Angewandte Chemie International Edition

Cover image for Vol. 41 Issue 24

December 16, 2002

Volume 41, Issue 24

Pages 4595–4905

    1. Cover Picture: Angew. Chem. Int. Ed. 24/2002 (page 4595)

      Dana S. Marlin, Eckhard Bill, Thomas Weyhermüller, Eva Rentschler and Karl Wieghardt

      Version of Record online: 12 DEC 2002 | DOI: 10.1002/anie.200290000

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      Chemical Strategies for Iron Acquisition in Plants (page 4610)

      Dorothee Staiger

      Version of Record online: 12 DEC 2002 | DOI: 10.1002/anie.200290053

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      Enantioselective Alkylative Double Ring Opening of Epoxides: Synthesis of Enantioenriched Unsaturated Diols and Amino Alcohols (page 4611)

      David M. Hodgson, Christopher R. Maxwell, Timothy J. Miles, Edyta Paruch, Matthew A. H. Stent, Ian R. Matthews, Francis X. Wilson and Jason Witherington

      Version of Record online: 12 DEC 2002 | DOI: 10.1002/anie.200290003

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      Polymerase Recognition of Unnatural Base Pairs (page 4612)

      Chengzhi Yu, Allison A. Henry, Floyd E. Romesberg and Peter G. Schultz

      Version of Record online: 12 DEC 2002 | DOI: 10.1002/anie.200290004

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      Supramolecular Amphiphiles: Spontaneous Formation of Vesicles Triggered by Formation of a Charge-Transfer Complex in a Host (page 4612)

      Young Jin Jeon, Parimal K. Bharadwaj, SooWhan Choi, Jae Wook Lee and Kimoon Kim

      Version of Record online: 12 DEC 2002 | DOI: 10.1002/anie.200290054

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      Synthesis of Amphiphilic Conjugated Diblock Oligomers as Molecular Diodes (page 4612)

      Man-Kit Ng and Luping Yu

      Version of Record online: 12 DEC 2002 | DOI: 10.1002/anie.200290056

    8. How Important is Parity Violation for Molecular and Biomolecular Chirality? (pages 4618–4630)

      Martin Quack

      Version of Record online: 12 DEC 2002 | DOI: 10.1002/anie.200290005

      Far more important (by orders of magnitude) than previously believed: this is the answer to the question in the title according to calculations based on recently introduced methods of electroweak quantum chemistry. However, the energy differences between enantiomers of chiral molecules are still very small, on the order of pico- to femtojoules per mole. This review covers the following aspects of parity violation: How can such small energies be measured and what are the consequences for our understanding of molecular chirality, biomolecular homochirality, and perhaps fundamental physics?

    9. Actin-Binding Marine Macrolides: Total Synthesis and Biological Importance (pages 4632–4653)

      Kap-Sun Yeung and Ian Paterson

      Version of Record online: 13 DEC 2002 | DOI: 10.1002/anie.200290057

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      Marine organisms provide a rich source of highly functionalized macrolides (such as swinholide A) that interact with the actin cytoskeleton by mechanisms similar to actin-binding proteins. Total syntheses of these potent cytotoxic natural products have been accomplished recently, making use of a variety of strategies for introducing the multiple stereogenic centers and constructing the characteristic 22- to 44-membered macrocycles.

    10. What Is a Discovery? Carbon Skeletal Rearrangements as Counter-Examples to the Rule of Minimal Structural Change (pages 4655–4660)

      Jerome A. Berson

      Version of Record online: 12 DEC 2002 | DOI: 10.1002/anie.200290007

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      Radical changes in the chemical community's thinking were required in the discovery of the pinacol rearrangment [Eq. (a)]. Clarity was achieved only after the incorrect “conventional” atomic weights, which gave completely erroneous molecular formulas, were rejected and people dared to violate Kekulé's rules of reaction concerning the connectivity of the carbon skeleton in chemical reaction.

    11. Efficient, Racemization-Free Peptide Coupling of N-Alkyl Amino Acids by Using Amino Acid Chlorides Generated In Situ—Total Syntheses of the Cyclopeptides Cyclosporin O and Omphalotin A (pages 4661–4663)

      Norbert Sewald

      Version of Record online: 12 DEC 2002 | DOI: 10.1002/anie.200290008

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      An efficient coupling reaction in peptide chemistry is achieved through the use of Fmoc-protected amino acid chlorides generated in situ. This method permits racemization-free incorporation of N-methyl amino acids into peptides, as could be shown in the syntheses of cyclosporin O (1) and omphalotin A.

