Angewandte Chemie International Edition in English

Cover image for Vol. 29 Issue 12

December 1990

Volume 29, Issue 12

Pages 1371–1522

Currently known as: Angewandte Chemie International Edition

    1. Cover Picture (Angew. Chem. Int. Ed. Engl. 12/1990)

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199013711

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      The cover picture shows the structure of a trigonal-bipyramidal rhodium complex, whose “beauty” stems from a chiral C3-symmetric triphosphane ligand (yellow, Rh; orange, CO; violet, P; black, C; white, H). The reduced number of asymmetric environs in mettal complexes with chiral tridentate C3-symmetric ligands should lead to high enatioselectivities in reactions which are catalyzed by such complexes. This was first achieved in the hydrogenation of olefins. To carry out organic reactions enantioselectively and catalytically is the ultimate aim of modern organic syntthesis. It can be achieved via the “bio-route” (enzyme-, antibody-catalyzed) and via the “metal-route” (Metal-complex-catalyzed). A contribution to the “metal-route” is described by M. J. Burk et al. on p. 1462. Cover picture computer graphic by J. C. Calabrese (DuPont Central Research & Development).

  1. Reviews

    1. Top of page
    2. Reviews
    3. Communications
    4. Book Reviews
    5. Author Index
    6. Subject Index
    1. CC Bond Formation by Addition of Carbenium Ions to Alkenes: Kinetics and Mechanism (pages 1371–1384)

      Prof. Herbert Mayr

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199013713

      A key step of numerous syntheses in organic and macromolecular chemistry, the addition of carbenium ions to CC double bonds, is analyzed mechanistically using the Lewis-acid induced reactions of alkyl chlorides with alkenes as example. Stereochemical and kinetic studies indicate a less bridged, product-similar transition state. Reactivity-selectivity relationships over a reactivity range of eight orders of magnitude show that the structure of the transition state is changed only on varying the substituents in the immediate proximity of the reaction center.

  2. Communications

    1. Top of page
    2. Reviews
    3. Communications
    4. Book Reviews
    5. Author Index
    6. Subject Index
    1. Acetylene-Cumulene Porphyrinoids (pages 1385–1387)

      Norbert Jux, Peter Koch, Dr. Hans Schmickler, Dr. Johann Lex and Prof. Dr. Emanuel Vogel

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199013851

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      The combination of porphyrin and acetylene chemistry leads to interesting novel molecules. This is illustrated by the synthesis of the first acetylene-cumulene-porphyrinoid 1, which can be regarded as a stretched porphycene.

    2. Porphyrin Homologues: [22]Porphyrin(, a “Stretched Porphycene” (pages 1387–1390)

      Prof. Dr. Emanuel Vogel, Norbert Jux, Eduardo Rodriguez-Val, Dr. Johann Lex and Dr. Hans Schmickler

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199013871

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      The close structural relationship of porphyrin system and porphycene system is strikingly demonstrated with the [22]porphyrin( 1/2: on grounds of strain [22]prophyrin( does not exist as the isomer with porphyrin symmetry (D2h) 1, but as stretched porphycene 2.

    3. Isocorroles: Novel Tetrapyrrolic Macrocycles (pages 1390–1393)

      Stefan Will, Afssaneh Rahbar, Dr. Hans Schmickler, Dr. Johann Lex and Prof. Dr. Emanuel Vogel

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199013901

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      The ring contraction of a porphycene derivative yields an isocorrole derivative whose ring skeleton deviates significantly more from planarity than that of corrole. According to spectroscopic findings, however, the derivative is an aromatic compound. 1 and 3 are the parent compounds corrole and isocorrole, respectively.

    4. Synthesis of a Bisvinylogous Octaethylporphyrin (pages 1393–1395)

      Dipl.-Chem. Hartmann König, Christian Eickmeier, Dr. Manfred Möller, Dipl.-Ing. Ute Rodewald and Prof. Dr. Burchard Franck

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199013931

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      Hans Fischer's octaethylporphyrin (OEP) is so far the best available and most investigated of all synthetic porphyrins. The bisvinylogue OEP 1 has now been synthesized in high yields in a few steps. Owing to its chemical stability, good accessibility, and hitherto most intense UV/VIS absorption for an organic dye, this is a system with wide-ranging perspectives.

    5. [22]Coproporphyrin II for Photodynamic Therapy (pages 1395–1397)

      Dipl.-Chem. Stefan Beckmann, Dipl.-Chem. Thomas Wessel, Prof. Dr. Burchard Franck, Dr. Wolfgang Hönle, Dr. Horst Borrmann and Prof. Dr. Hans-Georg von Schnering

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199013951

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      Hematoporphyrin has acclaimed world-wide importance in photodynamic tumor therapy (PDT). Functional disadvantages of the “upper” half of the molecule of this photosensitizer, such as chemical instability and stereoisomerism, however, still prevent its use medicinally. The novel [22]coproporphyrin II 1 synthesized from two ‘lower’ halves of the molecule is characterized by stability, steric homogeneity, and long-wave intense UV/VIS bands. 1 is an aromatic [22]annulene.

