Angewandte Chemie International Edition

Cover image for Vol. 45 Issue 24

June 12, 2006

Volume 45, Issue 24

Pages 3887–4035

    1. Cover Picture: Kinetically Controlled Ligation for the Convergent Chemical Synthesis of Proteins (Angew. Chem. Int. Ed. 24/2006) (page 3887)

      Duhee Bang, Brad L. Pentelute and Stephen B. H. Kent

      Version of Record online: 1 JUN 2006 | DOI: 10.1002/anie.200690082

      Convergent chemical ligation enables the more efficient total synthesis of protein molecules. S. B. H. Kent and co-workers describe in their Communication on page 3985 ff. how the two halves of the target peptide chain can be synthesized by kinetically controlled chemical ligation of unprotected peptide segments. A final native chemical ligation step then gives the full-length polypeptide chain, which folds with high efficiency to give the synthetic protein molecule. (The artwork for the coverpicture was prepared by David Boerema.)

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      Catalytic Enantioselective Hydrogenolysis of [Cr(CO)3(5,8-Dibromonaphthalene)] (page 3898)

      E. Peter Kündig, Piyali Datta Chaudhuri, David House and Gérald Bernardinelli

      Version of Record online: 1 JUN 2006 | DOI: 10.1002/anie.200690084

      This article corrects:

      Catalytic Enantioselective Hydrogenolysis of [Cr(CO)3(5,8-Dibromonaphthalene)]1

      Vol. 45, Issue 7, 1092–1095, Version of Record online: 11 JAN 2006

    3. Greener Media in Chemical Synthesis and Processing (pages 3904–3908)

      Martín Avalos, Reyes Babiano, Pedro Cintas, José L. Jiménez and Juan C. Palacios

      Version of Record online: 19 MAY 2006 | DOI: 10.1002/anie.200504285

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      When two solids make a liquid: The phenomenon is reproduced every winter when salt is spread on icy roads. Upon mixing certain solids, a variety of low-freezing and biodegradable liquids result (see picture). These eutectic mixtures offer a greener alternative to conventional ionic liquids and organic solvents.

    4. Chiral Phosphoric Acids: Powerful Organocatalysts for Asymmetric Addition Reactions to Imines (pages 3909–3912)

      Stephen J. Connon

      Version of Record online: 24 MAY 2006 | DOI: 10.1002/anie.200600529

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      Loaded with potential: The enormous potential of chiral phosphoric acids (see formulae) as promoters of novel, highly enantioselective addition reactions to imines under mild conditions has recently been recognized. The use of such catalysts has brought about the development of a number of new asymmetric reactions for the synthesis of amine-based chiral building blocks.

    5. Recent Advances in Metallabenzene Chemistry (pages 3914–3936)

      Christopher W. Landorf and Michael M. Haley

      Version of Record online: 24 MAY 2006 | DOI: 10.1002/anie.200504358

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      Chemical chameleons—with regard to properties normally associated with aromaticity—aptly describe metallabenzenes (see scheme for examples), as they exhibit delocalized bonding, possess downfield 1H NMR chemical shifts, and form arene-coordination complexes, but are often distinctly nonplanar, undergo [4+2] cycloaddition reactions, and rearrange to form cyclopentadiene complexes. This Review describes their synthesis, chemistry, and unusual physical properties.

    6. Highly Efficient Chemoenzymatic Synthesis of Naturally Occurring and Non-Natural α-2,6-Linked Sialosides: A P. damsela α-2,6-Sialyltransferase with Extremely Flexible Donor–Substrate Specificity (pages 3938–3944)

      Hai Yu, Shengshu Huang, Harshal Chokhawala, Mingchi Sun, Haojie Zheng and Xi Chen

      Version of Record online: 24 MAY 2006 | DOI: 10.1002/anie.200600572

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      Just relax: A one-pot, three-enzyme chemoenzymatic synthetic approach is highly efficient for obtaining complex sialosides that contain diverse naturally occurring sialic acid modifications. α-2,6-Linked sialosides containing twelve naturally occurring sialic acid forms and seven non-natural sialic acid forms have been obtained.