    12. New Principles of Protein Structure: Nests, Eggs—and What Next? (pages 4663–4665)

      Debnath Pal, Jürgen Sühnel and Manfred S. Weiss

      Version of Record online: 12 DEC 2002 | DOI: 10.1002/anie.200290009

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      Protein structure prediction, not only description: A step in this direction is the discovery that many anion and cation binding sites (where ions can be atoms exhibiting a full or partial charge) in proteins are made up of three amino acids of which two exhibit “enantiomeric” main-chain conformations. The combination of torsion angle pairs determines whether an RL or an LR nest is formed (see picture).

    13. Preparation of Resolved Fourfold Symmetric Amphiphilic Helices Using Chiral Metallacrown Building Blocks (pages 4667–4670)

      Annabel D. Cutland-Van Noord, Jeff W. Kampf and Vincent L. Pecoraro

      Version of Record online: 12 DEC 2002 | DOI: 10.1002/anie.200290010

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      The chirality of the ligand determines the nature of the helix: Coordination of a chain of [15]metallacrown-5 complexes based on phenylalanine hydroxamic acid results in an amphiphilic metallohelix with a 41 screw axis. The use of the L isomer of the acid gives the right-handed helix (see left structure) while the D isomer gives the mirror image structure.

    14. Novel Synthetic Approach to Trinuclear 3d-4f Complexes: Specific Exchange of the Central Metal of a Trinuclear Zinc(II) Complex of a Tetraoxime Ligand with a Lanthanide(III) Ion (pages 4670–4673)

      Shigehisa Akine, Takanori Taniguchi and Tatsuya Nabeshima

      Version of Record online: 12 DEC 2002 | DOI: 10.1002/anie.200290011

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      Only the central metal atom of the homotrinuclear complex [LZn3]2+, prepared by cooperative complexation between a linear ligand and Zn(OAc)2, is replaced with a Ln3+ ion by selective and quantitative transmetalation to give a helical heterotrinuclear complex [LZn2Ln]3+ (see scheme). Ln=lanthanide.

    15. The Structure of Neutral Proline (pages 4673–4676)

      Alberto Lesarri, Santiago Mata, Emilio J. Cocinero, Susana Blanco, Juan C. López and José L. Alonso

      Version of Record online: 12 DEC 2002 | DOI: 10.1002/anie.200290012

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      An intramolecular hydrogen bond of the type OH⋅⋅⋅N is present in both conformers of proline (see picture) that were observed in the gas phase using laser-ablation molecular-beam Fourier-transform microwave spectroscopy.

    16. Lewis Acidity in Transition-Metal-Doped Microporous Aluminophosphates (pages 4677–4680)

      Furio Corà, Iman Saadoune and C. Richard A. Catlow

      Version of Record online: 12 DEC 2002 | DOI: 10.1002/anie.200290013

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      Periodic quantum mechanical calculations on transition-metal-doped AlPO-34 show that the Lewis acidity is linked to the electronic distribution at the transition metal site. A “from behind” attack of 2+ dopant ions by Lewis bases is favored (see picture), and is expected to yield stronger Lewis acidity for polymorphs with single-wall framework structures or intersecting channels, rather than polymorphs with one-dimensional channels that are composed solely of double-walled structural units.

    17. Total Synthesis of (±)-Wortmannin (pages 4680–4682)

      Takashi Mizutani, Shinobu Honzawa, Shin-ya Tosaki and Masakatsu Shibasaki

      Version of Record online: 12 DEC 2002 | DOI: 10.1002/anie.200290014

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      A potent and specific phosphoinositide 3-kinase inhibitor (±)-wortmannin has been achieved through an intramolecular Heck reaction for the construction of an allylic quaternary carbon center and a diosphenol–Claisen rearrangement (see scheme). SEM=2-(Trimethylsilyl)ethoxymethyl.

