Angewandte Chemie International Edition in English

Cover image for Vol. 30 Issue 10

October 1991

Volume 30, Issue 10

Pages 1193–1386

Currently known as: Angewandte Chemie International Edition

    1. Cover Picture (Angew. Chem. Int. Ed. Engl. 10/1991)

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199111931

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      The cover picture is both a tribute to Switzerland on the occasion of its 700th anniversary and a symbol of the good contact between Angewandte Chemie and the Swiss chemical research. It shows within a chiral Swiss cross four principle routes to enantiomerically pure plant protection chemicals (outside the cross). Nature, the source of all chiral compounds, forms the centerpiece. The modern agrochemical industry follows all four pathways to produce chiral, bioactive compounds. The routes must satisfy two criteria in particular to be considered for industrial synthesis: ecological and economical viability. G. M. Ramos Tombo and D. Belluš report on the role of modern synthetic chemistry in this challenging field on p. 1193 ff.

  1. Reviews

    1. Top of page
    2. Reviews
    3. Highlights
    4. Communications
    5. Book Reviews
    6. Corrigenda
    1. Chirality and Crop Protection (pages 1193–1215)

      Dr. Gerardo M. Ramos Tombo and Prof. Dr. Daniel Belluš

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199111933

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      Decrease in dosage, increase in selectivity against target organisms, and minimal ecological disturbance are the broad aims of modern agrochemistry, and they can only be achieved by interdisciplinary research. If one stereoisomer of a promising new fungicide, herbicide, or insecticide that consists of a racemate or diastereomeric mixture proves to be superior in its biological activity to the mixture, the chemist's task is to develop an economical stereoselective synthesis for it. In favorable cases such as 1–3, the precursor stages of the undesired, often biologically inactive, stereoisomers can be recycled in the reaction. X = Y = H.

    2. Phytochrome, the Visual Pigment of Plants (pages 1216–1228)

      Prof. Dr. Wolfhart Rüdiger and Dr. Fritz Thümmler

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199112161

      The transformation of the photoreceptor phytochrome from the physiologically inactive red-absorbing form (Pr) into the physiologically active far-red form (Pfr) initiates processes that are essential for photomorphogenesis (the development of the plant under the influence of light). This chromoprotein comprises a tetrapyrrole chromophore and a peptide chain about 1130 amino acids long. To elucidate the mechanism by which it functions, molecular biological techniques have been increasingly applied, as well as the classical chemical methods. For instance, phylogenetic relationships and possible structure–function relationships have been deduced from known phytochrome genes.

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    3. The Elucidation of Peroxyl Radical Reactions in Aqueous Solution with the Help of Radiation-Chemical Methods (pages 1229–1253)

      Clemens von Sonntag and Dr. Heinz-Peter Schuchmann

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199112291

      In the presence of oxygen, all radicals, irrespective of how they are formed, are transformed into the corresponding peroxyl radicals. In nature (rivers, lakes,droplets in the atmosphere, living cells) these reactions take place in aqueous medium, but in the laboratory they were studied predominantly in the gas phase or in organic solvents. In the radiation chemistry experiments described here, however, water is the solvent. This is a distinct advantage, because water forms only OH˙ and H˙ as primary radicals besides the solvated electron, and the reactive radical intermediates react fast with substrates.

    4. Single-Crystal X-Ray Diffraction Studies of Oligonucleotides and Oligonucleotide–Drug Complexes (pages 1254–1277)

      Dr. Olga Kennard and Dr. William N. Hunter

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199112541

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      The extreme flexibility of the DNA conformation is only one result of X-ray structure studies on single crystals of oligonucleotides, which are reviewed here. Thus both the small and the large grooves of A-type helices can be very different in size; in one oligonucleotide A- and B-type helices coexist (see picture at the right, where the B-type helices fill a tunnel formed by one of the A-type helices); mismatched base pairs often disturb the overall conformation amazingly little. Of extreme importance (also for the synthesis of medicaments) are insights into the way the active molecules interact with the oligonucleotides.