    7. A Quadruply Azulene-Fused Porphyrin with Intense Near-IR Absorption and a Large Two-Photon Absorption Cross Section (pages 3944–3947)

      Kei Kurotobi, Kil Suk Kim, Su Bum Noh, Dongho Kim and Atsuhiro Osuka

      Version of Record online: 9 MAY 2006 | DOI: 10.1002/anie.200600892

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      Extending conjugation: Azulene-fused porphyrins (see example) are synthesized through the oxidation of meso-(4-azulenyl)porphyrins with FeCl3. The azulene-fused strategy allowed highly π-conjugated porphyrinic electronic systems, which are promising two-photon absorption pigments, to be realized.

    8. Synthesis and Characterization of [PhC(NtBu)2]SiCl: A Stable Monomeric Chlorosilylene (pages 3948–3950)

      Cheuk-Wai So, Herbert W. Roesky, Jörg Magull and Rainer B. Oswald

      Version of Record online: 3 MAY 2006 | DOI: 10.1002/anie.200600647

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      The single life: The reaction of [PhC(NtBu)2]SiCl3 (1) with potassium afforded the monomeric chlorosilylene [PhC(NtBu)2]SiCl (2). The X-ray crystal structure of 2 has been determined and natural-bond-orbital analysis carried out.

    9. Modular Asymmetric Synthesis of Aigialomycin D, a Kinase-Inhibitory Scaffold (pages 3951–3954)

      Sofia Barluenga, Pierre-Yves Dakas, Yoan Ferandin, Laurent Meijer and Nicolas Winssinger

      Version of Record online: 9 MAY 2006 | DOI: 10.1002/anie.200600593

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      On solid ground: Despite no obvious resemblance to adenosine analogues, the family of resorcyclic macrolides contains a high proportion of kinase and ATPase inhibitors. A solid-phase total synthesis of aigialomycin D extends the diversity of this class of natural product. Aigialomycin was found to inhibit CDK1/5 and GSK. EOM=ethoxymethyl.

    10. A Facile Experimental Method To Determine the Hydride Affinity of Polarized Olefins in Acetonitrile (pages 3954–3957)

      Xiao-Qing Zhu, Min Zhang, Qiao-Yun Liu, Xiao-Xiao Wang, Jian-Yu Zhang and Jin-Pei Cheng

      Version of Record online: 3 MAY 2006 | DOI: 10.1002/anie.200600536

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      Choosing a suitable hydride reducing agent and thermodynamic analysis of reduction mechanisms is facilitated by experimental hydride affinities ΔHmath image, which are reported herein for 28 polarized olefins 1 in acetonitrile (see scheme). The method should also be applicable to ketones, aldehydes, and imines.

    11. RhI-Catalyzed C[BOND]C Bond Activation: Seven-Membered Ring Synthesis by a [6+1] Carbonylative Ring-Expansion Reaction of Allenylcyclobutanes (pages 3957–3960)

      Paul A. Wender, Nicole M. Deschamps and Robert Sun

      Version of Record online: 9 MAY 2006 | DOI: 10.1002/anie.200600806

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      Ever expanding: A RhI-catalyzed C[BOND]C activation reaction of allenylcyclobutanes generates intermediate metallacycles that can be trapped with CO to produce a new [6+1] reaction. Functionalized monocyclic and bicyclic cycloheptenones are obtained in good-to-excellent yields with this [6+1] higher-order carbonylative cycloaddition reaction.

    12. Diastereoselective Synthesis of Methylenecyclopropanes from Chiral Cyclopropene Derivatives (pages 3960–3962)

      Zhe Yang, Xiaocong Xie and Joseph M. Fox

      Version of Record online: 9 MAY 2006 | DOI: 10.1002/anie.200600531

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      Directed delivery: Chiral methylenecyclopropanes were prepared from cyclopropene derivatives upon reaction with Grignard reagents. A higher-order dependence of the reaction on the concentration of the Grignard reagent was revealed, and based on this finding, it was possible to reverse the regioselectivity of the process (see scheme; MEM=methoxyethoxymethyl).