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      Concise Enantioselective Synthesis of (+)-FR66979 and (+)-FR900482: Dimethyldioxirane-Mediated Construction of the Hydroxylamine Hemiketal (pages 4683–4685)

      Ted C. Judd and Robert M. Williams

      Version of Record online: 12 DEC 2002 | DOI: 10.1002/anie.200290015

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      The remarkable one-step deprotection/oxidative cyclization of an eight-membered-ring aminoketone 1 in the presence of dimethyldioxirane gives rise to the unique hydroxylamine hemiketal ring system of FR66979 (2) and FR900482 (3), clinically important antitumor antibiotics. The concise 33-step enantioselective synthesis of 3 is the shortest route reported to date.

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      Facile Construction of N-Hydroxybenzazocine: Enantioselective Total Synthesis of (+)-FR900482 (pages 4686–4688)

      Masashi Suzuki, Mika Kambe, Hidetoshi Tokuyama and Tohru Fukuyama

      Version of Record online: 12 DEC 2002 | DOI: 10.1002/anie.200290016

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      Intramolecular hydroxylamination of ω-formyl nitrobenzene 1 followed by stereoselective hydroxymethylation led to the formation of N-hydroxybenzazocine 2, a key intermediate in the enantioselective total synthesis of the antitumor antibiotic FR900482 (3).

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      Total Synthesis of (±)-FR66979 (pages 4688–4691)

      Richard Ducray and Marco A. Ciufolini

      Version of Record online: 12 DEC 2002 | DOI: 10.1002/anie.200290017

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      An unusual fragmentation of aziridine 1, triggered by a preliminary homo-Brook transposition is the key step in the total synthesis of the racemate of the antitumor agent FR66979 (2).

    21. Polymer-Supported C2-Symmetric Ligands for Palladium-Catalyzed Asymmetric Allylic Alkylation Reactions (pages 4691–4693)

      Barry M. Trost, Zhengying Pan, Jorge Zambrano and Christof Kujat

      Version of Record online: 12 DEC 2002 | DOI: 10.1002/anie.200290018

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      The choice of scaffold and tether has a marked influence on the enantiomeric excesses obtained in Pd-catalyzed asymmetric allylic alkylations, such as the cyclization of the bisurethane 1 to the oxazolidin-2-one 2 [Eq. (1); Ts=p-toluenesulfonate], performed with polymer-supported chiral catalysts. The best results were obtained by using an ArgoGel resin, an amide tether, and a pyrrolidine scaffold.

    22. An Efficient One-Pot Enantio- and Diastereoselective Synthesis of Heterocycles (pages 4693–4697)

      Barry M. Trost and Michelle R. Machacek

      Version of Record online: 12 DEC 2002 | DOI: 10.1002/anie.200290019

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      Five- and six-membered nitrogen and oxygen heterocycles are accessible from two acyclic precursors in a one-pot reaction that comprises a Ru-catalyzed ene–yne addition followed by a Pd-catalyzed asymmetric allylic alkylation (see scheme). The stereochemistry of the products derives from the catalyst rather than from substrate control using chiral substrates.

    23. General Synthesis of Semiconductor Chalcogenide Nanorods by Using the Monodentate Ligand n-Butylamine as a Shape Controller (pages 4697–4700)

      Jian Yang, Can Xue, Shu-Hong Yu, Jing-Hui Zeng and Yi-Tai Qian

      Version of Record online: 12 DEC 2002 | DOI: 10.1002/anie.200290020

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      Solvothermal synthesis in a monodentate ligand, namely, n-butylamine, is a general route for the synthesis of semiconductor chalcogenide nanorods from cheap inorganic reactants. The amine proved to be a good shape controller for producing CdS, CdSe, ZnSe, and PbSe nanorods (see picture) under relatively mild conditions.

    24. Electron-Transfer Dynamics of Cytochrome C: A Change in the Reaction Mechanism with Distance (pages 4700–4703)

      Jianjun Wei, Haiying Liu, Dimitri E. Khoshtariya, Hiromichi Yamamoto, Allison Dick and David H. Waldeck

      Version of Record online: 12 DEC 2002 | DOI: 10.1002/anie.200290021

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      Directly linking a gold electrode coated with pyridine-terminated self-assembled monolayers (SAMs) to the redox-active heme unit of cytochrome c has enabled the electron-transfer mechanism to be studied as a function of distance. Comparison of the kinetic data for this system (see graph) with earlier data on COOH-terminated SAMs requires a change in the electron-transfer mechanism with distance from the electrode surface that does not involve large-amplitude conformational rearrangement.