    5. Medicinal Chemistry in the Golden Age of Biology: Lessons from Steroid and Peptide Research (pages 1278–1301)

      Prof. Ralph Hirschmann

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199112781

      Extremely useful medicines have been discovered and developed in the last forty years. The exceptional progress within this period is demonstrated well by examples of steroids and peptides. A historical survey including the aspect of pharmaceutical research reveals even more: neither chemists nor biologists could have achieved so much independently. The author concludes: “As history shows, we need each other.”

  2. Highlights

    1. Top of page
    2. Reviews
    3. Highlights
    4. Communications
    5. Book Reviews
    6. Corrigenda
    1. The Extraordinary Enzymes Involved in Erythromycin Biosynthesis (pages 1302–1306)

      Dr. James Staunton

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199113021

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      Nature's secret of how highly complicated molecules like erythromycin A are synthesized is no longer completely safe. Lately good progress has been made towards understanding the synthesis of polyketides (to which erythromycin A belongs) by polyketide synthases (PKS). Fatty acids are synthesized along similar lines. However, erythromycin-PKS is a covalently bonded giant protein (cassette/module organization) that shows many enzyme activities. The molecule's skeleton is built up in several reaction cycles by this giant protein.

    2. LiClO4 in Ether—an Unusual Solvent (pages 1306–1308)

      Prof. Dr. Herbert Waldmann

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199113061

      Ionic reactions with polarized transition states are favored by the solvent system LiClO4/Et2O (3–5M). This is demonstrated by (hetero) Diels–Alder reactions and by the sigmatropic rearrangement of ally1 vinyl ethers in this medium. The former react even faster and with higher endo selectivity than in water; the latter are not [3,3] but [1,3] sigmatropic rearrangements, which yield aldehydes. An important advantage of the LiClO4/Et2O system is it that may also be used for acceleration of reactions sensitive to hydrolysis.

  3. Communications

    1. Top of page
    2. Reviews
    3. Highlights
    4. Communications
    5. Book Reviews
    6. Corrigenda
    1. Globe-trotting Hydrogens on the Surface of the Fullerene Compound C60H6(N(CH2CH2)2O)6 (pages 1309–1310)

      Dr. Andreas Hirsch, Dr. Qiaoying Li and Prof. Dr. Fred Wudl

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199113091

      The [1,5] sigmatropic migration of hydrogen in the adduct between buckminsterfullerene C60 and morpholine (Hmorph) is fast at −25°C already. Elemental analysis, thermogravimetry, IR and NMR spectroscopy, and cyclic voltammetry all support the formulation of the adduct as C60H6 (morph)6. The amine is covalently added to six pyracylene units. The small activation barrier to the migration is astounding, especially as large changes in the C60 framework are involved.

    2. [Mo(CO)2(′buS′2)2] and [MoCO(PPh3)(′buS′2)2]: CO Coordination at [Mo[BOND]S] Centers Where Mo Is in a High Oxidation State (pages 1311–1312)

      Prof. Dr. Dieter Sellmann, Dipl.-Chem. Franz Grasser, Dr. Falk Knoch and Dr. Matthias Moll

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199113111

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      In an unusual redox elimination, the complex [MO(CO)2(′buS2′)2] (1, ′buS22− = 3,5-di-tert-butyl-l, 2-benzenedithiolate(2 [BOND])) is formed. For the first time CO has been coordinated to a high-valent [MoS] center, thereby forming a complex that can be regarded as a model for Fe/Mo nitrogenases. The structure of the analogous carbonyltriphenylphosphane complex has been determined by X-ray crystallography.

    3. Formation of Colloidal Transition Metals in Organic Phases and Their Application in Catalysis (pages 1312–1314)

      Prof. Dr. Helmut Bönnemann, Dr.-Ing. Werner Brijoux, Dipl.-Ing. Rainer Brinkmann, Dr. Thomas Joußen, Dipl.-Chem. Barbara Korall and Dr. Eckard Dinjus

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199113121

      Reduction of metal salts with tetraalkylammonium hydrotriorganoborates in organic phases yields a very narrow size range of metal colloids of the elements of groups 6–11. Adsorbed on carrier surfaces, these colloids are highly active hydrogenation catalysts whose activity can be further increased by doping with low-valent organotitanium compounds.