    13. Enantiomerically Pure Cyclopropenylcarbinols as a Source of Chiral Alkylidenecyclopropane Derivatives (pages 3963–3965)

      Samah Simaan, Ahmad Masarwa, Philippe Bertus and Ilan Marek

      Version of Record online: 20 APR 2006 | DOI: 10.1002/anie.200600556

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      The straightforward approach: The copper-catalyzed carbomagnesiation reaction of chiral cyclopropenylcarbinol derivatives, obtained through kinetic resolution of secondary allylic alcohols, leads to the preparation of enantiomerically pure alkylidenecyclopropane derivatives. The reaction mechanism is composed of a syn carbometalation followed by a syn elimination reaction.

    14. Microwave-Enhanced Ionothermal Synthesis of Aluminophosphate Molecular Sieves (pages 3965–3970)

      Yun-Peng Xu, Zhi-Jian Tian, Shao-Jun Wang, Yue Hu, Lei Wang, Bing-Chun Wang, Ying-Chong Ma, Lei Hou, Jia-You Yu and Li-Wu Lin

      Version of Record online: 9 MAY 2006 | DOI: 10.1002/anie.200600054

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      Fast and safe: The combination of microwaves and ionic liquids provides a new method for the preparation of aluminophosphate molecular sieves (see picture). This method has the advantage of enabling the synthesis to be carried out at ambient pressures and results in a rapid crystallization and high structural selectivity.

    15. Charge Transfer between Metal Nanoparticles Interconnected with a Functionalized Molecule Probed by Surface-Enhanced Raman Spectroscopy (pages 3970–3973)

      Qun Zhou, Xiaowei Li, Qiang Fan, Xingxia Zhang and Junwei Zheng

      Version of Record online: 9 MAY 2006 | DOI: 10.1002/anie.200504419

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      Good vibrations: Metal–molecule–metal nanosystems are fabricated by the self-assembly of gold and silver nanoparticles interconnected with 4-aminothiophenol (PATP) molecules (see picture). The b2 vibrational modes of the PATP molecules are greatly enhanced by near-infrared excitation, as a result of charge transfer between the metal nanoparticles coupled with the vibrations of the PATP molecules.

    16. “Green” Oxidation Catalysis for Rapid Deactivation of Bacterial Spores (pages 3974–3977)

      Deboshri Banerjee, Andrew L. Markley, Toshihiro Yano, Anindya Ghosh, Peter B. Berget, Edwin G. Minkley Jr., Sushil K. Khetan and Terrence J. Collins

      Version of Record online: 4 MAY 2006 | DOI: 10.1002/anie.200504511

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      A view to a kill: Iron(III)-coordinated tetraamide macrocyclic ligands (see example) activate peroxides in water in the presence of a cationic surfactant to rapidly deactivate spores of the common anthrax surrogate, Bacillus atrophaeus. A 99.99999 % kill can be achieved in 15 min at pH 10 and room temperature with tert-butyl hydroperoxide (see TEM images).

    17. Crystallization in a Mixture of Solvents by Using a Crystal Modifier: Morphology Control in the Synthesis of Highly Monodisperse CaCO3 Microspheres (pages 3977–3981)

      Xiao-Hui Guo, Shu-Hong Yu and Guo-Bing Cai

      Version of Record online: 4 MAY 2006 | DOI: 10.1002/anie.200600029

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      It's under control: In the presence of an artificial double-hydrophilic block copolymer, poly(ethylene glycol)-b-poly(L-glutamic acid), highly monodisperse vaterite microspheres crystallize from a mixture of N,N-dimethylformamide and water (see picture). Varying the ratio of the solvents can control the morphology of the CaCO3 crystals.

    18. Glycerol as a Source for Fuels and Chemicals by Low-Temperature Catalytic Processing (pages 3982–3985)

      Ricardo R. Soares, Dante A. Simonetti and James A. Dumesic

      Version of Record online: 9 MAY 2006 | DOI: 10.1002/anie.200600212

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      Lean and green: Glycerol can be catalytically converted into synthesis gas at relatively low temperatures. The combination of this process with Fischer–Tropsch and methanol-synthesis steps offers a new strategy for the production of liquid fuels and chemicals from renewable resources.

