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    2256 results match your criteria Beilstein Journal of Organic Chemistry [Journal]

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    Mechanochemical synthesis of thioureas, ureas and guanidines.
    Beilstein J Org Chem 2017 1;13:1828-1849. Epub 2017 Sep 1.
    Division of Organic Chemistry and Biochemistry, Ruđer Bošković Institute, Bijenička cesta 54, 10000 Zagreb, Croatia.
    In this review, the recent progress in the synthesis of ureas, thioureas and guanidines by solid-state mechanochemical ball milling is highlighted. While the literature is abundant on their preparation in conventional solution environment, it was not until the advent of solvent-free manual grinding using a mortar and pestle and automated ball milling that new synthetic opportunities have opened. The mechanochemical approach not only has enabled the quantitative synthesis of (thio)ureas and guanidines without using bulk solvents and the generation of byproducts, but it has also been established as a means to develop "click-type" chemistry for these classes of compounds and the concept of small molecule desymmetrization. Read More

    Iodoarene-catalyzed cyclizations of N-propargylamides and β-amidoketones: synthesis of 2-oxazolines.
    Beilstein J Org Chem 2017 31;13:1823-1827. Epub 2017 Aug 31.
    Department of Chemistry, University of Huddersfield, Queensgate, Huddersfield HD1 3DH, UK. Tel: +44-1484-473741.
    Two complementary iodoarene-catalyzed methods for the preparation of 2-oxazolines are presented. The first involves the cyclization of N-propargylamides and the second involves the cyclization of β-amidoketones. These are proposed to proceed through different mechanisms and have different substrate scopes. Read More

    NHC-catalyzed cleavage of vicinal diketones and triketones followed by insertion of enones and ynones.
    Beilstein J Org Chem 2017 30;13:1816-1822. Epub 2017 Aug 30.
    Department of Applied Chemistry, Graduate School of Engineering, Hiroshima University, Kagamiyama, Higashi-Hiroshima 739-8527, Japan.
    Thiazolium carbene-catalyzed reactions of 1,2-diketones and 1,2,3-triketones with enones and ynones have been investigated. The diketones gave α,β-double acylation products via unique Breslow intermediates isolable as acid salts, whereas the triketones formed stable adducts with the NHC instead of the coupling products. Read More

    Pd(OAc)2/Ph3P-catalyzed dimerization of isoprene and synthesis of monoterpenic heterocycles.
    Beilstein J Org Chem 2017 29;13:1807-1815. Epub 2017 Aug 29.
    Institute of Organic Chemistry, University of Regensburg, Universitätsstr. 31, 93040 Regensburg, Germany.
    The palladium-catalyzed dimerization of isoprene is a practical approach of synthesizing monoterpenes. Though several highly selective methods have been reported, most of them still required pressure or costly ligands for attaining the active system and desired selectivity. Herein, we present a simple and economical procedure towards the tail-to-tail dimer using readily available Pd(OAc)2 and inexpensive triphenylphosphine as ligand. Read More

    Ni nanoparticles on RGO as reusable heterogeneous catalyst: effect of Ni particle size and intermediate composite structures in C-S cross-coupling reaction.
    Beilstein J Org Chem 2017 28;13:1796-1806. Epub 2017 Aug 28.
    Department of Chemistry, University of North Bengal, Darjeeling 734013, India. ; Tel: +91 353 2776381.
    The present work demonstrates the C-S cross-coupling reaction between aryl halides and thiols using nickel nanoparticles (Ni NPs) supported on reduced graphene oxide (Ni/RGO) as a heterogeneous catalyst. It is observed that the uniformly dispersed Ni NPs supported on RGO could exhibit excellent catalytic activity in C-S cross-coupling reactions and the catalytic application is generalized with diverse coupling partners. Although the electron-rich planar RGO surface helps in stabilizing the agglomeration-free Ni NPs, the catalytic process is found to occur involving Ni(II) species and the recovered catalyst containing both Ni(0)/Ni(II) species is equally efficient in recycle runs. Read More

    Selective enzymatic esterification of lignin model compounds in the ball mill.
    Beilstein J Org Chem 2017 25;13:1788-1795. Epub 2017 Aug 25.
    Institute of Organic Chemistry, RWTH Aachen University, Landoltweg 1, D-52074 Aachen, Germany.
    A lipase-catalyzed esterification of lignin model compounds in the ball mill was developed combining the advantages of enzyme catalysis and mechanochemistry. Under the described conditions, the primary aliphatic hydroxy groups present in the substrates were selectively modified by the biocatalyst to afford monoesterified products. Amongst the tested lipases, CALB proved to be the most effective biocatalyst for these transformations. Read More

