Angewandte Chemie International Edition in English

Cover image for Vol. 33 Issue 17

September 16, 1994

Volume 33, Issue 17

Pages 1677–1786

Currently known as: Angewandte Chemie International Edition

    1. Cover Picture (Angew. Chem. Int. Ed. Engl. 17/1994)

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199416751

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      The cover picture shows schematically a liposome with a protective polymer coating encapsulating a drug. Such sterically stabilized “Stealth liposomes” in which the polymer chains are anchored in the lipid bilayer are much more stable under biological conditions than the classical, unprotected liposomes. The extended circulation achieved is crucial for cell-specific targetting of the drug. X-ray scattering and electron microscopy have shown that the encapsulated drug is precipitated, which greatly enhances the encapsulation efficiency and stability. Danilo D. Lasic reports more about this new generation of liposomes on p. 1685ff. The picture was designed by Alenka D. Lasic.

  1. Reviews

    1. Top of page
    2. Reviews
    3. Highlights
    4. Communications
    5. Book Reviews
    6. New Books
    1. Sterically Stabilized Vesicles (pages 1685–1698)

      Dr. Danilo D. Lasic

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199416851

      Great expectations were aroused in the seventies and early eighties for the application of liposomes as drug delivery agents. These were not fulfilled because of the poor stability of the liposomes, in particular in the biological milieu, in which conventional liposomes are rapidly degraded or phagocytosed. Recently liposomes with a protective coating of polymer brought the breakthrough. Examples of such liposomes encapsulating doxorubicin are promising developments in cancer chemotherapy and already undergoing clinical tests.

    2. Peptidomimetics—Tailored Enzyme Inhibitors (pages 1699–1720)

      Prof. Dr. Joachim Gante

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199416991

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      How should a peptide be altered to give an active drug? Tailored mimetics may not be available by de novo design in the near future, but refined conformational analyses and computer programs currently contribute to rational design beyond purely empirical observations. Compound 1, a peptoid-based ACE inhibitor with low toxicity obtained in this way, is now in clinical trials.

  2. Highlights

    1. Top of page
    2. Reviews
    3. Highlights
    4. Communications
    5. Book Reviews
    6. New Books
    1. Mills—Nixon Effect: Wherefore Art Thou? (pages 1721–1723)

      Prof. Dr. Jay S. Siegel

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199417211

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      Significant alternation of the bond lengths in benzene should be induced by small annelated rings—this is the basic tenet of the Mills–Nixon hypothesis formulated in 1930. Although the hypothesis was soon contested by Pauling et al., it has persisted doggedly ever since. Recent results from Vollhardt et al. revealed that the Mills–Nixon effect cannot be proved even in very highly strained systems such as 1–4.

    2. Detection and Imaging of Single Molecules by Optical Near-Field Microscopy (pages 1723–1725)

      Dr. Thomas Basché

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199417231

      Resolutions of λ/43 rather than λ/2 are achieved when surfaces are probed with optical near-field microscopy. Single molecules can thus be examined under ambient conditions and with low light intensity, an important requirement for the study of biomolecules.

    3. Blue-Violet Pentamethylbismuth (pages 1726–1728)

      Dr. Bernhard Neumüller and Prof. Dr. Kurt Dehnicke

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199417261

      The simplest pentaalkylbismuth(V) compound, pentamethylbismuth (1), was recently prepared by Seppelt et al. (Angew. Chem. Int. Ed. Engl.1994, 33, 976). Bismuth(V) has a very high oxidation potential, and for a long time, therefore, its compounds could only be isolated with the most electronegative bonding partners oxygen and fluorine; the only pentaorganobismuth(V) compounds known were pentaaryl derivatives. After the outstanding preparative achievement of Seppelt et al. theoreticians are challenged: The relationship between the color and the structure of penta-organobismuth(V) compounds is not yet fully understood.