    6. GeII and SnII Complexes of [2.2.2]Paracyclophane with Threefold Internal η6 Coordination (pages 1397–1398)

      Dipl.-Chem. Thomas Probst, Dipl.-Chem. Oliver Steigelmann, Jürgen Riede and Prof. Dr. Hubert Schmiclbaur

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199013971

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      SnII is significantly more tightly bound than GeII in the cavity of the [2.2.2]paracyclophane(L), as shown by the structure analyses of the complex cations [LSn(AlCl4)] and [LGeCl]1. In the tin complex the AlClmath image counterion is loosely coordinated via a Cl atom to the metal (Sn-Cl 3.073 Å) and thus hardly disturbs the expected trigonal-planar coordination, whereas the strong Ge[BOND]Cl bond (Ge[BOND]Cl 2.224 Å) in 1 leads to a weakening of the Ge-arene interaction and to a preferential tetrahedral environment for the metal.

    7. Assembly of the [CAu6]2⊕ Cluster with a Tailor-made Diphosphane Spanning the Octahedral Edges (pages 1399–1400)

      Dipl.-Chem. Oliver Steigelmann, Peter Bissinger and Prof. Dr. Hubert Schmidbaur

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199013991

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      Digold complexes bridged via chelate ligands are also suitable for the molecular “gilding” of carbon atoms, as shown by the structure of the CAu6, complex cation 1. Due to the asymmetry of the ligand sphere the cations are chiral. The formation of 1 demonstrates that the aurophilicity concept can also be extended to bidentate ligands.

    8. Amine-Template-Directed Synthesis of Cyclic Porphyrin Oligomers (pages 1400–1403)

      Harry L. Anderson and Dr. Jeremy K. M. Sanders

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199014001

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      The dimers 1 can be prepared in 70% yield by Glaser coupling, if the reaction is carried out in the presence of 4,4′-bipyridine as template. With a tripyridyltriazine as template, formation of the corresponding trimer (52%) is favored. Without template the reaction is unselective: Dimer and trimer are formed together in 20–25% and 30–50% yields, respectively. The yields correspond well with the bonding properties of these cage molecules, which are of interest as precursors for model enzymes.

    9. Synthesis and Structure of [Et2OZn(SC6H2tBu3)2], the First T-Shaped Zinc Complex (pages 1403–1404)

      Prof. Philip P. Power and Steven C. Shoner

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199014031

      The stacking of aryl groups once again appears to be structure-determining. The title complex, which is accessible by reaction of [Zn(CH2SiMe3)2] with two equivalents of 2,4,6-tBuC6H2SH in the presence of Et2O, has an S[BOND]Zn[BOND]S angle of ca. 160° and Zn[BOND]S distances of only 2.196 Å. In contrast, the Zn[BOND]O distance is relatively large and explains the ready cleavability of the ether ligands. Zinc thiolates are of interest as model complexes for zinc-containing proteins.

    10. A New Mode of Metal Encapsulation (pages 1404–1406)

      Dr. John S. Bartlett, James F. Costello, Dr. Shrock Mehani, Dr. S. Ramdas, Alexandra M. Z. Slawin, Dr. J. Fraser Stoddart and Dr. David J. Williams

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199014041

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      All ten oxygen atoms of the acyclic oligomer 1 c participate in the coordination of Ba2⊕ in the “scorpion” complex 1c · Ba(SCN)2 · Me2CO. The eleventh coordination site is occupied by the acetone molecule. A further characteristic of the complex are strong O[BOND]HċN hydrogen bonds to the thiocyanate counterion. The ligands 1 also exhibit a high selectivity for cations with ionic radii of 1.2–1.3 Å, which could be explained with the help of molecular modeling studies.

    11. Artificial Receptors for Carbohydrate Derivatives (pages 1407–1408)

      Richard P. Bonar-Law, Dr. Anthony P. Davis and Dr. Brian A. Murray

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199014071

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      Clear evidence of encapsulation of pyranosides in the macrocycle 1 (R [DOUBLE BOND] H, R′ [DOUBLE BOND] Bn) was afforded by NMR and IR spectroscopic investigations of the reaction of 1 with 2 in CDCl3 and force field calculations for the methyl analogue of 2. The macrocycle is thus one of the first synthetic carbohydrate receptors. Its cavity is large enough to fix the guest molecule from all sides by oriented hydrogen bonds.

    12. An Aluminaphosphacubane, a New Aluminum Phosphide Precursor (pages 1409–1410)

      Prof. Dr. Alan H. Cowley, Prof. Dr. Richard A. Jones, Miguel A. Mardones, Professor Dr. Jerry L. Atwood and Dr. Simon G. Bott

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199014091

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      The Al4P4 cube in [iBuAl(μ3-PSiPh3]4 is not only aesthetically attractive. Its behavior on thermal loading makes it also of interest as precursor for the III/V semiconductor AlP. Already at 150°C the substituents are split off as Ph3SiH and isobutene. Elevation of the temperature to 500 °C leads to pure A1P.

