Publication: Reactividad Diels-Alder de sulfinil dienos: aproximación a la síntesis de estenina y neoestenina
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2016-03-31
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Universidad Complutense de Madrid
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Abstract
La reacción de Diels-Alder es un proceso fundamental en Química Orgánica moderna, que se ha convertido en una herramienta fundamental para la construcción de anillos de 6 miembros. Desde su descubrimiento por Otto Diels y Kurt Alder en 1928, esta transformación ha sido ampliamente empleada como pilar fundamental sobre el que se han desarrollado diversas metodologías sintéticas para la síntesis de productos naturales. La relevancia de la reacción de Diels-Alder en el contexto de la Química Orgánica radica en el hecho de que esta transformación permite la creación directa de 4 centros estereogénicos en un solo paso y con elevado regio- y estereocontrol. Este hecho hace de la reacción de Diels-Alder una de las herramientas más potentes para la síntesis de sistemas policíclicos a partir de precursores comerciales. En este sentido, la versión asimétrica de la reacción de Diels-Alder añade una importante ventaja a la versión racémica y es que los 4 centros estereogénicos pueden ser formados con elevada enantio y diastereoselectividad, permitiendo la formación directa de sistemas policíclicos de forma enantiopura. Con respecto a las formas de inducir asimetría en un proceso Diels-Alder, existen 4 estrategias fundamentales: a) el uso de dienófilos quirales, b) el uso de ácidos de Lewis quirales, c) el uso de organocatalizadores quirales y d) el uso de dienos quirales. De estas cuatro estrategias, la menos empleada es el uso de dienos quirales, debido a la escasez de métodos eficientes y generales para la síntesis de estos sustratos. En este contexto y motivados por el limitado número de métodos de síntesis de dienos quirales, nuestro grupo ha desarrollado diferentes metodologías para la síntesis de sulfinil dienos enantiopuros, que han resultado bastante generales y muy efectivas. Además, en trabajos previos de nuestro grupo, se estudió preliminarmente la reactividad Diels-Alder de estos dienos quirales. El trabajo llevado a cabo en este tesis pretendía en primer lugar, completar el trabajo previamente iniciado por nuestro grupo en este sentido y en segundo lugar el empleo de esta metodología para la síntesis de la (–)-Estenina y la (–)-Neoestenina...
The Diels-Alder reaction is a fundamental process in modern Organic Chemistry that has become one of the key synthetic tools in the formation of 6-membered rings. Since its discovery by Otto Diels and Kurt Alder in 1928, this reaction has been widely employed as an essential pillar onto which several synthetic methodologies have been developed for the synthesis of complex natural products. The relevance of the Diels-Alder reaction in the context of Organic Chemistry relies on the fact that this transformation allows for the straightforward creation of 4 stereogenic centers in a single step, with high regio- and stereocontrol. This feature makes the Diels-Alder reaction to be one of the most powerful tools in the synthesis of polycyclic systems from available commercial precursors. In this sense, the asymmetric version of the Diels-Alder reaction adds one important advantage to the racemic version and it is that these 4 stereogenic centers can be created with high enantio- and diastereoselectivity, enabling the straightforward synthesis of enantiopure polycyclic systems. With regard to the ways to induce asymmetry in a Diels-Alder process, basically four main strategies have been employed so far: a) the use of quiral dienophiles, b) the use of quiral Lewis acids, c) the use of quiral organocatalysis and d) the use of quiral dienes. From these 4 strategies, the less employed one is the use of quiral dienes due to the lack of efficient and general methods for the synthesis of these substrates. In this context and motivated by the limited methods for the synthesis of quiral dienes, our group developed different methodologies for the synthesis of enantiopure sulfinyl dienes, which resulted quite general and highly effective. Furthermore, in some former studies preceding this thesis, our group studied preliminary the reactivity of these quiral dienes in the Diels-Alder reaction. The work performed in this thesis aims firstly at completing the work performed previously in our group to this regard and secondly at the use of the methodology in the synthesis of (–)-Stenine and (–)-Neostenine...
The Diels-Alder reaction is a fundamental process in modern Organic Chemistry that has become one of the key synthetic tools in the formation of 6-membered rings. Since its discovery by Otto Diels and Kurt Alder in 1928, this reaction has been widely employed as an essential pillar onto which several synthetic methodologies have been developed for the synthesis of complex natural products. The relevance of the Diels-Alder reaction in the context of Organic Chemistry relies on the fact that this transformation allows for the straightforward creation of 4 stereogenic centers in a single step, with high regio- and stereocontrol. This feature makes the Diels-Alder reaction to be one of the most powerful tools in the synthesis of polycyclic systems from available commercial precursors. In this sense, the asymmetric version of the Diels-Alder reaction adds one important advantage to the racemic version and it is that these 4 stereogenic centers can be created with high enantio- and diastereoselectivity, enabling the straightforward synthesis of enantiopure polycyclic systems. With regard to the ways to induce asymmetry in a Diels-Alder process, basically four main strategies have been employed so far: a) the use of quiral dienophiles, b) the use of quiral Lewis acids, c) the use of quiral organocatalysis and d) the use of quiral dienes. From these 4 strategies, the less employed one is the use of quiral dienes due to the lack of efficient and general methods for the synthesis of these substrates. In this context and motivated by the limited methods for the synthesis of quiral dienes, our group developed different methodologies for the synthesis of enantiopure sulfinyl dienes, which resulted quite general and highly effective. Furthermore, in some former studies preceding this thesis, our group studied preliminary the reactivity of these quiral dienes in the Diels-Alder reaction. The work performed in this thesis aims firstly at completing the work performed previously in our group to this regard and secondly at the use of the methodology in the synthesis of (–)-Stenine and (–)-Neostenine...
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Tesis inédita de la Universidad Complutense de Madrid, Facultad de Ciencias Químicas, Departamento de Química Orgánica I, leída el 25-09-2015