Pyrolysis of Aryl Azides. IX. Azomethines as Weak Neighboring Groups

Abstract

The following rates of pyrolysis (relative to azidobenzene at 120°) have been measured in decalin solution: 2-azidobenzaldehyde, 28.8; 2-azidobenzylideneaniline, 59.5; 2-azidobenzaldehyde phenylhydrazone, 8.9; 2-azidobenzaldehyde oxime O-methyl ether, 1.3;2-azidoacetophenone oxime O-methyl ether, 23.4; 2-azidobenzophenone phenylhydrazone, 9.7. It is argued that these relative rates are largely determined by the extent to which the ortho substituent is in the reactive conformation for an electrocyclic process. Indazoles substituted on N2 are isolated from pyrolysis of those azides with ortho-azomethine substituents.