A conceptual DFT approach towards analysing feasibility of the intramolecular cycloaddition Diels-Alder reaction of triene amide in Lewis acid catalyst

Abstract

The effect of Lewis acid catalysts, TiCl4 and Et2AlCl on the intramolecular cycloaddition Diels-Alder (IMDA) reaction of triene-amide have been studied theoretically using the DFT (Density Functional Theory) at the 6-31G(d,p) level of theory. The results obtained using the polar model of Domingo, electrophilicity, nucleophilicity indices and thermochemistry computations, demonstrate that these catalysts are coordinated with more nucleophilic atoms of diene fragment (nitrogen and oxygen of amide group). These catalysts affect negatively the feasibility of the reaction as well as the physico-chemical parameters of the IMDA reaction of triene-amide. Lewis acids have negative effects on the intramolecular Diels-Alder (IMDA) reaction of triene amide, neither acceleration nor better selectivity. In addition, the IMDA reaction is delayed or unfeasible when Lewis acids is coordinated to the more nucleophilic atoms of O11 and N9 in diene fragment.