Abstract
The global electrophilicity index, defined within the conceptual density functional theory (DFT), was used to classify the dienes and dienophiles currently used in Diels-Alder reactions on a unique scale of electrophilicity. The index, obtained within the Kohn-Sham scheme, is based on the HOMO and LUMO energies. A systematic study of the global reactivity indexes of the reagents involved in formal [4 + 2+] Diels-Alder cycloaddition reactions of nitrilium and immonium ions with isoprene is presented.
Keywords: Diels-Alder, reactivity indexes, nitrilium, immonium, electrophilicity, nucleophilicity, Huckel molecular orbital (HMO) theory, electrofugality and nucleofugality, Berny analytical gradient, isoprene