European Journal of Organic Chemistry

Cover image for Vol. 2015 Issue 10

April 2015

Volume 2015, Issue 10

Pages 2079–2302

  1. Cover Picture

    1. Top of page
    2. Cover Picture
    3. Graphical Abstract
    4. News
    5. Microreview
    6. Short Communications
    7. Full Papers
    1. Synthesis of (–)-Cryptopleurine by Combining Gold(I) Catalysis with a Free Radical Cyclization (Eur. J. Org. Chem. 10/2015)

      Alexander Stoye and Till Opatz

      Article first published online: 25 MAR 2015 | DOI: 10.1002/ejoc.201590024

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      The cover picture shows how the core of (–)-cryptopleurine was assembled by using a palladium-catalyzed cross coupling (cyan bond), a gold-catalyzed cyclization (yellow bond) and a radical cyclization (green bond). While the alkaloid itself was very light-sensitive and the fires of Mordor were not required for its degradation, the ring-shaped gold–NHC complex employed in the key cyclization step was crucial to achieve high regioselectivity. Literally, it was the “One Ring to rule them all”. Details are discussed in the article by A. Stoye and T. Opatz on 2149 ff. The background image (taken by Manfred Werner) shows the atmospheric glow of oxygen and nitrogen, the two kinds of heteroatoms present in cryptopleurine, in a polar light. The font for the Elvish runes on The One Ring was provided by Johan Winge, publication was kindly permitted by C. Blackburn (Tolkien Estate).

  2. Graphical Abstract

    1. Top of page
    2. Cover Picture
    3. Graphical Abstract
    4. News
    5. Microreview
    6. Short Communications
    7. Full Papers
  3. News

    1. Top of page
    2. Cover Picture
    3. Graphical Abstract
    4. News
    5. Microreview
    6. Short Communications
    7. Full Papers
  4. Microreview

    1. Top of page
    2. Cover Picture
    3. Graphical Abstract
    4. News
    5. Microreview
    6. Short Communications
    7. Full Papers
    1. Biologically Active Sesquiterpenes

      Trends in the Synthesis and Functionalization of Guaianolides (pages 2093–2110)

      Alejandro Santana, José M. G. Molinillo and Francisco A. Macías

      Article first published online: 15 JAN 2015 | DOI: 10.1002/ejoc.201403244

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      Guaianolides and their derivatives display diverse biological activities and have for decades been targets for synthesis. Semi-synthesis, usually staring from eudemane sesquiterpenes, or total synthesis by use of an extensive range of synthetic methodologies to obtain the hydroazulene skeleton are the two principal strategies.

  5. Short Communications

    1. Top of page
    2. Cover Picture
    3. Graphical Abstract
    4. News
    5. Microreview
    6. Short Communications
    7. Full Papers
    1. Reaction Mechanisms

      On the Mechanism of Phenolic Formylation Mediated by TiCl4 Complexes: Existence of Diradical Intermediates Induced by Valence Tautomerism (pages 2111–2118)

      Carlos Heras, Iván Ramos-Tomillero, Marc Caballero, Marta Paradís-Bas, Ernesto Nicolás, Fernando Albericio, Ibério de P. R. Moreira and Josep Maria Bofill

      Article first published online: 25 FEB 2015 | DOI: 10.1002/ejoc.201403548

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      The mechanism of phenolic formylation mediated by TiCl4 has been investigated both theoretically and experimentally. Stable diradical intermediates induced by valence tautomerism have been detected and characterized. These diradical species are expected to be of fundamental significance in organic and bioorganic chemistry.

    2. Hydrosilylation

      Stable and Easily Handled FeIII Catalysts for Hydrosilylation of Ketones and Aldehydes (pages 2119–2123)

      Kailong Zhu, Michael P. Shaver and Stephen P. Thomas

      Article first published online: 27 FEB 2015 | DOI: 10.1002/ejoc.201500090

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      The iron(III)-catalysed hydrosilylation is reported for the operationally simple reduction of ketones and aldehydes (20 examples, 55–93 % yield).

    3. Hydro-Heteroarylation

      Remote Amide-Controlled Gold-Catalyzed Stereoselective Hydro-heteroarylation of Acrylamides: Access to Pyrido[3,4-b]indoles (pages 2124–2128)

      Himanshu H. Butani, Dipak D. Vachhani, Umed C. Bhoya, Anamik K. Shah and Erik V. Van der Eycken

      Article first published online: 25 FEB 2015 | DOI: 10.1002/ejoc.201403682

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      The amide functionality is used as a remote control for the stereoselective hydro-heteroarylation of acrylamides. This gold-catalyzed carbocyclization provides a diversity-oriented and concise route to biologically important pyrido[3,4-b]indoles. Moreover, the adverse effect of silver salts on this hydro-heteroarylation is also studied; U-4CR = Ugi 4-component reaction.