    4. Herbicide Resistance in Transgenic Plants through Degradation of the Phytotoxin to Urea (pages 1314–1315)

      Dr. Ursula H. Maier-Greiner, Dipl.-Chem. Christian B. A. Klaus, Dipl.-Chem. Lydia M. Estermaier and Prof. Dr. Guido R. Hartmann

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199113141

      The incorporation of the gene for cyanamide hydratase can make transgenic tobacco plants resistant to the herbicide cyanamide H2N[BOND]CN. The herbicide is degraded by the expressed gene to the physiologically harmless urea H2NCONH2. In the presence of the ubiquitous plant enzyme urease, which degrades urea, the hydrolysis product NHmath image can, in fact, serve as nitrogen source. The efficiency of this new approach is impressively demonstrated.

    5. On the Enigma of Chlorophyll Degradation: The Constitution of a Secoporphinoid Catabolite (pages 1315–1318)

      Priv.-Doz. Dr. Bernhard Kräutler, Dr. Bernhard Jaun, Prof. Dr. Philippe Matile, Dr. Karlheinz Bortlik and Maja Schellenberg

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199113151

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      The fall colors of leaves is caused by the degradation of the green plant pigment chlorophyll—a complex process about which not much is yet known. Now for the first time with the constitution of the chlorophyll catabolite 1, a 1-formyl-19-oxobilane, a structural pointer has been found which throws light on the degradation of chlorophyll. M = K.

    6. Anti-Selective and Diastereofacially Selective Aldol Reactions with (R)-2-Siloxy-1,2,2-triphenylethyl propionate (pages 1318–1320)

      Prof. Dr. Manfred Braun and Dipl.-Chem. Huber Sacha

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199113181

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      The zirconium enolate of the (R)-propionate 1 attacks aldehydes preferentially at the Si side to afford anti-configurated adducts. The chiral auxiliary triphenylglycol, which is the precursor to the ester 1, is easily accessible in both enantiomeric forms. Thus, access to the carboxylic acids 2 and diols 3 is provided with enantiomeric excesses of > 94%.

    7. Addition of Chiral Nucleophiles to Pyridine Compounds: Total Synthesis of (−)-Isovallesiachotamine and (+)-Vallesiachotamine (pages 1320–1321)

      Dipl.-Chem. Robert Amann and Prof. Dr. Dietrich Spitzner

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199113201

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      An enantiomerically pure skeleton of indol alkaloids can be constructed in a one-pot procedure by adding chiral nucleophiles such as lithiated 2 to the pyridinium compound 1 and carrying out the Pictet–Spengler ring closure according to Wenkert. The product of this reaction has five chiral centers and can be transformed into the title compounds in few steps.

    8. 2,2-Dimethyl-α,α,α′,α′-tetrakis(β-naphthyl)-1,3-dioxolan-4,5-dimethanol (DINOL) for the Titanate-Mediated Enantioselective Addition of Diethylzinc to Aldehydes (pages 1321–1323)

      Dipl.-Chem. Beat Schmidt and Prof. Dr. Dieter Seebach

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199113211

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      Et2Zn can be also added selectively to aliphatic aldehydes in selectivities that are hardly ever achievable otherwise (in some cases greater than 99.5:0.5), if 1, a seven-membered ring containing titanium, is used as catalyst in the presence of stoichiometric quantities of Ti-(OCHMe2)4. A linear relationship exists between the enantiomeric purity of auxiliary and product.

    9. The Radical Cations of Silaketene and Several Isomers of [C,H2,Si,O]˙⊕: An Ab Initio MO Investigation (pages 1323–1325)

      Dr. J. Hrušák, Dr. Ragampeta Srinivas, Prof. Diethard K. Böhme and Prof. Dr. Helmut Schwarz

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199113231

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      The relative stabilities of ketene and silaketene radical cations are distinctly different. According to this result from MO calculations, 1 corresponds to the global minimum in the case of silicon, while in the case of carbon H2CCO˙⊕ is more stable than H2COC˙⊕. For the silicon analogue of the former, H2SiCO˙⊕, a minimum also results, but for structure 2 rather than a structure with C2v symmetry.

