Pyridin系アミンオキシドの一新脱オキシ反応 (第5報)

活性水素を有する4-置換-ピリジン-N-オキシド及び4-置換-ヒノリン-N-オキシドとPCl₃との反応

抄録

1) 4-Hydroxy- and 4-amino-pyridine or -quinoline 1-oxide are desoxidated by phosphorus trichloride but the yield is generally poor.
2) In either case, reaction with their acetates gives a better yield. The 4-hydroxy compound yields the 4-hydroxy product but 4-amino compound yields invariably 4-acetamino compound.
3) The reaction of 4-hydroxyquinoline 1-oxide sometimes yields 4-chloroquinoline as a by-product but not 4-hydroxypyridine. This fact suggests that the reactivity of the 4-hydroxy group in quinoline derivatives is greater than that in pyridine derivatives.
4) 4-Ethoxyquinoline 1-oxide undergoes facile desoxidation by the action of phosphorus trichloride to form 4-ethoxyquinoline in a good yield.