Chemistry - A European Journal

Cover image for Vol. 14 Issue 23

August 8, 2008

Volume 14, Issue 23

Pages 6823–7087

  1. Cover Picture

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    1. Cover Picture: pKa-Directed Host–Guest Assemblies: Rational Analysis of Molecular Adducts of 2,4-Diamino-6-methyl-1,3,5-triazine with Various Aliphatic Dicarboxylic Acids (Chem. Eur. J. 23/2008) (page 6823)

      Amit Delori, Eringathodi Suresh and V. R. Pedireddi

      Version of Record online: 30 JUL 2008 | DOI: 10.1002/chem.200890089

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      pKa-Directed host–guest assemblies composed of 2,4-diamino-6-methyl-1,3,5-triazine and a range of aliphatic dicarboxylic acids in a ratio of 2:1 have been prepared and characterized by Pedireddi et al., as demonstrated in their Full Paper on page 6967 ff. Two different types of host–guest system were observed depending on the pKa of the acid.

  2. Graphical Abstract

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  3. News

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  4. Concept

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    1. New Strategies for the Synthesis of Pyrimidine Derivatives (pages 6836–6844)

      Matthew D. Hill and Mohammad Movassaghi

      Version of Record online: 2 APR 2008 | DOI: 10.1002/chem.200800014

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      Recent advances in pyrimidine synthesis are described. Methods, including N–C fragment condensation strategies, provide reactive intermediates capable of intramolecular cyclization and formation of pyrimidine derivatives. These recently developed methodologies offer a valuable addendum to protocols for azaheterocycle synthesis.

  5. Communications

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    1. Nickel-Catalyzed Coupling of Aryl Bromides in the Presence of Alkyllithium Reagents (pages 6845–6848)

      Sarav B. Jhaveri and Kenneth R. Carter

      Version of Record online: 25 JUN 2008 | DOI: 10.1002/chem.200801008

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      Easy aryl couplings: In efforts to develop an improved catalytic method for transition-metal-catalyzed aryl coupling reactions, a one-pot, one-step, nickel-catalyzed coupling of aryl bromides aided by alkyllithium reagents is reported. By using catalytic amounts of nickel(II) and 0.5 equiv of alkyllithium, the homocoupling of various aryl bromides under mild conditions is accomplished in good yields (see scheme).

    2. Reaction of Epoxyketones with Hydrogen Peroxide—Ethane-1,1-dihydroperoxide as a Surprisingly Stable Product (pages 6849–6851)

      Hans-Jürgen Hamann, Alexander Bunge and Jürgen Liebscher

      Version of Record online: 4 JUL 2008 | DOI: 10.1002/chem.200800932

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      Stable peroxide: Ethane-1,1-dihydroperoxide as a surprisingly stable product was formed together with several other products (see scheme) when cyclic epoxyketones were treated with H2O2 under acid catalysis following a complex novel reaction pathway. Several C[BOND]C bond cleavages under Baeyer–Villiger oxidation and hydroperoxide rearrangements occur.

    3. A Novel Selective Aza-Morita–Baylis–Hillman (aza-MBH) Domino Reaction and Aza-MBH Reaction of N-Sulfonated Imines with Acrolein Catalyzed by a Bifunctional Phosphine Organocatalyst (pages 6852–6856)

      Xiangtai Meng, You Huang and Ruyu Chen

      Version of Record online: 25 JUN 2008 | DOI: 10.1002/chem.200800753

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      Simple domino reaction: The first aza-MBH/Michael/aldol/dehydrate domino reaction has been described. In the presence of a bifunctional phosphine organocatalyst the N-sulfonated imines and acrolein gave the tetrahydropyridine derivatives and aza-MBH products selectively in good to excellent yields (see scheme; aza-MBH=aza-Morita–Baylis–Hillman).

    4. Self-Immolative Comb-Polymers: Multiple-Release of Side-Reporters by a Single Stimulus Event (pages 6857–6861)

      Roy Weinstain, Amit Sagi, Naama Karton and Doron Shabat

      Version of Record online: 25 JUN 2008 | DOI: 10.1002/chem.200800917

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      Novel “smart” comb-ploymers that disintegrate from head-to-tail upon a single stimulus event (see scheme) are described. Upon activation of the head group, the comb-polymer undergoes complete disassembly to release multiple copies of side-reporter groups.