    4. Vinyl Iodides

      Copper(I)-Catalyzed (Z)-β-(Tosyloxy)alkenyl Iodide Synthesis from (Aryl)[(E)-β-(tosyloxy)alkenyl]iodonium Tosylates: Diversity-Oriented Synthesis of Trisubstituted Alkenes (pages 2129–2132)

      Keshab Mondal and Subhas Chandra Pan

      Article first published online: 23 FEB 2015 | DOI: 10.1002/ejoc.201500039

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      A highly efficient and stereoselctive synthesis of (Z)-β-(tosyloxy)alkenyl iodide has been developed from (aryl)[(E)-(β-tosyloxy)alkenyl]iodonium tosylates by using cheap cuprous chloride as the catalyst. A variety of trisubstituted alkenes have been prepared by sequential Suzuki coupling reactions of the alkenyl iodide products.

    5. Nitrogen Heterocycles

      A General Synthesis of Bis(o-azaheteroaryl)methane Derivatives from N-Oxides of Azines and Azoles (pages 2133–2137)

      Magdalena Szpunar and Rafał Loska

      Article first published online: 23 FEB 2015 | DOI: 10.1002/ejoc.201500072

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      1,3-Dipolar cycloaddition between N-oxides of azines or azoles and in situ generated terminal difluoroalkenes provides a general method of the synthesis of bis(o-azaheteroaryl)methane derivatives containing different 5- and 6-membered heterocyclic units. Selected products were used for the preparation of two new unsymmetrical analogues of BODIPY fluorescent dyes.

    6. Glycosylation

      Phenyliodine Bis(trifluoroacetate) (PIFA) as an Excellent Promoter of 2-Deoxy-2-phthalimido-1-thioglycosides in the Presence of Triflic Acid in Glycosylation Reactions (pages 2138–2142)

      Tetsuya Kajimoto, Koji Morimoto, Ryosuke Ogawa, Toshifumi Dohi and Yasuyuki Kita

      Article first published online: 2 MAR 2015 | DOI: 10.1002/ejoc.201500186

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      Glycosylation reactions using p-(octyloxy)phenyl 2-deoxy-2-phthalimido-1-thio-D-glucopyranoside or p-(octyloxy)phenyl 2-deoxy-2-phthalimido-1-thio-D-galactopyranoside as the donor substrate afforded β-glycosylated products in good to excellent yields by activating the thioglycosides with PIFA (1 equiv.) and TfOH (2 equiv.).

    7. Asymmetric Fluorination

      Organocatalytic Asymmetric Fluorination of 4-Substituted Isoxazolinones (pages 2143–2147)

      Huanrui Zhang, Baomin Wang, Longchen Cui, Xiaoze Bao, Jingping Qu and Yuming Song

      Article first published online: 27 FEB 2015 | DOI: 10.1002/ejoc.201500046

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      A straightforward method for the asymmetric fluorination of 4-substituted isoxazolinones catalyzed by a bis-cinchona alkaloid catalyst was developed. A series of 4-fluoroisoxazolinone derivatives with a fluorine-containing quaternary stereocenter were obtained in good to high yields with good enantioselectivities (up to 91 % yield, 85 % ee).

  6. Full Papers

    1. Top of page
    2. Cover Picture
    3. Graphical Abstract
    4. News
    5. Microreview
    6. Short Communications
    7. Full Papers
    1. Alkaloid Synthesis

      Synthesis of (–)-Cryptopleurine by Combining Gold(I) Catalysis with a Free Radical Cyclization (pages 2149–2156)

      Alexander Stoye and Till Opatz

      Article first published online: 17 FEB 2015 | DOI: 10.1002/ejoc.201403700

      Thumbnail image of graphical abstract

      (R)-(–)-Cryptopleurine, a highly bioactive phenanthroquinolizidine alkaloid, was synthesized in high optical purity using a combination of gold(I)-NHC catalyzed regioselective ring closure of an unsymmetrical phenanthrene precursor and free radical cyclization chemistry to install ring C in the penultimate step.