    10. K2Cu5Te5, a Novel Mixed-Valence Layered Compound with Metallic Properties (pages 1325–1328)

      Younbong Park, Prof. Mercouri G. Kanatzidis, Prof. Carl R. Kannewurf, Donald C. Degroot and Jon Schindler

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199113251

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      Edge-sharing rhombic [Cu2Te2] units form the building blocks in the corrugated anionic [Cu5Te5]math image layers (see the sketch at the right) in mixed-valent K2Cu5Te5—a metallic conductor of the p type. K2Cu5Te5 is formed on treatment of Cu with K2Tex (x ≈ 4) at 350°C in vacuum as black crystals and is stable to air and moisture.

    11. Amino-substituted ß-Benzyl-C-glycosides; Novel ß-Glycosidase Inhibitors (pages 1328–1329)

      Prof. Dr. Richard R. Schmidt and Dipl.-Chem. Hansjörg Dietrich

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199113281

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      Deoxy and amino substituted benzyl-C-glucosides were prepared and their properties as β-glucosidase inhibitors were studied. Compound 1 proved to be an efficient competitive inhibitor (Ki = 7.0 × 10−5 M), with an activity comparable with that of deoxynojirimycin.

    12. HETLOC, an Efficient Method for Determining Heteronuclear Long-Range Couplings with Heteronuclei in Natural Abundance (pages 1329–1331)

      Dipl.-Chem. Michael Kurz, Dipl.-Chem. Peter Schmieder and Prof. Dr. Horst Kessler

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199113291

      Exceptionally high accuracy and detection limits characterize the NMR experiment, a variant of TOSCY (TOSCY = Total Correlation Spectroscopy), described here for the determination of heteronuclear 3J couplings. No enrichment of the heteroatom is necessary. The process, which also yields coupling constants smaller than the signal width, is only applicable to proton-bearing heteroatoms. In addition, the protons linked by TOSCY transfer should belong to the same spin system. Application in the determination of the angle ϕ in peptides demonstrates the performance of the process.

    13. A New Macrobicyclic Tris-bipyridine Ligand and Its Cumath image and Agmath image Complexes (pages 1331–1333)

      Prof. Dr. Javier de Mendoza, Esther Mesa, Dr. Juan-Carlos Rodríguez-Ubis, Dr. Purificación Vázquez, Prof. Dr. Fritz Vögtle, Dipl.-Chem. Paul-Michael Windscheif, Priz.-Doz. Dr. Kari Rissanen, Prof. Dr. Jean-Maríe Lehn, Daniel Lilienbaum and Dr. Raymond Ziessel

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199113311

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      The novel cage ligand of Agmath image-cryptate 1 is formed in a one-pot synthesis through condensation of the corresponding bipyridinedialdehyde with tris(2-aminoethy1)amine in greater than 70 % yield. The cryptate 1 is the first Ag1 complex in which three Ag1 ions are direct neighbors within the same cavity. All 14 N atoms of the ligand are involved in coordination. Drastic conformational changes during complexation, particularly for the trisbipyridine fragment, were revealed by X-ray structure analyses of the cage ligand and of 1.

    14. Endoreceptors with Convergent Phenanthroline Units: A Molecular Cavity for Six Guest Molecules (pages 1333–1336)

      Prof. Dr. Fritz Vögtle, Dipl.-Chem. Ingo Lüer, Prof. Dr. Vincenzo Balzani and Dr. Nicola Armaroli

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199113331

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      Three docking sites ensure that six guests jostle in the cavity of a new endo receptor. Three phenanthroline molecules are brought into close proximity by coordination of each with a CuI ion. In the FAB mass spectrometer the host complete with all six guests exists as the molecular supercomplex 1. Three bulky guest molecules are not„ invited” simultaneously (R = CH3, p-C6H4CH3; R′ = H) because of the limited space in the cavity.