    5. A Flexible, Stereoselective Approach to the Decorated cis-Hydrindane Skeleton: Synthesis of the Proposed Structure of Faurinone (pages 6862–6865)

      Thomas J. K. Findley, David Sucunza, Laura C. Miller, David T. Davies and David J. Procter

      Version of Record online: 4 JUL 2008 | DOI: 10.1002/chem.200800930

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      Two electrons, three new stereocentres: The cis-hydrindane motif is found in a number of natural products that display important biological activity. A flexible, stereoselective approach to the framework has been developed that features highly diastereoselective, SmI2-mediated cyclisations. The strategy has been exploited in the first synthesis of the proposed structure of faurinone, a sesquiterpene ketone isolated from Valeriana officinalis.

    6. Facile Route to Supramolecular Structures: Self-Assembly of Dendrimers and Naphthalene Dicarboxylic Acids (pages 6866–6869)

      Franziska Gröhn, Katja Klein and Sabrina Brand

      Version of Record online: 24 JUN 2008 | DOI: 10.1002/chem.200800650

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      Cylinders and spheres can be formed by simple self-assembly of cationic dendrimers and oppositely charged small divalent organic ions in methanol (see graphic). The counterion not only controls the morphology of the nanosized assembly, but also provides functionality, such as fluorescence. The concept may lead to versatile functional supramolecular architectures.

  6. Full Papers

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    1. Dipeptide-Based Low-Molecular-Weight Efficient Organogelators and Their Application in Water Purification (pages 6870–6881)

      Sisir Debnath, Anshupriya Shome, Sounak Dutta and Prasanta Kumar Das

      Version of Record online: 18 JUL 2008 | DOI: 10.1002/chem.200800731

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      Dye away! The structure–property correlation of newly developed dipeptide organogelators was investigated by spectroscopic and microscopic techniques. All dipeptide gelators showed selective gelation of oil (aromatic solvents) in the presence of water. The xerogels of the organogelators can adsorb dyes, a property that was exploited in water purification (see graphic).

    2. Reactivity of Ammonia Ligands of the Antitumor Agent Cisplatin: A Unique Dodecanuclear Pt4,Pd4,Ag4 Platform for Four Cytosine Model Nucleobases (pages 6882–6891)

      Gunnar Kampf, Pablo J. Sanz Miguel, Marta Morell Cerdà, Michael Willermann, Alexandra Schneider and Bernhard Lippert

      Version of Record online: 23 JUN 2008 | DOI: 10.1002/chem.200800586

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      Cisplatin ligands are anything but inert! A simple monoadduct of cisplatin with a cytosine nucleobase condenses, in the presence of (ethylenediamine)PdII species and Ag+ ions, to form heteronuclear Pt2,Pd2,Ag and Pt4,Pd4,Ag4 species displaying μ-NH2 and μ-OH bridges (see structure), stacked nucleobases, and metal[RIGHTWARDS ARROW]metal donor bonds, as well as a surprising unreactivity of the Ag+ ion in the Pt2,Pd2,Ag species toward Cl ions.

    3. Highly Sensitive and Fast Responsive Fluorescence Turn-On Chemodosimeter for Cu2+ and Its Application in Live Cell Imaging (pages 6892–6900)

      Mengxiao Yu, Mei Shi, Zhigang Chen, Fuyou Li, Xinxin Li, Yanhong Gao, Jia Xu, Hong Yang, Zhiguo Zhou, Tao Yi and Chunhui Huang

      Version of Record online: 7 JUL 2008 | DOI: 10.1002/chem.200800005

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      Imaging intracelluar Cu2+: A rhodamine B derivative 1 containing a highly electron-rich sulfur atom was found to be a fluorescence turn-on chemodosimeter that responds stoichiometrically, rapidly, highly sensitively and selectively to Cu2+ through Cu2+-promoted ring-opening, redox and hydrolysis reactions.

    4. Hypervalent versus Nonhypervalent Carbon in Noble-Gas Complexes (pages 6901–6911)

      Simon C. A. H. Pierrefixe, Jordi Poater, Chan Im and F. Matthias Bickelhaupt

      Version of Record online: 24 JUN 2008 | DOI: 10.1002/chem.200800013

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      Disk-between-balls model: Based on MO theoretical analyses, we show how carbon can acquire the capability to form stable hypervalent structures [X[BOND]CH3[BOND]X]q when the axial C[BOND]X bonds become much weaker than the equatorial C[BOND]H bonds, for example, when X=noble gas (Ng) and q=+1. Under such conditions, the methyl moiety behaves as a rigid, planar disk between two balls (see picture). This corresponds to a hypervalent [Ng[BOND]CH3[BOND]Ng]+ structure.

