European Journal of Organic Chemistry

Cover image for Vol. 2016 Issue 5

February 2016

Volume 2016, Issue 5

Pages 856–1065

  1. Cover Picture

    1. Top of page
    2. Cover Picture
    3. News
    4. Microreviews
    5. Communications
    6. Full Papers
    1. Convenient Access to Di- and Tri­fluoroethylamines for Lead Structure Research (Eur. J. Org. Chem. 5/2016)

      Amrei Deutsch, Christian Wagner, Carl Deutsch and Anja Hoffmann-Röder

      Article first published online: 12 FEB 2016 | DOI: 10.1002/ejoc.201690008

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      The cover picture shows an easy and reliable approach towards the synthesis of novel carboxamide surrogates for lead structure research. Di- or trifluoroethylamines might represent missing puzzle pieces in the search for hydrolytically stable amide bioisosteres, and their convenient preparation is reported starting from di- and trifluoromethylated N-aryl N,O-acetal precursors. Nucleophilic addition of Grignard reagents or heteroatom nucleophiles allows a flexible, yet simple access to various functionalized di- and trifluoromethylated amines. Details are discussed in the article by C. Deutsch, A. Hoffmann-Röder et al. on p. 930 ff.

  2. News

    1. Top of page
    2. Cover Picture
    3. News
    4. Microreviews
    5. Communications
    6. Full Papers
  3. Microreviews

    1. Top of page
    2. Cover Picture
    3. News
    4. Microreviews
    5. Communications
    6. Full Papers
    1. Versatile Molecules

      Fifty Years of π-Conjugated Triaz­enes (pages 860–870)

      Siddappa Patil and Alejandro Bugarin

      Article first published online: 3 DEC 2015 | DOI: 10.1002/ejoc.201501218

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      This microreview highlights progress in synthetically manipulating π-conjugated triazenes in order to increase their reactivity and pinpoint potential applications towards different organic transformations and other research areas.

    2. Benzylic Fluorination

      Mono- and Difluorination of Benz­ylic Carbon Atoms (pages 871–886)

      Ana Koperniku, Hongqiang Liu and Paul B. Hurley

      Article first published online: 15 JAN 2016 | DOI: 10.1002/ejoc.201501329

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      A summary of procedures for mono- and difluorination of benzylic carbon atoms is presented. Base-mediated, transition-metal-catalyzed and radical-initiated reactions for the monofluorination of benzylic carbon atoms are described, whereas procedures for their difluorination include base-mediated and radical-initiated reactions.

  4. Communications

    1. Top of page
    2. Cover Picture
    3. News
    4. Microreviews
    5. Communications
    6. Full Papers
    1. Asymmetric Catalysis

      Tuning the Basicity of a Metal-Templated Brønsted Base to Facilitate the Enantioselective Sulfa-Michael Addition of Aliphatic Thiols to α,β-Unsaturated N-Acylpyrazoles (pages 887–890)

      Xiaobing Ding, Cheng Tian, Ying Hu, Lei Gong and Eric Meggers

      Article first published online: 22 JAN 2016 | DOI: 10.1002/ejoc.201501494

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      An effective catalyst for the enantioselective sulfa-Michael addition (SMA) of aliphatic thiols to α,β-unsaturated N-acylpyrazoles is developed by increasing the basicity of the iridium-templated Brønsted base in a straightforward fashion by ligand modification.

    2. N Ligands

      Conjugated, trans-Spanning Ligands as Models for Multivalent p-Phenyleneethynylenes (pages 891–895)

      Herh G. Vang, Zakarias L. Driscoll, Emily R. Robinson, Casey E. Green, Eric Bosch and Nathan P. Bowling

      Article first published online: 19 JAN 2016 | DOI: 10.1002/ejoc.201501528

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      Conjugated ligands: A trans-spanning ligand that binds AgI and PdII has been developed and studied by X-ray crystallography and 1H NMR spectroscopy. UV/Vis spectroscopy was used to investigate what effect metal binding might have on the conjugation in the para-phenyleneethynylene backbone.

