Search results for "IOS"
showing 10 items of 8115 documents
ChemInform Abstract: A Catalytic Highly Enantioselective Direct Synthesis of 2-Bromo-2-nitroalkan-1-ols Through a Henry Reaction.
2009
Highly enantiomerically enriched 2-bromo-2-nitroalkan-1-ols are prepared by direct condensation of aliphatic and aromatic aldehydes with bromonitromethane in the presence of a catalytic amount of copper(II) acetate and a C1-symmetric camphor-derived amino pyridine ligand.
ChemInform Abstract: Radical Addition to Iminium Ions and Cationic Heterocycles
2015
Carbon-centered radicals represent highly useful reactive intermediates in organic synthesis. Their nucleophilic character is reflected by fast additions to electron deficient C=X double bonds as present in iminium ions or cationic heterocycles. This review covers diverse reactions of preformed or in situ-generated cationic substrates with various types of C-radicals, including alkyl, alkoxyalkyl, trifluoromethyl, aryl, acyl, carbamoyl, and alkoxycarbonyl species. Despite its high reactivity, the strong interaction of the radical’s SOMO with the LUMO of the cation frequently results in a high regioselectivity. Intra- and intermolecular processes such as the Minisci reaction, the Porta react…
Enantioselective synthesis of 2-substituted-1,4-diketones from (S)-mandelic acid enolate and α,β-enones
2006
[EN] An approach for the synthesis of chiral non-racemic 2-substituted-1,4-diketones from (S)-mandelic acid and ¿,ß-enones has been developed. The reaction of lithium enolate of the 1,3-dioxolan-4-one derived from optically active (S)-mandelic acid and pivalaldehyde with ¿,ß-unsaturated carbonyl compounds proceeds readily to give the corresponding Michael adducts in good yields and with high diastereoselectivities. The addition of HMPA (3 equiv) reverses and strongly enhances the diastereoselectivity of the reaction. A change in the reaction mechanism from a lithium catalyzed to the one where catalysis has been suppressed by coordination of HMPA to lithium is proposed to explain these resul…
ChemInform Abstract: Synthesis of 2-Isoxazolines: Enantioselective and Racemic Methods Based on Conjugate Additions of Oximes.
2011
Acidic anilinium salts catalyze the direct formation of racemic 2-isoxazolines from enals and oximes by means of consecutive oxime conjugate-addition and intramolecular oxime-transfer reaction.
ChemInform Abstract: Enantioselective Zinc-Mediated Conjugate Addition of Terminal Alkynes to Enones.
2013
Zinc for conjugate alkynylation: The enantioselective conjugate addition of terminal alkynes to 2-arylidene-1,3-diketones in the presence of diethylzinc and a catalytic amount of (R)-VANOL has been developed. The reaction can be applied to different aromatic and heteroaromatic alkynes and enones, giving the expected products in good yield and with enantiomeric excesses up to 91%. The products can be enantiomerically enriched up to 99% ee by crystallization (see scheme).
ChemInform Abstract: Enantioselective Addition of Nitromethane to 2-Acylpyridine N-Oxides. Expanding the Generation of Quaternary Stereocenters with …
2014
The direct asymmetric Henry reaction with prochiral ketones, leading to tertiary nitroaldols, is an elusive reaction so far limited to a reduced number of reactive substrates such as trifluoromethyl ketones or α-keto carbonyl compounds. Expanding the scope of this important reaction, the direct asymmetric addition of nitromethane to 2-acylpyridine N-oxides catalyzed by a BOX-Cu(II) complex to give the corresponding pyridine-derived tertiary nitroaldols having a quaternary stereogenic center with variable yields and good enantioselectivity, is described.
1,4-regioselective iodofunctionalizations of 1,3-butadiene
1988
Abstract Addition reactions of benzene and acetonitrile to 1,3-butadiene are described. This new iodofunctionalization process proceeds “via” iodonium ion-allylic cation equilibrium and gives regioselectively 1,4-adducts, which can be alternatively obtained by acid treatment of the 1,2-derivative 8 .
La negociación colectiva de empresas vinculadas en el marco de las redes de empresas integradas por empresas multiservicios
2018
Ante la plena consolidación de las empresas multiservicios (en adelante, EM) y la anomia legal en la materia, el análisis de la negociación colectiva de los convenios de empresas multiservicios, deviene fundamental para impedir el dumping social. La comunicación examina la vía abierta por el convenio de empresas vinculadas que se ha negociado en Adecco Outsourcing S.A.U. y en Atlas Servicios Empresariales, S.A.U. Se trata de una experiencia negocial de gran interés, por buscar proteger la negociación sectorial, salvando algunos problemas como la alegación de las empresas multiservicios de la existencia de un vacío sectorial a la hora de determinar el convenio colectivo de referencia en el s…
redes entre actores a través del presupuesto: los casos de Alicante y Valencia
2019
Resumen El presente artículo tiene como principal objetivo analizar la forma de provisión de bienes y servicios de los Ayuntamientos de Alicante y València (2005-2016). Para ello, llevaremos a cabo un análisis del presupuesto por capítulos para determinar el reparto de fondos entre los distintos actores que forman las redes de políticas públicas de cada consistorio. Entre las evidencias que hemos encontrado podemos destacar que dicho fenómeno se ha visto, ciertamente, afectado por la crisis económica que ha hecho variar las estrategias. Asimismo, hemos podido constatar el reparto de dinero público entre actores de distinta naturaleza lo que denota un escenario propio de la gobernanza urbana…
Relation between health literacy, self-care and adherence to treatment with oral anticoagulants in adults: a narrative systematic review
2018
Background Oral anticoagulants (OAC) are widely used in patients with cardiovascular diseases. However, for optimal OAC self-care patients must have skills, among which health literacy (HL) is highlighted. We aimed to describe the relation between HL and self-care in cardiovascular patients on OAC treatment. Methods Electronic searches were carried out in the PubMed, Scopus, Embase, CINAHL, Web of Science, Cochrane Library, SciELO, IME-Biomedicina, CUIDEN Plus and LILACS databases, limited to Spanish and English language and between January 2000–December 2016. Papers reported on adults older than 18 years, taking OAC by themselves for at least three months. PRISMA guidelines were used for p…