Azonia-azulene salts. Part III. The thermal decomposition of o-benzylphenyl azides to give azepinoindoles

Abstract

Thermal decomposition of o-benzylphenyl azides usually gave 10H-azepino[1,2-a]indoles [(2), (3), (19), (26)—(28), (37), and (39)]. In one case steric obstruction led to a 6H-azepino[1,2-a]indole (29) and an 8H-azepino-[1,2-a]indole (30). When a o-methoxy-group was present on the benzyl residue the major products were acridines and acridans; the formation of 1-substituted acridines suggests that an azanorcaradiene is an intermediate. Azepino[1,2-a]indol-6-ones [(38) and (42)] have been isolated; azepino[1,2-a]indol-8-one (21) has been prepared in good yield and converted into hydroxy- and ethoxy-azepino[1,2-a]indolium salts [(23) and (24)]. 1-(o-Azidophenyl)-1-phenylethanol (47) decomposed to give some o-anilinoacetophenone (49), showing the occurrence of another nitrene insertion pathway.