247 resultados para Aza-propargylglycine


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Resumen tomado de la publicaci??n

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La duraci??n de la cinta de v??deo es de siete minutos

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Conocer el universo pedag??gico del maestro republicano: plan de formaci??n, selecci??n, perfeccionamiento, etc. Analiza la ense??anza durante el Bienio Aza??ista republicano, estudiando la formaci??n del magisterio primario nacional y su perfeccionamiento, interes??ndose especialmente en el Plan de Formaci??n de 1931 ( todo enmarcado dentro de unas coordenadas hist??ricas imprescindibles) as?? como la Constituci??n, los Presupuestos, etc. 1) La Segunda Rep??blica se impuso metas demasiado ambiciosas al pretender abarcar las necesidades educativas que urg??an al pa??s careciendo de base econ??mica y pol??tica as?? como de infraestructuras. 2) Educativamente, la Segunda Rep??blica puede estudiarse desde varios niveles: a un nivel de ideas, aspiraciones y disposiciones oficiales y a un nivel de consecuencias pr??cticas. 3) La educaci??n de la segunda Rep??blica contienen aspectos pedag??gicos importantes y de actualidad. 4) Los aumentos presupuestarios destinados a ense??anza correspond??an al esfuerzo llevado a cabo en la primera ense??anza. 5) El maestro fue el eje de la reforma emprendida. 6) La Instrucci??n Primaria fue la tarea m??s cuidada y sobre la que se hicieron los proyectos m??s ambiciosos. 7) La cantidad de escuelas creadas no llegaron a ser las deseadas por los republicanos y por lo tanto no se lleg?? al n??mero que precisaba Espa??a.

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Se pone en com??n una experiencia pedag??gica realizada en el IES A??aza, que se encuentra en un contexto socio econ??mico medio-bajo, problem??tico, con escasa participaci??n de las familias, aunque se detecta a una minor??a de alumnado con gran inquietud y ganas de aprender. Se hace necesario fomentar y difundir entre docentes y alumnado el uso de las nuevas tecnolog??as con un doble finalidad: trabajar de manera interdisciplinar y optimizar los recursos inform??ticos de los que se disponen en el centro. Se convierte en un reto continuo de formaci??n y actualizaci??n para todos y todas.

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Se comenta una experiencia realizada con alumnado de 4.?? de la ESO basada en una metodolog??a que opta por una visi??n global del conocimiento que rompe con la estructura cerrada de las ??reas, adapt??ndose a las necesidades y ritmo de aprendizaje de un alumnado diverso. Se presenta una propuesta de curr??culum integrado para realizar un eje cronol??gico paralelo de algunas materias o disciplinas del conocimiento. La coordinaci??n se asume desde los departamentos de sociales y matem??ticas.

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In this work we demonstrate the value of performing a Hetero Diels-Alder reaction (HDAR) between Danishefsky’s diene and a range of aldehydes or imines, under microwave irradiation. By using a range of aldehydes and imines, including those derived from carbohydrates, access to functionalised 2,3-dihydro-4H-pyran-4-ones or 2,3-dihydro-4-pyridinones in good to excellent synthetic yields is possible. A particular strength of the methodology is its ability to access mimetics of C-linked disaccharides and C-linked aza disaccharides, targets of current therapeutic interest, in a rapid, convenient and diastereoselective manner. The effect of high pressure on the HDARs involving carbohydrate derived aldehydes and imines is also explored, with enhancement in yields occurring for the aldehyde substrates. Finally, HDARs using carbohydrate derived ketones, enones and enals are described under a range of conditions. Optimum results were obtained under high pressure conditions, with highly functionalized carbohydrate derivatives being afforded, in good yields, in this way.

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(R)-3-Arylalanines may be prepared in high enantiomeric purity from N-dpp imines by a four-step reaction sequence involving asymmetric aza-Darzens reaction, dephosphinylation, hydrogenolysis and hydrolysis. The amino acids thus obtained were of >95% enantiomeric purity.

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The development of new methods for the efficient synthesis of aziridines has been of considerable interest to researchers for more than 60 years, but no single method has yet emerged as uniformly applicable, especially for asymmetric synthesis of chiral aziridines. One method which has been intensely examined and expanded of late involves the nucleophilic addition to imines by anions bearing a-leaving groups; by analogy with the glycidate epoxide synthesis, these processes are often described as "aza-Darzens reactions". This Microreview gives a summary of the area, with a focus on contemporary developments. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

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The aza-Darzens ('ADZ') reactions of N-diphenylphosphinyl ('N-Dpp') imines with chiral enolates derived from N-bromoacetyl 2S-2,10-camphorsultam proceed in generally good yield to give N-diphenylphosphinyl aziridinoyl sultams. However, the stereoselectivity of the reaction is dependent upon the structure of the imine substituent: when the chiral enolate was reacted with arylimines substituted in the ortho-position, mixtures of cis- and trans-2'R,3'R-aziridines were obtained, often with a complete selectivity in favour of the trans-isomer. (c) 2006 Elsevier Ltd. All rights reserved.

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Theaza-Darzens ('ADZ') reactions off-diphenylphosphinyl (W-Dpp') imines with chiral enolates derived from oxazolidinones and camphorsultam have been Studied. Whilst oxazolidinone enolates reacted poorly in terms of aziridination, the use of the chiral enolate derived from both antipodes of N-bromoacetyl 2, 10-camphorsultam, 2R-(5) and 2S-(5), with N-diphehenylphosphinyl aryl and tert-butylimines proceeded in generally good yield to give, respectively, (2'R,3'R)- or (2'S,3'S)-cis-N-diphenylphosphinyl aziridinoyl sultams of high de. (c) 2006 Elsevier Ltd. All rights reserved.

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N-Benzyl- and N-(alpha-methoxycarbonylethyl)-2,4,6-triphenyl-1,2-dihydropyridines were submitted to Diels-Alder reactions with maleic anhydride or N-phenylmaleimide yielding, diastereoselectively, the corresponding endo-anti adducts. These novel isoquinuclidines showed to be resistant to N-alkylation or N-protonation, undergoing an unexpected fragmentation via a retro aza Diels-Alder process.

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Homoallylic alcohols (primary, secondary, or tertiary containing an endocyclic or an exocyclic double bond) react with equimolar amounts of aldehydes (aliphatic or aromatic) and ketones (aliphatic) in the presence of 5 mol % of iodine. This Prins cyclization was used in the preparation of hexahydrobenzo[f]isochromenes and of a 4-hydroxy-tetrahydropyran, in 54-81% yield. The procedure is also efficient for an aza-Prins cyclization of a homoallylic sulfonamide and benzaldehyde, producing a hexahydrobenzo[f]isoquinoline. (C) 2009 Elsevier Ltd. All rights reserved.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)