Substituent Effect on the Himbert Intramolecular Arene/Allene Diels-Alder Reaction: NBO analysis and State Specific Dual Descriptors

Conceptual density functional theory has been applied to study the Himbert intramolecular arene/allene Diels-Alder reaction. The effect of substitutions at different positions on the kinetics of these reactions has been analyzed. Therefore, from the calculation of the activation energies of more than 27 reactions involving concerted mechanisms, the selectivity of these reactions can be predicted and rationalized with the aid of conceptual DFT descriptors. An application of the two concepts, natural population analysis (NBO) and the state-specific dual descriptor (SSDD) for evaluating substituent effects, allows the investigation of the different interactions that promote a reaction compared to another. The SSDDs computed for the transition state structures provide important information about charge transfer interactions during the chemical reaction. The SSDD results show that the substituents promoting Himbert reaction have the lowest excitation energies which facilitate the allene/arene interaction. The ...