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  3. Communications

    1. Top of page
    2. Reviews
    3. Highlights
    4. Communications
    5. Book Reviews
    6. New Books
    1. Synthesis of Cyclotheonamide B and Its Derivatives (pages 1729–1731)

      Jingen Deng, Prof. Dr. Yasumasa Hamada, Prof. Dr. Takayuki Shioiri, Dr. Shigeki Matsunaga and Prof. Dr. Nobuhiro Fusetani

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199417291

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      A high-yielding macrolactonization is the key step in the convergent synthesis of the macrocyclic pentapeptide 1. The hydroxy derivatives 1b and 1c are not inhibitors of serine protease, since they do not have the α-carbonylamide unit (X, Y [DOUBLE BOND] O) found in the naturally occurring cyclotheonamide B (1a).

    2. Decaphenylferrocene and Decaphenylferrocenium Tetrafluoroborate (pages 1731–1733)

      Prof. Dr. Herbert Schumann, Dr. Alexander Lentz, Dr. Roman Weimann and Prof. Dr. Joachim Pickardt

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199417311

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      Decaphenylferrocene (1) is a symmetric sandwich complex after all! The X-ray structure analysis (right) shows a propeller-like arrangement of interleaving phenyl rings. The distance between the cyclopentadienyl ligands and iron is such that maximum orbital overlap is still possible. Analogous structural features are observed for decaphenylferrocenium tetrafluoroborate, obtained by oxidation of 1 with NOBF4.

    3. Organolanthanoid—Carbene-Adducts (pages 1733–1734)

      Prof. Dr. Herbert Schumann, Dr. Mario Glanz, Dr. Jörn Winterfeld, Dr. Holger Hemling, Prof. Dr. Norbert Kuhn and Dipl.-Chem. Thomas Kratz

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199417331

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      Its not a classical carbene complex even if the C2 atom of the heterocycle in 1 (R [DOUBLE BOND] Me, iPr) is sp2 configurated and the bond lengths in the carbene ligand alternate, because the Yb[BOND]C bond length corresponds to that of an extended single bond. Nevertheless, 1 opens the way to a class of substances for f-block elements that has great significance in the d-block elements.

    4. Regio- and Stereoselective Electrophilic C-Substitution of 2-(N,N-Dibenzylamino)-1,ω-alkanediols by Lithiation of Their Carbamates (pages 1734–1737)

      Walter Guarnieri, Dr. Matthias Grehl and Prof. Dr. Dieter Hoppe

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199417341

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      A flexible system of building blocks can be used for the synthesis of the potential enzyme inhibitors 1 and 2 (n = 1, 2) in high enantiomeric purity. The regiochemistry of the deprotonation is determined by the reaction conditions. 1, ω-Alkanediols 1 and 2 are available from (S)-aspartic and (S)-glutamic acid, respectively; a variety of electrophiles El can be added at C-1 or C-ω.

    5. Synthesis of a New Unnatural Amino Acid with a Benzodiazepine-Containing Side Chain and Incorporation into a Tripeptide (pages 1737–1739)

      Prof. Johann Mulzer, Dr. Fridtjof Schröder, Dr. Alessandro Lobbia, Jürgen Buschmann and Peter Luger

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199417371

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      Peptidomimetics based on benzodiazepines can be made from nonnatural amino acids such as 1. They can function both as peptidic and nonpeptidic receptor ligands, owing to the modified amino acid side chains. Compound 1 was synthesized from monomethyl L-glutamate in seven steps in 15% overall yield.

    6. Dendritic Porphyrins: Modulating Redox Potentials of Electroactive Chromophores with Pendant Multifunctionality (pages 1739–1742)

      Peter J. Dandliker, Prof. Dr. François Diederich, Prof. Dr. Maurice Gross, Dr. Carolyn B. Knobler, Dr. Alain Louati and Dr. Elizabeth M. Sanford

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199417391

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      Strong through-space interactions with the dendritic shell surrounding the chromophore are at the root of the unusual redox properties of the porphyrin unit in 1. Compound 1, measuring approximately 4 nm in diameter with a molecular weight of over 19 kDa, represents a new class of synthetic, densely packed, globular electrontransfer protein mimics. R [DOUBLE BOND] NHC[CH2OCH2CH2CONH-(CH2OCH2CH2CO2CH3)3]3.

