Insights into the mechanism, selectivity, and substituent effects in the Diels-Alder reaction of azatrienes with electron-rich dienophiles: An MEDT study

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.

NMR and experimental reinvestigation of the condensation reaction between γ-methylene-α,β-unsaturated aldehydes and propargyl aldehydes

An experimental and computational study of the reaction between γ-methylene enals and propargyl aldehydes uncovered a deconjugative aldol condensation.

Domino aza/oxa-hetero-Diels–Alder reaction for construction of novel spiro[pyrido[3′,2′:5,6]pyrano[2,3-d]pyrimidine-7,5′-pyrimidine]

The unprecedented reaction of α,β-unsaturated N-arylaldimines with two molecular 5-arylidene-1,3-dimethylbarbituric acids in methylene dichloride at room temperature afforded unique spiro[pyrido[3′,2′:5,6]pyrano[2,3-d]pyrimidine-7,5′-pyrimidines] in moderate to good yields and with high diastereoselectivity.

Regiospecific inverse electron demand Diels–Alder reactions of 7-methylcoumarin-4-azadienes

Condensation of 7-methylcoumarin-4-carbaldehyde with different anilines affords 7-methylcoumarin-4-azadienes which on Diels–Alder reaction with dihydropyran gives coumarinyl substituted pyranoquinolines.