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49. Halogenation reactions in position 3 of quinoline-2,4-dione-systems by electrophilic substitution and halogen exchange (Organic azides in heterocyclic synthesis, 16)
Stadlbauer W., Laschober R., Lutschounig H., Schindler G., Kappe Th., Monatsh. Chem. 123 (1992) 617-636

Abstract: 3-Substituted 4-hydroxy-2(1H)-quinolones were halogenated with bromine or sulfuryl chloride to yield quinolinediones. Reaction with chloroform gave dichloromethyl quinolinediones. Halogen exchange lead from the chloro quinolinedionesto fluoro quinolinedones and to azido quinolinediones. Similar the di loro quinolinedione react to the difluoro quinolinedione, which were reduced to the 3-fluoro-4-hydroxyquinolone and react again with sulfuryl chloride to give the mixed 3-chloro-3-fluoroquinolinedione.

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