    Conformational impact of structural modifications in 2-fluorocyclohexanone.
    Beilstein J Org Chem 2017 24;13:1781-1787. Epub 2017 Aug 24.
    Department of Chemistry, Federal University of Lavras, 37200-000, Lavras, MG, Brazil.
    2-Haloketones are building blocks that combine physical, chemical and biological features of materials and bioactive compounds, while organic fluorine plays a fundamental role in the design of performance organic molecules. Since these features are dependent on the three-dimensional chemical structure of a molecule, simple structural modifications can affect its conformational stability and, consequently, the corresponding physicochemical/biological property of interest. In this work, structural changes in 2-fluorocyclohexanone were theoretically studied with the aim at finding intramolecular interactions that induce the conformational equilibrium towards the axial or equatorial conformer. Read More

    18-Hydroxydolabella-3,7-diene synthase - a diterpene synthase from Chitinophaga pinensis.
    Beilstein J Org Chem 2017 23;13:1770-1780. Epub 2017 Aug 23.
    Swammerdam Institute for Life Sciences, University of Amsterdam, Sciencepark 904, 1098 XH Amsterdam, The Netherlands.
    The product obtained in vitro from a diterpene synthase encoded in the genome of the bacterium Chitinophaga pinensis, an enzyme previously reported to have germacrene A synthase activity during heterologous expression in Escherichia coli, was identified by extensive NMR-spectroscopic methods as 18-hydroxydolabella-3,7-diene. The absolute configuration of this diterpene alcohol and the stereochemical course of the terpene synthase reaction were addressed by isotopic labelling experiments. Heterologous expression of the diterpene synthase in Nicotiana benthamiana resulted in the production of 18-hydroxydolabella-3,7-diene also in planta, while the results from the heterologous expression in E. Read More

    Chiral phase-transfer catalysis in the asymmetric α-heterofunctionalization of prochiral nucleophiles.
    Beilstein J Org Chem 2017 22;13:1753-1769. Epub 2017 Aug 22.
    Institute of Organic Chemistry, Johannes Kepler University Linz, Altenbergerstrasse 69, 4040 Linz, Austria.
    Chiral phase-transfer catalysis is one of the major catalytic principles in asymmetric catalysis. A broad variety of different catalysts and their use for challenging applications have been reported over the last decades. Besides asymmetric C-C bond forming reactions the use of chiral phase-transfer catalysts for enantioselective α-heterofunctionalization reactions of prochiral nucleophiles became one of the most important field of application of this catalytic principle. Read More

    Mechanochemical N-alkylation of imides.
    Beilstein J Org Chem 2017 22;13:1745-1752. Epub 2017 Aug 22.
    Laboratory for Physical-organic Chemistry, Division of Organic Chemistry and Biochemistry, Ruđer Bošković Institute, Bijenička c. 54, 10000 Zagreb, Croatia.
    The mechanochemical N-alkylation of imide derivatives was studied. Reactions under solvent-free conditions in a ball mill gave good yields and could be put in place of the classical solution conditions. The method is general and can be applied to various imides and alkyl halides. Read More

    An efficient Pd-NHC catalyst system in situ generated from Na2PdCl4 and PEG-functionalized imidazolium salts for Mizoroki-Heck reactions in water.
    Beilstein J Org Chem 2017 21;13:1735-1744. Epub 2017 Aug 21.
    College of Chemical Engineering, Zhejiang University of Technology, Hangzhou 310032, China.
    Three PEG-functionalized imidazolium salts L1-L3 were designed and prepared from commercially available materials via a simple method. Their corresponding water soluble Pd-NHC catalysts, in situ generated from the imidazolium salts L1-L3 and Na2PdCl4 in water, showed impressive catalytic activity for aqueous Mizoroki-Heck reactions. The kinetic study revealed that the Pd catalyst derived from the imidazolium salt L1, bearing a pyridine-2-methyl substituent at the N3 atom of the imidazole ring, showed the best catalytic activity. Read More

    Mechanochemical enzymatic resolution of N-benzylated-β(3)-amino esters.
    Beilstein J Org Chem 2017 18;13:1728-1734. Epub 2017 Aug 18.
    Departamento de Química, Centro de Investigación y de Estudios Avanzados, Avenida I.P.N. 2508, Ciudad de México, 07360, Mexico.
    The use of mechanochemistry to carry out enantioselective reactions has been explored in the last ten years with excellent results. Several chiral organocatalysts and even enzymes have proved to be resistant to milling conditions, which allows for rather efficient enantioselective transformations under ball-milling conditions. The present article reports the first example of a liquid-assisted grinding (LAG) mechanochemical enzymatic resolution of racemic β(3)-amino esters employing Candida antarctica lipase B (CALB) to afford highly valuable enantioenriched N-benzylated-β(3)-amino acids in good yields. Read More

    An effective Pd nanocatalyst in aqueous media: stilbene synthesis by Mizoroki-Heck coupling reaction under microwave irradiation.
    Beilstein J Org Chem 2017 18;13:1717-1727. Epub 2017 Aug 18.
    INFIQC-CONICET- Universidad Nacional de Córdoba, Departamento de Química Orgánica, Facultad de Ciencias Químicas, Haya de la Torre y Medina Allende, Ciudad Universitaria, X5000HUA, Córdoba, Argentina.
    Aqueous Mizoroki-Heck coupling reactions under microwave irradiation (MW) were carried out with a colloidal Pd nanocatalyst stabilized with poly(N-vinylpyrrolidone) (PVP). Many stilbenes and novel heterostilbenes were achieved in good to excellent yields starting from aryl bromides and different olefins. The reaction was carried out in a short reaction time and with low catalyst loading, leading to high turnover frequency (TOFs of the order of 100 h(-1)). Read More