    3. Oxidation of Phenols

      Solvent-Dependent Regio- and Stereo­selective Oxidation of [2.2]Para­cyclophane-Derived Phenols (pages 896–901)

      Roman P. Zhuravsky, Dmitrii Yu. Antonov, Elena V. Sergeeva, Ivan A. Godovikov, Zoya A. Starikova, Anna V. Vologzhanina and Natalia V. Atman

      Article first published online: 25 JAN 2016 | DOI: 10.1002/ejoc.201501565

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      Oxidation of 4-hydroxy[2.2]paracyclophane and its derivatives with Cu(OH)Cl·TMEDA in MeOH leads to ortho-cyclohexadienones of (Rp*,Rp*) relative configuration, whereas in CH2Cl2 regio- and stereoselective oxidative coupling occurs to produce variously substituted 7,7′-bis[2.2]paracyclophan-4,4′(7H,7′H)-diones with (Sp*,Rc*,Rc*,Sp*) and (Rp,Sc,Rc,Sp) relative configurations.

    4. Regioselective Sulfation

      Regioselective, Tin-Free Sulfation of Unprotected Hexopyranosides by Using Phenylboronic Acid (pages 902–905)

      Kenji Fukuhara, Naoyuki Shimada, Takashi Nishino, Eisuke Kaji and Kazuishi Makino

      Article first published online: 26 JAN 2016 | DOI: 10.1002/ejoc.201501568

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      Regioselective, tin-free sulfation of a number of unprotected glycopyranosides was achieved by using a 2,2,2-trichloroethyl-protected sulfurylimidazolium salt as the sulfating reagent and phenylboronic acid for masking the hydroxy groups.

    5. Cyclopropanation

      Stereoselective Synthesis of (Sulfonimidoyl)cyclopropanes with (R)-PhSO(NTs)CH2Cl and α,β-Unsaturated Weinreb Amides: Tuning the of Selectivity between C–Cl and C–S Bond Cleavage (pages 906–909)

      Xiao Shen, Qinghe Liu, Wei Zhang and Jinbo Hu

      Article first published online: 26 JAN 2016 | DOI: 10.1002/ejoc.201501611

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      The first (sulfonimidoyl)cyclopropanation of α,β-unsaturated carbonyl compounds with (R)-PhSO(NTs)CH2Cl was achieved to afford optically enriched (sulfonimidoyl)cyclopropanes in good yields with excellent diastereoselectivities. The reaction shows a broad substrate scope. The Weinreb amide group and the counter cation of the base were found to be important for the selective C–Cl bond cleavage of the sulfoximine reagent.

    6. Oxysulfonylation

      Oxysulfonylation of Alkenes with Sulfonyl Hydrazides under Transition-Metal-Free Conditions (pages 910–912)

      Congrong Liu, Lianghui Ding, Guang Guo and Weiwei Liu

      Article first published online: 26 JAN 2016 | DOI: 10.1002/ejoc.201501613

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      An unprecedented method to synthesise β-keto sulfones is demonstrated by trifluoroacetic acid promoted oxysulfonylation of alkenes with sulfonyl hydrazides under transition-metal-free conditions.

    7. Ionic Liquids

      Solvate Ionic Liquids as Reaction Media for Electrocyclic Transformations (pages 913–917)

      Daniel J. Eyckens, Megan E. Champion, Bronwyn L. Fox, Prusothman Yoganantharajah, Yann Gibert, Tom Welton and Luke C. Henderson

      Article first published online: 25 JAN 2016 | DOI: 10.1002/ejoc.201501614

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      Solvate ionic liquids have been explored for their suitability as reaction media for organic transformations. These ILs are able to undergo typical optimisation procedures, are inexpensive, and easy to handle.

    8. Oxidative Umpolung

      You have full text access to this OnlineOpen article
      Synthesis of 1,4-Diketones from β-Oxo Esters and Enol Acetates by ­Cerium-Catalyzed Oxidative Umpo­lung Reaction (pages 918–920)

      Irina Geibel and Jens Christoffers

      Article first published online: 29 JAN 2016 | DOI: 10.1002/ejoc.201600057

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      1,4-Diketones were prepared by cerium-catalyzed, oxidative Umpolung reaction of β-oxo esters with enol acetates. Atmospheric oxygen is the oxidant in this process, which can be regarded as ideal from economic and ecological points of view. The precatalyst is the nontoxic and inexpensive CeCl3·7H2O.

    9. Acyclic Nucleoside Synthesis

      A Chemoenzymatic Route To Prepare Acyclic Nucleoside Analogues (pages 921–924)

      Martín A. Palazzolo, Mariano J. Nigro, Adolfo M. Iribarren and Elizabeth Sandra Lewkowicz

      Article first published online: 29 JAN 2016 | DOI: 10.1002/ejoc.201501412

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      The first aldolase-biocatalyzed synthesis of acyclic nucleoside monophosphates is reported. The products are obtained through a clean, simple and effective procedure comprising the regioselective N-alkylation of nucleobases, as cheap starting materials, and the use of a commercially available biocatalyst such as rabbit muscle aldolase.