    7. Linear Coordination Polymers of Copper(II) and Fourfold Deprotonated Sugar Alcohols (pages 1742–1744)

      Prof. Dr. Peter Klüfers and Dipl.-Chem. Jörg Schuhmacher

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199417421

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      Complex structures with polyols as ligands: The respective tetra- and hexaalcohols erythritol and dulcitol undergo fourfold deprotonation in the presence of CuII to form linear, anionic coordination polymers. In addition, dulcitol forms intramolecular hydrogen bonds (see right).

    8. The Simplest Metallocene Sandwich: the Lithocene Anion (pages 1744–1746)

      Dr. Sjoerd Harder and Dipl.-Chem. Marc Heinrich Prosenc

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199417441

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      A staggered conformation with D5d symmetry is adopted by the lithocene anion, the simplest metal-locene of the main group metals with a sandwich structure (see picture). [Cp2Li] forms on treatment of [CpLi] with Ph4PCl in a 2:1 molar ratio in THF and is isolated as the Ph4P+ salt.

    9. The Structures of Two Lithium Hydrazides: Is There Electron-Deficient Bonding? (pages 1746–1748)

      Dr. Nils Metzler, Prof. Dr. Heinrich Nöth and Dipl.-Chem. Hermann Sachdev

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199417461

      A dimer with tetracoordinated N atoms and tricoordinated Li centers describes the structure of lithium hydrazide 1 in the crystal, whereas 2 is a trimer with pentacoor-dinated N atoms. In 1 additional Li[BOND]H interactions stabilize the molecular framework. According to Wade's rules, 2 can also be described as an arachno cluster.

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    10. Thianickelacycles by Ring-Opening Reactions of Cyclic Thioethers and Their Subsequent Carbonylation to Thioesters (pages 1748–1749)

      Dr. Phillip T. Matsunaga and Prof. Gregory L. Hillhouse

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199417481

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      A functional model for the nickel-containing CO-dehydrogenase? Oxidative addition reactions of ethylene sulfide, propylene sulfide, and thietane with nickel complexes like 1 yield thianickelacycles. Formally analogous to the biosynthesis of acetyl coenzyme A, 2 undergoes an insertion reaction with CO followed by reductive elimination of the thiobutyrolactone 3.

    11. Redox Control for the Recognition of Ag +Ions in a Macrocycle Containing Two SH Groups or an S[BOND]S Bridge inside the Cavity (pages 1750–1751)

      Prof. Dr. Tatsuya Nabeshima, Hiroyuki Furusawa and Prof. Dr. Yumihiko Yano

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199417501

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      A completely reversible dithiol-disulfide conversion regulates the recognition properties of the macrocycle 1. Whereas the open form 1A recognizes the Ag+ ion selectively and can transport them across a membrane, the closed form 1B lacks this ability entirely. This concept could be the basis for the development of other receptors with variable recognition properties.

    12. The First Metal Complexes with a Doubly S3-Bridged Ferrocene Ligand (pages 1752–1753)

      Dr. Scott L. Ingham and Dr. Nicholas J. Long

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199417521

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      Bidentate coordination is observed with the sulfur-bridged ferrocenophane 1: [Cu(CH3CN)4]BF4 and 1 react to form the salt [(1)2Cu]BF4. In the cation, the central copper atom is surrounded by a distorted tetrahedral arrangement of four sulfur atoms, each belonging to a different sulfur bridge.

    13. Donor-Stabilized Aluminum(I) Bromide (pages 1754–1755)

      Dipl.-Chem. Mario Mocker, Prof. Dr. Christian Robl and Prof. Dr. Hansgeorg Schnöckel

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199417541

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      The first AlI halide that can be manipulated at room temperature, AlBr-NEt3, is obtained by coconden-sation of AlBr, NEt3, and toluene as yellow crystals and is stable to disproportionation up to about 95°C. In the crystal four Al atoms form a square, and the Br and NEt3 ligands alternate above and below this plane (shown on the right).