    Theoretical simulation of the infrared signature of mechanically stressed polymer solids.
    Beilstein J Org Chem 2017 17;13:1710-1716. Epub 2017 Aug 17.
    Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria.
    Mechanical stress leads to deformation of strands in polymer solids, including elongation of covalent bonds and widening of bond angles, which changes the infrared spectrum. Here, the infrared spectrum of solid polymer samples exposed to mechanical stress is simulated by density functional theory calculations. Mechanical stress is described with the external force explicitly included (EFEI) method. Read More

    A recursive microfluidic platform to explore the emergence of chemical evolution.
    Beilstein J Org Chem 2017 17;13:1702-1709. Epub 2017 Aug 17.
    WestCHEM, School of Chemistry, University of Glasgow, University Avenue, Glasgow G12 8QQ, UK.
    We propose that a chemically agnostic approach to explore the origin of life, using an automated recursive platform based on droplet microfluidics, could be used to induce artificial chemical evolution by iterations of growth, speciation, selection, and propagation. To explore this, we set about designing an open source prototype of a fully automated evolution machine, comprising seven modules. These modules are a droplet generator, droplet transfer, passive and active size sorting, splitter, incubation chamber, reservoir, and injectors, all run together via a LabVIEW(TM) program integration system. Read More

    Block copolymers from ionic liquids for the preparation of thin carbonaceous shells.
    Beilstein J Org Chem 2017 16;13:1693-1701. Epub 2017 Aug 16.
    Institute for Organic Chemistry, University of Mainz, Duesbergweg 10-14, 55128 Mainz, Germany.
    This paper describes the controlled radical polymerization of an ionic-liquid monomer by RAFT polymerization. This allows the control over the molecular weight of ionic liquid blocks in the range of 8000 and 22000 and of the block-copolymer synthesis. In this work we focus on block copolymers with an anchor block. Read More

    Oxidative dehydrogenation of C-C and C-N bonds: A convenient approach to access diverse (dihydro)heteroaromatic compounds.
    Beilstein J Org Chem 2017 15;13:1670-1692. Epub 2017 Aug 15.
    Department of Chemistry, School of Natural Sciences, Shiv Nadar University, Dadri, Chithera, GautamBuddha Nagar, Uttar Pradesh 201314, India.
    Nitrogen heteroarenes form an important class of compounds which can be found in natural products, synthetic drugs, building blocks etc. Among the diverse strategies that were developed for the synthesis of nitrogen heterocycles, oxidative dehydrogenation is extremely effective. This review discusses various oxidative dehydrogenation strategies of C-C and C-N bonds to generate nitrogen heteroarenes from their corresponding heterocyclic substrates. Read More

    Encaging palladium(0) in layered double hydroxide: A sustainable catalyst for solvent-free and ligand-free Heck reaction in a ball mill.
    Beilstein J Org Chem 2017 14;13:1661-1668. Epub 2017 Aug 14.
    National Engineering Research Center for Process Development of Active Pharmaceutical Ingredients, Collaborative Innovation Center of Yangtze River Delta Region Green Pharmaceuticals, Zhejiang University of Technology, Hangzhou, 310014, Zhejiang, China.
    In this paper, the synthesis of a cheap, reusable and ligand-free Pd catalyst supported on MgAl layered double hydroxides (Pd/MgAl-LDHs) by co-precipitation and reduction methods is described. The catalyst was used in Heck reactions under high-speed ball milling (HSBM) conditions at room temperature. The effects of milling-ball size, milling-ball filling degree, reaction time, rotation speed and grinding auxiliary category, which would influence the yields of mechanochemical Heck reactions, were investigated in detail. Read More

    The chemistry and biology of mycolactones.
    Beilstein J Org Chem 2017 11;13:1596-1660. Epub 2017 Aug 11.
    Department of Chemistry and Applied Biosciences, Institute of Pharmaceutical Sciences, ETH Zürich, Vladimir-Prelog-Weg 4, 8093 Zürich, Switzerland.
    Mycolactones are a group of macrolides excreted by the human pathogen Mycobacterium ulcerans, which exhibit cytotoxic, immunosuppressive and analgesic properties. As the virulence factor of M. ulcerans, mycolactones are central to the pathogenesis of the neglected disease Buruli ulcer, a chronic and debilitating medical condition characterized by necrotic skin ulcers. Read More