    25. Enantiopure β-Hydroxy Morpholine Amides from Terminal Epoxides by Carbonylation at 1 atm (pages 4703–4705)

      Steven N. Goodman and Eric N. Jacobsen

      Version of Record online: 12 DEC 2002 | DOI: 10.1002/anie.200290022

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      Keeping the CO pressure down is a crucial, practical feature of the new methodology for the carbonylation of terminal epoxides. β-Hydroxy morpholinyl amides are generated directly in optically pure form [Eq. (1)], and these building blocks can be applied in a variety of acyl transfer reactions. A useful illustration is provided in the concise synthesis of δ-hydroxy-β-ketoesters, key intermediates for the preparation of the statin class of HMG-CoA reductase inhibitors.

    26. Mutually Induced Formation of Host–Guest Complexes between p-Sulfonated Calix[8]arene and Photolabile Cholinergic Ligands (pages 4706–4708)

      Alexandre Specht, Philippe Bernard, Maurice Goeldner and Ling Peng

      Version of Record online: 12 DEC 2002 | DOI: 10.1002/anie.200290023

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      Adaptive systems: The conformationally flexible p-sulfonated calix[8]arene and photolabile cholinergic ligands adapt to each other and select the right conformers to form ditopic binding complexes (see schematic representation), thus mimicking ligand binding in biological receptors or enzymes.

    27. New Ferrocenyl Ligands with Broad Applications in Asymmetric Catalysis (pages 4708–4711)

      Matthias Lotz, Kurt Polborn and Paul Knochel

      Version of Record online: 12 DEC 2002 | DOI: 10.1002/anie.200290024

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      A new synthetic approach allows the synthesis of taniaphos-analogous ligands 2 with inverted α configuration (SpS). This new class of ferrocenyl ligands displays excellent enantioselectivity and enhanced reactivity in several types of asymmetric hydrogenation reactions (e.g. 1[RIGHTWARDS ARROW]3).

    28. A Remarkable 14-Nuclear ReV8 AgI6 Coordination Oligomer Derived from a 2D (ReV2 AgI2)n Coordination Polymer with d-Penicillaminate (pages 4711–4715)

      Takumi Konno, Yuichi Shimazaki, Tadashi Yamaguchi, Tasuku Ito and Masakazu Hirotsu

      Version of Record online: 12 DEC 2002 | DOI: 10.1002/anie.200290025

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      ReVpolymer/oligomer switching: The aggregation of ReV octahedra, [ReO(d-pen-N,O)(d-pen-N,O,S)] (d-H2pen=d-penicillamine), assisted by AgI ions, leads to the formation of a 2D (Reequation imageAgequation image)n coordination polymer 1, which is converted into a Reequation imageAgequation image coordination oligomer 2 (see picture; Ag green, S yellow, Re purple, O red, N blue). While 1 results from the self-assembly of Reequation imageAgequation image units through Ag[BOND]O coordination bonding, the self-assembly of Reequation imageAgequation image molecules in 2 is through COOH⋅⋅⋅OOC hydrogen bonding.

    29. Using Mass Spectrometry to Characterize Self-Assembled Monolayers Presenting Peptides, Proteins, and Carbohydrates (pages 4715–4718)

      Jing Su and Milan Mrksich

      Version of Record online: 12 DEC 2002 | DOI: 10.1002/anie.200290026

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      Peptide and carbohydrate biochips can be assayed with MALDI mass spectrometry. Self-assembled monolayers (SAMs) that are modified with ligands provide a platform for identifying selective protein–ligand and enzyme–substrate interactions. MALDI provides a rapid and sensitive method for detection and avoids the need to label protein analytes with fluorescent or radioactive tags. The picture shows the mass spectrum of a SAM presenting a carbohydrate.