    10. Polysubstituted Pyrroles

      I2-Promoted Condensation/Cyclization of Aryl Methyl Ketones with Anilines for Facile Synthesis of 1,2,4-Triarylpyrroles (pages 925–929)

      Hui Xu, Fang-Jian Wang, Ming Xin and Ze Zhang

      Article first published online: 22 JAN 2016 | DOI: 10.1002/ejoc.201501477

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      A novel iodine-mediated cascade condensation/cyclization of aryl methyl ketones with anilines has been successfully developed. According to this straightforward strategy, a variety of 1,2,4-triarylpyrroles were synthesized in moderate to good yields from very simple and readily available starting materials.

  5. Full Papers

    1. Top of page
    2. Cover Picture
    3. News
    4. Microreviews
    5. Communications
    6. Full Papers
    1. Fluorinated Amines

      Convenient Access to Di- and Tri­fluoroethylamines for Lead Structure Research (pages 930–945)

      Amrei Deutsch, Christian Wagner, Carl Deutsch and Anja Hoffmann-Röder

      Article first published online: 3 FEB 2016 | DOI: 10.1002/ejoc.201501576

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      In this manuscript a practical and reliable protocol for the synthesis of new functionalized di- and trifluoroethylamine derivatives is described. Upon addition of Grignard reagents or heteroatom nucleophiles to fluoroalkylated N-aryl-substituted N,O-acetals a broad range of substituted α-difluoro- and α-trifluoroethylamines can be accessed for potential medicinal chemistry applications.

    2. Natural Product Synthesis

      Synthesis and Configurations of (–)-Furospongin-1 and (+)-Dihydrofuro­spongin-2 (pages 946–957)

      Dong-Xing Tan, Ze-Jun Xu, Hui-Jun Chen, Yikang Wu and Jun You

      Article first published online: 15 JAN 2016 | DOI: 10.1002/ejoc.201501489

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      Despite repeated revisions over the years, the C-13 absolute configuration of both furospongin-1 and dihydrospongin-2 remains questionable, as critical comparisons of optical rotations were made using data recorded in very different solvents. These doubts are now cleared using synthetic samples obtained by a chiral-pool-based route. The configuration of furospongin-1 at C-11 is also fully secured.

    3. Asymmetric Synthesis

      A Modular Approach to the Asymmetric Synthesis of Cytisine (pages 958–964)

      Felix R. Struth and Christoph Hirschhäuser

      Article first published online: 15 JAN 2016 | DOI: 10.1002/ejoc.201501435

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      The asymmetric synthesis of (+)- and (–)-cytisine was achieved by modular application of Matteson homologations to construct the critical asymmetric moiety which is incorporated into a versatile late stage precursor (4a). Intermediate 4a was converted into cytisine in five steps.

    4. Drug Discovery

      One-Pot Synthesis of Benzopyran-4-ones with Cancer Preventive and Therapeutic Potential (pages 965–975)

      Oualid Talhi, Lidia Brodziak-Jarosz, Jana Panning, Barbora Orlikova, Clemens Zwergel, Tzvetomira Tzanova, Stéphanie Philippot, Diana C. G. A. Pinto, Filipe A. Almeida Paz, Clarissa Gerhäuser, Tobias P. Dick, Claus Jacob, Marc Diederich, Denyse Bagrel, Gilbert Kirsch and Artur M. S. Silva

      Article first published online: 15 JAN 2016 | DOI: 10.1002/ejoc.201501278

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      Chromanones 3p and 3r and 2-styrylchromones 3k potently activate the Nrf2 response in the AREc32 cell line at low micromolar concentrations (C5 <3 µM). Compounds 3k and 3r are also the most active in inhibiting cell proliferation by 50 % after 72 h incubation at concentrations of 4.5 and 7.7 µM, whereas normal peripheral blood mononuclear cells were not affected.