    New electroactive asymmetrical chalcones and therefrom derived 2-amino- / 2-(1H-pyrrol-1-yl)pyrimidines, containing an N-[ω-(4-methoxyphenoxy)alkyl]carbazole fragment: synthesis, optical and electrochemical properties.
    Beilstein J Org Chem 2017 10;13:1583-1595. Epub 2017 Aug 10.
    Laboratory of Active Reagents Synthesis, Institute of Technical Chemistry, Russian Academy of Sciences, Ural Division, Academician Korolev street, 3, 614990, Perm, Russia.
    In this paper we present a synthetic approach to six new D-π-A-D conjugated chromophores containing the N-[ω-(4-methoxyphenoxy)alkyl]carbazole fragment. Such readily functionalizable heterocycle as carbazole was used as a main starting compound for their preparation. The investigation of the optical properties has shown that the positive solvatochromism is inherent to the chromophores containing an electron-withdrawing prop-2-en-1-one fragment, while the compounds containing a 2-aminopyrimidine moiety exhibit both positive and negative solvatochromism. Read More

    Molecular recognition of N-acetyltryptophan enantiomers by β-cyclodextrin.
    Beilstein J Org Chem 2017 9;13:1572-1582. Epub 2017 Aug 9.
    Institute of Nanoscience & Nanotechnology, National Center for Scientific Research "Demokritos", Patriarchou Gregoriou E' & Neapoleos 27, 15310 Aghia Paraskevi Attikis, Greece.
    The enantioselectivity of β-cyclodextrin (β-CD) towards L- and D-N-acetyltryptophan (NAcTrp) has been studied in aqueous solution and the crystalline state. NMR studies in solution show that β-CD forms complexes of very similar but not identical geometry with both L- and D-NAcTrp and exhibits stronger binding with L-NAcTrp. In the crystalline state, only β-CD-L-NAcTrp crystallizes readily from aqueous solutions as a dimeric complex (two hosts enclosing two guest molecules). Read More

    A novel approach to oxoisoaporphine alkaloids via regioselective metalation of alkoxy isoquinolines.
    Beilstein J Org Chem 2017 8;13:1564-1571. Epub 2017 Aug 8.
    Department für Pharmazie - Zentrum für Pharmaforschung, Ludwig-Maximilians Universität München, Butenandtstr. 5-13, D-81377 Munich, Germany.
    Oxoisoaporphine alkaloids are conveniently prepared via direct ring metalation of alkoxy-substituted isoquinolines at C-1, followed by reaction with iodine. Subsequent Suzuki cross-coupling of the resulting 1-iodoisoquinolines to methyl 2-(isoquinolin-1-yl)benzoates and intramolecular acylation of the corresponding carboxylic acids with Eaton's reagent afforded five alkaloids of the oxoisoaporphine type. The yield of the cyclization step strongly depends on the electrophilic properties of ring B. Read More

    Chemical systems, chemical contiguity and the emergence of life.
    Beilstein J Org Chem 2017 7;13:1551-1563. Epub 2017 Aug 7.
    Institute of Physics, Chemistry and Pharmacy, University of Southern Denmark, Campusvej 55, 5230 Odense M, Denmark.
    Charting the emergence of living cells from inanimate matter remains an intensely challenging scientific problem. The complexity of the biochemical machinery of cells with its exquisite intricacies hints at cells being the product of a long evolutionary process. Research on the emergence of life has long been focusing on specific, well-defined problems related to one aspect of cellular make-up, such as the formation of membranes or the build-up of information/catalytic apparatus. Read More

    Synthesis and metal binding properties of N-alkylcarboxyspiropyrans.
    Beilstein J Org Chem 2017 4;13:1542-1550. Epub 2017 Aug 4.
    Biosciences, University of Exeter, Stocker Road, Exeter EX4 4QD, UK.
    Spiropyrans bearing an N-alkylcarboxylate tether are a common structure in dynamic, photoactive materials and serve as colourimetric/fluorimetric cation receptors. In this study, we describe an efficient synthesis of spiropyrans with 2-12 carbon atom alkylcarboxylate substituents, and a systematic analysis of their interactions with metal cations using (1)H NMR and UV-visible spectroscopy. All N-alkylcarboxyspiropyrans in this study displayed a strong preference for binding divalent metal cations and a modest increase in M(2+) binding affinity correlated with increased alkycarboxylate tether length. Read More

    Effect of uridine protecting groups on the diastereoselectivity of uridine-derived aldehyde 5'-alkynylation.
    Beilstein J Org Chem 2017 4;13:1533-1541. Epub 2017 Aug 4.
    Laboratoire de Chimie et Biochimie Pharmacologiques et Toxicologiques, UMR 8601 CNRS, Université Paris Descartes, Sorbonne Paris Cité (USPC), Centre Interdisciplinaire Chimie Biologie-Paris (CICB-Paris), 45 rue des Saints Pères, 75270 Paris 06, France.
    The 5'-alkynylation of uridine-derived aldehydes is described. The addition of alkynyl Grignard reagents on the carbonyl group is significantly influenced by the 2',3'-di-O-protecting groups (R(1)): O-alkyl groups led to modest diastereoselectivities (65:35) in favor of the 5'R-isomer, whereas O-silyl groups promoted higher diastereoselectivities (up to 99:1) in favor of the 5'S-isomer. A study related to this protecting group effect on the diastereoselectivity is reported. Read More

