prof. Dr. Hans Joachim Breunig, Tamara Krüger and Dr. Enno Lork

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199706151

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      A cage structure with two quadruply bridging peroxo groups forms the center of the organoantimony peroxide 1 (R [DOUBLE BOND] o-tolyl), which is readily accessible by oxidation of the corresponding tetraaryldistibane with atmospheric oxygen and H2O2. The protecting periphery of o-tolyl groups is responsible for the good solubility of the antimony–oxygen cage.

    10. A Samarium-Mediated, Highly Stereoselective Reaction of 1,1-Dihaloalkanes with Aldehydes: Generation of a Chiral α-Iodoethyl Building Block from Achiral 1,1-Diiodoethane (pages 617–618)

      Dr. Seijiro Matsubara, Masahito Yoshioka and Prof. Kiitiro Utimoto

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199706171

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      High syn-selectivity and an extremely convenient procedure characterize the novel SmI2-mediated addition of α-iodoalkyl building blocks to aldehydes [Eq. (a); R, R′ [DOUBLE BOND] alkyl]. The chiral 1,2-iodohydrins formed are attractive synthetic intermediates for further conversions.

    11. Solid-Phase Synthesis of a Tumor-Associated Sialyl-TN Antigen Glycopeptide with a Partial Sequence of the “Tandem Repeat” of the MUC-1 Mucin (pages 618–621)

      Dipl.-Chem. Beate Liebe and Prof. Dr. Horst Kunz

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199706181

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      An allylic anchor was used for the solid-phase synthesis of glycopeptide 1 from the tandem repeat of the tumor-associated mucin MUC-1 with a sialyl-TN antigen side chain. The sialyl-TN antigen is one of the most promising of the tumor-associated antigens for the development of vaccines against epithelial tumors. Subsequent hydrolysis of the sialic acid methyl ester proceeds without epimerization in the peptide or β-elimination of the carbohydrate side chain.

    12. Synthesis and Structure of a Dimeric Peralkylated Hexaaminobenzene: Hexakis(dimethylamino)hexamethyl-hexaaza[63] (1,3,5)cyclophane (pages 621–623)

      Priv.-Doz. Dr. J. Jens Wolff, Dipl.-Chem. Andreas Zietsch, Prof. Dr. Hermann Irngartinger and Dr. Thomas Oeser

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199706211

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      Increasing the reorganization energy slows intramolecular electron transfer (ET) in 1, a compound thus well-suited for studying the kinetics of ET processes. A surprisingly smooth, threefold nucleophilic aromatic substitution reaction is the key step in the synthesis of 1.

    13. [(CF3)2Hg(μ-F)2Hg(CF3)2]2−: Synthesis, Structure, and Reactivity (pages 623–624)

      Dr. Detlef Viets, Dr. Enno Lork, Dr. Paul G. Watson and Prof. Dr. Rüdiger Mews

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199706231

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      The first anionic fluoromercury complex [(CF3)2Hg-(μ-F)2Hg(CF3)2]2− was prepared from Hg(CF3)2 and TAS fluoride (Me2N)3S+ (Me3Si)Fmath image, and characterized by X-ray crystal structure analysis (structure depicted on the right). In contrast to the neutral compound, the anions can be used as nucleophilic CF3-transfer reagents.

    14. Selective Activation of Alkyl– and Aryl–Oxygen Single Bonds in Solution with Transition Metal Complexes (pages 625–626)

      Drs. Ing. Milko E. van der Boom, Dr. Shyh-Yeon Liou, Yehoshoa Ben-David, Arkadi Vigalok and Prof. Dr. David Milstein

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199706251

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      An unprecedented metal insertion into the strong sp2[BOND]sp3 aryl[BOND]O bond to form 2 is observed for the reaction of [{RhCl(C8H14)2}2] (C8H14 = cyclooctene) with two equivalents of the aryl ether phosphane 1. This reaction proceeds directly, even at room temperature, with no rhodium insertion into the adjacent weaker ArO[BOND]CH3 bond. However, the alkyl[BOND]O bond is activated by the reaction of 1 with [Pd-(CF3CO2)2] to give 3. Selectivity of C[BOND]O activation can therefore be directed by choice of metal complex.