    30. A Method for Determining the Difference in Relative Apicophilicity of Carbon-Containing Substituents of 10-P-5 Phosphoranes (pages 4718–4722)

      Shiro Matsukawa, Kazumasa Kajiyama, Satoshi Kojima, Shin-ya Furuta, Yohsuke Yamamoto and Kin-ya Akiba

      Version of Record online: 12 DEC 2002 | DOI: 10.1002/anie.200290027

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      Position of importance: The relative apicophilicity of two substituents linked by a carbon atom to a pentacoordinate phosphorus center such as that in compounds 1 was determined based on the equilibrium ratio of pseudorotamers (1 A and 1 B) in solution. A distinct solvent effect on the relative apicophilicity and a novel phenomenon in which two different pseudorotamers cocrystallized in the same single crystal were observed.

    31. Preferential Location of Ge Atoms in Polymorph C of Beta Zeolite (ITQ-17) and Their Structure-Directing Effect: A Computational, XRD, and NMR Spectroscopic Study (pages 4722–4726)

      German Sastre, Jose A. Vidal-Moya, Teresa Blasco, Jordi Rius, Jose L. Jordá, Maria T. Navarro, Fernando Rey and Avelino Corma

      Version of Record online: 12 DEC 2002 | DOI: 10.1002/anie.200290028

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      Ge-directed zeolites. Forcefield atomic simulations are used to investigate the location of the Ge atoms and the structure-directing agents (SDAs) in the Ge containing ITQ-17 zeolite (see picture). The Ge atoms are found to locate preferentially at the T1 sites which form double four-ring (D4R) units. A combined theoretical and experimental treatment has allowed us to prove the preferential location of Ge atoms in the double four-member rings of the polymorph C of Beta zeolite, and its corresponding structure-directing effect to be demonstrated.

    32. Solid-State NMR Studies of MCM-41 Supported with a Highly Catalytically Active Cluster (pages 4726–4729)

      Matthew D. Jones, Melinda J. Duer, Sophie Hermans, Yaroslav Z. Khimyak, Brian F. G. Johnson and John Meurig Thomas

      Version of Record online: 12 DEC 2002 | DOI: 10.1002/anie.200290029

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      New insight into the binding modes of bimetallic clusters and catalytically active nanoparticles to the mesoporous solid MCM-41 has been obtained from solid-state NMR spectroscopic data (see figure, right). From this study, a model has been proposed to explain the interactions between the pore walls and the cluster. It has been shown that the counterion plays an important role in the anchoring process (see figure, left).

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      Low-Temperature Destruction of Chlorinated Hydrocarbons over Lanthanide Oxide Based Catalysts (pages 4730–4732)

      Pieter Van der Avert and Bert M. Weckhuysen

      Version of Record online: 12 DEC 2002 | DOI: 10.1002/anie.200290030

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      Getting all steamed up: The active phase formed in situ in the catalytic hydrolysis of chlorinated compounds, such as CCl4, at relatively low temperatures consists of a lanthanide oxide chloride, as evident from vibrational frequencies at 125, 188, 215, 335, and 440 cm−1 in the Raman spectrum (see picture). This active phase remains stable as long as steam is provided, and produces CO2 and HCl as the only reaction products.

    34. Selective Isomerization of a Terminal Olefin Catalyzed by a Ruthenium Complex: The Synthesis of Indoles through Ring-Closing Metathesis (pages 4732–4734)

      Mitsuhiro Arisawa, Yukiyoshi Terada, Masako Nakagawa and Atsushi Nishida

      Version of Record online: 12 DEC 2002 | DOI: 10.1002/anie.200290031

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      A ruthenium complex, generated from the Grubbs carbene catalyst with vinyloxytrimethylsilane, catalyzed the isomerization of terminal alkenes RCH2[BOND]CH[DOUBLE BOND]CH2 to internal alkenes RCH[DOUBLE BOND]CH[BOND]CH3. Application of this olefin isomerization to 2-(N-allylamino)styrene gave the corresponding enamines, which were converted into indoles by a standard ring-closing metathesis, see scheme (Ts=tosyl).

    35. The Structure of the Peroxo Species in the TS-1 Catalyst as Investigated by Resonant Raman Spectroscopy (pages 4734–4737)

      Silvia Bordiga, Alessandro Damin, Francesca Bonino, Gabriele Ricchiardi, Carlo Lamberti and Adriano Zecchina

      Version of Record online: 12 DEC 2002 | DOI: 10.1002/anie.200290032

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      The characteristic yellow color of the TS-1/H2O2/H2O system is attributed to a “side-on” Ti–peroxo species, presumed to be the active intermediate in partial oxidation reactions. Resonance Raman spectroscopic analysis of both the zeolite system and a model salt ((NH4+)3(TiO2F5)3−, see picture) are combined with the analysis of a Ti-free silicalite to prove the structure of the hitherto unknown species.

