Angewandte Chemie International Edition

Cover image for Vol. 42 Issue 33

August 25, 2003

Volume 42, Issue 33

Pages 3839–3969

    1. Cover Picture: Catalytic Enantioselective Synthesis of Oxindoles and Benzofuranones That Bear a Quaternary Stereocenter (Angew. Chem. Int. Ed. 33/2003) (page 3839)

      Ivory D. Hills and Gregory C. Fu

      Article first published online: 22 AUG 2003 | DOI: 10.1002/anie.200390555

      The enantioselective rearrangement of O-acylated benzofuranones and oxindoles with the generation of a quaternary stereocenter at C3 of the heterocycle is catalyzed by a planar-chiral derivative of 4-dimethylaminopyridine. As shown in the cover picture, the catalyst itself is red, whereas the resting state of the complex during the rearrangement of benzofurans is a green ion pair. Diazonamide A, an oxindole-derived natural product with potent anticancer activity, is shown in the background. More on the asymmetric syntheses of such heterocycles is provided by I. D. Mills and G. C. Fu on page 3921 ff.

    2. Molecular Dialane and Other Binary Hydrides (pages 3856–3858)

      Norbert W. Mitzel

      Article first published online: 22 AUG 2003 | DOI: 10.1002/anie.200301659

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      The dialane molecule (Al2H6, see structure) is highly unstable in the condensed phase, and hence it was more than half a century after the discovery of aluminum hydride that it was identified in a hydrogen matrix. Apart from such fundamental findings, the rapidly developing chemistry of the binary main-group hydrides is also aimed at synthetic applications.

    3. The Origin of Macromolecule Ionization by Laser Irradiation (Nobel Lecture) (pages 3860–3870)

      Koichi Tanaka

      Article first published online: 22 AUG 2003 | DOI: 10.1002/anie.200300585

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      Without fragmentation: The mass spectrometric analysis of biological macromolecules can be achieved without fragmentation of the parent molecule by using the technique of soft laser (matrix-assisted laser desorption/ionization (MALDI; see scheme, UFMP=ultrafine metal-powder matrix). The development of this technique was greatly influenced by the work of Koichi Tanaka for which he was awarded the Nobel Prize for Chemistry in 2002.

    4. Electrospray Wings for Molecular Elephants (Nobel Lecture) (pages 3871–3894)

      John B. Fenn

      Article first published online: 22 AUG 2003 | DOI: 10.1002/anie.200300605

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      From flames to flying elephants: A few years ago the idea of making proteins or polymers “fly” by electrospray ionization (ESI) seemed as improbable as a flying elephant, but today it is a standard part of modern mass spectrometers. The key to this success was the development of free jet technology.

    5. Structural Evaluation of Systematically Enumerated Hypothetical Uninodal Zeolites (pages 3896–3899)

      Martin D. Foster, Olaf Delgado Friedrichs, Robert G. Bell, Filipe A. Almeida Paz and Jacek Klinowski

      Article first published online: 1 AUG 2003 | DOI: 10.1002/anie.200351556

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      Along theoretical channels: Although 139 distinct structural types of zeolite are currently known, the search for new structures with improved applications in catalysis and ion exchange is of extreme interest. Recent advances in mathematical tiling theory has given rise to the enumeration of 294 uninodal frameworks with an empirical formula SiO2 (an energetically stable example of which is shown).

    6. Building Blocks for n-Type Organic Electronics: Regiochemically Modulated Inversion of Majority Carrier Sign in Perfluoroarene-Modified Polythiophene Semiconductors (pages 3900–3903)

      Antonio Facchetti, Myung-Han Yoon, Charlotte L. Stern, Howard E. Katz and Tobin J. Marks

      Article first published online: 22 AUG 2003 | DOI: 10.1002/anie.200351253

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      A new family of perfluoroarene-modified thiophene semiconductors 13 has been synthesized to assess the influence of perfluoroarene introduction and regiochemistry on molecular and thin-film transistor properties. Compound 1 is an n-type semiconductor with a mobility approaching 0.1 cm2 V−1 s−1 whereas 2 and 3 exhibit p-type behavior. These results show that the origin of n-type carrier mobility is not solely a consequence of solution/film LUMO and HOMO energies.