    13. The Structure of Cyclic C6S6 and C6O6 (pages 1410–1412)

      Prof. Dr. Gernot Frenking

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anieback.199014101

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      The energetically most favorable isomer of C6S6 detected in the gas phase is not aromatic but quinoid. The difference in energy between A and B was determined by ab initio calculations to be 10.9 kcal mol−1. In contrast, the hexathioketone C, which should have a chair conformation, has an energy almost equal to that of B.

    14. Isotope Effects Associated with α-Olefin Insertion in Zirconocene-Based Polymerisation Catalysts: Evidence for an α-Agostic Transition State (pages 1412–1413)

      Dipl.-Chem. Hehmuth Krauledat and Prof. Dr. Hans-Herbert Brintzinger

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199014121

      The hydrodimerization of trans- and of cis-1-deuterio-l-hexene to the threo- and erythro-isomers of 6-deuterio-5-deuteriomethylundecane with the chiral pre-catalyst rac-ethylenebis(tetrahydroindenyl)zirconium dichloride gave diastereomeric ratios of 2.4:1, which, depending on (E)- or (Z)-configuration of the diene, reverse. The results confirm observations by Pino et al. that α-olefins insert into Zr—H and Zr—alkyl bonds with opposite enantiofacial orientation.

    15. 2-Pentylcyclopent-2-en-1-one by Catalytic Pauson-Khand Reaction (pages 1413–1416)

      Prof. Dr. Valentin Rautenstrauch, Patrick Mégard, José Conesa and Dr. Wilhelm Küster

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199014131

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      Only 0.0022 mole equivalents of the catalyst [Co2(CO)8] are necessary for the preparation of the cyclopentenone 1 from 1-heptyne, ethylene, and CO with an exchange number of about 220. This first catalytic Pauson-Khand reaction (PKR) with an unstrained alkene affords 1, a precursor of methyl-trans-dihydrojasmonate that is important for the perfumery industry, in about 50% yield. The main byproducts of this PKR were also identified and possible routes for their formation proposed.

    16. s-trans-1, 3-Dienes as Ligands for Cationic Group 8 Metal Centers (pages 1416–1417)

      Dr. Stephen A. Benyunes, Dr. Jeremy P. Day, Prof. Michael Green, Dr. Abdul Wahab Al-Saadoon and Dr. Tracey L. Waring

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199014161

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      1,3-Dienes very frequently assume an s-cis-conformation upon coordination to metal centers. The Ru-complex 1 is the first cationic s-trans-diene complex which is stable in solution at room temperature. Such complexes are conceivable as reactive intermediates in the catalytic reaction of conjugated dienes.

    17. A Synthetic Equivalent for [2.2]Paracyclophane-1,9-diyne: Octaphenyl-1:2,9:10-dibenzo[2,2]paracyclophane-l,9-diene and Its Reduction to the Hexaanion (pages 1418–1419)

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

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199014181

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      The readily accessible tetrabromo[2.2]paracyclophane can be dehydrobrominated stepwise four times with potassium tert-butoxide, and the [2.2]paracyclophanines formed thereby are trapped efficiently by furan, diphenyl-isobenzofuran and tetraphenylcyclopentadienone to give the corresponding cycloadducts. The octaphenyldibenzo[2.2]paracyclophane-l,9-diene 1, which formally consists of two hexaphenylbenzene units, is isolated in particularly high yields (69%).

    18. [Cu4(ddtp)2Br4], a Unique Tetranuclear Copper(I) Complex with Bridging Thioethers and Bridging Bromides (pages 1419–1420)

      Adrianus L. E. Stoffels, Willem G. Haanstra, Willem L. Driessen and Dr. Jan Reedijk

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199014191

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      A spontaneous reduction of CuII to CuI takes place when CuBr2 is allowed to react with the tridentate SN2 ligand ddtp in boiling ethanol/ acetone. The Cu4 title complex obtained contains thioether bridges with large Cu-S distances and Cu-S-Cu angles (160.6°!). The Cu2Cu2 rectangular structure is without precedent for CuI complexes. [Cu4(ddtp)2Br4] can serve as reference compound for EXAFS studies on blue copper-proteins.

    19. Asymmetric Protonation of Enolates (pages 1420–1422)

      Dominique Potin, Kevin Williams and Prof. Julias Rebek Jr.

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199014201

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      Efficient chiral proton sources have long been the organic chemist's dream. With the lactam 1 based on Kemp's tricarboxylic acid, cyclic enolates have now been protonated with an enantiomeric excess (ee) of up to 91%. The reason for the high ee values is the asymmetric microenvironment of the acidic NH group.

