Aromatic substitution by n-arylhydroxylamines—I : Formation of 8-amino-5,8′-iminobis(6-methoxyquinoline) by an intermolecular aromatic nitrene insertion reaction

Thermolysis of 8-hydroxylamino-6-methoxyquinoline at 65° in methanol gave 8-amino-5,8′-iminobis(6-methoxyquinoline), the same product being formed by thermolysis of 8-azido-6-methoxyquinoline as well as by deoxygenation of 6-methoxy-8-nitroquinoline with triethylphosphite in the presence of 8-amino-6-methoxyquinoline. Solvent effects were also consistent with the involvement of a nitrenoid species in these intermolecular aromatic substitutons. 8-Hydroxylaminoquinoline behaved in an analogous fashion but no iminobis compound was obtained from the corresponding 6-hydroxylaminoquinoline, indicating an internal interaction of the ring N atom with the 8-hydroxylamino function. Thermolysis of 8-hydroxylamino-6-methoxyquinoline in the presence of amines gave rise to o-diamines reconcilable with a nitrene intermediate.