    5. Fragrances

      Synthesis and Olfactory Properties of Silicon-Containing Analogs of Rosamusk, Romandolide, and Applelide: Insights into the Structural Parameters of Linear Alicyclic Musks (pages 976–982)

      Junhui Liu, Yue Zou, Wu Fan, Jian Mao, Guobi Chai, Peng Li, Zhan Qu, Yongli Zong, Jianxun Zhang and Philip Kraft

      Article first published online: 5 JAN 2016 | DOI: 10.1002/ejoc.201501338

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      Sila-Rosamusk, sila-Romandolide, sila-Applelide, and their dehydro derivatives were synthesized from sila-analogs of Artemone and Herbac by hydride reduction and subsequent esterification. The olfactory properties of these compounds allowed a refined musk olfactophore model to be developed. The model shows that it is likely that linear and macrocyclic musks address the same odorant receptors.

    6. Nucleoside Synthesis

      4-Heterosubstituted Cyclopentenone Antiviral Compounds: Synthesis, Mechanism, and Antiviral Evaluation (pages 983–991)

      Daniele Mantione, Olatz Olaizola Aizpuru, Misal Giuseppe Memeo, Bruna Bovio and Paolo Quadrelli

      Article first published online: 15 JAN 2016 | DOI: 10.1002/ejoc.201501406

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      Racemic 4-oxocyclopent-2-en-1-yl acetate was used in a short synthesis of nucleoside analogues with pyrimidine and purine heterobases.

    7. Pyrazine-Based Porphyrinoids

      Pyrazinoporphyrins: Expanding a Pyrrolic Building Block in meso-Tetraphenylporphyrin by a Nitrogen Atom (pages 992–998)

      Michelle L. Head, Gloria Zarate and Christian Brückner

      Article first published online: 20 JAN 2016 | DOI: 10.1002/ejoc.201501436

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      The stepwise modification of meso-tetraphenylporphyrin to affect the formal replacement of a pyrrolic building block by a pyrazine moiety is described. The optical properties of the resulting pyrazinoporphyrins are porphyrin-like.

    8. Axially Chiral Ligands

      Asymmetric Synthesis of Aromatic and Heteroaromatic α-Amino Acids Using a Recyclable Axially Chiral Ligand (pages 999–1006)

      Jia Li, Shengbin Zhou, Jiang Wang, Aki Kawashima, Hiroki Moriwaki, Vadim A. Soloshonok and Hong Liu

      Article first published online: 20 JAN 2016 | DOI: 10.1002/ejoc.201501442

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      This work introduces a new chiral nucleophilic glycine equivalent containing a recyclable axially chiral ligand. This glycine reagent undergoes alkylation with various benzylic bromides to give aromatic and heteroaromatic α-amino acids of high pharmaceutical potential. The alkylation products were typically isolated in >80 % yield with excellent diastereoselectivity (up to 99:1).

    9. Enantioselective Reduction

      Enantioselective Reduction of Ethyl 3-Oxo-5-phenylpentanoate with Whole-Cell Biocatalysts (pages 1007–1011)

      Anna Zadlo, Joerg H. Schrittwieser, Dominik Koszelewski, Wolfgang Kroutil and Ryszard Ostaszewski

      Article first published online: 12 JAN 2016 | DOI: 10.1002/ejoc.201501460

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      Both enantiomers of ethyl 3-hydroxy-5-phenylpentanoate were obtained with excellent optical purities and in high yields by using a whole-cell biocatalyst system.

    10. Bridging Chiral Calix[4]arenes

      Bridging Chiral Calix[4]arenes: Description, Optical Resolution, and Absolute Configuration Determination (pages 1012–1016)

      Feng-Jing An, Wen-Qiang Xu, Shuang Zheng, Shi-Kun Ma, Shao-Yong Li, Run-Ling Wang and Jun-Min Liu

      Article first published online: 15 JAN 2016 | DOI: 10.1002/ejoc.201501467

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      Bridging chiral calix[4]arenes (–)-4a and (+)-4b are a pair of new chiral calix[4]arene enantiomers that have point chirality on their substituted bridging methylene. Their optical resolution is easily achieved with chiral auxiliary (S)-Binol. The absolute configurations of the enantiomers were determined by X-ray crystallographic analysis.

    11. Modified Neurotensin

      Stereoselective Synthesis of β-(5-Arylthiazolyl) α-Amino Acids and Use in Neurotensin Analogues (pages 1017–1024)

      Denisa Hapău, Emmanuelle Rémond, Roberto Fanelli, Mélanie Vivancos, Adeline René, Jérôme Côté, Élie Besserer-Offroy, Jean-Michel Longpré, Jean Martinez, Valentin Zaharia, Philippe Sarret and Florine Cavelier

      Article first published online: 18 JAN 2016 | DOI: 10.1002/ejoc.201501495

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      New β-arylthiazole alanines were synthesized in good chemical yields and with 98 % ee using a diastereoselective alkylation; these alanine derivatives were then used as Tyr11 replacements in the construction of neurotensin (NT)[8–13] analogues. The new NT analogues showed improved plasma stability and selectivity towards NTS1 thus preserving the hypotensive properties of the native peptide.