    7. Supramolecular Assemblies of Hydrogen-Bonded Carboxylic Acid Dimers Mediated by Phenyl–Pentafluorophenyl Stacking Interactions (pages 3903–3906)

      Maria Gdaniec, Wojciech Jankowski, Maria J. Milewska and Tadeusz Połoñski

      Article first published online: 22 AUG 2003 | DOI: 10.1002/anie.200351432

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      Stacks of acids: Pentafluorobenzoic acid forms heterodimers with benzoic acid and 2,4,6-trimethylbenzoic acid that assemble into π stacks with alternating phenyl and pentafluorophenyl residues (see picture). Cocrystals of these acids with 1,4-bisarylbutadiynes contain acid homodimers sandwiched between the diacetylene molecules.

    8. Design of Frameworks with Mixed Triangular and Octahedral Building Blocks Exemplified by the Structure of [Zn4O(TCA)2] Having the Pyrite Topology (pages 3907–3909)

      Hee K. Chae, Jaheon Kim, Olaf Delgado Friedrichs, Michael O’Keeffe and Omar M. Yaghi

      Article first published online: 22 AUG 2003 | DOI: 10.1002/anie.200351546

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      Building blocks, octahedral (basic zinc acetate units) and triangular (tritopic carboxylic acid), are assembled into a metal-organic framework (MOF-150) having the topology of the FeS2 pyrite net (see picture). Two independent nets interpenetrate, forming the first example of a fully catenated structure with mixed coordination, an occurrence that is ascribed to the self-dual property of the pyrite net (TCA=4,4′,4′′-Tricarboxytriphenylamine).

    9. Multicomponent Assembly of a Pyrazine-Pillared Coordination Cage That Selectively Binds Planar Guests by Intercalation (pages 3909–3913)

      Kazuhisa Kumazawa, Kumar Biradha, Takahiro Kusukawa, Takashi Okano and Makoto Fujita

      Article first published online: 22 AUG 2003 | DOI: 10.1002/anie.200351797

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      A prismlike cage composed of six end-capped PtII ions, two panel-like ligands, and three pyrazine pillars assembles quantitatively through the template effect of a planar aromatic guest (see space-filling structure). The cage thus obtained is stable even when the template is removed. Other large aromatic molecules are also strongly bound and a β-diketone is shown to exist only in a planar enol form in the cage with the keto–enol tautomerization being almost completely suppressed.

    10. Total Synthesis of the Ubiquitin-Activating Enzyme Inhibitor (+)-Panepophenanthrin (pages 3913–3917)

      Xiaoguang Lei, Richard P. Johnson and John A. Porco Jr.

      Article first published online: 22 AUG 2003 | DOI: 10.1002/anie.200351862

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      The [4+2] dimerization of epoxyquinol 1 is rendered irreversible by formation of a hemiacetal in the enantioselective total synthesis of the ubiquitin-activating enzyme inhibitor (+)-panepophenanthrin (2).

    11. Biosynthesis of Epothilone Intermediates with Alternate Starter Units: Engineering Polyketide–Nonribosomal Interfaces (pages 3917–3921)

      Sarah E. O’Connor, Christopher T. Walsh and Fei Liu

      Article first published online: 22 AUG 2003 | DOI: 10.1002/anie.200352077

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      The early steps of epothilone biosynthesis were reprogrammed in vitro by incorporating enzyme subunits (e.g. EntB, EntE) from other biosynthetic pathways into the epothilone (Epo) assembly line (see scheme). Recognition sequences identified at the C termini of the epothilone biosynthetic proteins enabled heterologous enzyme transfer when fused to noncognate proteins, as a step toward the reengineering of biosythetic pathways to produce natural product analogues in vivo.

    12. Catalytic Enantioselective Synthesis of Oxindoles and Benzofuranones That Bear a Quaternary Stereocenter (pages 3921–3924)

      Ivory D. Hills and Gregory C. Fu

      Article first published online: 3 JUL 2003 | DOI: 10.1002/anie.200351666

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      A common feature in indole- and benzofuran-derived natural products is a quaternary stereocenter in the 3-position of the heterocycle. The catalyst (−)-1 promotes the asymmetric synthesis of such compounds 3 (with up to 99 % ee) through the rearrangement of O-acylated benzofuranones (X=O) and oxindoles (X=NR2) 2.