    15. The 2-Silanorbornyl Cation: An Internally Stabilized Silyl Cation (pages 626–628)

      Dipl.-Chem. Hans-Uwe Steinberger, Dr. Thomas Müller, Prof. Dr. Norbert Auner, Dipl.-Chem. Christoph Maerker and Prof. Dr. Paul von Ragué Schleyer

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199706261

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      The Si analog of the norbornyl cation is a free but internally π-stabilized silyl cation (1) prepared by a hydride transfer reaction [Eq. (a)]. Ab initio calculations confirm the experimental observation that there is no coordination to solvent or counterions.

    16. The Reaction of Primary and Secondary Amines with LiAIH4 and Na(AlHEt3) (pages 629–631)

      Dipl.-Chem. Mavis L. Montero, Dipl.-Chem. Helge Wessl, Prof. Dr. Herbert W. Roesky, Dipl.-Chem. Markus Teichert and Dr. Isabel Usón

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199706291

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      Cyclic and bicyclic intermediates such as the THF-adduct 1 can be isolated from the reaction of a primary amine with LiAlH4. It is assumed that these compounds are generally formed in the reduction of organic nitrogen-containing compounds with LiAlH4. The reaction of Na(AlHR3) with secondary amines also affords crystalline intermediates, but with polymeric structure.

    17. Polyphenylene Dendrimers: From Three-Dimensional to Two-Dimensional Structures (pages 631–634)

      Dipl.-Chem. Frank Morgenroth, Erik Reuther and Prof. Dr. Klaus Müllen

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199706311

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      An elegant route to aromatic hydrocarbon dendrimers, such as 1 with pentaphenylbenzene units, and to extremely large polybenzenoid hydrocarbons is based on Diels–Alder cycloadditions of 3,4-bis-[4-(triisopropylsilylethynyl)phenyl]-2, 5-diphenylcyclopenta-2,4-dienone and aromatic oligoethynyl compounds such as 3,3′,5,5′-tetraethynylbiphenyl. The type of linkage and the high packing density of the benzene rings facilitate the cyclodehydrogenation of appropriate dendrimeric subunits to yield planar disks.

    18. Asymmetric Cyclopentannulation of Cyclic Enones with a Chiral 1,3-Dipole Equivalent (pages 634–636)

      Dr. Catherine Huart and Prof. Dr. Léon Ghosez

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199706341

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      A highly selective cis-fusion is observed for the reaction of the chiral 1,3-dipole equivalent 1 with cyclic enone 2 to form the bicyclic cyclopentenone 3. This multistep method, which does not require isolation of intermediates, is conceptually analogous to the Robinson annulation and should find wide applicability.

    19. Solvolysis of [B(C6H5)4] in Methanol To Give the Chiral Coordination Polymer Cd(tcm)[B(OMe)4] · xMeOH, x ≈ 1.6 (pages 636–637)

      Dr. Stuart R. Batten, Dr. Bernard F. Hoskins and Dr. Richard Robson

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199706361

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      Sixfold helices of the borate-bridged cadmium ion are the outstanding structural feature of this chiral, channel-containing coordination polymer (shown schematically on the right), which was formed by solvolysis of (BPh4) in methanol in the presence of Cd2+ and [C(CN)3].

    20. News from an Old Ligand: The Triple-Decker Ion Triple, Tris([18]Crown-6)-disodium Bis(tetraphenycyclopentadienide) (pages 638–639)

      Prof. Dr. Hans Bock, Dr. Tim Hauck, Dr. Christian Näther and Dr. Zdenek Havlas

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199706381

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      Three [18]crown-6 ligands and two sodium ions surprisingly form a triple-decker sandwich dication, pictured schematically on the right. Due to sixfold O-coordination of each sodium ion to the outer crown ethers, but only two Na+ ċ O contacts each to the central ligand, the outer macrocyclic rings are distorted to a hemispherical conformation, whereas the central ring adopts a rectangular shape.

