Modelación in sílico de la reacción tipo aza-diels-alder entre (1s,2r,4r)-1 ((n.ndietilsulfamoil)metil)-7,7 dimetilbiciclo [2.2.1]heptan-2-il-2h-azirina-3-carboxilato y (1e,3e)-buta-1,3-dien-1,4-diil diacetato
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Fecha
2010-06-25
Autores
Ruiz Blanco, Yasser B.
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Universidad Central "Marta Abreu" de las Villas
Resumen
Las reacciones aza-Diels – Alder, son una de las principales herramientas con las que cuenta un químico experimentalista para la síntesis de compuestos heterocíclicos nitrogenados, de mediano y gran tamaño, muchos de ellos con importante o potencial actividad biológica. Es necesario profundizar el conocimiento del mecanismo por el que transcurren estas reacciones. El principal objetivo de este trabajo es identificar los parámetros estructurales que rigen una reacción de esta clase partiendo de la hipótesis de que una modelación in silico de la misma es posible. Se desarrolló el modelado a nivel AM1, rHF/6-31g (d, p) y rB3LYP/6-31g (d, p) de una síntesis recientemente practicada por la Universidad de Porto. La modelación se realizó en fase gaseosa y en diclorometano (disolvente de la síntesis) encontrándose que este disolvente no es el más adecuado para la reacción. Del estudio de las energías relativas de los puntos fundamentales de los IRCs, de las interacciones de segundo orden y de los principios de reactividad, MPP y MHP, se concluye que el IRC_exo-R es el más favorecido, coincidiendo con el resultado experimental. Este trabajo constituye una prueba más de la validez de los métodos cuánticos en la descripción de mecanismos de reacción así como la aplicabilidad de principios empíricos tales como MPP y MHP en la predicción de la estereoselectividad de reacciones aza-Diels- Alder.
Aza-Diels-Alder reactions are one of the main tools which experimentalist chemists usually use to synthesize nitrogen containing compounds of medium and large size, many of them with huge or possible biologic activity. It is necessary to know better this kind of mechanism. Our main goal is toidentify the structural parameters that rule a reaction of this class from the hypothesis that a model in silico of the reaction is possible. The study was developed at AM1, rHF/6-31g (d, p) and rB3LYP/6- 31g (d, p) level of theory to a recently performed synthesis by the University of Porto. The model was done in vacuum and in dicloromethane (the solvent of the synthesis) finding that this solvent isn’t the more appropriated for the reaction because it produces an increase in the activation energy. From the study of the relative energies of the fundamental points of the IRCs, the second order interactions and the reactivity principles, MPP and MHP, it is concluded that the IRC_exo-R is the more favored, in agreement with the experimental result. This thesis constitute one more probe of the validity of quantum methods in the description of reaction mechanisms as well as the applicability of empirical principles such as MPP and MHP in the prediction of the stereoselectivity of aza-Diels-Alder reactions
Aza-Diels-Alder reactions are one of the main tools which experimentalist chemists usually use to synthesize nitrogen containing compounds of medium and large size, many of them with huge or possible biologic activity. It is necessary to know better this kind of mechanism. Our main goal is toidentify the structural parameters that rule a reaction of this class from the hypothesis that a model in silico of the reaction is possible. The study was developed at AM1, rHF/6-31g (d, p) and rB3LYP/6- 31g (d, p) level of theory to a recently performed synthesis by the University of Porto. The model was done in vacuum and in dicloromethane (the solvent of the synthesis) finding that this solvent isn’t the more appropriated for the reaction because it produces an increase in the activation energy. From the study of the relative energies of the fundamental points of the IRCs, the second order interactions and the reactivity principles, MPP and MHP, it is concluded that the IRC_exo-R is the more favored, in agreement with the experimental result. This thesis constitute one more probe of the validity of quantum methods in the description of reaction mechanisms as well as the applicability of empirical principles such as MPP and MHP in the prediction of the stereoselectivity of aza-Diels-Alder reactions
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Palabras clave
Parámetros Estructurales, Reacción de Diels-Alder, Estereoisomerismo, Stereoisomerism, Estereoquimica Molecular, Structural Parameters