    5. Ultrafast Excited State Dynamics Controlling Photochemical Isomerization of N-Methyl-4-[trans-2-(4-pyridyl)ethenyl]pyridinium Coordinated to a {ReI(CO)3(2,2′-bipyridine)} Chromophore (pages 6912–6923)

      Michael Busby, František Hartl, Pavel Matousek, Mike Towrie and Antonín Vlček Jr.

      Version of Record online: 4 JUL 2008 | DOI: 10.1002/chem.200800188

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      Multifunctional photoactive complexes: ReI complexes with a multifunctional MeDpe+ (MeDpe+=N-methyl-4-[trans-2-(4-pyridyl)ethenyl]pyridinium) ligand combine rich photonic and redox behavior. Their excited-state dynamics are determined by the energetic balance between low-lying excited states, which can be fine-tuned by structural variations. Ultrafast conversion of charge transfer to intraligand excited states followed by picosecond isomerization is preferred over intramolecular electron transfer (see graphic).

    6. A Rigid, Chiral, Dendronized Polymer with a Thermally Stable, Right-Handed Helical Conformation (pages 6924–6934)

      Afang Zhang, Francisco Rodríguez-Ropero, David Zanuy, Carlos Alemán, E. W. Meijer and A. Dieter Schlüter

      Version of Record online: 4 JUL 2008 | DOI: 10.1002/chem.200800325

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      Helical polymers: Dendronization of a linear polymethacrylate with chiral and compact peptidic dendrons affords a thermally stable helical polymer (see picture; Boc=tert-butoxycarbonyl), the handedness of which is independent of backbone tacticity. The right-handed helical model obtained from molecular dynamics simulations (tBu groups and H atoms removed for clarity) is shown on the right.

    7. Photoinduced Intramolecular Charge Transfer and S2 Fluorescence in Thiophene-π-Conjugated Donor–Acceptor Systems: Experimental and TDDFT Studies (pages 6935–6947)

      Guang-Jiu Zhao, Rui-Kui Chen, Meng-Tao Sun, Jian-Yong Liu, Guang-Yue Li, Yun-Ling Gao, Ke-Li Han, Xi-Chuan Yang and Licheng Sun

      Version of Record online: 24 JUN 2008 | DOI: 10.1002/chem.200701868

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      Do the twist! Newly synthesized thiophene-π-conjugated donor–acceptor compounds with different electron-withdrawing substituents exhibit efficient intramolecular charge-transfer (ICT) emission in polar solvents with large Stokes shifts (>220 nm) and strong solvatochromism. A combination of TDDFT calculations on electronically excited states and spectroscopic studies unambiguously demonstrated a twisted ICT mechanism (see picture).

    8. Belizeanic Acid: A Potent Protein Phosphatase 1 Inhibitor Belonging to the Okadaic Acid Class, with an Unusual Skeleton (pages 6948–6956)

      Patricia G. Cruz, José Javier Fernández, Manuel Norte and Antonio Hernández Daranas

      Version of Record online: 4 JUL 2008 | DOI: 10.1002/chem.200800593

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      Simplified by nature: Belizeanic acid is a novel marine metabolite from the dinoflagellate Prorocentrum belizeanum, and was characterised as a serine/threonine protein phosphatase inhibitor (see graphic). Its activity is comparable to that of okadaic acid, but with important structural differences involving the opening of the tricyclic ring system, characteristic of okadaic acid.

    9. Rigid–Flexible Block Molecules Based on a Laterally Extended Aromatic Segment: Hierarchical Assembly into Single Fibers, Flat Ribbons, and Twisted Ribbons (pages 6957–6966)

      Eunji Lee, Zhegang Huang, Ja-Hyoung Ryu and Myongsoo Lee

      Version of Record online: 4 JUL 2008 | DOI: 10.1002/chem.200800664

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      Supramolecular ribbons: Laterally extended aromatic amphiphiles self-assemble into a fibrous structure that laterally assembles, in a hierarchical way, into well-defined nanoribbons (see figure) with solvent exchange from diethyl ether to methanol.

