A photochemical electrocyclization of the benzothiazolylphenylethenes involving a CN bond formation

A novel oxidative photodehydrocyclization of benzothiazolylphenylethenes to a polycyclic heteroaromatic cations with good yields was described. Starting from the trans-derivative, the phototransformation is a multistep process. It includes two photochemical reactions, a trans-cis-isomerization reaction followed by an 1-aza-1,3,5-hexatrienic electrocyclic reaction involving the formation of CN bond. The cyclized product gives the stable heteroaromatic cations from hydride elimination with oxygen from air.