    20. Chiral Lithium-1-oxyalkanides by Asymmetric Deprotonation; Enantioselective Synthesis of 2-Hydroxyalkanoic Acids and Secondary Alkanols (pages 1422–1424)

      Prof. Dr. Dieter Hoppe, Folker Hintze and Dipl.-Chem. Petra Tebben

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199014221

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      A Very simple general, solution to the problem of preparing chiral synthons of the type 3 is provided by the lithium complexes 1. They are generated by asymmetric deprotonation of the corresponding prochiral “non-activated” alkyl carbanates with sec-butyllithium/(–)-sparteine. 1 can be substituted by electrophiles stereospecifically to give the protected hydroxy-derivatives 2 (> 95 ee), and the Cbx group is readily cleavable. R1 [DOUBLE BOND] alkyl, Cbx [DOUBLE BOND] carbamoyl idue of 1.

    21. Generation of a Configurationally Stable Chiral Benzyllithium Derivative, and the Capricious Stereochemistry of Its Electrophilic Substitution (pages 1424–1425)

      Prof. Dr. Dieter Hoppe, Axel Carstens and Dr. Thomas Krámer

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199014241

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      Depending on the electrophile, substitution of the chiral benzyllithium compound 2, which is configurationally stable in solution, takes place with retention or inversion of configuration. 2 was generated by deprotonation of the Corresponding optically active benzyl carbamate 1. The products 3 are of interest as synthetic building blocks. Cb [DOUBLE BOND] C([DOUBLE BOND]O)NiPr2.

    22. Building Up Metal-Stabilized Fourfold Bridged Cyclobutadienophanes (pages 1426–1427)

      Prof. Dr. Rolf Gleiter and Dr. Volker Schehlmann

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199014261

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      Starting from 5-cyclodecinol, metal-stabilized, quadruply bridged cyclobutadiaphosphanes such as 1–4 can be synthesized according to a building block principle.

    23. Doubly Bridged Prismanes, Dewar Benzenes and Benzene Derivatives from Cyclooctyne and 1, 8-Cyclotetradecadiyne: En Route to Propella[n3]prismanes (pages 1427–1429)

      Prof. Dr. Rolf Gleiter and Dipl.-Chem. Björn Treptow

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199014271

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      The highly strained Dewer-benzene 1 and the prismane 2 can be obtained from Cyclooctyne in a few steps. 2 is formed by irradiation of 1 with long wavelength light; at λ = 250 nm only polymers are formed, presumably via the corresponding [5]paracyclophane.

    24. Spontaneous Formation of Stable Phosphino(silyl)-carbenes from Unstable Diazo Compounds (pages 1429–1431)

      Dr. Gregory R. Gillette, Dr. Antoine Baceiredo and Dr. Guy Bertrand

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199014291

      The carbene-like compounds 1, which are formed almost quantitatively from phosphanyldiazomethanes already at T ≤ 35°C if the tetramethylpiperidine(tmp)-R residue is one of the substituents on the phosphorus, are stable for several weeks in solution. With the exception of 1a, the compounds 1 react with BuNC to give the ketenimines 2. a, R [DOUBLE BOND] NiPr2, R′ [DOUBLE BOND] Me; b, R [DOUBLE BOND] NMe2, R′ [DOUBLE BOND] Me; c, R [DOUBLE BOND] NMe2, R′ [DOUBLE BOND] iPr; d, R [DOUBLE BOND] Ph, R′ [DOUBLE BOND] Me.

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    25. Fe-Catalyzed Gas-Phase Oxidation of Ethane by N2O (pages 1431–1433)

      Dipl.-Chem. Detlef Schröder and Prof. Dr. Helmut Schwarz

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199014311

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      The transferance of the N2O oxygen atom to a Fe(C2H4) ion with formation of the metallacycle 1 is the key step of the title reaction (a). This follows from ion cyclotron resonance experiments as well as from mechanistic and thermo-chemical considerations. After decomposition of the “hot” intermediate 1 to Fe and acetaldehyde a novel catalytic cycle can be initiated [Eq. (a)].

    26. FeO Activates Methane (pages 1433–1434)

      Dipl.-Chem. Detlef Schröder and Prof. Dr. Helmut Schwarz

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199014331

      —whereby predominantly FeOH + CHmath image and Fe + CH3OH are formed. This reaction is, however, four times slower than that described in the previous communication; nevertheless, the chances for a catalytic activation are not bad, since the Fe regenerated from the intermediate 1 during the course of the reductive elimination by N2O can easily be reintroduced in the cycle for further reaction.

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    27. Sterically Hindered Internal Rotation in an Acyclic α,β-Unsaturated Ketone. 2, 2, 5-Trimethyl-4-isopropylhex-4-en-3-one (pages 1435–1436)

      Prof. John M. Nuss, Steven J. Bark, Dr. Daniel B. Borchardt and Prof. Thomas Hellmann Morton

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199014351

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      An activation barrier of 45 kJ mol−1 follows from the 1H-NMR spectra in the case of the first detected hindered rotation about the sp2—sp2 single bond of an acylic α,β-unsaturated ketone (1). The intensities of the UV bands of the π[RIGHTWARDS ARROW]π* and n [RIGHTWARDS ARROW] π* transitions are consistent with a skewed conformation of 1. However, molecular mechanics calculations predict a much higher steric barrier than is observed, which demonstrates the limitations of our current understanding of sterically hindered rotation about sp2—sp2 single bonds in aliphatic systems.