    10. pKa-Directed Host–Guest Assemblies: Rational Analysis of Molecular Adducts of 2,4-Diamino-6-methyl-1,3,5-triazine with Various Aliphatic Dicarboxylic Acids (pages 6967–6977)

      Amit Delori, Eringathodi Suresh and V. R. Pedireddi

      Version of Record online: 15 JUL 2008 | DOI: 10.1002/chem.200800649

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      Networking skills: The molecular adducts of 2,4-diamino-6-methyl-1,3,5-triazine (1) with different aliphatic dicarboxylic acids form a range of interesting host–guest systems. If the pKa value of the acid is >3, the host network is formed by 1 only, whereas if the acid pKa value is <3, the host network is composed of both 1 and the acid (see graphic).

    11. Visible-Light Photochromism of Triarylamine- or Ferrocene-Bound Diethynylethenes that Switches Electronic Communication between Redox Sites and Luminescence (pages 6978–6986)

      Ryota Sakamoto, Shoko Kume and Hiroshi Nishihara

      Version of Record online: 23 JUN 2008 | DOI: 10.1002/chem.200800732

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      Photochromism in diethynylethenes: Triarylamine-based diethynylethene 1 undergoes efficient and reversible photochromism upon irradiation with visible light (405 and 578 nm). This Z/E conversion is accompanied by a reduction in the through-bond electronic communication between the two triarylamine sites, as well as a reduction in fluorescence efficiency (see diagram).

    12. A General Synthetic Route to Mixed NHC–Phosphane Palladium(0) Complexes (NHC=N-Heterocyclic Carbene) (pages 6987–6993)

      Serena Fantasia and Steven P. Nolan

      Version of Record online: 4 JUL 2008 | DOI: 10.1002/chem.200800815

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      In the metal mix: Mixed NHC–phosphane palladium(0) complexes [(NHC)Pd(PR3)] (NHC: N-heterocyclic carbene) are synthesized directly from commercially available reagents, with the possibility to tune the nature of both the NHC and the phosphane. The structure of the complexes was unambiguously confirmed by X-ray analysis (see scheme).

    13. Ligand-Free Sonogashira Coupling Reactions with Heterogeneous Pd/C as the Catalyst (pages 6994–6999)

      Shigeki Mori, Takayoshi Yanase, Satoka Aoyagi, Yasunari Monguchi, Tomohiro Maegawa and Hironao Sajiki

      Version of Record online: 4 JUL 2008 | DOI: 10.1002/chem.200800387

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      Go green! A copper-, ligand-, and amine-free Pd/C-catalyzed Sonogashira coupling reaction in aqueous media was developed (see scheme). This protocol will provide a facile, efficient, safe, and environmentally friendly process that could find industrial applications.

    14. Cyclophanes of Perylene Tetracarboxylic Diimide with Different Substituents at Bay Positions (pages 7000–7010)

      Junqian Feng, Yuexing Zhang, Chuntao Zhao, Renjie Li, Wei Xu, Xiyou Li and Jianzhuang Jiang

      Version of Record online: 4 JUL 2008 | DOI: 10.1002/chem.200800136

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      An influential position: Cyclophanes of perylene tetracarboxylic diimides (PDIs) linked by a triazine ring have optical and electrochemical properties that are sensitive to the relative conformation of the two PDI units in the cyclophanes (see picture).

    15. A Gold(I)-Catalyzed Intramolecular Reaction of Propargylic/Homopropargylic Alcohols with Oxirane (pages 7011–7018)

      Lun-Zhi Dai and Min Shi

      Version of Record online: 4 JUL 2008 | DOI: 10.1002/chem.200701954

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      All that glitters… The gold(I)-catalyzed cycloisomerization of epoxy alkynes in the presence of a nucleophile is an efficient protocol to provide a ketal skeleton with high stereoselectivity. Intramolecular reactions of propargylic/homopropargylic alcohols with oxirane produce ketal/spiroketals in moderate yields under mild conditions (see scheme).

    16. Solution-, Solid-Phase, and Fluorous Synthesis of β,β-Difluorinated Cyclic Quaternary α-Amino Acid Derivatives: A Comparative Study (pages 7019–7029)

      Santos Fustero, María Sánchez-Roselló, Vanessa Rodrigo, Juan F. Sanz-Cervera, Julio Piera, Antonio Simón-Fuentes and Carlos del Pozo

      Version of Record online: 25 JUN 2008 | DOI: 10.1002/chem.200702009

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      The diastereoselective synthesis of cyclic β,β-difluorinated α-amino acid derivatives bearing a quaternary stereocenter is described (see scheme). The process relies on the chemo- and diastereoselective addition of allylic organometallic reagents to fluorinated α-imino esters and a subsequent ring-closing metathesis reaction.