    15. [3 + 2] Cycloadditions with Azirine Radical Cations: A New Synthesis of N-Substituted Imidazoles (pages 1336–1337)

      Dipl.-Chem. Felix Müller and Prof. Dr. Jochen Mattay

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199113361

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      Photoinduced electron-transfer conditions (the photoexcitation of the electron acceptor naphthalenedicarbonitrile (DCN)) are required for [3 + 2] cycloadditions of azirines (1) with imines, which afford N-substituted imidazoles (3). Probable intermediates are the radical cations 2, which were detected by the trapping reaction with trifluoroethanol.

    16. Laser Flash Photolysis Generation, Spectra, and Lifetimes of Phenylcarbenium Ions in Trifluoroethanol and Hexafluoroisopropyl Alcohol. On the UV Spectrum of the Benzyl Cation (pages 1337–1339)

      Prof. Dr. Robert A. McClelland, Christopher Chan, Frances Cozens, Dr. Agnieszka Modro and Prof. Dr. Steen Steenken

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199113371

      What UV/VIS properties are anticipated for the benzyl cation? Studies on substituted benzyl cations created by laser flash photolysis predict a strong band at λ = 300–310 nm and a (ca. 90%) weaker band at λ = 430–460 nm for PhCH2. This indicates that the transient formed by pulse radiolysis and described in the literature as a benzyl cation with λmax = 363 nm is probably another carbenium ion, perhaps a cyclohexadienyl cation. The lifetime for PhChmath image in (CF3)2CHOH is probably only 2–20 ns.

    17. ACRL Toxin I: Convergent Total Synthesis of Its 3-Methyl Enol Ether from D-Glucose (pages 1339–1343)

      Prof. Dr. Frieder W. Lichtenthaler, Dipl.-Ing. Jürgen Dinges and Dr. Yoshimasa Fukuda

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199113391

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      Toxin 1 is released by the pathogenic moldAlternaria citri, which attacks citrus fruit causing the Brown spot disease so dangerous to the harvest. A synthesis for it was developed that constructed the C5[BOND]C10 and C11[BOND]C16 fragments 2 and 3 in “enantiopure” form from D-glucose and introduced the C1[BOND]C4 unit as an acetic acetate derivative.

    18. mer-[Cr(CO)34-norbornadiene)(η2-ethene)]: A Key Compound in Understanding the Mechanism of the Photocatalytic Diene Hydrogenation with Chromium Carbonyl Complexes (pages 1343–1345)

      Dipl.-Chem. Dietmar Chmielewski, Prof. Dr. Friedrich-Wilhelm Grevels, Dr. Jürgen Jacke and Prof. Dr. Kurt Schaffner

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199113431

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      The catalytic active species in the photoinduced hydrogenation of norbornadiene (NBD) that leads to nortricyclene and norbornene are the complex fragments fac- and mer-[Cr(C0)34-nbd)]. This conclusion is drawn from experiments in the dark with the labile ethene complex 1 as catalyst: the product distribution, pressure dependence, and results from labeling experiments correspond to those found for photoinduced catalysis with [Cr(CO)44-nbd)] as starting complex.

    19. The Mechanism of Interaction of Triplet 3-Methylcyclohex-2-en-1-one with Maleo- and fumarodinitrile: Evidence for Direct Formation of Triplet 1,4-Biradicals in [2 + 2] Photocyclo- additions without the Intermediacy of Exciplexes (pages 1345–1347)

      Prof. David I. Schuster, Dr. George E. Heibel and Dr. Jan Woning

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199113451

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      Alkene–enone exciplexes can be excluded as intermediates in the [2 + 2] cycloaddition of fumarodinitrile and triplet 3-methylcyclohex-2-en-1-one. Instead, the experimental results demonstrate that the triplet 1,4-diradical intermediate 1 is favored, which rapidly forms an equilibrium mixture of rotamers about the newly formed single bond before reacting to form the corresponding cycloadducts.