    28. A 1 -Silyl-1H-phosphirene/1, 2-Dihydro-1,2-phosphasilete Rearrangement—The Decisive Step in the Synthesis of Heterocycles Containing 2-Phospha-1,3-diene Units (pages 1436–1438)

      Dipl.-Chem. Steffen Haber, Dr. Roland Boese and Prof. Dr. Manfred Regitz

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199014361

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      The silyl-substituted l-H-phosphirene 1 rearranges photochemically to the dihy-drophosphasilete 2. When 2 is acylated at the phosphorus atom a spontaneous 1, 3-silyl shift leads to formation of 3, a heterocycle with a 2-phospha-l, 3-diene unit. R1 [DOUBLE BOND] R3 [DOUBLE BOND] tBu, R2 [DOUBLE BOND] Ph.

    29. Vanadium(-I) Dinitrogen Complexes with N2 Coordinated End-on: Functional Models for the “Alternative Nitrogenase” (pages 1438–1440)

      Dipl.-Chem. Claus Woitha and Prof. Dr. Dieter Rehder

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199014381

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      A sensitive probe for the formation of the anionic N2-complexes 1 and 2 upon reaction of [VCl3(thf)3] with N2, dmpe, and Na is their centeral metal. Thus, the 51V-NMR signal of the trans-complex 1 is a quintet at δ = − 1123. If the reduction is carried out under 15N2, the individual multiplet components additionally split to triplets, a direct indication of the incorporation of nitrogen in the complex. dmpe = dimethylphosphinoethane.

    30. Lewis-Base-Dictated Structural Variations in Sodium Amide Chemistry: X-Ray Crystal Structures of Phenyl(2-pyridyl)amidosodium with Hexamethylphosphoric Triamide (HMPA) and with Pentamethyldiethylenetriamine (PMDETA) (pages 1440–1441)

      Philip C. Andrews, Dr. William Clegg and Dr. Robert E. Mulvey

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199014401

      Two Crystalline adducts of sodium amide 1 and 2 adopt contrasting binuclear structures, as revealed by X-ray diffraction. Thus, the bidentate anions are linked to the Na ions in a terminal manner in 1 but in a bridging manner in 2. Each structure also displays unusual donor-acceptor coordinations, with PA bridging to Na in 1, while only two of the three available PMDETA nitrogen centers complex to Na in 2.

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    31. Decameric and Dodecameric Sodium Amides and an Organosodium Amide with Stack Structures: [Na10 (NMe2)10(tmeda)4],|Na12(NMe2)12(tmeda)4|, and [Na12(NMe2)10(CH2C6H4Me)2(tmeda)4] (pages 1441–1444)

      Dr. Nis Peter Lorenzen, Priv.-Doz. Dr. Jürgen Kopf, Dipl.-Chem. Falk Olbrich, Dr. Uwe Schümann and Prof. Dr. Erwin Weiss

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199014411

      The oligomeric sodiumamides 1–3, which were formed during attempts to metalate hydrocarbons with n-butylsodium in the presence of teteramethylethylenediamine, have stacked ring structures. Correspondingly structured lithium amides are not known; rather, in this case ladder structures should be preferred.

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    32. Synthesis and Direct NMR Spectroscopic Observation of [(η4-Arene)Cr(CO)3] Dianions (pages 1444–1445)

      Dr. Hans G. Wey and Dr. Holger Bittenschön

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199014441

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      Use of Lithium sand instead of naphthalenepotassium in the synthesis of the dianions 1 and 2 from the η6-coordinated neutral complexes affords pure products, since there is no possibility of an exchange reaction with naphthalene, striking feature of 2 is that the most strained double bond of the cyclobutabenzene unit also remains bound to the metal center after the reduction.

    33. Organoosmium Oxides: Efficient Syntheses and Structures (pages 1445–1448)

      Prof. Dr. Wolfgang A. Herrmann, Stefan J. Eder, Paul Kiprof, Dr. Kristin Rypdal and Petra Watzlowik

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199014451

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      Not only the hitherto simplest alkylosmium oxide, Me4OsO, which is stable in the gas phase, and whose structure (figure on the right) can elucidated by electron diffraction analysis, but also the thermolabile Et4OsO and a mixed alkylated derivative could be prepared good yields. In addition, the structurally novel trimer [{(py)OsO2Me2}3] with planar Os3O3 six-membered ring is reported.

    34. CsF·Br2, an Alkali-Metal Halide Intercalation Compound (pages 1448–1449)

      Prof. Darryl D. DesMarteau, Thomas Grelbig, Sun-Hee Hwang and Prof. Konrad Seppelt

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199014481

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      At 80°C, cesium fluoride takes up bromine in the ratio 1:1. Thereby, the host lattice widens parallel to one of the (l00)-faces (figure on the right). The loss in lattice energy is already compensated for by a very weak BrċFe intraction of the order of a few kJ mol−1.