    2. Protein–Ligand Interactions

      High Affinity Fluorescent Ligands for the Estrogen Receptor (pages 2157–2166)

      Frank Abendroth, Marthe Solleder, Dorothea Mangoldt, Pia Welker, Kai Licha, Marcus Weber and Oliver Seitz

      Article first published online: 19 FEB 2015 | DOI: 10.1002/ejoc.201403489

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      Dual click reactions have facilitated hydrophobic tagging of selective estrogen receptor modulators (SERMs). Raloxifene conjugation with fluorescent dyes afforded fluorescent ER with affinities superior to estradiol. These stains accumulate in ER expressing cells at low nanomolar concentrations and molecular dynamics simulations suggest dye–ER associations via helix 12 contacts.

    3. Chromophores

      Benz-Bisimidazole-Bridged Perylenes – Linearly Expanded Chromophores (pages 2167–2174)

      Jörg Schönamsgruber and Andreas Hirsch

      Article first published online: 19 FEB 2015 | DOI: 10.1002/ejoc.201403561

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      We present the synthesis and characterization of a new type of perylene chromophore. Two perylene moieties are combined to form an overall conjugated π system. Parts of the molecule could be protonated and, thereby, the absorption and fluorescence emission spectra shifted bathochromically. The electronic band gap was determined to be 1.33–1.35 eV.

    4. Alkaloid Synthesis

      Synthesis of Condensed Tetrahydroisoquinoline Class of Alkaloids by Employing TfOH-Mediated Imide Carbonyl Activation (pages 2175–2188)

      Jayaraman Selvakumar, Ramana Sreenivasa Rao, Vijayan Srinivasapriyan, Srinivasan Marutheeswaran and Chinnasamy Ramaraj Ramanathan

      Article first published online: 19 FEB 2015 | DOI: 10.1002/ejoc.201403617

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      The isoquinoline-based polycyclic lactams and simple isoquinoline alkaloids were successfully assembled from the corresponding imides by using a TfOH-mediated (TfOH = trifluoromethanesulfonic acid) imide carbonyl activation and cyclization strategy. The regioselective cyclization of unsymmetrical phenethylimides with TfOH was studied by experimental and computational methods.

    5. Acidity

      Are Benzoic Acids Always More Acidic Than Phenols? The Case of ortho-, meta-, and para-Hydroxybenzoic Acids (pages 2189–2196)

      Renan S. Galaverna, Giovana A. Bataglion, Gabriel Heerdt, Gilberto F. de Sa, Romeu Daroda, Valnei S. Cunha, Nelson H. Morgon and Marcos N. Eberlin

      Article first published online: 18 FEB 2015 | DOI: 10.1002/ejoc.201403528

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      Solvent and counterion effects operate in solution to make benzoic acids far more acidic than phenols, but in the gas phase, as shown herein for model bifunctional ortho-, meta-, and para-hydroxybenzoic acids, the acidities are close, and care should, therefore, be taken in predicting acidity orders. Values are close and are affected by interfering inductive, resonance, and/or H-bonding effects.

    6. Radical Decarboxylative Fluorination

      Radical Decarboxylative Fluorination of Aryloxyacetic Acids Using N-Fluorobenzenesulfonimide and a Photosensitizer (pages 2197–2204)

      Joe C. T. Leung and Glenn M. Sammis

      Article first published online: 5 FEB 2015 | DOI: 10.1002/ejoc.201500038

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      Photodecarboxylative fluorination methodology involving the use of photosensitizers and N-fluorobenzenesulfonimide (NFSI) provides facile access to monofluoromethoxy-substituted arenes through the direct fluorodecarboxylation of carboxylic acids. Utilization of NFSI enables the synthesis of fluoromethyl ethers that were previously inaccessible with decarboxylative fluorinations performed with Selectfluor.

    7. Synthesis Design

      Conformationally Constrained Penta(hetero)cyclic Molecular Architectures by Photoassisted Diversity-Oriented Synthesis (pages 2205–2213)

      Weston J. Umstead, Olga A. Mukhina and Andrei G. Kutateladze

      Article first published online: 16 FEB 2015 | DOI: 10.1002/ejoc.201403620

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      Intramolecular cycloadditions of photogenerated azaxylylenes in conjunction with straightforward postphotochemical transformations of the primary photoproducts provide access to unprecedented polyheterocyclic scaffolds possessing a minimal number of rotatable bonds and a high content of sp3-hybridized carbon atoms.