    20. 6-Deoxy-6-N-histamino-β-cyclodextrin Copper(II) Complex, a New Enantioselective Receptor for Aromatic Amino Acids (pages 1348–1349)

      Giuseppe Impellizzeri, Giuseppe Maccarrone, Prof. Dr. Enrico Rizzarelli, Graziella Vecchio, Roberto Corradini and Prof. Dr. Rosangela Marchelli

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199113481

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      Chiral recognition of D- and L-tryptophan in the mobile phase in the presence of the title complex [CuL]2⊕ is the reason for their successful HPLC separation on a conventional achiral reversed-phase column. The separation is based on mixed inclusion–ligand-exchange chromatography, in which the more stable complex [CuL(D-Trp)] probably has the form shown here.

    21. Competing Occurrence of Isomeric (Dialkyltartrato)zirconocene Dimers with Dimetallatricyclic and Ten-Membered Dimetallamonocyclic Frameworks (pages 1349–1351)

      Prof. Dr. Gerhard Erker, Dipl.-Chem. Mathias Rump, Dr. Stefan Dehnicke, Prof. Dr. Carl Krüger, Dipl.-Chem. Stefan Werner and Dipl.-Chem. Matthias Nolte

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199113491

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      Is the question of catalytically active species for Sharpless epoxidations again open? The results of NMR spectroscopy and X-ray structural analysis on catalytically inactive (tartrato)zirconocene dimers show how complicated the situation can be. Simple stereochemical changes and variation of the substituents in the crystal and in solution result in these complexes forming either ten-membered dimetallacycles (type A) or dimetallatricycles (type B). E = CO2CHMe2, CO2Me.

    22. Bis(hydroperoxy)naphthaldiimide as a “Photo-Fenton Reagent”: Sequence-Specific Photocleavage of DNA (pages 1351–1353)

      Dr. Seiichi Matsugo, Dr. Shosuke Kawanishi, Koji Yamamoto, Dr. Hiroshi Sugiyama, Prof. Teruo Matsuura and Prof. Dr. Isao Saito

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199113511

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      Light of wavelength 360nm is sufficient to form hydroxyl radicals from the bis(hydroperoxide) 1 (R = CH2CH(OMe)[BOND]OOH). Thus 1 is an attractive photo-Fenton reagent for biological applications. First experiments showed that 1 can cut doublestranded DNA selectively at the 5′ site of 5′-GG-3′ sequences.

    23. The Interaction of Tri-tert-butylgallium with White Phosphorus: Isolation of an Unusual Gallium Phosphorus Cluster (pages 1353–1354)

      Dr. Michael B. Power and Prof. Dr. Andrew R. Barron

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199113531

      A Gap4 tricycle of type [] is found in the structure of Ga2P4tBu6, which forms at room temperature already from elemental phosphorus (P4) and the Lewis acid GatBu3. This reaction, in which one side of the P4 tetrahedron is opened, provides a surprisingly simple access to potential precursors for semiconductor materials of the III/IV type.

    24. A Simple Way to Predict the Products of Topochemical Photoreactions on the Basis of Force Field Calculations (pages 1354–1356)

      Dr. Klaus Angermund, Prof. Dr. Carl Krüger, Dipl.-Chem. Matthias Nolte and Dr. Ingo Klopp

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199113541

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      Not only topochemically allowed, but also the topochemically forbidden products that are partly formed on the photodimerization of crystalline butenolides 1 can be qualitatively correctly predicted with the modified Cohen model presented here. Thus the way is clear for the application of standardized molecular-modeling procedures to problems in organic solid state chemistry.

    25. Flash Photolytic Generation and Study of Ynamines. First Observation of Primary and Secondary Ynamines in Solution (pages 1356–1358)

      Yvonne Chiang, Dr. Andrew S. Grant, Prof. Dr. A. Jerry Kresge, Dr. Przemyslaw Pruszynski, Dr. Norman P. Schepp and Prof. Dr. Jakob Wirz

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199113561

      Primary and secondary ynamines (1 and 2, respectively) have been observed in solution for the first time, and the mechanism of their subsequent reactions were studied. The acid- and base-catalyzed isomerizations of primary and secondary ynamines afford ketenimines which tautomerize to nitriles or to carboxylic acids. Tertiary ynamines (3) are hydrated directly to amines.