    35. (NBu4)[Sn{Pt(μ-Cl)(C6F5)2}3], an Unusual Cluster with Three PtII [RIGHTWARDS ARROW] SnII Bonds (pages 1449–1450)

      Prof. Rafael Usón, Prof. Juan Forniés, Dr. Milagros Tomás and Isabel Usón

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199014491

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      A puckered six-membered Pt3Cl3 ring, which coordinates a “naked” SnII center via its basic Pt centers characterizes the cluster core (picture on the right) of the title compound. Not only the Pt-Sn interactions but also short contacts between SnII and the o-F atoms of the C6F5-substituents on the platinum contribute to the stabilization of this unusual complex anion.

    36. Electrical and Magnetic Properties and X-Ray Structure of a Highly Conductive 4:1 Complex of Tetracyanoquinodimethane and a Tetrathiafulvalene Derivative (pages 1450–1452)

      Dr. Martin R. Bryce, Dr. Adrian J. Moore, Dr. Masihul Hasan, Dr. Geoffrey J. Ashwell, Alexander T. Fraser, Dr. William Clegg, Professor Michael B. Hursthouse and Dr. A. I. Karaulov

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199014501

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      Despite strong twisting of the conjugated system, the tetrathiafulvalene homologue 1 reacts with the electron acceptor tetracyanoquinonodimethane to give the dication 12⊕. The anthracene moiety is embedded in the 12⊕ [(TCNQ)4]2⊖, and the dithiol rings are twisted 86° with respect to the anthracene plane: The 1:4 stoichiometry of the highly conductive salt (σ300K = 60S cm−1) is very unusual for TCNQ complexes.

    37. New Copper Clusters Containing Se and PEt3 as Ligands: [Cu70Se35(PEt3)22] and [Cu20Se13(PEt3)12] (pages 1452–1454)

      Prof. Dr. Dieter Fenske and Dipl.-Chem. Harald Krautscheid

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199014521

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      The largest cluster so far characterized X-ray crystallographically is formed together with a little 2 (structure: figure on right) in the reaction of CuCl with Se(SiMe3), and PEt3. An intermediate en route to 1 could be Cu9, cluster. On heating 1 to 160°C Cu2Se is formed.

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    38. New Benzyl(β-oxido)phosphorus and -arsenic Ylides: Reactivity and Stereoselectivity in the Wittig Reaction (pages 1454–1456)

      Dr. Benaissa Boubia, Dr. André Mann, Dr. François D. Bellamy and Dr. Charles Mioskowski

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199014541

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      Writing reactions with semistabilized ylides are generally stereo-unselective. Carefully taking into account previous data, the benzyl-ylides 1a and 1b were prepared and allowed to react with aldehydes. Upon reaction with piperonal and hexanal the arsenic ylide 1b afforded in each case 100% of the (E)-olefin (GC analysis).

    39. A Stereoselective π Cyclization to a Combined Bridgehead Olefin–Bridgehead Alcohol (pages 1456–1457)

      Dr. Uwe Vogt, Ulrike Eggert, Alexandra M. Z. Slawin, Dr. David J. Williams and Prof. H. M. R. Hoffmann

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199014561

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      Bridgehead olefin and bridgehead alcohol units are formed simultaneously in one molecule upon solvolysis of the mesylate to give 2 (R [DOUBLE BOND] H). The synthesis of 1 from caryophyllene epoxide was achieved for the first time stereoselectively and in good yields. An X-ray structure analysis of the 4-bromobenzoate of 2 confirms the structural assignment.

    40. The 3-(3-Pyridyl)allyloxycarbonyl (Paloc) Moiety—a Stable, Amino-Protecting Group for Peptide Syntheses in Organic Media and in Water That Is Cleavable under Neutral Conditions (pages 1457–1459)

      Dipl.-Chem. Karsten von dem Bruch and Prof. Dr. Horst Kunz

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199014571

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      The Paloc-protected amino function in dipeptide esters such as 1 is stable even towards strong acids. This enables selective, quantitative cleavage of the tBu group with HCl in Et2O/CH2Cl2. Conversely, the directed removal of the Paloc-protecting group is achieved by palladium(0)-catalyzed allyl transfer to weakly basic nucleophiles such as N-methylaniline. In this reaction many protecting groups remain intact, i.e. sensitive structures are not destroyed.

    41. Synthesis and Transmission Electron Microscopic Investigation of Bi(Pb)[BOND]Sr[BOND]Ca[BOND]Cu[BOND]O Superconductors (pages 1459–1462)

      Jan-Henrik Müller, Dr. Martin Schwarz and Prof. Dr. Reginald Gruehn

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199014591

      High-resolution transmission electron microscopic photographs have shown that the real structures of the (BiO)2Sr2Can−1CunO2n+2 superconductors are characteized by a high proportion of structural defects, e.g. by changing layer seences. The type and extent of defects can differ in individual cases so that the difficulty of obtaining reproducible sample properties is not surprising.

