2,497 research outputs found

    Regioselective synthesis of elusive 4,9-Dihydro-1H-Carbazoles by gold-catalyzed cycloisomerization of 3-Allenylmethylindoles

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    A general and efficient synthesis of 4,9-dihydro- 1H-carbazoles from 3-allenylmethylindoles is reported. The process, catalyzed by a cationic gold(I) complex, involves a formal C2−H bond activation of the indole unit by reaction with the allene. The nature of the substituents at the allylic and terminal positions of the allene moiety has a crucial effect on the regioselectivity of the cyclization, which is also influenced by the catalyst and the solvent employed. Moreover, some evidence of the contribution of different reaction routes is provided, which led us to propose a plausible multipathway mechanism consistent with all of the results described.MICINN and FEDER (CTQ2010-15358 and CTQ2009-09949/BQU) for financial support. E.A. thanks MEC for an FPU predoctoral fellowship. P.G.-G. and M.A.F.-R. thank MICINN for "Juan de la Cierva" and "Ramon y Cajal" contractsThis document is the Accepted Manuscript version of a Published Work that appeared in final form in Journal of organic chemistry, copyright © American Chemical Society after peer review and technical editing by the publisher

    Solvent- and ligand-induced switch of selectivity in gold(I)-catalyzed tandem reactions of 3-propargylindoles

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    The selectivity of our previously described gold-catalyzed tandem reaction, 1,2-indole migration followed by aura-iso-Nazarov cyclization, of 3-propargylindoles bearing (hetero)aromatic substituents at both the propargylic and terminal positions, was reversed by the proper choice of the catalyst and the reaction conditions. Thus, 3-(inden-2-yl)indoles, derived from an aura-Nazarov cyclization (instead of an aura-iso-Nazarov cyclization), were obtained in moderate to good yields from a variety of 3-propargylindolesMICINN (CTQ2010-15358 and CTQ2009-09949), Junta de Castilla y Leon (BU021A09 and GR-172), MEC (FPU predoctoral fellowship to D.M.), Ramón y Cajal (contract to M.A F R.), Juan de la Cierva (contract to P.G.G.

    Retailing farmed fish In southern Europe: supermarkets lead other seafood retailers.

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    Seafood retail channels in Southern Europe include four main classes: traditional fish markets and fishmongers, supermarkets and hypermarkets. Location, primary products and typical level of interaction with customers vary among the formats. In a survey in Spain, price was much more important for customers of supermarkets and hypermarkets than for those of the traditional channels, who rated quality more important. The empathy and reliability of vendors were scored higher for the traditional stores

    Synthesis of Fused Polycyclic Indoles by Brønsted Acid-Catalyzed Intramolecular Alkylation of Indoles with Alcohols

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    An efficient methodology for the synthesis of a series of new fused polyclyclic indoles has been developed by Brønsted acidcatalyzed intramolecular Friedel−Crafts reactions of properly designed indolyl alcohols.Ministerio de Economiá y Competitividad (MINECO) and FEDER (CTQ2013-48937- C2-1-P) and Junta de Castilla y León (BU237U13

    Brønsted Acid-Catalyzed Cascade Reactions Involving 1,2-Indole Migration

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    A cascade reaction of indoles with propargylic diols involving an unprecedented metal-free 1,2-indole migration onto an alkyne is here described. DFT calculations support a mechanism consisting in a concerted nucleophilic attack of the indole nucleus with loss of water followed by the 1,2-migration and subsequent Nazarov cyclization. This Brønsted acid-catalyzed protocol affords indole-functionalized benzofulvene derivatives in high yields.Junta de Castilla y León(BU237U13) and Ministerio de Economía y Competitividad (MINECO) and FEDER (CTQ2013-48937-C2-1P and 2-P