    Direct catalytic arylation of heteroarenes with meso-bromophenyl-substituted porphyrins.
    Beilstein J Org Chem 2017 3;13:1524-1532. Epub 2017 Aug 3.
    Department of Chemistry, Lomonosov Moscow State University, Leninskie Gory 1-3, Moscow, 119991, Russia.
    The arylation of mono-, di- and tetra-meso-bromophenyl-substituted porphyrins with the heteroarenes containing "acidic" C-H bonds, such as benzoxazole, benzothiazole and N-methylimidazole was studied in the presence of three alternative catalytic systems: Pd(dba)2/DavePhos/Cs2CO3, Pd(PPh3)4/PivOH/K2CO3 and Pd(OAc)2/Cu(OAc)2/PPh3/K2CO3. The first catalytic system was found to be successful in the reaction with benzoxazole, the second one was less efficient for our purpose, while the third system proved to be most versatile and afforded corresponding mono-, di-, tri- and even tetraarylated derivatives of porphyrins. Read More

    Bifunctional organocatalysts for the asymmetric synthesis of axially chiral benzamides.
    Beilstein J Org Chem 2017 2;13:1518-1523. Epub 2017 Aug 2.
    Department of Material Chemistry, Graduate School of Engineering, Kyoto University, Kyotodaigaku-Katsura, Nishikyo, Kyoto 615-8510, Japan.
    Bifunctional organocatalysts bearing amino and urea functional groups in a chiral molecular skeleton were applied to the enantioselective synthesis of axially chiral benzamides via aromatic electrophilic bromination. The results demonstrate the versatility of bifunctional organocatalysts for the enantioselective construction of axially chiral compounds. Moderate to good enantioselectivities were afforded with a range of benzamide substrates. Read More

    Phenylsilane as an effective desulfinylation reagent.
    Beilstein J Org Chem 2017 1;13:1513-1517. Epub 2017 Aug 1.
    Centre of Molecular and Macromolecular Studies, Polish Academy of Sciences, Department of Heteroorganic Chemistry, Sienkiewicza 112, 90-363 Łódź, Poland.
    The reduction using phenylsilane in a KOH-catalyzed system was applied successfully to the conversion of sulfinyl-substituted cyclopropylcarboxylates into the corresponding alcohols. The presence of sulfinyl substituents in the α-position to the carboxylate group caused a desulfinylation product formation with full regio- and stereoselectivity, instead of a carbonyl group reduction. Investigations performed on different α-sulfinylcarbonyl compounds revealed that phenylsilane treatment constitutes a regiospecific method for the desulfinylation of a-sulfinylesters; for corresponding ketones the reaction course depends on the character of the carbonyl group. Read More

    Base-promoted isomerization of CF3-containing allylic alcohols to the corresponding saturated ketones under metal-free conditions.
    Beilstein J Org Chem 2017 1;13:1507-1512. Epub 2017 Aug 1.
    Division of Applied Chemistry, Institute of Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Nakamachi, Koganei 184-8588, Japan.
    Following to the computational expectation, our previously reported intriguing 1,3-proton shift of 4,4,4-trifluorobut-2-yn-1-ols was successfully extended to the 4,4,4-trifluorobut-2-en-1-ol system under metal-free conditions to afford the corresponding saturated ketones in high to excellent chemical yields using such a convenient and easy-to-handle base as DBU at the toluene refluxing temperature, and utilization of the corresponding optically active substrates unambiguously demonstrated that this transformation proceeded in a highly stereoselective fashion. Read More

    2-Methyl-2,4-pentanediol (MPD) boosts as detergent-substitute the performance of ß-barrel hybrid catalyst for phenylacetylene polymerization.
    Beilstein J Org Chem 2017 31;13:1498-1506. Epub 2017 Jul 31.
    Institute of Biotechnology, RWTH Aachen University, Worringer Weg 3, 52074 Aachen, Germany.
    Covering hydrophobic regions with stabilization agents to solubilize purified transmembrane proteins is crucial for their application in aqueous media. The small molecule 2-methyl-2,4-pentanediol (MPD) was used to stabilize the transmembrane protein Ferric hydroxamate uptake protein component A (FhuA) utilized as host for the construction of a rhodium-based biohybrid catalyst. Unlike commonly used detergents such as sodium dodecyl sulfate or polyethylene polyethyleneglycol, MPD does not form micelles in solution. Read More

    Grip on complexity in chemical reaction networks.
    Beilstein J Org Chem 2017 28;13:1486-1497. Epub 2017 Jul 28.
    Institute for Molecular Materials, Radboud University Nijmegen, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands.
    A new discipline of "systems chemistry" is emerging, which aims to capture the complexity observed in natural systems within a synthetic chemical framework. Living systems rely on complex networks of chemical reactions to control the concentration of molecules in space and time. Despite the enormous complexity in biological networks, it is possible to identify network motifs that lead to functional outputs such as bistability or oscillations. Read More