    42. New Chiral C3-Symmetric Tripodal Phosphanes (pages 1462–1464)

      Dr. Mark J. Burk and Dr. Richard L. Harlow

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199014621

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      Compared to bidentale chiral ligands with C2 symmetry, tridentate ligands with C2 symmetry give rise to a reduced number of non-equivalent residual coordination sites in octahedral transition metal complexes. Hence, an increased enantioselectivity can be expected in catalytic reactions. The tripod ligands 1 and 2, which are readily accessible from 2,5-dimethyl-l- phenylphospholanes, have been examined as ligands in Rh complexes.

    43. C2S2(Ethene-l, 2-dithione), an Example for the Violation of Hund's Rule? (pages 1464–1466)

      Prof. Dr. Günther Maier, Dr. Hans Peter Reisenauer, Dipl.-Chem. Jürgen Schrot and Prof. Dr. Rudolf Janoschek

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199014641

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      For C2S2, quantum chemical calculations suggest the first violation of Hund's rule in an equilibrium structure, for, contrary to expectation, they give a singlet ground state. The experimental findings of the IR and UV spectroscopic investigation of the C2S2 obtained in an argon matrix from precursor compounds such as 1 are in good agreement with the calculations.

    44. Soluble, Oligomeric Bridged Phthalocyaninatoiron(II) Complexes (pages 1467–1468)

      Prof. Dr. Michael Hanack, Dr. Andreas Hirsch and Dr. Helmut Lehmann

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199014671

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      On average 110 coupled metallocycles are present in an oligomer stack when the phthalocyaninatoiron complex 1, R1 [DOUBLE BOND] R2 [DOUBLE BOND] 2-Et-C6H12, is allowed to react with benzene diisocyanide. This and other oligomers could be characterized by 57Fe-Mössbauer and NMR spectroscopy.

    45. Amino Acid Esters as Chiral Auxiliary Groups in Lewis Acid Catalyzed Reactions of Electron-rich Siloxydienes with Imines (pages 1468–1471)

      Dr. Herbert Waldmann, Dipl.-Chem. Matthias Braun and Prof. Dr. Martin Dräger

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199014681

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      In the presence of various Lewis acids, the amino acid ester-imines 1 undergo tandem Mannich-Michael reactions and aza-Diels-Alder reactions respectively with the Danishefsky diene 2 and the Brassard diene 3. The products are formed in good yields and high diastereomeric excesses. Cleavage of the chiral auxiliary group—achieved by means of a Curtius rearrangement, by which the α-C of the amino acid is converted into an aminal—and subsequent hydrolysis afforded unsaturated lactams such as 4 and enaminones 5, which find use as synthetic building blocks.

    46. Oxidative Degradation of Aromatic Pollutants by Chemical Models of Ligninase Based on Porphyrin Complexes (pages 1471–1473)

      Dr. Gilles Labat, Dr. Jean-Louis Seris and Dr. Bernard Meunier

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199014711

      Microbially nondegradable or only difficultly degradable chlorophenols and methoxylated arenes are oxidized to quinones in a few minutes by a peroxidase model system. This model system is obtained by reaction of a sulfonated metalloporphyrin complex with KHSO5. It also oxidizes arenes such as 1,3,5-trimethoxybenzene, which is attacked neither by ligninase nor by radish peroxidase.

    47. π/σ Equilibria in Metal Complexes of Organic Carbonyl Compounds; Synthesis and Structure of Chiral Rhenium Complexes [(η5-C5H5)Re(NO)(PPh3)(O [DOUBLE BOND] CHAr)]X (pages 1473–1474)

      Mr. N. Quirós Méndez, Dr. Atta M. Arif and Prof. J. A. Gladysz

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199014731

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      π/σ ratios of > 96: < 4 to 15:85 (at 299 K) occur in the complexes 1, depending on the aryl substituents. Aside from this strong electronic effect, marked solvent and temperature effects could also be detected. These findings are of great importance for an understanding of the bonding behavior of adducts of carbonyl compounds and metal-complex fragments.

    48. Thermodynamic Aldehyde Enantioface Binding Selectivities in Complexes of Chiral Metal Fragments; Mechanism of Interconversion of Diastereomeric π-Aldehyde Complexes [(η5-C5H5)Re(NO)(PPh3)(η2-O[DOUBLE BOND]CHAr)]BF4 (pages 1475–1476)

      Mr. N. Quirós Méndez, Dr. Charles L. Mayne and Prof. J. A. Gladysz

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199014751

      The higher the π-acidity of the aldehyde ligand the more pronounced the chiral recognition in its bonding to the chiral complex 1. This emerges from low-temperature NMR spectroscopic investigations on reactions of the complex 1 with the aromatic aldehydes 2, which, in addition, showed that the diastereomeric π-aldehyde complexes of 1 and 2 interconvert intramolecularly via a σ-aldehyde complex.

