{"id":14800,"date":"2018-03-09T09:01:39","date_gmt":"2018-03-09T09:01:39","guid":{"rendered":"https:\/\/www.deberes.net\/tesis\/sin-categoria\/aplicaciones-de-derivados-quirales-del-acido-acetoacetico\/"},"modified":"2018-03-09T09:01:39","modified_gmt":"2018-03-09T09:01:39","slug":"aplicaciones-de-derivados-quirales-del-acido-acetoacetico","status":"publish","type":"post","link":"https:\/\/www.deberes.net\/tesis\/quimica\/aplicaciones-de-derivados-quirales-del-acido-acetoacetico\/","title":{"rendered":"Aplicaciones de derivados quirales del \u00e1cido acetoac\u00e9tico"},"content":{"rendered":"<h2>Tesis doctoral de <strong> Elisenda Trepat Guixer <\/strong><\/h2>\n<p>Las glicinas alfa,alfa-disubstituidas pueden actuar como inhibidores de enzimas o modificar la conformaci\u00f3n de los p\u00e9ptidos en los cuales son incorporadas. en la primera parte de la tesis describimos una nueva metodolog\u00eda para preparar alfa,alfa-dialquilglicinas basadas en el uso de la d=ribonolactona (asequible comercialmente) como auxiliar quiral. La primera etapa es la preparaci\u00f3n del acetoacetato de la 2,3- o-isoporpiliden-gamma-d-ribonolactona.  este se alquila en condiciones b\u00e1sicas con ioduro de metilo o ioduro de butilo. Los acetoacetatos dialquilados se han preparado mediante una etapa de alquilaci\u00f3n diastereoselectiva utilizando nah como base y varios agentes alquilantes (bromuro de bencilo, de 4-bromobencilo, de 2-metilnaftilo). a continuaci\u00f3n se realiza una etapa de transesterificaci\u00f3n y una posterior transposici\u00f3n de shmidt obteni\u00e9ndose los amido\u00e9steres. Finalmente una hidr\u00f3lisis \u00e1cida permite obtener los clorhidratos de los amino\u00e1cidos en forma enantiopura. la configuraci\u00f3n absoluta fue asignada preparando las 3-metil-2-pirazolin-5-onas 4,4-disubstituidas enantiom\u00e9ricamente puras.  en la segunda parte de la tesis se han preparado varios precursores enantiom\u00e9ricamente puros de la esfinganina, el precursor biol\u00f3gico de la esfingosina. Estos se han preparado partiendo de los 3-oxoestearatos de varios auxiliares quirales (sultama de oppolzer, oxazolidinona de evans y la d-ribonolactona). la primera etapa es una adici\u00f3n de michael catalizada por salicilaldehiato de n\u00edquel (ii) y los aceptores de michael son varios azodicarboxilatos (azodicarboxilato de dietilo, dibencilo, di-tert-butilo, bis-tricloroetilo). la segunda etapa es una reducci\u00f3n con bh3sme2 utilizando ticl4 como agente quelatante. Se obtienen los alcoholes de configuraci\u00f3n syn con buenas relaciones diastereom\u00e9ricas y rendimientos correctos. Adem\u00e1s se han preparado pirazoles enantiom\u00e9ricamente puros que presentan un auxiliar quiral y una cadena<\/p>\n<p>&nbsp;<\/p>\n<h3>Datos acad\u00e9micos de la tesis doctoral \u00ab<strong>Aplicaciones de derivados quirales del \u00e1cido acetoac\u00e9tico<\/strong>\u00ab<\/h3>\n<ul>\n<li><strong>T\u00edtulo de la tesis:<\/strong>\u00a0 Aplicaciones de derivados quirales del \u00e1cido acetoac\u00e9tico <\/li>\n<li><strong>Autor:<\/strong>\u00a0 Elisenda Trepat Guixer <\/li>\n<li><strong>Universidad:<\/strong>\u00a0 Aut\u00f3noma de barcelona<\/li>\n<li><strong>Fecha de lectura de la tesis:<\/strong>\u00a0 19\/12\/2001<\/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>Adelina Vallribera Mass\u00f3<\/li>\n<\/ul>\n<\/li>\n<li><strong>Tribunal<\/strong>\n<ul>\n<li>Presidente del tribunal: marcial Moreno ma\u00f1as <\/li>\n<li>Carlos Cativiela mar\u00edn (vocal)<\/li>\n<li>jordi Marquet cortes (vocal)<\/li>\n<li>christine Courillon (vocal)<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<p>&nbsp;<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Tesis doctoral de Elisenda Trepat Guixer Las glicinas alfa,alfa-disubstituidas pueden actuar como inhibidores de enzimas o modificar la conformaci\u00f3n 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 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