    36. Pd0-Catalyzed Three-Component Tandem Double-Addition–Cyclization Reaction: Stereoselective Synthesis of cis-Pyrrolidine Derivatives (pages 4737–4740)

      Shengming Ma and Ning Jiao

      Version of Record online: 12 DEC 2002 | DOI: 10.1002/anie.200290033

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      cis-2,5-Disubstituted pyrrolidine skeletons have been constructed by the Pd0-catalyzed three-component tandem double-addition–cyclization reaction of 2-(2,3-butadienyl)malonates, organohalides, and imines (see scheme, yields: 81–100 %; cis/trans >95:5).

    37. Catalytic Electronic Activation: Indirect “Wittig” Reaction of Alcohols (pages 4740–4743)

      Michael G. Edwards and Jonathan M. J. Williams

      Version of Record online: 12 DEC 2002 | DOI: 10.1002/anie.200290034

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      Hydrogen atoms are borrowed during the in situ oxidation of the starting alcohol to the corresponding aldehyde and are subsequently returned in the hydrogenation of the alkene intermediate, which is formed by Wittig olefination of the aldehyde. This process permits an indirect Wittig reaction of alcohols without overall oxidation and offers an alternative to traditional methods that involve, for example, conversion of an alcohol into an alkyl halide.

    38. A Straightforward Detection of Deprotonated Conformers of Malonic Acid by Solid-State 13C NMR Spectroscopy (pages 4743–4745)

      Roxane Colsenet, Carole Gardiennet, Bernard Henry and Piotr Tekely

      Version of Record online: 12 DEC 2002 | DOI: 10.1002/anie.200290035

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      Information about the presence and the nature of various deprotonated forms of malonic acid in lyophilizates prepared from parent solutions at different pH values can be obtained by solid-state, natural abundance 13C NMR spectroscopy, particularly if a 13C-enriched substrate is used (see picture). pK values calculated from solid-state acid:base ratios are found to be equal to those classically measured in the liquid state.

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      Unparalleled Rates for the Activation of Aryl Chlorides and Bromides: Coupling with Amines and Boronic Acids in Minutes at Room Temperature (pages 4746–4748)

      James P. Stambuli, Ryoichi Kuwano and John F. Hartwig

      Version of Record online: 12 DEC 2002 | DOI: 10.1002/anie.200290036

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      Exceptionally fast oxidative addition of an aryl chloride (or a deactivated aryl bromide) to the active Pd0 center, which is ligated by sterically demanding phosphanes, occurs during coupling reactions catalyzed by air-stable PdI dimers as shown in the scheme. As a result, the reactions of aryl chlorides and bromides with amines and boronic acids at room temperature are complete within a few minutes. 1-Ad=1-adamantyl.

    40. A New Entry to the Stereoselective Introduction of an Ethynyl Group by a Radical Reaction: Synthesis of the Potential Antimetabolite 2′-Deoxy-2′-C-ethynyluridine (pages 4748–4750)

      Makoto Sukeda, Satoshi Ichikawa, Akira Matsuda and Satoshi Shuto

      Version of Record online: 12 DEC 2002 | DOI: 10.1002/anie.200290037

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      Atom-transfer 5-exo cyclization and subsequent elimination occur when ethynyldimethylsilyl ethers of iodohydrins are treated with Et3B followed by tetrabutylammonium fluoride (TBAF) to give the corresponding cis-configured α-hydroxy ethynyl compounds in high yield (see scheme). This is the first example of the use of a radical reaction to introduce an ethynyl group.

    41. Stereoselective Total Synthesis of Mucocin, an Antitumor Agent (pages 4751–4754)

      Shunya Takahashi, Akemi Kubota and Tadashi Nakata

      Version of Record online: 12 DEC 2002 | DOI: 10.1002/anie.200290038

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      The THP and THF rings which are regarded as the characteristic structural features of mucocin (1) were constructed by a SmI2-induced reductive cyclization of β-alkoxy acrylate and oxidative cyclization of a homoallyl alcohol, respectively. The key intermediates were synthesized through an efficient desymmetrization of a C2-symmetric tetraol.