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    26. Solvent Dependence of Photoinduced Intramolecular Electron Transfer: Criteria for the Design of Systems with Rapid, Solvent-Independent Charge Separation (pages 1358–1361)

      Drs. Jan Kroon, Prof. Dr. Jan W. Verhoeven, Prof. Dr. Michael N. Paddon-Row and Dr. Anna M. Oliver

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199113581

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      The interplay between structure and environment of the charge-separated state is the decisive factor determining the rate of the photo-induced charge transfer of donor–bridge–acceptor compounds. In the case of 1a and 1b, which differ only in the substituents on the donor unit, the “environment” (solvent effects) can be quantified. Design criteria are derived for systems that can undergo medium- and temperature-independent charge separation at a maximum rate for any given donor–acceptor separation.

    27. A General Entry to Rigid Systems with Alternatingly Orthogonal Arene Units via Diels-Alder Reactions (pages 1361–1363)

      Dipl.-Chem. Burkhard König, Prof. Dr. Jürgen Heinze, Dipl.-Chem. Klaus Meerholz and Prof. Dr. Armin de Meijere

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199113611

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      The [2.2]paracyclophanes 1 and 2 containing annelated furan units on the bridges can be prepared by retro-Diels–Alder reactions from tetrabromine[2.2]paracyclophane in a two-step procedure. On treatment with dehydro- and bisdehydroarenes they afford, after deoxygenation, novel polycyclenes such as 3 with alternating orthogonal arene units.

    28. Metal-Ion Dependent Regioselectivity in Cyclometalation Reactions (pages 1363–1364)

      Dr. Edwin C. Constable, Dr. Roland P. G. Henney, Dr. Paul R. Raithby and Professor Lynn R. Sousa

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199113631

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      A dimeric gold(III) complex, the 18-membered ring system 1, is formed on treatment of Na[AuCl4] with the potentially chelating lig-and 6-(2-thienyl)-2,2′-bipyridine (HL). Metalation of the thienyl unit occurs in the 5-position, and the coordination sphere of gold also includes two trans Cl ligands and an N atom from the terminal pyridine of the second HL ligand. In contrast, PdII and PtII form cyclometalated complexes of the type [MLCl].

    29. Novel Reactions of Disubstituted 1,2-Dioxetanes with Olefins as π-Nucleophiles: Cycloadditions via 1,6-Dipoles (pages 1365–1366)

      Prof. Dr. Waldemar Adam, Simone Andler and Dipl.-Chem. Markus Heil

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199113651

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      The 1,6 dipole 5 is the probable intermediate in the novel reaction of 3,3-disubstituted 1,2-dioxetanes 1 (X = H, C1, Br) with electron-rich olefins 2. The products are the cycloadducts 3 and the enes 4 (R1–R4 = OEt; R1, R2 = OCH2CH2O; R3, R4 = H, etc.)

    30. The Mechanism of Acylcarbene Insertion into O[BOND]H Bonds—Direct Observation of the Enol of a Carboxylic Acid Ester in Aqueous Solution (pages 1366–1368)

      Yvonne Chiang, Prof. Dr. A. Jerry Kresge, Dr. Przemyslaw Pruszynski, Dr. Norman P. Schepp and Prof. Dr. Jakob Wirz

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199113661

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      The addition of water to the acyl carbene function as a whole is a better description for the reaction (a) than the insertion of carbene 1 into the O[BOND]H bond of water. The enol tautomer 2 of methyl mandelate was shown to be an intermediate. If the photolysis is conducted in 18O-enriched water, 3 is marked exclusively at the α-hydroxyl group.

    31. Importance of Oxyanion Orientation to the Stereochemical Control of Anionic Oxy-Cope Rearrangements (pages 1368–1370)

      Prof. Dr. Leo A. Paquette and Dr. George D. Maynard

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199113681

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      The enantiomerically pure alcohols 1 and 2 react in an anionic oxy-Cope rearrangement to afford mixtures of (S)- and (R)-4-methyl-5-hexenal(3 and ent-3, respectively). The findings demonstrate that transition states with the oxido group in equatorial position are not as favored in acyclic systems as previously assumed. The oxido group occupies an axial position in 36–40% of the transition states.