    12. Homogeneous Catalysis

      Catalytic Oxidative Coupling of Primary Amines under Air: A Flexible Route to Benzimidazole Derivatives (pages 1025–1032)

      Khac Minh Huy Nguyen and Martine Largeron

      Article first published online: 19 JAN 2016 | DOI: 10.1002/ejoc.201501520

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      Atom-economical! Factors influencing the success of the biomimetic cooperative action of CuBr2 as electron-transfer mediator and a topaquinone-like substrate-selective catalyst in the oxidative cyclocondensation of primary aliphatic amines with o-aminoanilines are disclosed in order to provide a flexible route to benzimidazole derivatives under green conditions.

    13. Molecular Devices

      Synthesis and Characterization of Constitutionally Isomeric Oriented Calix[6]arene-Based Rotaxanes (pages 1033–1042)

      Valeria Zanichelli, Giulio Ragazzon, Arturo Arduini, Alberto Credi, Paola Franchi, Guido Orlandini, Margherita Venturi, Marco Lucarini, Andrea Secchi and Serena Silvi

      Article first published online: 20 JAN 2016 | DOI: 10.1002/ejoc.201501522

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      Oriented rotaxanes based on a calix[6]arene wheel and nonsymmetric bipyridinium axles have been synthesized. The selective formation of orientational isomers was achieved. Spectroelectrochemistry and electron spin resonance measurements were used to investigate the relative direction of motion of the components.

    14. Reductive Sulfidation

      Indium-Catalyzed Reductive Sulfid­ation of Esters by Using Thiols: An Approach to the Diverse Synthesis of Sulfides (pages 1043–1049)

      Takahiro Miyazaki, Shinsei Kasai, Yohei Ogiwara and Norio Sakai

      Article first published online: 15 JAN 2016 | DOI: 10.1002/ejoc.201501559

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      The reductive preparation of unsymmetrical sulfides from esters and thiols by using InI3 and either 1,1,3,3-tetramethyldisiloxane (TMDS) or PhSiH3 was developed. Several mechanistic studies support that the present transformation proceeds through O,S- and S,S-acetals as the reaction intermediates. TMDS = 1,1,3,3-tetramethyldisiloxane, R = aliphatic group.

    15. Ammosamide B

      An Efficient Approach to the Total Synthesis of Ammosamide B (pages 1050–1053)

      Sheng-Wei Yang, Chun-Meng Wang, Kai-Xiang Tang, Jin-Xin Wang and Li-Ping Sun

      Article first published online: 15 JAN 2016 | DOI: 10.1002/ejoc.201501560

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      A new total synthesis of ammosamide B has been realized by using key pyrroloquinoline skeleton precursor 6 (generated in 80 % yield over three steps). The construction of ammosamide B, achieved in 23 % overall yield, required 12 simple steps from a commercially available starting material. Importantly, intermediate 6 serves as an important precursor to other pyrroloquinoline-based natural products.

    16. Peptide Synthesis

      Chemical Synthesis of Monomeric, Dimeric and Tetrameric Forms of the Ectodomain of Influenza Matrix 2 Protein (pages 1054–1059)

      Weiguang Zeng, Kylie J. Horrocks, Amabel C. L. Tan and David C. Jackson

      Article first published online: 21 JAN 2016 | DOI: 10.1002/ejoc.201501569

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      A facile chemical synthesis of the disulfide bond linked tetrameric form of the ectodomain of influenza matrix 2 protein has been established. Acidic conditions were used throughout to minimize randomized thiol-exchange reactions. The synthetic strategies can be adapted for the preparation of other dimeric or tetrameric constructs.

    17. Asymmetric Hydrosilylation

      Diastereoselective Hydrosilylation of N-(tert-Butylsulfinyl)imines Catalyzed by Zinc Acetate (pages 1060–1065)

      Anna Adamkiewicz and Jacek Mlynarski

      Article first published online: 20 JAN 2016 | DOI: 10.1002/ejoc.201501318

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      An efficient zinc-catalyzed diastereoselective hydrosilylation of N-(tert-butylsulfinyl)imines has been developed to provide the corresponding secondary amines in high yields with excellent diastereoselectivities (up to 98 % de).

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