    8. Asymmetric Catalysis

      Olefin Hydrogenation with Rigid Mono-P-stereogenic Diphosphines: A Flexible Rhodium Ring to Rule Them All? (pages 2214–2225)

      Slavko Rast, Michel Stephan and Barbara Mohar

      Article first published online: 17 FEB 2015 | DOI: 10.1002/ejoc.201403570

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      P-(o-Ph2P-Ph)-based P-stereogenic diphosphines prepared through the Jugé–Stephan route were studied in the RhI-catalyzed hydrogenation of olefins. For the first time, retention of P-configuration was observed in the methanolysis step. This rigid design brought further mechanistic insights on the relationship between steric and electronic factors of related C2-symmetric P,P,P′,P′-tetraarylic CH2CH2-bridged ligands.

    9. Natural Products

      First Enantioselective Synthesis of Marine Diterpene Ambliol-A (pages 2226–2234)

      Stefano Serra and Veronica Lissoni

      Article first published online: 17 FEB 2015 | DOI: 10.1002/ejoc.201403610

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      The enantioselective synthesis of diterpene (+)-ambliol-A and diastereoselective synthesis of its non-natural epimer are accomplished from racemic α-ionone. The key steps are diastereoselective epoxidation, lipase-mediated resolution, and copper-catalyzed cross coupling. The chemical structure of natural ambliol-A is confirmed and its absolute configuration corrected and now assigned as (1R,2R).

    10. Aminocarbonylation

      Palladium-Catalyzed Oxidative Aminocarbonylation by Decarboxylative Coupling: Synthesis of Alkynyl Amides (pages 2235–2243)

      Jinil Hwang, Jinseop Choi, Kyungho Park, Wonyoung Kim, Kwang Ho Song and Sunwoo Lee

      Article first published online: 16 FEB 2015 | DOI: 10.1002/ejoc.201403644

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      Alkynyl amides were synthesized from a palladium-catalyzed coupling reaction of alkynyl carboxylic acids and amines under carbon monoxide. The reactions were conducted with palladium(II) acetate and silver(I) oxide in acetonitrile at 80 °C for 1 h. This method provides good to moderate product yields and good functional group tolerance towards ketone, ester, and nitrile groups.

    11. Pyridylpurine Nucleosides

      Synthesis of C6-Pyridylpurine Nucleosides by Reaction of Nebularine N1-Oxide with Pyridinyl Grignard Reagents (pages 2244–2249)

      Stefano D'Errico, Giorgia Oliviero, Nicola Borbone, Fabrizia Nici, Vincenzo Piccialli, Brunella Pinto, Daniele D'Alonzo, Luciano Mayol and Gennaro Piccialli

      Article first published online: 19 FEB 2015 | DOI: 10.1002/ejoc.201403648

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      The synthesis of a set of C6-pyridylpurine nucleosides is reported, exploiting the reactivity of nebularine N1-oxide towards pyridinyl Grignard reagents.

    12. Gold Nanopartilcles

      Dispersed Gold Nanoparticles Supported in the Pores of Siliceous Mesocellular Foam: A Catalyst for Cycloisomerization of Alkynoic Acids to γ-Alkylidene Lactones (pages 2250–2255)

      Kristofer Eriksson, Oscar Verho, Leif Nyholm, Sven Oscarsson and Jan-E. Bäckvall

      Article first published online: 19 FEB 2015 | DOI: 10.1002/ejoc.201403664

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      An electrochemical method for generating heterogeneously supported AuI thiolates that can be reduced to highly active Au nanoparticles by subsequent treatment with NaBH4 is described. The corresponding Au nanocatalyst was applied in the cycloisomerization of a set of alkynoic acids into the corresponding γ-alkylidene lactones in high yields under mild conditions.

    13. Natural Products

      Oximoaspergillimide, a Fungal Derivative from a Marine Isolate of Aspergillus sp. (pages 2256–2261)

      Faviola Cardoso-Martínez, José M. de la Rosa, Ana R. Díaz-Marrero, José Darias, Luis D'Croz, Claudia Cerella, Marc Diederich and Mercedes Cueto

      Article first published online: 17 FEB 2015 | DOI: 10.1002/ejoc.201403668

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      Oximoaspergillimide (1), a new alkaloid derivative, was isolated from a cultured marine-derived fungus (strain CF07002) identified as a member of the genus Aspergillus. Oximoaspergillimide (1) is the first natural product reported to contain an oxime–imide functionality.

