<i>ortho</i>‐Azobenzenophanes: Photochemical and Thermal Reactions of [2,2][2,2′]Azobenzenophane

Abstract

Abstract The cyclic azo compounds 6 and 7 were synthesized. The chemical properties of 6 were investigated. Irradiation of the trans,trans form 6 t,t leads to isomerization to the trans,cis form 6 t,c and to the cis,cis form 6 c,c . Compounds 6 t,c and 6 c,c can be isolated. However, thermally, 6 t,c and 6 c,c react slowly back to 6 t,t . All attempts to convert 6 by light into the tetrazetidine 10 have been unsuccessful until now. In boiling toluene 6 undergoes an interesting rearrangement, namely a ring contraction, during which an azo group is cleaved with formation of an indole ring and a primary amino group.