    14. Crystal Structure of 2,5-Di-tert-butyl-hydroquinone: Polar Stacking of Nonpolar Hydrogen-Bonded Sheets with Trigonal Symmetry (pages 1755–1757)

      Prof. Dr. Otto Ermer and Christof Röbke

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199417551

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      The molecule centrosymmetric and nonpolar, its crystal structure noncentrosymmetric and polar! This was the unexpected result of the investigation of the hydroquinone 1 in the solid. Furthermore, 1 contains much larger centrosymmetric, nonpolar subunits, namely, layers with trigonal symmetry held together by strained hydrogen bonds. The polarity of the overall structure arises from the peculiar stacking of these layers.

    15. A New Synthetic Route to 1,2-Dihydrocyclobutaarenes (pages 1757–1758)

      Prof. Dr. Fumio Toda, Prof. Dr. Koichi Tanaka, Isao Sano and Toru Isozaki

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199417571

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      In a two- or three-step sequence, dihydrocyclobutabenzene derivatives 4 can be obtained from 1,2-dihalocycloalkenes or ortho-dihaloarenes 1 (see below). The intermediate allenes 3 need not and cannot always be isolated, because cyclization occurs at room temperature. X [DOUBLE BOND] Cl, Br.

    16. Two-Dimensional Sheets of Tetragonal Copper(II) Lattices: X-Ray Crystal Structure and Magnetic Properties of [Cu(C6O4Cl2)(C4H4N2)]n (pages 1759–1761)

      Dr. Satoshi Kawata, Prof. Dr. Susumu Kitagawa, Dr. Mitsuru Kondo, Isamu Furuchi and Prof. Dr. Megumu Munakata

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199417591

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      CuII chains linked by chloranilate dianions function as the warp and pyrazine ligands as the woof in a “woven” two-dimensional coordination polymer. A section of the title compound is shown below. This arrangment leads to weak antiferromagnetic interactions between the metal centers and a singlet ground state. An analogous coordination polymer can be constructed with methanol as a hydrogen-bond donor.

    17. Dendritic Macromolecules Incorporating Tetrathiafulvalene Units (pages 1761–1763)

      Dr. Martin R. Bryce, Wayne Devonport and Dr. Adrian J. Moore

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199417611

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      Reversible multielectron transfers are observed in dendrimers containing tetrathiafulvalene (TTF) units. The synthesis of compounds such as 1 will pave the way for investigations into charge-transfer interactions in dendrimers.

    18. Substituent Effects and Complexation Phenomena in the Diastereoselective Protonation of Chiral Enolates (pages 1764–1765)

      Dr. Norbert Krause

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199417641

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      Ethyl salicylate is the best proton source for the cis-selective protonation of chiral five-, six-, and seven-membered ring enolates [e.g., Eq. (a)]. This was the conclusion of investigations based on a series of phenols and enolates. The selectivity was found to depend markedly on, for example, the substitution pattern in the proton source.

    19. A Novel Approach to the Stereoselective Synthesis of β-Mannosides (pages 1765–1767)

      Dr. Yukishige Ito and Prof. Dr. Tomoya Ogawa

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199417651

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      A simple procedure and compatibility with a variety of manipulations encountered in oligosaccharide synthesis–these advantages are features of this stereoselective synthesis of β-mannosides. The acetal 2 was obtained smoothly from the protected fluoride 1. Subsequent activation of the anomeric position afforded β-mannoside stereoselectively in good yields. CH2X = p-methoxybenzyl.