    Development of a method for the synthesis of 2,4,5-trisubstituted oxazoles composed of carboxylic acid, amino acid, and boronic acid.
    Beilstein J Org Chem 2017 27;13:1478-1485. Epub 2017 Jul 27.
    Faculty of Pharmaceutical Sciences, Institute of Medical, Pharmaceutical, and Health Sciences, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan.
    A novel method for the synthesis of trisubstituted oxazoles via a one-pot oxazole synthesis/Suzuki-Miyaura coupling sequence has been developed. One-pot formation of 5-(triazinyloxy)oxazoles using carboxylic acids, amino acids and a dehydrative condensing reagent, DMT-MM, followed by Ni-catalyzed Suzuki-Miyaura coupling with boronic acids provided the corresponding 2,4,5-trisubstituted oxazoles in good yields. Read More

    Syntheses of 3,4- and 1,4-dihydroquinazolines from 2-aminobenzylamine.
    Beilstein J Org Chem 2017 27;13:1470-1477. Epub 2017 Jul 27.
    Universidad de Buenos Aires. CONICET. Departamento de Química Orgánica. Facultad de Farmacia y Bioquímica. Junín 956, (1113) Buenos Aires, Argentina.
    A straightforward strategy for the synthesis of dihydroquinazolines is presented, which allows for the preparation of 3,4- and 1,4-dihydroquinazolines with different substitution patterns from 2-aminobenzylamine (2-ABA) as common precursor. The required functionalization of both amino groups present in 2-ABA was achieved by different routes involving selective N-acylation and cesium carbonate-mediated N-alkylation reactions, avoiding protection/deprotection steps. The heterocycles were efficiently synthesized in short reaction times by microwave-assisted ring closure of the corresponding aminoamides promoted by ethyl polyphosphate (PPE). Read More

    Mechanochemical borylation of aryldiazonium salts; merging light and ball milling.
    Beilstein J Org Chem 2017 26;13:1463-1469. Epub 2017 Jul 26.
    Institute of Organic Chemistry, RWTH Aachen University, Landoltweg 1, D-52074 Aachen, Germany.
    Merging of photo- and mechanochemical activation permitted studying the role of eosin Y in the borylation of aryldiazonium salts in a ball mill. Simultaneous neat grinding/irradiation of the reactants and the photocatalyst led to the formation of boronates in a molten state. On the other hand, the catalyst-free liquid-assisted grinding/irradiation reaction also led to product formation, featuring a direct photolysis pathway facilitated by substrate-solvent charge-transfer complex formation. Read More

    Photocatalyzed synthesis of isochromanones and isobenzofuranones under batch and flow conditions.
    Beilstein J Org Chem 2017 25;13:1456-1462. Epub 2017 Jul 25.
    Università degli Studi di Genova, Dipartimento di Chimica e Chimica Industriale, Via Dodecaneso 31, Genova, Italy.
    Photocatalyzed reactions of 2-(alkoxycarbonyl)benzenediazonium tetrafluoroborates with various alkenes afforded isochromanones in good yields, according to a mechanism that was investigated. The advantage of using highly soluble esters rather than carboxylic acids as starting compounds became evident when the reactions were performed under flow conditions. On the other hand, when 2-vinylbenzoic acid derivatives were employed as reagents, isobenzofuranones were obtained together with unprecedented benzo[e][1,3]oxazepin-1(5H)-ones, with the latter derived from incorporation of the solvent (acetonitrile). Read More

    1-Imidoalkylphosphonium salts with modulated Cα-P(+) bond strength: synthesis and application as new active α-imidoalkylating agents.
    Beilstein J Org Chem 2017 24;13:1446-1455. Epub 2017 Jul 24.
    Department of Chemical Organic Technology and Petrochemistry, Silesian University of Technology, B. Krzywoustego 4, 44-100 Gliwice, Poland.
    An effective synthesis of the hitherto unknown 1-imidoalkylphosphonium salts has been developed in the reported study. The crucial step in the method included the decarboxylative α-methoxylation of N-phthaloyl- or N-succinylamino acids to the corresponding N-(1-methoxyalkyl)imides, followed by the displacement of the methoxy group by the triarylphosphonium group through melting of the imide derivative with triarylphosphonium tetrafluoroborate. The imidoalkylating properties of the obtained 1-imidoalkylphosphonium salts were tested using the Tscherniac-Einhorn-type reaction with aromatic hydrocarbons as a model reaction. Read More

    Mechanochemical synthesis of graphene oxide-supported transition metal catalysts for the oxidation of isoeugenol to vanillin.
    Beilstein J Org Chem 2017 21;13:1439-1445. Epub 2017 Jul 21.
    Departamento de Química Orgánica, Universidad de Cordoba Campus de Rabanales, Edificio Marie Curie (C-3), Ctra Nnal IV-A, Km 396, E14014, Cordoba, Spain.
    Vanillin is one of the most commonly used natural products, which can also be produced from lignin-derived feedstocks. The chemical synthesis of vanillin is well-established in large-scale production from petrochemical-based starting materials. To overcome this problem, lignin-derived monomers (such as eugenol, isoeugenol, ferulic acid etc. Read More

