Nitration of 3-substituted-4-hydroxy-2(1H)-quinolones 1 with nitric acid leads either to 3-nitro- 2 or 3-hydroxyquinolinediones 3, depending on the reaction conditions. 3-Substituted-3-hydroxyquinolinediones 3 are also obtained by oxidative hydroxylation with peracetic acid. Amination of 3-substituted-3-chloroquinolinediones 4 with ammonium hydroxide predominantly leads again to 3-substituted-3-hy
3-Substituted 4-hydroxy-2(1 H)-quinolones 3, 5, 7 are halogenated with bromine or sulfuryl chloride to yield the quinolinediones 9 or 10. Reaction of 3, 5, 7 with chloroform gives the dichloromethyl quinolinediones 11. Halogen exchange leads from the chloro quinolinediones 10 to fluoro quinolinedones 12 and to azido quinolinediones 13. Similarly the dichloro quinolinedione 10 an reacts to the difluoro quinolinedione 14, which is reduced to the 3-fluoro-4-hydroxyquinolone 16 and reacts again with sulfuryl chloride to give the mixed 3-chloro-3-fluoroquinolinedione 15.
MALLE, ERNST;STADLBAUER, WOLFGANG;OSTERMANN, GUNTER;HOFMANN, BARBARA;LEIS+, EUR. J. MED. CHEM., 25,(1990) N, C. 137-142
A simple and effective method for the reduction of acyl substituted heterocyclic 1,3-dicarbonyl compounds to alkyl derivatives by zinc - acetic acid - hydrochloric acid
3-Acyl-4-hydroxy-2(1H)-quinolones (1a–k) were reduced in good yields (66–97%) to 3-alkyl-4-hydroxy-2(1H)-quinolinones (2a–k) using zinc powder (particle size <45 μm) in acetic acid/hydrochloric acid. This method could be transformed to 3-acetyl-4-hydroxy-coumarin (1l), 3-acetyl-4-hydroxy-2-pyranone (3a) and 3-acetyl-4-hydroxy-2(1H)-pyridinone (3b), which yielded the 3-ethyl derivatives 2l, 4a and 4b, respectively