Halogenation reactions in position 3 of quinoline-2,4-dione systems by electrophilic substitution and halogen exchange

Summary 3-Substituted 4-hydroxy-2(1H)-quinolones3,5,7 are halogenated with bromine or sulfuryl chloride to yield the quinolinediones9 or10. Reaction of3,5,7 with chloroform gives the dichloromethyl quinolinediones11. Halogen exchange leads from the chloro quinolinediones10 to fluoro quinolinedones12 and to azido quinolinediones13. Similarly the dichloro quinolinedione10 an reacts to the difluoro quinolinedione14, which is reduced to the 3-fluoro-4-hydroxyquinolone16 and reacts again with sulfuryl chloride to give the mixed 3-chloro-3-fluoroquinolinedione15.Herrn Prof. Dr. Erich Ziegler in freundschaftlicher Verbundenheit zum 80. Geburtstag gewidmet.