    20. Isomeric Lactam Catenanes and the Mechanism of their Formation (pages 1767–1770)

      Dipl.-Chem. Stephan Ottens-Hildebrandt, Dipl.-Chem. Stephan Meier, Dipl.-Chem. Wolfgang Schmidt and Prof. Dr. Fritz Vögtle

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199417671

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      A pivotal role in the formation of lactam catenanes is attributed to macromonocycle 1. The synthesis of a monosubstituted catenane, in which 1 acts as host, provides evidence for the proposed mechanism. Three iso-meric disubstituted catenanes are also prepared.

    21. Synthesis and Characterization of the First Thiaselanes (pages 1770–1772)

      Prof. Dr. Josef Hahn and Dipl.-Chem. René Klünsch

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199417701

      Stable as a solid at −40°C, dithiatriselane 1 was formed in the reaction of Se2Cl2 with liquid H2S in CS2, in addition to other disproportionation products such as 2 and 3. Reactions in H2S2 provided sulfur-rich thiaselanes. The 1H and 77Se NMR spectra of the product mixtures could be interpreted unambiguously.

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    22. Magnetic Spin Effects on Photooxidation Quantum Yields of RuII-tris(bipyridine) Type Complexes in Magnetic Fields up to 17.5 Tesla (pages 1772–1775)

      Dieter Bürßner, Hans-Joachim Wolff and Prof. Dr. Ulrich E. Steiner

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199417721

      Spin-control of the rate of electron transfer processes can also be detected in systems with very strong spin-orbit coupling such as in the ruthenium complex [Ru(bpy)3]2+, bipy = 2, 2′-bipyridine. From the influence of an external magnetic field, which was varied continuously up to the extremely high fields of 17.5 Tesla, the kinetic details of the very fast photooxidation of [Ru(bpy)3]2+ by methylviologen were determined quantitatively.

    23. Pronounced Electronic Coupling in Rigidly Connected N,C,N-Coordinated Diruthenium Complexes over a Distance of Up to 20 Å (pages 1775–1778)

      Dr. Marc Beley, Sandrine Chodorowski-Kimmes, Dr. Jean-Paul Collin, Dr. Philippe Lainé, Dr. Jean-Pierre Launay and Dr. Jean-Pierre Sauvage

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199417751

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      Despite the distance of four para-phenylene units between them, the Ru centers in complex 1 are strongly coupled. This system, in which two aromatic rings separate the Ru-coordinating benzene anions, has the same strong metal-metal coupling as the isoelectronic system in which two coordinating pyridine rings are directly connected. The strong coupling in 1 can be explained by the efficient interaction of the energetically similar metal and ligand orbitals.

    24. Isofagomine, a Potent, New Glycosidase Inhibitor (pages 1778–1779)

      Tina M. Jespersen, Wenling Dong, Dr. Michael R. Sierks, Dr. Troels Skrydstrup, Dr. Inge Lundt and Dr. Mikael Bols

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199417781

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      Replacing the anomericCatom of 2-deoxy-O-glucose with an N atom and the ring O atom with a C atom leads to 1, the most potent β-glycosidase inhibitor known to date. This synthetic monosaccharide derivative also inhibits other glucosidases better than naturally occurring sugar derivatives in which only the O atom in the ring is exchanged for an N atom.

    25. Human Oxalate—Really Just an End-Product of Metabolism? (pages 1780–1781)

      Dr. rer. nat. habil. Steffen Albrecht, StR Herbert Brandl and Dipl.-Biochem. Christoph Schönfels

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199417801

      Red and white blood cells contain oxalate at concentrations more than 100 times higher than extracellular levels. This surprising result was obtained by sensitive and specific chemoluminometric measurements for the determination of oxalate in human body fluids. It is not yet known whether oxalate has any useful physiological function in humans; it is excreted and the calcium salt crystallizes as gall and kidney stones.

  4. Book Reviews

    1. Top of page
    2. Reviews
    3. Highlights
    4. Communications
    5. Book Reviews
    6. New Books
  5. New Books

    1. Top of page
    2. Reviews
    3. Highlights
    4. Communications
    5. Book Reviews
    6. New Books