11,833 research outputs found

    Neutrinoless double-beta decay. A brief review

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    In this brief review we discuss the generation of Majorana neutrino masses through the see-saw mechanism, the theory of neutrinoless double-beta decay, the implications of neutrino oscillation data for the effective Majorana mass, taking into account the recent Daya Bay measurement of theta_13, and the interpretation of the results of neutrinoless double-beta decay experiments.Comment: 22 page

    Short asymmetric synthesis of phenanthroindolizidines through chiral homoallylic sulfinamine

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    An efficient stereocontrolled preparation of chiral phenanthroindolizidines is detailed. The synthesis relies on the stereoselective indium-mediated allylation of 2-(phenanthren-9-yl)acetaldehyde derivatives with chiral tert-butylsulfinamide. Chemoselective transformations from the corresponding homoallylic sulfinamine allow the synthesis of the phenanthroindolizidines in only three synthetic operations, without any detectable racemization. Following this procedure, the synthesis of natural (−)-tylophorine was successfully accomplished.We thank the Spanish Ministerio de Ciencia e Innovación for their financial support (CTQ2011-24165). C. A.-T. thanks the ISO for a grant

    A general protocol to afford enantioenriched linear homoprenylic amines

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    The reaction of a readily obtained chiral branched homoprenylamonium salt with a range of aldehydes, including aliphatic substrates, affords the corresponding linear isomers in good yields and enantioselectivities.We thank the Spanish Ministerio de Ciencia e Innovación for their financial support (CTQ2011-24165). I. B. acknowledges the Generalitat Valenciana for a predoctoral fellowship (ACIF/2011/159)

    Vortex Image Processing (VIP) package for high-contrast direct imaging

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    VIP is a Python instrument-agnostic toolbox featuring a flexible framework for reproducible and robust data reduction. VIP currently supports three high-contrast imaging observational techniques: angular, reference-star and multi-spectral differential imaging. The code can be downloaded from our git repository on Github: http://github.com/vortex-exoplanet/VI

    Regio- and Stereoselective Aminopentadienylation of Carbonyl Compounds

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    A simple and robust protocol is detailed for the preparation of enantioenriched α-substituted (1,4-pentadien-3-yl)amine derivatives. The methodology involves the addition of an in situ formed pentadienyl indium reagent to chiral tert-butylsulfinimines, previously formed in the same pot. The addition takes place with excellent γ-regio- and diastereoselectivity for a wide range of carbonyl compounds, including α-unsubstituted aldehydes and methyl alkyl ketones. The catalytic hydrogenation of the sulfinamines obtained provides a convenient access to chiral α-substituted (3-pentyl)amines. The hydroboration–oxidation of the α-(1,4-pentadien-3-yl)amine derivatives, followed by a cyclization under Mitsunobu conditions, takes place with an excellent diastereoselectivity governed by the chiral sulfinyl group.We thank the Spanish Ministerio de Ciencia e Innovación (CTQ2011-24165) for financial support. I.B. acknowledges the Generalitat Valenciana for a predoctoral fellowship (ACIF/2011/159). E.B. acknowledges the Council of Higher Education- Turkey for a postdoctoral fellowship (16.10.12-B.09.6.YÖK.0.71.01-207.02-12285)

    Diastereoselective Allylation of Carbonyl Compounds and Imines: Application to the Synthesis of Natural Products

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    We thank the Spanish Ministerio de Ciencia e Innovación (Grant Nos. CTQ2007-65218 and Consolider Ingenio 2010-CSD-2007-00006 and CTQ2011-24165), the Generalitat Valenciana (Grant No. PROMETEO/2009/039 and FEDER), and the University of Alicante for generous and continuous financial support

    A radical addition/cyclization of diverse ethers to 2-isocyanobiaryls under mildly basic aqueous conditions

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    Mildly basic aqueous conditions facilitated the tert-butyl peroxybenzoate (TBPB) mediated dehydrogenative addition of a range of ethers, including acetals, to diverse substituted 2-isocyanobiaryls. Mechanistic studies suggest that this radical cascade is an example of base promoted homolytic aromatic substitution (BHAS).We thank the Ministerio de Economia y Competitividad (CTQ2015-66624-P) and the University of Alicante (VIGROB-173) for financial support. C. A.-T. thanks the ISO for a grant
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