Estudi de l’aromaticitat de reaccions pericícliques que involucren estats de transició de sis membres

Abstract

Since Woodward and Hoffman's approach to pericyclic reactions, they have aroused great interest to the chemical community and have been extensively studied, although due to their complexity there are still many open questions regarding this type of reactions. They have achieved this interest thanks to the fact that they are increasingly involved in more types of reactions, both organic synthesis and biological reactions. In this work, a study of six examples of these reactions has been carried out, characterizing the respective transition states and evaluating their aromaticity, in order to validate the prediction by Zimmerman on the fact that pericyclic reactions allowed by symmetry possess aromatic transition states. The study was performed using computational calculations using the DFT method (using the B3LYP functional) with the base set cc-PVDZ. The NICS (0), FLU, HOMA, PDI, Iring, and MCI indices have been used to evaluate the aromaticity of the transition states, although it will be seen throughout the work that some of them are not useful for assessing the aromaticity of these types of species. The prediction by Zimmerman has been demonstrated correct, since all transition states have aromaticity, although it has been shown that there is no direct relationship between the magnitude of the energy barrier of the reactions and the aromaticity of the transition state of these