    17. The Influence of Densely Organized Maltose Shells on the Biological Properties of Poly(propylene imine) Dendrimers: New Effects Dependent on Hydrogen Bonding (pages 7030–7041)

      Barbara Klajnert, Dietmar Appelhans, Hartmut Komber, Nina Morgner, Simona Schwarz, Sven Richter, Bernhard Brutschy, Maksim Ionov, Anatoly K. Tonkikh, Maria Bryszewska and Brigitte Voit

      Version of Record online: 24 JUN 2008 | DOI: 10.1002/chem.200800342

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      Sugar coated: The hydrogen-bond-driven bio-interactions of neutral poly(propylene imine) (PPI) dendrimers possessing densely organized maltose shells (see figure) result in the retention of the biological functions known for cationic PPI. This behavior, combined with their low toxicity, gives them the potential to be used in the development of diagnostic and therapeutic agents.

    18. Non-natural Amino Acids as Modulating Agents of the Conformational Space of Model Glycopeptides (pages 7042–7058)

      Alberto Fernández-Tejada, Francisco Corzana, Jesús H. Busto, Gonzalo Jiménez-Osés, Jesús M. Peregrina and Alberto Avenoza

      Version of Record online: 4 JUL 2008 | DOI: 10.1002/chem.200800460

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      An à la carte menu of glucopeptides: Different α- and or β-substituted α-amino acid diamides derived from serine, threonine, and their corresponding model β-O-glucopeptides (see picture) were synthesized and studied in aqueous solution. The different conformations exhibited by these molecules could be a useful tool to obtain systems with conformational preferences “à la carte”.

    19. The First Example of Molecularly Imprinted Nanogels with Aldolase Type I Activity (pages 7059–7065)

      Davide Carboni, Kevin Flavin, Ania Servant, Veronique Gouverneur and Marina Resmini

      Version of Record online: 4 JUL 2008 | DOI: 10.1002/chem.200800675

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      Nanogels mimicking enzymes: Molecularly imprinted nanogels with aldolase type I activity have been synthesised. The shape of the catalytic pocket was designed through exploitation of the analogy between the intermediate of the cross-aldol reaction (1) and the complex between the diketone template and the functional monomer (2).

    20. Synthesis of a New Seleninic Acid Anhydride and Mechanistic Studies into Its Glutathione Peroxidase Activity (pages 7066–7071)

      Sun-Chol Yu, Astrid Borchert, Hartmut Kuhn and Igor Ivanov

      Version of Record online: 4 JUL 2008 | DOI: 10.1002/chem.200800694

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      Inflame your chemistry! Starting from low toxic 1 (see scheme), a novel seleninic acid anhydride 2 was synthesized that lacks Se⋅⋅⋅N or Se⋅⋅⋅O non-bonded interactions. Surprisingly, this compound exhibits a higher glutathione peroxidase-like activity than the standard compound ebselen and the catalytic mechanism combines three independent catalytic cycles. It inhibits mammalian lipoxygenases and thus, may constitute a lead compound for development of anti-inflammatory drugs.

    21. Pre-Activation-Based One-Pot Synthesis of an α-(2,3)-Sialylated Core-Fucosylated Complex Type Bi-Antennary N-Glycan Dodecasaccharide (pages 7072–7081)

      Bin Sun, Balasubramanian Srinivasan and Xuefei Huang

      Version of Record online: 7 JUL 2008 | DOI: 10.1002/chem.200800757

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      Highly efficient synthesis: The challenging N-glycan dodecasaccharide was successfully assembled in a stereo-controlled and convergent manner. The pre-activation-based chemoselective glycosylation strategy minimizes the protective group manipulation and aglycon transformation steps on oligosaccharide intermediates, thus greatly improving the overall synthetic efficiency.

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    4. News
    5. Concept
    6. Communications
    7. Full Papers
    8. Preview
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      Preview: Chem. Eur. J. 24/2008 (page 7087)

      Version of Record online: 30 JUL 2008 | DOI: 10.1002/chem.200890092

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