Orbital correlations for aza-derivatives of butadiene and hexatriene

Abstract

Molecular orbital theory predicts that electrocyclic reactions of 2-azabutadiene and of aza- and diaza-hexatrienes should proceed along a pathway similar to that of their hydrocarbon analogues. Thermal reaction of 2-azabutadiene should be conrotatory, while photochemical excitation should lead to a disrotatory cyclisation mechanism. The reverse is expected for the aza- and diaza-hexatrienes. Some experimental evidence is presented to support these observations.