    A new member of the fusaricidin family - structure elucidation and synthesis of fusaricidin E.
    Beilstein J Org Chem 2017 20;13:1430-1438. Epub 2017 Jul 20.
    Institute of Organic Chemistry, Johannes Gutenberg-University, Duesbergweg 10-14, 55128 Mainz, Germany.
    Two hitherto unknown fusaricidins were obtained from fermentation broths of three Paenibacillus strains. After structure elucidation based on tandem mass spectrometry and NMR spectroscopy, fusaricidin E was synthesized to confirm the structure and the suggested stereochemistry. The synthesis was based on a new strategy which includes an efficient access to the 15-guanidino-3-hydroxypentadecanoyl (GHPD) side chain from erucamide. Read More

    Sustainable synthesis of 3-substituted phthalides via a catalytic one-pot cascade strategy from 2-formylbenzoic acid with β-keto acids in glycerol.
    Beilstein J Org Chem 2017 19;13:1425-1429. Epub 2017 Jul 19.
    College of Chemistry and Chemical Engineering, Qiqihar University, Qiqihar 161006, China.
    Background: Phthalides are privileged constituents of numerous pharmaceuticals, natural products and agrochemicals and exhibit several biological and therapeutic activities. Therefore, the development of new, facile, and sustainable strategies for the construction of these moieties is highly desired. Results: A broad substrate scope for β-keto acids was found to be strongly compatible with this catalytic process, affording a wide variety of 3-substituted phthalides in good to excellent yields. Read More

    A speedy route to sterically encumbered, benzene-fused derivatives of privileged, naturally occurring hexahydropyrrolo[1,2-b]isoquinoline.
    Beilstein J Org Chem 2017 18;13:1413-1424. Epub 2017 Jul 18.
    Institute of Chemistry, Saint Petersburg State University, 26 Universitetsky prospekt, Peterhof 198504, Russia.
    A series of 15 benzene-fused hexahydropyrrolo[1,2-b]isoquinolonic acids with substantial degree of steric encumbrance has been prepared via a novel variant of the Castagnoli-Cushman reaction of homophthalic anhydride (HPA) and various indolenines. The employment of a special kind of a cyclic imine component reaction allowed, for the first time, isolating a Mannich-type adduct between HPA and an imine component which has been postulated but never obtained in similar reactions. Read More

    Synthesis of the heterocyclic core of the D-series GE2270.
    Beilstein J Org Chem 2017 17;13:1407-1412. Epub 2017 Jul 17.
    Normandie Univ, INSA Rouen, UNIROUEN, CNRS, COBRA (UMR6014), 76000 Rouen (France), Rue Tesnière, 76821 Mont-Saint-Aignan Cedex, France.
    A straightforward enantiomerically pure synthesis of the heterocyclic core of the D-series GE2270 is reported. The synthetic strategy combines the Hantzsch thiazole's building condensation with a cross-coupling reaction including direct C-H hetarylation to build and connect step-by-step thiazolyl moieties to the 5-bromopicolinate as readily available starting material. Read More

    Nitration of 5,11-dihydroindolo[3,2-b]carbazoles and synthetic applications of their nitro-substituted derivatives.
    Beilstein J Org Chem 2017 14;13:1396-1406. Epub 2017 Jul 14.
    Postovsky Institute of Organic Synthesis, Ural Division of the Russian Academy of Sciences, Ekaterinburg, 620990, Russia.
    A new general approach to double nitration of 6,12-di(hetero)aryl-substituted and 6,12-unsubstituted 5,11-dialkyl-5,11-dihydroindolo[3,2-b]carbazoles by acetyl nitrate has been developed to obtain their 2,8-dinitro and 6,12-dinitro derivatives, respectively. A formation of mono-nitro derivatives (at C-2 or C-6) from the same indolo[3,2-b]carbazoles has also been observed in several cases. Reduction of 2-nitro and 2,8-dinitro derivatives with zinc powder and hydrochloric acid has afforded 2-amino- and 2,8-diamino-substituted indolo[3,2-b]carbazoles, while reduction of 6,12-dinitro derivatives under similar reaction conditions has been accompanied by denitrohydrogenation of the latter compounds into 6,12-unsubstituted indolo[3,2-b]carbazoles. Read More

    Framing major prebiotic transitions as stages of protocell development: three challenges for origins-of-life research.
    Beilstein J Org Chem 2017 13;13:1388-1395. Epub 2017 Jul 13.
    Dept. Logic and Philosophy of Science, University of the Basque Country, Spain.
    Conceiving the process of biogenesis as the evolutionary development of highly dynamic and integrated protocell populations provides the most appropriate framework to address the difficult problem of how prebiotic chemistry bridged the gap to full-fledged living organisms on the early Earth. In this contribution we briefly discuss the implications of taking dynamic, functionally integrated protocell systems (rather than complex reaction networks in bulk solution, sets of artificially evolvable replicating molecules, or even these same replicating molecules encapsulated in passive compartments) as the proper units of prebiotic evolution. We highlight, in particular, how the organisational features of those chemically active and reactive protocells, at different stages of the process, would strongly influence their corresponding evolutionary capacities. Read More

