  The reactivity and mechanistic intricacies of azatrienes in Diels-Alder
reactions have been relatively unexplored despite their intriguing potential
applications. In this study, we employ Molecular Electron Density Theory to
theoretically investigate the hetero-Diels-Alder reaction involving azatrienes
with ethyl vinyl ether and allenyl methyl ether. Analysis of Conceptual Density
Functional Theory, energetic profiles, and the topological characteristics is
conducted to elucidate the reactions. The revealed mechanism manifests as a
polar one-step two-stages process under kinetic control. We establish a clear
relationship of between the periselectivity, regioselectivity, and
stereoselectivity on one hand and the characteristics of the reactions
mechanism on the other hand. The influence of weak interactions on reaction
activation barriers and bonding evolution are discussed in detail. We
demonstrate that substituents enhancing the reverse electron density flux
facilitate the feasibility of the reactions. The results lay ground for a
meticulous control of the reaction of azatriene in similar synthetic scenarios.