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    49. Enantio- and Regiocontrolled Synthesis of a Central Ionophoric Antibiotic Building Block by Sequential Opening of Two Epoxide Rings with Cuprate Reagents (pages 1476–1478)

      Prof. Dr. Johann Mulzer and Dipl.-Chem. Bernd Schöllhorn

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199014761

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      The sequential opening of two vicinal epoxide groups by cuprate reagents in one step is the key reaction in the synthesis of the stereotetrads 1 and 2. D-Mannitol serves as educt for both compounds, which are contained in several ionophoric antibiotics.

    50. Induction and Variation of Chirality in Discotic Liquid Crystalline Polymers (pages 1478–1481)

      Prof. Dr. Mark M. Green, Prof. Dr. Helmut Ringsdorf, Dr. Jürgen Wagner and Dipl.-Chem. Renate Wüstefeld

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199014781

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      Chiral discotic liquid crystalline polymers are of interest because of their similarity to helical polymers, and for a comparison with chiral rod-shaped liquid crystals. They are now accessible in several forms, e.g. by doping achiral donor polymers with chiral acceptors (see Figure). The chirality of the discotic phases was investigated CD-spectroscopically on thin films.

    51. Multiple Bonds Between Metal Atoms in Ordered Assemblies: Liquid Crystals Containing Mo[BOND]Mo Quadruple Bonds (pages 1481–1483)

      Dr. Roger H. Cayton, Prof. Malcolm H. Chisholm and Frank D. Darrington

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199014811

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      The temperature range of the mesophases of the carboxylato complexes [Mo2(O2CCnH2n+1)4] 1 depends significantly on the length of the hydrocarbon chain. Thus, 1, n [DOUBLE BOND] 5 (hexanoate) is converted at 108°C into the mesophase, and only at 172°C into the isotropic liquid. In the case of 1, n [DOUBLE BOND] 9 (decanoate), these values are 105 and 116°C, respectively, and in 1, n [DOUBLE BOND] 11 (dodecanoate) a mesophase no longer occurs.

    52. Synthesis and Structure of [Ba3(OSiPh3)6(THF)] · 0.5 THF, a Trinuclear Barium Siloxide Containing Low-Coordinate Barium Ions (pages 1483–1485)

      Prof. Kenneth G. Caulton, Prof. Malcolm H. Chisholm, Dr. Simon R. Drake and Dr. William E. Streib

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199014831

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      A Triangle of Ba ions capped by two μ3-OSiPh3 ligands and further linked by three μ2-OSiPh3 moieties are present in the central structural unit of the title compound. All three Ba ions are, however, differently coordinated: thus, a terminal siloxido ligand on Ba3 caters for electrical neutrality, whereas a THF ligand is bound to Ba 1. This unusual trinuclear complex is formed in 77% yield on passage of NH3 into a reaction mixture granulated Ba and Ph3SiOH in THF.

    53. Synthesis of Phospholyltetrahydroboratouranium Complexes. Crystal Structure of [(η5-C4Me4P)2U(BH4)2] (pages 1485–1486)

      Dr. Denise Baudry, Dr. Michel Ephritikhine, Dr. François Nief, Dr. Louis Ricard and Dr. François Mathey

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199014851

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      P-NMR chemical shifts of δ = 3471(!) and δ = 227 reflect the unusual bonding situation in the dimeric, paramagnetic organouranium(III) complex 1. The signal shifted extremely downfield can be assigned to the P atom of the bridging phospholyl ligand. 1 can be oxidized with TlBH4 to the uranium(IV) sand-°Ch [(C4Me4P)2U(BH4)2], which on reduction with Na-amalgam forms 1 again.

    54. Preparation and Structure of [Se[DOUBLE BOND]W(PSe4)(PSe2)]2⊖; a Cluster Containing a Heteroallylic PSemath image Unit (pages 1486–1488)

      Samuel C. O'Neal, William T. Pennington and Prof. Joseph W. Kolis

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199014861

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      A nitrile analogous lower coordinated phosphorus chalcogenide is the most surprising structural feature of the anionic wolfram complex 1. The bent PSemath image unit is bonded side-on to the tungsten; a terminal seleno-ligand and a bidentate tetrahedral PSemath image ligand. Complete the coordination sphere of the metal center.

  3. Book Reviews

    1. Top of page
    2. Reviews
    3. Communications
    4. Book Reviews
    5. Author Index
    6. Subject Index
    1. Book Review: Gaps and Verges. By R. Hoffmann (page 1489)

      George B. Kauffman and Laurie M. Kauffman

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199014891

  4. Author Index

    1. Top of page
    2. Reviews
    3. Communications
    4. Book Reviews
    5. Author Index
    6. Subject Index
  5. Subject Index

    1. Top of page
    2. Reviews
    3. Communications
    4. Book Reviews
    5. Author Index
    6. Subject Index
    1. Subject Index (pages 1505–1522)

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199015051