    32. π-Coordination of Diorganotin Dications (pages 1370–1372)

      Prof. Dr. Bernd Wrackmeyer, Dipl.-Chem. Gerald Kehr and Dr. Roland Boese

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199113701

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      The understanding of the mechanism of organoboration in 1 rests on the stabilization of the diorganotin dication by two C[BOND]C triple bonds. Compound 1 where R = Me was isolated from tetra-1-propynylstannane and triethyl borane. X-ray analysis shows that the halves of the molecule are not exactly symmetric, but have different bond lengths and angles.

    33. Stable Phosphazenium Ions in Synthesis—an Easily Accessible, Extremely Reactive “Naked” Fluoride Salt (pages 1372–1375)

      Priv.-Doz. Dr. Reinhard Schwesinger, Dipl.-Chem. Reinhard Link, Prof. Dr. Gerhard Thiele, Dr. Heinz Rotter, Dr. Dieter Honert, Prof. Dr. Hans-Heinrich Limbach and Dipl.-Chem. Ferdinand Männle

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199113721

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      The strongest metal-free base is the cation 1, which can be prepared in a one-pot procedure from PCl5, NH4Cl, Me2NH, and NaBF4. Anion exchange affords 1-F, which mediates in the alkylation of an anionic allylic species produced from allyltrimethylsilane; furthermore, the unsolvated floride ion is an excellent proton-selective base for E2 eliminations.

    34. Complexation of Transition Metal Ions with Substituted Aza Macrocycles: Induction of Columnar Mesophases by Molecular Recognition (pages 1375–1377)

      Dipl.-Phys. Andrea Liebmann, Dipl.-Chem. Carlo Mertesdorf, Thomas Plesnivy, Prof. Dr. Helmut Ringsdorf and Prof. Dr. Joachim H. Wendorff

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199113751

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      The influence of molecule dynamics on the phase properties is evident in the polyaza macrocycle 1 and the corresponding amide (CO in place of CH2 groups). The amide, but not 1, forms a columnar discotic mesophase, because of the restricted rotation of the side groups, which results from the partial double bond character of the exocyclic C[BOND]N bond. Compound 1 needs to be coordinated, for example to cobalt ions, to fix its conformation and thus to induce a liquid crystalline phase. The preliminary susceptibility measurements on an analogous copper complex suggests an electronic coupling between the metal ions.

    35. Azarhoda-closo-dodecaborane (pages 1377–1379)

      Hans-Peter Hansen, Jens Müller, Dr. Ulrich Englert and Prof. Dr. Peter Paetzold

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199113771

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      A distorted RhNB10 icosahedron containing a six-fold coordinated N atom forms the basic structure of the complex [{(Ph3P)2RhH}NB10H11] (1, depicted to the right without the PPh3 substituents), which is accessible from the anion nido-NB10Hmath image and [(Ph3P)3RhCl]. The open pentagonal side of the anion becomes a pentahapto ligand and the bridging H atoms migrate to rhodium.

    36. Surface Fractality of Dendrimers (pages 1379–1380)

      Dr. Dina Farin and Prof. David Avnir

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199113791

      The surface of the polyamidoamine (PAMAM) starburst dendrimers of Tomalia et al. is indeed fractal. Two independent analyses yielded as fractal dimension D 2.41 ± 0.04 and 2.42 ± 0.07. The fractal dimension of several enzymes lie in this region, so the starburst dendrimers will probably mimic biomolecules.

  4. Book Reviews

    1. Top of page
    2. Reviews
    3. Highlights
    4. Communications
    5. Book Reviews
    6. Corrigenda
    1. Book Review: Atomic and Molecular Clusters. Edited by E. R. Bernstein (page 1382)

      Thomas Lange and T. Patrick Martin

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199113821

  5. Corrigenda

    1. Top of page
    2. Reviews
    3. Highlights
    4. Communications
    5. Book Reviews
    6. Corrigenda
    1. You have free access to this content
      Corrigendum (page 1386)

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199113862