13 research outputs found

    Lewis Acid Enabled Copper-Catalyzed Asymmetric Synthesis of Chiral β-Substituted Amides

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    Here we report that readily available silyl- and boron-based Lewis acids in combination with chiral copper catalysts are able to overcome the reactivity issues of unactivated enamides, known as the least reactive carboxylic acid derivatives, toward alkylation with organomagnesium reagents. Allowing unequaled chemo-reactivity and stereocontrol in catalytic asymmetric conjugate addition to enamides, the method is distinguished by its unprecedented reaction scope, allowing even the most challenging and synthetically important methylations to be accomplished with good yields and excellent enantioselectivities. This catalytic protocol tolerates a broad temperature range (-78 °C to ambient) and scale up (10 g), while the chiral catalyst can be reused without affecting overall efficiency. Mechanistic studies revealed the fate of the Lewis acid in each elementary step of the copper-catalyzed conjugate addition of Grignard reagents to enamides, allowing us to identify the most likely catalytic cycle of the reaction

    The Imaging Magnetograph eXperiment (IMaX) for the Sunrise balloon-borne solar observatory

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    The Imaging Magnetograph eXperiment (IMaX) is a spectropolarimeter built by four institutions in Spain that flew on board the Sunrise balloon-borne telesocope in June 2009 for almost six days over the Arctic Circle. As a polarimeter IMaX uses fast polarization modulation (based on the use of two liquid crystal retarders), real-time image accumulation, and dual beam polarimetry to reach polarization sensitivities of 0.1%. As a spectrograph, the instrument uses a LiNbO3 etalon in double pass and a narrow band pre-filter to achieve a spectral resolution of 85 mAA. IMaX uses the high Zeeman sensitive line of Fe I at 5250.2 AA and observes all four Stokes parameters at various points inside the spectral line. This allows vector magnetograms, Dopplergrams, and intensity frames to be produced that, after reconstruction, reach spatial resolutions in the 0.15-0.18 arcsec range over a 50x50 arcsec FOV. Time cadences vary between ten and 33 seconds, although the shortest one only includes longitudinal polarimetry. The spectral line is sampled in various ways depending on the applied observing mode, from just two points inside the line to 11 of them. All observing modes include one extra wavelength point in the nearby continuum. Gauss equivalent sensitivities are four Gauss for longitudinal fields and 80 Gauss for transverse fields per wavelength sample. The LOS velocities are estimated with statistical errors of the order of 5-40 m/s. The design, calibration and integration phases of the instrument, together with the implemented data reduction scheme are described in some detail.Comment: 17 figure

    El derecho del trabajo y de la seguridad social en España en 2014

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    Este documento intenta reflejar algunos de los principales cambios y novedades del ordenamiento laboral español en 2014, levantando acta de cómo la mutabilidad de nuestro Derecho del Trabajo es imparable. Este informe, consciente de ello, ofrece una selección de elementos esenciales, a juicio de sus autores, especialistas en cada una de las materias, encuadrados en la Sección Juvenil de la Asociación Española de Derecho del Trabajo y de la Seguridad Social. En él, conforme a la organización de dicha Sección en grupos de trabajo, se abordan las novedades más relevantes en materia de derechos fundamentales inespecíficos, contratación laboral, vicisitudes del contrato de trabajo, Derecho colectivo, conciliación y corresponsabilidad, protección social y prevención de riesgos laborales. This paper tries to show some of the many changes and novelties in Spanish Labour Law during 2014, drawing up a record of the unstoppable character of our Labour legal system. This report offers a selection of essential elements, according to its authors, all of them specialists in each one of the subjects, being part of the Young Scholars’ Section of the Spanish Association for Labour and Social Security Law. According to the organization of the said Section in working groups, we can find novelties concerning unspecific fundamental rights, work contracts, the life of the work contract and collective Labour Law, work-life balance and co responsibility, social protection and occupational risk prevention

    Informe: Derecho del trabajo y de la seguridad social en España en 2013. Algunos puntos críticos

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    Este documento intenta reflejar algunos de los principales cambios y novedades del ordenamiento laboral español en 2013, levantando acta de cómo la mutabilidad de nuestro Derecho del Trabajo es imparable. Este informe, consciente de ello, ofrece una selección de elementos esenciales, a juicio de sus autores, especialistas en cada una de las materias, encuadrados en la Sección Juvenil de la Asociación Española de Derecho del Trabajo y de la Seguridad Social. En él, conforme a la organización de dicha Sección en grupos de trabajo, se abordan las novedades más relevantes en materia de derechos fundamentales inespecíficos, contratación laboral, vicisitudes del contrato de trabajo, Derecho colectivo, conciliación y corresponsabilidad, protección social y prevención de riesgos laborales. This paper tries to show some of the many changes and novelties in Spanish Labour Law during 2013, drawing up a record of the unstoppable character of our Labour legal system. This report offers a selection of essential elements, according to its authors, all of them specialists in each one of the subjects, being part of the Young Scholars’ Section of the Spanish Association for Labour and Social Security Law. According to the organization of the said Section in working groups, we can find novelties concerning unspecific fundamental rights, work contracts, the life of the work contract and collective Labour Law, reconciliation and co responsibility, social protection and occupational risk prevention

    The European Solar Telescope

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    The European Solar Telescope (EST) is a project aimed at studying the magnetic connectivity of the solar atmosphere, from the deep photosphere to the upper chromosphere. Its design combines the knowledge and expertise gathered by the European solar physics community during the construction and operation of state-of-the-art solar telescopes operating in visible and near-infrared wavelengths: the Swedish 1m Solar Telescope, the German Vacuum Tower Telescope and GREGOR, the French Télescope Héliographique pour l’Étude du Magnétisme et des Instabilités Solaires, and the Dutch Open Telescope. With its 4.2 m primary mirror and an open configuration, EST will become the most powerful European ground-based facility to study the Sun in the coming decades in the visible and near-infrared bands. EST uses the most innovative technological advances: the first adaptive secondary mirror ever used in a solar telescope, a complex multi-conjugate adaptive optics with deformable mirrors that form part of the optical design in a natural way, a polarimetrically compensated telescope design that eliminates the complex temporal variation and wavelength dependence of the telescope Mueller matrix, and an instrument suite containing several (etalon-based) tunable imaging spectropolarimeters and several integral field unit spectropolarimeters. This publication summarises some fundamental science questions that can be addressed with the telescope, together with a complete description of its major subsystems
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