    13. Equilibrium and Kinetic Deuterium Isotope Effects on the Hetero-Diels–Alder Addition of Sulfur Dioxide (pages 3924–3927)

      Frédéric Monnat, Pierre Vogel, Rubén Meana and José A. Sordo

      Article first published online: 22 AUG 2003 | DOI: 10.1002/anie.200351732

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      The C[BOND]S bond is formed to a greater extent than the C[BOND]O bond in the transition state of the [4+2] cycloaddition of SO2 to dimethylidenecyclohexane (see scheme). Both deuterium isotope effects and quantum calculations lead to this conclusion.

    14. Catalytic Asymmetric Allylation of Hydrazono Esters in Aqueous Media by Using ZnF2–Chiral Diamine (pages 3927–3930)

      Tomoaki Hamada, Kei Manabe and Shū Kobayashi

      Article first published online: 22 AUG 2003 | DOI: 10.1002/anie.200351778

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      Chiral homoallylic hydrazines are synthesized by catalytic asymmetric allylation of acylhydrazono esters with allyltrimethoxysilane by using a chiral Zn catalyst (see picture). The reactions proceed smoothly in aqueous media to give the allylated products in good to high yields and selectivities. Water played an essential role in this reaction, and this is the first example of catalytic asymmetric allylation of C[DOUBLE BOND]N bonds in aqueous media. R1=Me, Et; R2=p-C6H4OMe, p-C6H4OEt; R3=H, Me, Ph.

    15. Synthesis of Large-Pore Iaequation imaged Mesoporous Silica and Its Tubelike Carbon Replica (pages 3930–3934)

      Shunai Che, Alfonso E. Garcia-Bennett, Xiaoying Liu, Robert P. Hodgkins, Paul A. Wright, Dongyuan Zhao, Osamu Terasaki and Takashi Tatsumi

      Article first published online: 22 AUG 2003 | DOI: 10.1002/anie.200351752

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      A synthetic route to tubelike mesoporous carbon materials with a cubic structure has been developed by using propylsulfonic acid groups anchored onto a silica wall, which act as an acid catalyst for carbon-source polymerization. Pores with diameters of 2.4 and 4.0 nm were recorded for the carbon replicas obtained after removing the silica walls (see isotherm).

    16. Formal Synthesis of Leucascandrolide A (pages 3934–3938)

      David R. Williams, Scott V. Plummer and Samarjit Patnaik

      Article first published online: 22 AUG 2003 | DOI: 10.1002/anie.200351817

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      Asymmetric allylation reactions of stannane-derived allyl diazaborolanes, and the use of the Terashima reagent for the highly selective asymmetric hydride reduction of a β-alkoxy ketone are key features of a highly convergent, stereocontrolled formal synthesis of leucascandrolide A (see picture).

    17. Elimination of Zero-Quantum Interference in Two-Dimensional NMR Spectra (pages 3938–3941)

      Michael J. Thrippleton and James Keeler

      Article first published online: 1 AUG 2003 | DOI: 10.1002/anie.200351947

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      The simultaneous application of a swept-frequency pulse and a gradient pulse Gf enables z-magnetization to be distinguished from zero-quantum coherence (see picture). This new and highly effective method enables the elimination of strong interference caused by zero-quantum coherence, which is often present in NOESY, TOCSY, and many other types of NMR spectra obtained by traditional methods of signal selection, and can be readily implemented on any modern NMR spectrometer.

    18. New P,N Ligands for Asymmetric Ir-Catalyzed Reactions (pages 3941–3943)

      Tanasri Bunlaksananusorn, Kurt Polborn and Paul Knochel

      Article first published online: 22 AUG 2003 | DOI: 10.1002/anie.200351936

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      Chiral Ir complexes such as 1 catalyze the hydrogenation of (E)-1,2-diphenylpropene at 1 bar of H2 to give (S)-1,2-diphenylpropane with up to 95 % ee and full conversion (see scheme). Methyl (Z)-α-(acetamido)cinnamate underwent enantioselective hydrogenation under similar conditions to the corresponding amino acid derivative with up to 96 % ee. BARF=tetrakis(3,5-bis(trifluoromethyl)phenyl)borate, cod=1,5-cyclooctadiene.