    19. Kinetically Controlled Ligation for the Convergent Chemical Synthesis of Proteins (pages 3985–3988)

      Duhee Bang, Brad L. Pentelute and Stephen B. H. Kent

      Version of Record online: 26 APR 2006 | DOI: 10.1002/anie.200600702

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      Converging on the goal: New chemistry enables the key Cys-peptide-(αthioester) intermediate to be extended by ligation at either the N or C termini in a controlled fashion. This approach forms the basis for a set of novel tactics for the fully convergent synthesis of proteins by the chemical ligation of multiple peptide segments.

    20. [1,3]Dithian-2-ylidene (pages 3989–3992)

      Peter R. Schreiner, Hans Peter Reisenauer, Jaroslaw Romanski and Grzegorz Mloston

      Version of Record online: 10 MAY 2006 | DOI: 10.1002/anie.200600669

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      Free at last: Two free dithiocarbenes, a dithianylidene and a di-n-propyldithiocarbene generated thermally from the respective dialkylthiooxadiazoline precursors, are characterized and their reactivity examined. (The picture shows a cut through the Cs plane of the [1,3]dithian-2-ylidene, thus revealing the carbene sp2 orbital.)

    21. Oxygen-Atom Transfer between Mononuclear Nonheme Iron(IV)–Oxo and Iron(II) Complexes (pages 3992–3995)

      Chivukula V. Sastri, Kyungeun Oh, Yoon Jin Lee, Mi Sook Seo, Woonsup Shin and Wonwoo Nam

      Version of Record online: 10 MAY 2006 | DOI: 10.1002/anie.200504422

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      Completing the move: The intermetal transfer of an oxygen atom from nonheme iron(IV)–oxo to iron(II) complexes (see example, purple: Fe, red: O, blue: N, gray: C) has been unambiguously evidenced spectrophotometrically, mass spectrometrically, and electrochemically. The transfer of the oxygen atom was found to be dependent on the oxidizing power of the iron(IV)–oxo complexes.

    22. From a Lamellar to Hexagonal Self-Assembly of Bis(4,4′-(m,m′-di(dodecyloxy)phenyl)-2,2′-difluoro-1,3,2-dioxaborin) Molecules: A trans-to-cis-Isomerization-Induced Structural Transition Studied with STM (pages 3996–4000)

      Dirk Rohde, Cun-Ji Yan, Hui-Juan Yan and Li-Jun Wan

      Version of Record online: 4 MAY 2006 | DOI: 10.1002/anie.200600725

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      Lick into shape: Molecular adlayer symmetry can be transformed from lamellar to hexagonal through a thermal-annealing process which causes a trans-to-cis isomerization of the molecules within the adlayer. Different temperatures resulted in the formation of pure trans- and cis-isomer adlayers on the surface.

    23. Coupling of Electrochemistry and Fluorescence Microscopy at Indium Tin Oxide Microelectrodes for the Analysis of Single Exocytotic Events (pages 4000–4003)

      Christian Amatore, Stéphane Arbault, Yong Chen, Cécile Crozatier, Frédéric Lemaître and Yann Verchier

      Version of Record online: 9 MAY 2006 | DOI: 10.1002/anie.200600510

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      One-off analysis: Quantitative, kinetic, and spatial monitoring of single biological events involving vesicular secretion such as exocytosis may be achieved by combining electrochemistry with fluorescence microscopy at indium tin oxide (ITO) transparent microelectrodes. This method paves the way for real-time tracking of the intracellular fate of vesicles while monitoring precisely their dynamics of fusion.

    24. A Noninterpenetrating Three-Dimensional 4669 Iron(ii) Coordination Polymer Built with a Trigonal-Antiprismatic Iron(iii) Metalloligand (pages 4003–4007)

      Kyoung-Tae Youm, Min Gyu Kim, Jaejung Ko and Moo-Jin Jun

      Version of Record online: 4 MAY 2006 | DOI: 10.1002/anie.200503992

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      A second coordination sphere of six Nexo atoms in a trigonal-antiprismatic arrangement allows the metalloligand [FeIII(L)2]+ (red spheres, L=hydrotris(1,2,4-triazolyl)borate) to assemble with Rh2(OAc)4 linear spacers (blue rods) in an unprecedented noninterpenetrating 3D framework with 4669 topology. The metalloligand is reduced to the iron(II) state during the reaction by the borate ligand.