    42. Structure of a Drug-Induced DNA T-Bulge: Implications for DNA Frameshift Mutations (pages 4754–4756)

      Michelle L. Colgrave, Huw E. L. Williams and Mark S. Searle

      Version of Record online: 12 DEC 2002 | DOI: 10.1002/anie.200290039

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      A bulged conformation in which the T3 base is flipped-out of the helical stack of the novel DNA hairpin H2 allowing complementary pairing downstream of the intercalation site (see picture) is stabilized by binding of the drug nogalamycin. This finding was readily confirmed by detailed analysis of the chemical shift and NOE data.

    43. Traceless Solid-Phase Synthesis of 2-Aminothiazoles: Receptor Tyrosine Kinase Inhibitors with Dual Selectivity for Tie-2 and VEGFR-2 (pages 4757–4761)

      Frank Stieber, Ralph Mazitschek, Natascha Soric, Athanassios Giannis and Herbert Waldmann

      Version of Record online: 12 DEC 2002 | DOI: 10.1002/anie.200290040

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      A 10-step (!) solid-phase synthesis employing the traceless hydrazide linker provides efficient access to a 2-aminothiazole library (see scheme) that yielded access to a new class of tyrosine kinase inhibitors with dual selectivity for the vascular endothelial growth factor receptor VEGFR-2 and the Tie-2 receptor tyrosine kinases.

    44. [Pd3(InCp*)42-InCp*)4]: Three Linearly Arranged Palladium Atoms Wrapped into a Fluxional Shell of Eight InCp* Ligands (pages 4761–4763)

      Tobias Steinke, Christian Gemel, Manuela Winter and Roland A. Fischer

      Version of Record online: 12 DEC 2002 | DOI: 10.1002/anie.200290041

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      There is still much to discover: The assumption that monovalent Group 13 organometallic compounds exhibit a high potential as ligands in organometallic chemistry beyond their analogy to CO is confirmed by the synthesis of the title compound 1. Complex 1, the structure of which is unique and has no analogue in carbonyl cluster chemistry, is prepared by reaction of [(tmeda)Pd(CH3)2] with [InCp*]. tmeda=N,N,N′,N′-tetramethylethylenediamine, Cp*=pentamethylcyclopentadienide.

    45. Total Synthesis of Amphidinolide T4 (pages 4763–4766)

      Alois Fürstner, Christophe Aïssa, Ricardo Riveiros and Jacques Ragot

      Version of Record online: 12 DEC 2002 | DOI: 10.1002/anie.200290042

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      Organometallic chemistry in general and catalysis in particular are used in the first total synthesis of amphidinolide T4 (see scheme); a prototype member of a series of macrolide antibiotics of marine origin with rings containing an odd number of carbon atoms.

    46. Tuning PCR Specificity by Chemically Modified Primer Probes (pages 4766–4769)

      Michael Strerath and Andreas Marx

      Version of Record online: 12 DEC 2002 | DOI: 10.1002/anie.200290043

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      Increased selectivity in PCR! Robust systems that allow the direct detection of single nucleotide variations through PCR methods will be increasingly important for rapid comparative genome analysis or mutation detection. Primer probes bearing supplemental chemical modifications (R=vinyl) significantly increase the selectivity of PCR compared to unmodified probes (R=H), even when the target sequences differ in only one nucleotide (see picture).

    47. Detection of Individual p53-Autoantibodies by Using Quenched Peptide-Based Molecular Probes (pages 4769–4773)

      Hannes Neuweiler, Andreas Schulz, Andrea C. Vaiana, Jeremy C. Smith, Sepp Kaul, Jürgen Wolfrum and Markus Sauer

      Version of Record online: 12 DEC 2002 | DOI: 10.1002/anie.200290044

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      Single-molecule spectroscopy for cancer diagnostics: Short dye-labeled peptide epitopes derived from human p53 show strong fluorescence quenching owing to efficient electron transfer from a tryptophan residue to the fluorophore (1, see picture). The specific recognition of the peptide epitope by the antibody induces a change in the conformation which is accompanied by a strong increase in fluorescence intensity. The fluorescing antibody–peptide complex can be detected at the single-molecule level even in slightly diluted serum samples by using confocal fluorescence microscopy.