    Halocyclization of o-(Alkynyl)styrenes. Synthesis of 3-Halo-1H-indenes

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    Junta de Castilla y Leon (BU021A09 and GR-172), Ministerio de Educacion y Ciencia (MEC), FEDER (CTQ2007-61436/BQU and CTQ2009-09949/BQU), MEC (FPU grant), Juan de la Cierva, Ramon y Cajal and "Young Foreign Researchers" (SB2009-0186) contract

    Numerical analysis of anisotropic stiffness and strength for geomaterials

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    In numerical modelling, selection of the constitutive model is a critical factor in predicting the actual response of a geomaterial. The use of oversimplified or inadequate models may not be sufficient to reproduce the actual geomaterial behaviour. That selection is especially relevant in the case of anisotropic rocks, and particularly for shales and slates, whose behaviour may be affected, e.g. well stability in geothermal or oil and gas production operations. In this paper, an alternative anisotropic constitutive model has been implemented in the finite element method software CODE_BRIGHT, which is able to account for the anisotropy of shales and slates in terms of both deformability and strength. For this purpose, a transversely isotropic version of the generalised Hooke's law is adopted to represent the stiffness anisotropy, while a nonuniform scaling of the stress tensor is introduced in the plastic model to represent the strength anisotropy. Furthermore, a detailed approach has been proposed to determine the model parameters based on the stress–strain results of laboratory tests. Moreover, numerical analyses are performed to model uniaxial and triaxial tests on Vaca Muerta shale, Bossier shale and slate from the northwest of Spain (NW Spain slate). The experimental data have been recovered from the literature in the case of the shale and, in the case of the slate, performed by the authors in terms of stress-strain curves and strengths. A good agreement can be generally observed between numerical and experimental results, hence showing the potential applicability of the approach to actual case studies. Therefore, the presented constitutive model may be a promising approach for analysing the anisotropic behaviour of rocks and its impact on well stability or other relevant geomechanical problems in anisotropic rocks.The experimental part of the slate in this work was funded by REPSOL S.A. The numerical part of this work was supported by the CODE_BRIGHT Project (International Centre for Numerical Methods in Engineering). The work of the second and fourth authors was possible thanks to the Spanish Ministry of Science and Innovation, who funded the project, awarded under Contract Reference No. RTI 2018-093563-B-I00, partially financed by means of the European regional development fund (ERDF) funds from the European Union (EU).Peer ReviewedPostprint (published version

    1,3-Dien-5-ynes: Versatile Building Blocks for the Synthesis of Carbo- and Heterocycles

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    1,3-Dien-5-ynes have been extensively used as starting materials for the synthesis of a wide number of different carbo- and heterocycles. The aim of this review is to give an overview of their utility in organic synthesis, highlighting the variety of compounds that can be directly accessed from single reactions over these systems. Thus, cycloaromatization processes are initially commented, followed by reactions directed toward the syntheses of five-membered rings, other carbocycles and, finally, heterocycles. The diverse methodologies that have been developed for the synthesis of each of these types of compounds from 1,3-dien-5-ynes are presented, emphasizing the influence of the reaction conditions and the use of additional reagents in the outcome of the transformations.Ministerio de Economía y Competitividad (MINECO) and FEDER (CTQ2013-41336-P, CTQ2013- 48937-C2-1-P, and CTQ2014-52488-R), Universidad de Alcalá (CCG2015/EXP-003) and Junta de Castilla y León (BU237U13

    Observation of a tricritical wedge filling transition in the 3D Ising model

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    In this letter we present evidences of the occurrence of a tricritical filling transition for an Ising model in a linear wedge. We perform Monte Carlo simulations in a double wedge where antisymmetric fields act at the top and bottom wedges, decorated with specific field act- ing only along the wegde axes. A finite-size scaling analysis of these simulations shows a novel critical phenomenon, which is distinct from the critical filling. We adapt to tricritical filling the phenomenological theory which successfully was applied to the finite-size analysis of the critical filling in this geometry, observing good agreement between the simulations and the theoretical predictions for tricritical filling
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