    21. N(CH3)4 · ZnH3(PO4)2: A Large-Pore Zincophosphate Built Up from a 12-Ring Architecture with a Remarkably Low Tetrahedral-Framework-Atom Density (pages 640–641)

      Dr. William T. A. Harrison and Lakshitha Honnooman

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199706401

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      An open framework structure built up from tetrahedral building blocks characterizes the zincophosphate N(CH3)4 · ZnH3(PO4)2. Its topology is based on 12-rings (depicted on the right) that form a pearshaped cavity occupied by tetramethylammonium ions. N(CH3)4 · ZnH3(PO4)2 has the lowest framework density yet observed in microporous materials built up from tetrahedral building blocks.

    22. Metal-Ion-Templated Polymers: Synthesis and Structure of N-(4-Vinylbenzyl)-1,4,7-Triazacyclononanezinc(II) Complexes, Their Copolymerization with Divinylbenzene, and Metal-Ion Selectivity Studies of the Demetalated Resins—Evidence for a Sandwich Complex in the Polymer Matrix (pages 642–645)

      Dr. Hong Chen, Dr. Marilyn M. Olmstead, Dr. Robert L. Albright, Dr. Jozsef Devenyi and Dr. Richard H. Fish

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199706421

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      The spatial arrangement of ligands 1 oriented by the complexed template ion during polymerization explains the unexpectedly high Cu2+: Fe3+ selectivity of the polymer formed from [Zn(1)]2+ with a cross-linking agent, divinylbenzene. The ionic radius of the Cu2+ ion is similar to that of the Zn2+ template. The distinct loss of Zn2+ on polymerization strongly suggests that a sandwich arrangement results; that is, the [Zn(1)2]2+ complex forms from [Zn(1)]2+.

    23. Isolation of a Nonicosahedral Intermediate in the Isomerization of an Icosahedral Metallacarborane (pages 645–647)

      Shirley Dunn, Dr. Georgina M. Rosair, Dr. Rhodri Ll. Thomas, Dr. Andrew S. Weller and Prof. Alan J. Welch

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199706451

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      After more than 30 years of speculation on the mechanism of the isomerization of icosahedral carboranes and their analogues, isolation of 1 provides the first clue. This intermediate has an unprecendented, closed, nonicosahedral structure. [Mo] = [Mo(η3−C3H5)(CO)2].

    24. The Phenylacetyl Group—The First Amino Protecting Group That Can Be Removed Enzymatically from Oligonucleotides in Solution and on a Solid Support (pages 647–649)

      Prof. Dr. Herbert Waldmann and Dr. Armin Reidel

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199706471

      Penicillin G acylase from E. coli was used to cleave the phenylacetyl group—the first enzyme-labile protecting group for the amino function of nucleobases. Now protected oligonucleotides can be unmasked both in solution and on solid supports with this versatile enyzme under mild conditions (pH 7, room temperature). These results may lead to the development of new enzymatic reactions in oligonucleotide and solid-phase chemistry as well as in combinatorial chemistry.

    25. A Tetrakis(imido) Phosphate Anion Isoelectronic with POmath image (pages 649–650)

      Dr. Paul R. Raithby, Dr. Christopher A. Russell, Dr. Alexander Steiner and Dr. Dominic S. Wright

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199706491

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      The product of 1-aminonaphthalene and P2I4 reacts with nBuLi to form complex 1, whose anion (structure on the right; only oxygen atoms of thf ligands are shown) is isoelectronic with orthophosphate. R = naphthyl.

      • equation image
  4. Book Reviews

    1. Top of page
    2. Reviews
    3. Highlights
    4. Communications
    5. Book Reviews
    1. Book Review: Deciphering the Chemical Code. By N . D. Epiotis (pages 652–653)

      Wolfram Koch

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199706521

    2. Book Review: Directory of Solvents. Edited by B. P. Whim and P. G. Johnson (pages 655–656)

      Christian Reichardt

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199706551

    3. Book Review: Chemistry of the Environment. By T. C. Spiro and W. M. Stigliani (page 656)

      Yuegang Zuo and Yiwei Deng

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199706561