    Synthesis of oligonucleotides on a soluble support.
    Beilstein J Org Chem 2017 12;13:1368-1387. Epub 2017 Jul 12.
    Department of Chemistry, University of Turku, FIN-20014 Turku, Finland.
    Oligonucleotides are usually prepared in lab scale on a solid support with the aid of a fully automated synthesizer. Scaling up of the equipment has allowed industrial synthesis up to kilogram scale. In spite of this, solution-phase synthesis has received continuous interest, on one hand as a technique that could enable synthesis of even larger amounts and, on the other hand, as a gram scale laboratory synthesis without any special equipment. Read More

    An improved preparation of phorbol from croton oil.
    Beilstein J Org Chem 2017 11;13:1361-1367. Epub 2017 Jul 11.
    Dipartimento di Scienze del Farmaco, Università degli Studi del Piemonte Orientale, Largo Donegani 2, 28100 Novara, Italy.
    Background: Croton oil is the only commercial source of the diterpenoid phorbol (1a), the starting material for the semi-synthesis of various diesters extensively used in biomedical research to investigate cell function and to evaluate in vivo anti-inflammatory activity. While efficient chemoselective esterification protocols have been developed for phorbol, its isolation from croton oil is technically complicated, and involves extensive manipulation of very toxic materials like the oil or its native diterpenoid fraction. Results: The preparation of a crude non-irritant phorboid mixture from croton oil was telescoped to only five operational steps, and phorbol could then be purified by gravity column chromatography and crystallization. Read More

    Switchable highly regioselective synthesis of 3,4-dihydroquinoxalin-2(1H)ones from o-phenylenediamines and aroylpyruvates.
    Beilstein J Org Chem 2017 10;13:1350-1360. Epub 2017 Jul 10.
    Department of Organic Chemistry, Faculty of Natural Sciences, Comenius University in Bratislava, Mlynská dolina, Ilkovičova 6, 842 15 Bratislava, Slovakia.
    3-Acylmethylidene-3,4-dihydroquinoxalin-2(1H)-ones are compounds which possess a wide range of physical and pharmaceutical applications. These compounds can be easily prepared by cyclocondensation of o-phenylenediamines and aroylpyruvates. Unsymmetrically substituted o-phenylenediamines can be obtained form regioisomeric mixtures of 3,4-dihydroquinoxalin-2(1H)-ones. Read More

    Construction of highly enantioenriched spirocyclopentaneoxindoles containing four consecutive stereocenters via thiourea-catalyzed asymmetric Michael-Henry cascade reactions.
    Beilstein J Org Chem 2017 7;13:1342-1349. Epub 2017 Jul 7.
    CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555, Zu Chong Zhi Road, Shanghai 201203, China.
    The thiourea-catalyzed asymmetric synthesis of highly enantioenriched spirocyclopentaneoxindoles containing chiral amide functional groups using simple 3-substituted oxindoles and nitrovinylacetamide as starting materials was achieved successfully. This protocol features operational simplicity, high atom economy, and high catalytic asymmetry, thus representing a versatile approach to the synthesis of highly enantioenriched spirocyclopentaneoxindoles. Read More

    Mechanochemistry-assisted synthesis of hierarchical porous carbons applied as supercapacitors.
    Beilstein J Org Chem 2017 6;13:1332-1341. Epub 2017 Jul 6.
    Institute of Inorganic Chemistry, Technische Universität Dresden, Dresden, Germany.
    A solvent-free synthesis of hierarchical porous carbons is conducted by a facile and fast mechanochemical reaction in a ball mill. By means of a mechanochemical ball-milling approach, we obtained titanium(IV) citrate-based polymers, which have been processed via high temperature chlorine treatment to hierarchical porous carbons with a high specific surface area of up to 1814 m(2) g(-1) and well-defined pore structures. The carbons are applied as electrode materials in electric double-layer capacitors showing high specific capacitances with 98 F g(-1) in organic and 138 F g(-1) in an ionic liquid electrolyte as well as good rate capabilities, maintaining 87% of the initial capacitance with 1 M TEA-BF4 in acetonitrile (ACN) and 81% at 10 A g(-1) in EMIM-BF4. Read More

    Detection of therapeutic radiation in three-dimensions.
    Beilstein J Org Chem 2017 5;13:1325-1331. Epub 2017 Jul 5.
    Department of Chemistry, Biochemistry and Physics, Rider University, 2083 Lawrenceville Road, Lawrenceville, NJ 08648-3099, USA.
    For over the last twenty years there has been a multitude of sophisticated three-dimensional radiation delivery procedures developed which requires a corresponding verification of the impact on patients. This article reviews the state of the art in the development of chemical detectors used to characterize the three-dimensional shape of therapeutic radiation. These detectors are composed of polyurethane, radical initiator and a leuco dye, which is radiolytically oxidized to a dye absorbing at 630 nm. Read More

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