    19. An Enantioselective Biomimetic Total Synthesis of (−)-Siccanin (pages 3943–3947)

      Barry M. Trost, Hong C. Shen and Jean-Philippe Surivet

      Article first published online: 22 AUG 2003 | DOI: 10.1002/anie.200351868

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      A convergent asymmetric synthesis of the clinically important antifungal agent (−)-siccanin (1) mimics the proposed biosynthetic pathway. A Pd-catalyzed asymmetric allylic alkylation was used to establish the stereochemistry, and sequential radical processes (a TiIII-promoted cyclization followed by diacetoxyiodobenzene-promoted tetrahydrofuran formation) led to the completion of the first asymmetric synthesis of 1.

    20. Tandem β-C[BOND]H Activation/Si[BOND]H Elimination Reactions: Stabilization of C[BOND]H Activation Products by β-Agostic Si[BOND]H Interactions (pages 3947–3949)

      Vladimir K. Dioumaev, Patrick J. Carroll and Donald H. Berry

      Article first published online: 22 AUG 2003 | DOI: 10.1002/anie.200352078

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      Conversion of [(Me3P)3Ru(H)SiMe3] into 1 and further on into the structurally characterized fac- and mer-2 (see scheme) is the first example of a transformation from a [M]SiMe3 species into a β-agostic [M]CH2SiMe2-H complex; a reversal of the typical sequence observed in the rearrangement of silaalkyl metal complexes. This reversal is likely the result of Si[BOND]H coordination to the unsaturated metal center.

    21. Sodium Oligophosphanediide Ions in the PhPCl2/Na System: Syntheses and Structural Characterization (pages 3951–3954)

      Jens Geier, Heinz Rüegger, Michael Wörle and Hansjörg Grützmacher

      Article first published online: 22 AUG 2003 | DOI: 10.1002/anie.200250725

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      A new look into an old pot: A new cluster structure is found for the cage anion 1 (see picture, L=dme) in the salt [Na(dme3)]+[Na5(P2Ph2)(dme)3]. This (structurally characterized) ionic compound is obtained in excellent yield when PhPCl2 is simply reduced with sodium in a toluene/tetramethylethylene mixture. This method delivers catena-oligophosphane-α,ω-diides with two, three, or four phosphorus atoms.

    22. Dibenzophosphasemibullvalene (pages 3955–3957)

      Jens Geier, Gilles Frison and Hansjörg Grützmacher

      Article first published online: 22 AUG 2003 | DOI: 10.1002/anie.200351388

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      Strain is not to blame: Controlled thermolysis of 1 afforded dibenzo-1-phosphasemibullvalene 2 (see scheme). This unstable compound can be stabilized as a ligand in the complex [W(CO)5(2)]. Although the sum of bond angles at phosphorus (220°) is very small, 2 is only a little strained.

    23. Polycyclic Aromatic DNA-Base Surrogates: High-Affinity Binding to an Adenine-Specific Base-Flipping DNA Methyltransferase (pages 3958–3960)

      Christine Beuck, Ishwar Singh, Anupam Bhattacharya, Walburga Hecker, Virinder S. Parmar, Oliver Seitz and Elmar Weinhold

      Article first published online: 22 AUG 2003 | DOI: 10.1002/anie.200219972

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      Filling the hole is a strategy that confers high-affinity DNA binding to the M⋅TaqI DNA methyltransferase. Aromatic base surrogates (e.g. pyrene, red in picture) were introduced into DNA by means of organocuprate-mediated C-glycosylations. A new competitive binding assay revealed that DNA with aromatic base surrogates placed opposite to the target base binds to M⋅TaqI with up to 400-fold-enhanced affinity.

    24. From Rigidity to Conformational Flexibility: Macrocyclic Templates Derived from ansa-Steroids (pages 3961–3964)

      Stefan Bäurle, Thorsten Blume, Anne Mengel, Christian Parchmann, Werner Skuballa, Siegfried Bäsler, Martina Schäfer, Detlev Sülzle and Hans-Peter Wrona-Metzinger

      Article first published online: 22 AUG 2003 | DOI: 10.1002/anie.200351385

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      More than a curiosity in the field of steroid derivatives, the 17-membered macrocycle 1 was obtained from a more rigid ansa-steroid. Compound 1 serves as a prototype of a template with differentiable functional groups, which can be used in the synthesis of libraries of novel macrocycles.

    25. Preview: Angew. Chem. Int. Ed. 33/2003 (page 3969)

      Article first published online: 22 AUG 2003 | DOI: 10.1002/anie.200390560

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