1,494 research outputs found

    The role of force dynamics and intentionality in the reconstruction of L2 verb meanings: A Danish-Spanish bidirectional study

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    This paper examines the role of force dynamics and intentionality in the description of placement events by two groups of native speakers of typologically and genetically different languages, Danish and Spanish, and by two groups of intermediate adult learners, Danish learners of L2 Spanish and Spanish learners of L2 Danish. The results of the study showed that (a) force dynamics and intentionality are important semantic components in both languages, but their distribution and relative focus differed crosslinguistically, and (b) the two learner groups had difficulties in reconstructing the meanings of the L2 verbs involving these two semantic components. Learning difficulties were observed when moving from a less to a more complex L2 system, when moving in the opposite direction, i.e., from a more to a less complex L2 system and when moving to an L2 system that is as complex as the learners native one

    The intermolecular hydro-oxycarbonylation of internal alkynes: current state of the art

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    The authors acknowledge the Spanish MINECO (projects CTQ2013-40591-P and CTQ2016-75986-P) and the Gobierno del Principado de Asturias (project GRUPIN14-006) for financial support. J. F. thanks MINECO and ESF for the award of a Juan de la Cierva contract

    Asymmetric Hydrogenation of 1-alkyl and 1-aryl vinyl benzoates: a broad scope procedure for the highly enantioselective synthesis of 1-substituted ethyl benzoates

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    The enantioselective hydrogenation of enol esters of formula CH2=C(OBz)R with rhodium catalysts based on phosphine-phosphite ligands (P-OP) has been studied. The reaction has a broad scope and it is suitable for the preparation of products possessing a wide variety of R substituents. For the cases where R is a primary alkyl high catalyst activity (S/C = 500) and enantioselectivities (95-99 % ee) were obtained with a catalyst characterized by an ethane backbone and a PPh2 fragment. In contrast, for R = tBu a catalyst possessing a benzene backbone provided the best results (97 % ee). Derivatives with a cycloalkyl R substituent were particularly difficult substrates for this reaction. A broader catalyst screening was required for these substrates, which identified a catalyst possessing a P(m-xylyl)2 fragment as the most appropriate one, affording enantioselectivities between 90 and 95 % ee. Outstanding enantioselectivities (99 % ee) and high catalyst activity (S/C = 500-1000) were also obtained in the case of substrates bearing a Ph or a fluoroaryl R substituent. In addition, the system is also appropriate for the preparation of other synthetically useful esters as those for R = benzyl, 2-phenylethyl or Nphthalimido alkyl chains. Likewise, the hydrogenation of divinyl dibenzoates proceeded with very high diastero- and enantioselectivity, generating rather low amounts of the meso isomer (3-6 %). On the other hand, substrates with Br- and MeO- substituents at the phenyl benzoate ring, suitable for further functionalization, have also been examined. The results obtained indicate no detrimental effect of these substituents in the hydrogenation. Alternatively, the methodology has been applied to the highly enantioselective synthesis of deuterium isotopomers of 1-octyl benzoate bearing CDH2, CD2H or CD3 fragments. Finally, as a practical advantage of the present system, it has been observed that the high performance of the catalysts is retained in high concentrated solutions or even in the neat substrate, then minimizing both the amount of solvent added and the volume of the reactionJunta de Andalucía 2009/FQM-4832CSIC 201480E03 1Ministerio de Ciencia e Innovación CTQ2010- 14796/BQ

    Apple snail perivitellin precursor properties help explain predatorsï feeding behavior

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    Fil: Cadierno, María Pilar. Universidad Nacional de La Plata. Instituto de Investigaciones Bioquímicas de La Plata; ArgentinaFil: Dreon, Marcos Sebastián. Universidad Nacional de La Plata. Instituto de Investigaciones Bioquímicas de La Plata; ArgentinaFil: Heras, Horacio. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Cátedra de Química Biológica; Argentin

    Palladium(II) complexes with a phosphino-oxime ligand: synthesis, structure and applications to the catalytic rearrangement and dehydration of aldoximes

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    The treatment of [PdCl2(COD)] (COD = 1,5-cyclooctadiene) with 1 and 2 equivalents of 2-(diphenylphosphino)benzaldehyde oxime in dichloromethane at room temperature led to the selective formation of [PdCl2{κ2-(P,N)-2-Ph2PC6H4CH[double bond, length as m-dash]NOH}] (1) and [Pd{κ2-(P,N)-2-Ph2PC6H4CH[double bond, length as m-dash]NOH}2][Cl]2 (2), respectively, which represent the first examples of Pd(II) complexes containing a phosphino-oxime ligand. These compounds, whose structures were fully confirmed by X-ray diffraction methods, were active in the catalytic rearrangement of aldoximes. In particular, using 5 mol% complex 1, a large variety of aldoximes could be cleanly converted into the corresponding primary amides at 100 °C, employing water as solvent and without the assistance of any cocatalyst. Palladium nanoparticles are the active species in the rearrangement process. In addition, when the same reactions were performed employing acetonitrile as solvent, selective dehydration of the aldoximes to form the respective nitriles was observed. For comparative purposes, the catalytic behaviour of an oxime-derived palladacyclic complex has also been briefly evaluated.This work was supported by Spanish MINECO (projects CTQ2013-40591-P, CTQ2013-43446-P and CTQ2014-51912-REDC) and Gobierno del Principado de Asturias (project GRUPIN14-006). L.M.-R. and E.T.-M. thank MINECO, MECD and ESF for the award of FPI and FPU fellowships, respectively
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