    48. Long-Distance Magnetic Interaction between a MnIIIMnIV (S=1/2) Core and an Organic Radical: A Spectroscopic Model for the S2Yz. State of Photosystem II (pages 4775–4779)

      Dana S. Marlin, Eckhard Bill, Thomas Weyhermüller, Eva Rentschler and Karl Wieghardt

      Version of Record online: 12 DEC 2002 | DOI: 10.1002/anie.200290045

      An excellent tool for gaining a better understanding of long-distance exchange interactions in complicated systems, such as the S2YZ. state of photosystem II, is provided by a relatively simple model for similar interactions between a dimanganese core and an organic radical in the complex [(Me4dtne)MnIIIMnIV(μ-O)2(μ-O2CPhNIT)](ClO4)2. Dual-mode EPR spectroscopy serves as an additional tool for determining the extent of these long-distance dipolar coupling interactions. Me4dtne=1,2-bis(4,7-dimethyl-1,4,7-triazacyclonon-1-yl)ethane; HO2CPhNIT=2-(4-carboxyphenyl)-4,4,5,5-tetramethyl-3-oxyimidazolidin-1-oxide.

    49. Real-Time Single-Molecule Imaging of the Formation and Dynamics of Coordination Compounds (pages 4779–4783)

      Nian Lin, Alexandre Dmitriev, Jens Weckesser, Johannes V. Barth and Klaus Kern

      Version of Record online: 12 DEC 2002 | DOI: 10.1002/anie.200290046

      Thumbnail image of graphical abstract

      Reaction sequences under the microscope: Scanning tunneling microscopy has been used to follow the association and dissociation of the cloverleaf-shaped complex from 1,3,5-benzenetricarboxylic acid and Cu atoms from a metal surface one molecule at a time (see images). The lifetime of the complexes depends crucially on their local chemical enviroment.

    50. Low-Temperature Synthesis of Single-Crystal Germanium Nanowires by Chemical Vapor Deposition (pages 4783–4786)

      Dunwei Wang and Hongjie Dai

      Version of Record online: 12 DEC 2002 | DOI: 10.1002/anie.200290047

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      Live-wire potential: Low-temperature growth of Ge nanowires has been achieved by the chemical vapor deposition of GeH4 onto a SiO2 substrate coated with Au nanoparticles (see picture). This technique, which represents the mildest growth conditions for single-crystal nanowire synthesis, can also be used for patterned growth processes. Under such conditions, the growth of high-quality nanowires on a variety of substrates is possible, which may yield many possibilities in nanotechnological applications.

    51. Experimental Observation and Confirmation of Icosahedral W@Au12 and Mo@Au12 Molecules (pages 4786–4789)

      Xi Li, Boggavarapu Kiran, Jun Li, Hua-Jin Zhai and Lai-Sheng Wang

      Version of Record online: 12 DEC 2002 | DOI: 10.1002/anie.200290048

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      Yes, W@Au12is icosahedral! We provide experimental verification of the recently proposed new class of gold clusters. Anion photoelectron spectroscopy and relativistic density functional calculations were used to show that both W@Au12 and Mo@Au12 are highly stable icosahedral clusters with large HOMO–LUMO gaps. The HOMO and LUMO of the Ih M@Au12 clusters, both of hg symmetry, are bonding and antibonding orbitals between the W(Mo) 5d(4d) and the Au 6s–5dmath image hybrids oriented along the radial directions of the icosahedron, similar to the C 2s–2pz radial hybrids in C60.

    52. Synthesis and Characterization of Lanthanide Hydroxide Single-Crystal Nanowires (pages 4790–4793)

      Xun Wang and Yadong Li

      Version of Record online: 12 DEC 2002 | DOI: 10.1002/anie.200290049

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      It's a small world! The hydrothermal synthesis of a family of lanthanide hydroxide single-crystal nanowires has been achieved (see picture), the properties and dimensions of which can be tailored by changes in chemical potential and the pH value of the reaction media. Such materials might serve as templates for biological labeling agents, as one of many potential applications.

    53. Web Site: Electronic Data Refinement (page 4797)

      Wolfgang Schrader

      Version of Record online: 12 DEC 2002 | DOI: 10.1002/anie.200290051