    25. The Direct Formation of Glycosyl Thiols from Reducing Sugars Allows One-Pot Protein Glycoconjugation (pages 4007–4011)

      Gonçalo J. L. Bernardes, David P. Gamblin and Benjamin G. Davis

      Version of Record online: 4 MAY 2006 | DOI: 10.1002/anie.200600685

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      Sweet and easy: A one-pot method consisting of direct thionation (1) followed by thiol-mediated chemoselective ligation (2) can be used for site-selective protein glycosylation. This procedure, which uses the Lawesson reagent, has been shown to be fully compatible with unprotected sugars, the products of which can be directly used in a selenenylsulfide protein glycosylation strategy.

    26. A Metal-Ion-Releasing Probe for DNA Detection by Catalytic Signal Amplification (pages 4013–4015)

      Nora Graf, Mareike Göritz and Roland Krämer

      Version of Record online: 9 MAY 2006 | DOI: 10.1002/anie.200504319

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      Seeing the light: Upon binding to a complementary nucleic acid, a metal-complex–DNA conjugate releases copper(II) ions that activate the precatalyst 1,10-phenanthroline (phen) and amplify the primary signal through catalytic production of a fluorescent dye (DCF). This combination of allosteric signal transduction and catalytic signal amplification imitates biological signaling cascades. tpy=2,2′:6′,2′′-terpyridine.

    27. Synthesis and Reactions of Highly Strained 2,3-Bridged 2H-Azirines (pages 4015–4019)

      Klaus Banert and Barbara Meier

      Version of Record online: 9 MAY 2006 | DOI: 10.1002/anie.200600483

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      Take the strain: Despite extreme ring strain and reactivity, the heterocycles 2, which are easily obtained from azides 1 and detectable by NMR spectroscopy, can be converted stereoselectively by novel addition and cycloaddition reactions.

    28. A General and Versatile Method for C[BOND]C Cross-Coupling Synthesis of Conjugated Enynes: One-Pot Sequence Starting from Carbonyl Compounds (pages 4019–4023)

      Ilya M. Lyapkalo and Michael A. K. Vogel

      Version of Record online: 9 MAY 2006 | DOI: 10.1002/anie.200504594

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      Ultimate coupling partners: Widely available enolizable aldehydes and ketones undergo Sonogashira cross-coupling with other carbonyl compounds to give conjugated enynes in a newly devised general method (see scheme; NfF=nonafluorobutane-1-sulfonyl fluoride). The synthetic protocol comprises at least four operating steps, which are carried out in one pot using common reagents, catalysts, and additives.

    29. Total Synthesis of the Light-Harvesting Carotenoid Peridinin (pages 4023–4027)

      Thomas Olpp and Reinhard Brückner

      Version of Record online: 9 MAY 2006 | DOI: 10.1002/anie.200600502

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      Light work: The light-harvesting marine C37 carotenoid peridinin was synthesized from (+)-diethyl tartrate and (−)-actinol. Key transformations were the differential reduction of an ester-containing Weinreb amide, an E-selective olefination by an Ando-type bromophosphonate, the anti-selective β-elimination establishing the C1′[DOUBLE BOND]C5 bond Z selectively, and a cis[RIGHTWARDS ARROW]trans isomerization of the C6′[DOUBLE BOND]C7′ bond (see picture).

    30. Proton Transfer in Ionic Water Clusters (pages 4027–4030)

      Zheng Sun, Chi-Kit Siu, O. Petru Balaj, Mirko Gruber, Vladimir E. Bondybey and Martin K. Beyer

      Version of Record online: 9 MAY 2006 | DOI: 10.1002/anie.200504135

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      How waterlike are ionic water clusters? Clusters with 10 to 100 water molecules are frequently used as model systems for reactions in aqueous solution. Concerted proton transfer, a key feature of liquid water, can be probed by observing the formation of HDO when D2O is used as a reactant (see scheme). Mass spectrometry shows that proton transfer occurs in H(H2O)n+, whereas the individual water molecules stay intact in (H2O)n and O2(H2O)n.

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