{"id":75744,"date":"2018-03-09T23:21:02","date_gmt":"2018-03-09T23:21:02","guid":{"rendered":"https:\/\/www.deberes.net\/tesis\/sin-categoria\/aproximacion-estereoselectiva-a-alcaloides-de-stemona-basada-en-nitronas-en-ruta-hacia-stenina\/"},"modified":"2018-03-09T23:21:02","modified_gmt":"2018-03-09T23:21:02","slug":"aproximacion-estereoselectiva-a-alcaloides-de-stemona-basada-en-nitronas-en-ruta-hacia-stenina","status":"publish","type":"post","link":"https:\/\/www.deberes.net\/tesis\/quimica\/aproximacion-estereoselectiva-a-alcaloides-de-stemona-basada-en-nitronas-en-ruta-hacia-stenina\/","title":{"rendered":"Aproximaci\u00f3n estereoselectiva a alcaloides de stemona basada en nitronas. en ruta hacia (-)- stenina"},"content":{"rendered":"<h2>Tesis doctoral de <strong> Eva Casas Arce <\/strong><\/h2>\n<p>Como primer objetivo de la presente tesis doctoral se abord\u00f3 la s\u00edntesis enantioselectiva de la nitronia 4, que servir\u00eda de material de partida para la obtenci\u00f3n de varios alcaloides de los grupos tuberostemospironina y stemoamida. La estrategia dise\u00f1ada para la s\u00edntesis de esta nitrona consist\u00eda en realizar una parimera reacci\u00f3n de cicloadici\u00f3n 1,3-dipolar entre la nitrona aquiral 1 y el alcohol al\u00edlico, controlando el curso estereoqu\u00edmico del proceso mediante cat\u00e1lisis asim\u00e9trica, y una segunda reacci\u00f3n de oxidaci\u00f3n de los cicloaductos obtenidos.  entre los \u00e1cidos de lewis ensayados, la combinaci\u00f3n de et2zn con etzncl ha resultado ser efectiva para la formaci\u00f3n de la isoxazolidina trans-3. se han estudiado varios dioles quirales de simetr\u00eda c2, consigui\u00e9ndose en todos los casos una diastereoselectividad exo total.  resulta crucial conseguir el m\u00e1ximo n\u00famero de puntos de coordinaci\u00f3n con el centro de zinca y, contrariamente a lo que quiz\u00e1s cabr\u00eda esperar a priori, se ha inducido una mayor enantioselectividad en la reacci\u00f3n cuanto menor ha sido el tama\u00f1o del diol, obteni\u00e9ndose mejores resultados para el tartrato de dimetilio frente otros tartratos de mayor demanda est\u00e9tica. Finalmente, la introducci\u00f3n de yodo en el medio de reacci\u00f3n ha permitido mejorar sensiblemente el exceso enantiom\u00e9rico, hasta un 18%.  dado que los mejores resultados en la reacci\u00f3n de cicloadici\u00f3n entre la nitrona 1 y el alcohol al\u00edlico han llevado a un exceso anantiom\u00e9rico del 48%, la oxidaci\u00f3n del aducto trans-3 conducir\u00eda a la nitrona 4 con un exceso enantiom\u00e9rico moderado.  como segundo objetivo de la presente tesis doctoral se abord\u00f3 la s\u00edntesis del alcaloide (-)-stenina, partiendo de la nitrona 14, que se ha sintetizado siguiendo el protocolo descrito 1, a escala de multigramo. Los avances en la s\u00edntesis de (-)-stenina a partir de 14 se resumen en el esquema 2. se ha llegado al intermedio 44, que ya contiene 3 de los<\/p>\n<p>&nbsp;<\/p>\n<h3>Datos acad\u00e9micos de la tesis doctoral \u00ab<strong>Aproximaci\u00f3n estereoselectiva a alcaloides de stemona basada en nitronas. en ruta hacia (-)- stenina<\/strong>\u00ab<\/h3>\n<ul>\n<li><strong>T\u00edtulo de la tesis:<\/strong>\u00a0 Aproximaci\u00f3n estereoselectiva a alcaloides de stemona basada en nitronas. en ruta hacia (-)- stenina <\/li>\n<li><strong>Autor:<\/strong>\u00a0 Eva Casas Arce <\/li>\n<li><strong>Universidad:<\/strong>\u00a0 Aut\u00f3noma de barcelona<\/li>\n<li><strong>Fecha de lectura de la tesis:<\/strong>\u00a0 14\/07\/2005<\/li>\n<\/ul>\n<p>&nbsp;<\/p>\n<h3>Direcci\u00f3n y tribunal<\/h3>\n<ul>\n<li><strong>Director de la tesis<\/strong>\n<ul>\n<li>Marta Figueredo Galimany<\/li>\n<\/ul>\n<\/li>\n<li><strong>Tribunal<\/strong>\n<ul>\n<li>Presidente del tribunal: josep Font cierco <\/li>\n<li>rosario Fernandez fernandez (vocal)<\/li>\n<li>joaquin Plumet ortega (vocal)<\/li>\n<li>Jos\u00e9 Mar\u00eda Lassaletta simon (vocal)<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<p>&nbsp;<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Tesis doctoral de Eva Casas Arce Como primer objetivo de la presente tesis doctoral se abord\u00f3 la s\u00edntesis enantioselectiva de [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"site-sidebar-layout":"default","site-content-layout":"","ast-site-content-layout":"","site-content-style":"default","site-sidebar-style":"default","ast-global-header-display":"","ast-banner-title-visibility":"","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"","ast-breadcrumbs-content":"","ast-featured-img":"","footer-sml-layout":"","theme-transparent-header-meta":"","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"default","ast-page-background-enabled":"default","ast-page-background-meta":{"desktop":{"background-color":"var(--ast-global-color-4)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-gradient":""},"tablet":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-gradient":""},"mobile":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-gradient":""}},"ast-content-background-meta":{"desktop":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-gradient":""},"tablet":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-gradient":""},"mobile":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-gradient":""}},"footnotes":""},"categories":[1412,902,17,416],"tags":[163631,1652,42611,1414,54048,11339],"class_list":["post-75744","post","type-post","status-publish","format-standard","hentry","category-compuestos-heterociclicos","category-estereoquimica-y-analisis-conformacional","category-quimica","category-quimica-organica","tag-eva-casas-arce","tag-joaquin-plumet-ortega","tag-jose-maria-lassaletta-simon","tag-josep-font-cierco","tag-marta-figueredo-galimany","tag-rosario-fernandez-fernandez"],"_links":{"self":[{"href":"https:\/\/www.deberes.net\/tesis\/wp-json\/wp\/v2\/posts\/75744","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.deberes.net\/tesis\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.deberes.net\/tesis\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.deberes.net\/tesis\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.deberes.net\/tesis\/wp-json\/wp\/v2\/comments?post=75744"}],"version-history":[{"count":0,"href":"https:\/\/www.deberes.net\/tesis\/wp-json\/wp\/v2\/posts\/75744\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.deberes.net\/tesis\/wp-json\/wp\/v2\/media?parent=75744"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.deberes.net\/tesis\/wp-json\/wp\/v2\/categories?post=75744"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.deberes.net\/tesis\/wp-json\/wp\/v2\/tags?post=75744"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}