    14. Amino Acids

      Cross-Claisen Condensation of N-Fmoc-Amino Acids – A Short Route to Heterocyclic γ-Amino Acids (pages 2262–2270)

      Loïc Mathieu, Clément Bonnel, Nicolas Masurier, Ludovic T. Maillard, Jean Martinez and Vincent Lisowski

      Article first published online: 16 FEB 2015 | DOI: 10.1002/ejoc.201500012

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      Cross-Claisen condensations between N-Fmoc-amino acids and sterically hindered 1,1-dimethylallyl acetate provide a short route to 4-amino(methyl)-1,3-thiazole-5-carboxylic acids (ATCs), a new class of constrained heterocyclic γ-amino acids built around a thiazole ring. A wide variety of lateral chains can be introduced on the γ-carbon atom or on the thiazole core.

    15. Chromophores

      Stimuli-Responsive Cyclopenta[ef]heptalenes: Synthesis and Optical Properties (pages 2271–2276)

      Ebrahim H. Ghazvini Zadeh, Adam W. Woodward, David Richardson, Mykhailo. V. Bondar and Kevin D. Belfield

      Article first published online: 19 FEB 2015 | DOI: 10.1002/ejoc.201500059

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      Cyclopenta[ef]heptalenes 4ac, prepared by annulation of 3-formylguaiazulene (1), revealed a stimuli-responsive behavior upon treatment with strong acids. 1D and 2D NMR spectroscopy indicated that protonation occurred on C-6, while photoacid titrations demonstrated that the reported tricyclic systems can serve as efficient visible sensitizers of UV-activated photoacid generators (PAGs).

    16. Reductive Monoalkylation

      Indium(III)-Catalyzed Reductive Monoalkylation of Electron-Rich Benzenes with Aliphatic Carboxylic Acids Leading to Arylalkane Derivatives (pages 2277–2281)

      Toshimitsu Moriya, Kentaro Takayama, Takeo Konakahara, Yohei Ogiwara and Norio Sakai

      Article first published online: 18 FEB 2015 | DOI: 10.1002/ejoc.201500096

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      A combination of InI3, 1,1,3,3-tetramethyldisiloxane (TMDS), and molecular iodine effectively undergoes one-pot monoalkylation of electron-rich benzene derivatives with aliphatic carboxylic acids having a variety of substituents, leading to the preparation of arylated alkane derivatives.

    17. Polycationic Fullerene Derivative

      Formation of Highly Charged Quasi-Molecular Ions of a Polycationic [60]Fullerene Hexakis-Adduct and Their Fragmentation Behavior in the Gas Phase (pages 2282–2290)

      Jing Li, Leanne C. Nye, Lennard K. Wasserthal, Chau Vinh, Rolf W. Kirschbaum, Ivana Ivanović-Burmazović, Andreas Hirsch and Thomas Drewello

      Article first published online: 19 FEB 2015 | DOI: 10.1002/ejoc.201500102

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      A novel polycationic [60]fullerene hexakis-adduct (12 pre-formed charges) has been synthesized and investigated by electrospray ionization and tandem mass spectrometry. The polycation showed neutral losses and Coulomb explosions.

    18. Natural Products

      Asymmetric Synthesis of Concentricolide (pages 2291–2296)

      Xiaojing Liu, Lingling Hu, Lizhen Jiang, Junhao Jia, Di Zhang and Xiaochuan Chen

      Article first published online: 18 FEB 2015 | DOI: 10.1002/ejoc.201403604

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      A practical strategy for the synthesis of both (–)- and (+)-concentricolide from salicylic acid has been developed. The key step of the approach is sequential ortho-lithiation on the aryl ring and condensation with aldehyde aided by stereocontrol through a chiral oxazoline derived from L- or D-phenylalaninol.

    19. Flavonoids

      The First Total Synthesis of Sophoflavescenol, Flavenochromane C, and Citrusinol (pages 2297–2302)

      Van-Son Nguyen, Lin-Pei Dong, Sheng-Chun Wang and Qiuan Wang

      Article first published online: 17 FEB 2015 | DOI: 10.1002/ejoc.201403689

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      The first total syntheses of sophoflavescenol, flavenochromane C, and citrusinol were achieved in 23, 17, and 16 % yields, respectively, starting from 2,4,6-trihydroxyacetophenone and substituted benzaldehydes. The key step was a regioselective microwave-assisted Claisen rearrangement to form an 8-prenylated flavonoid from a 5-O-prenylflavonoid.

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