Syntheses of heterocyclic compounds of nitrogen. CX. Azaphenoxazine derivatives.

Abstract

3-Bromo-4-(o-hydroxyphenylamino)-5-nitropyridine prepared from the potassium salt of o-aminophenol and 3-bromo-4-chloro-5-nitropyridine easily yielded 4-nitro-5H-benzo [b] pyrido [4, 3-e]-1, 4-oxazine by the intramolecular condensation in the presence of piperidine or potassium hydroxide. Attempts to prepare a ring-fused azaphenoxazine from the potassium salts of o-aminophenol and 2-chloro-3, 5-dinitropyridine in alkaline medium ended in failure, only giving 2-(o-hydroxyphenylamino)-3, 5-dinitropyridine. On the other hand, when 2-chloro-3, 5-dinitropyridine was allowed to react with o-methylaminophenol, 3-nitro-10-methylbenzo [e] pyrido [3, 2-b]-1, 4-oxazine was obtained. These facts are well explainable from the hypothesis of a chelate ring formation forwarded by Brady. 3-Amino-5-chloro-2-pyridone was condensed with s-trinitroanisole giving 3-chloro-6, 8-dinitro-5H-benzo [b] pyrido [3, 2-e]-1, 4-oxazine.