Reactions of 3-Acyl-4-Hydroxy-2(1h)-Quinolones With Nitrogen Bases

Abstract

3-Acyl-4-hydroxy-2-quinolones 1 react with amines to yield 3-aminomethylene quinolinediones 2. With hydroxylamine the corresponding oximes 3 are obtained, which cyclize on heating via a thermal Beckmann rearrangement to oxazolo[5,4-c]quinolones 4. The oxazoles can be ringopened in the presence of acids to give 3-acylamino-4-hydroxyquinolones 5. The hydrazones 6, obtained from 3-acyl-4-hydroxy-2-quinolones 1 and hydrazines, cyclize either to pyrazolo[4,3-c]quinolones 7 or give mixtures of 7 and the dimeric azino-diethylidenequinolones 8.

4-Hydroxy-2-quinolones 166*. Synthesis, isomerism, and antitubercular activity of 3-arylaminomethylene-quinoline-2,4-(1H,3H)-diones

“…The structure of the Schiff base obtained by reaction of 3-acyl-4-hydroxy-2-oxo-1,2-dihydroquinolines with N-nucleophiles has repeatedly attracted the attention of investigators. As a result they have been reported as a mixture of two tautomers azomethine 3 and enamine 4 with a predominance of the latter [13][14][15][16]. The experiments we have carried out show a somewhat different picture.…”

Effect of substituents on the formation of isomeric isoxazolo heterocycles: rationalization by semi-empirical PM3 molecular orbital calculations

“…However, under the reaction conditions, by thermal Beckmann rearrangement, the corresponding oxazolo[5,4-c]quinolones 6 were obtained. 6 Recently, we have described a synthesis of both isomers of fused isoxazole derivatives with an interesting dependence of the preferred cyclization mode on the 4-substituent of the 3-acyl lactams 7 and 8: 4-aminosubstituted derivatives 7 preferentially yield isoxazolo [4,3-c]pyridinones 9; in contrast, 4-hydroxy derivatives 8 lead to the formation of isoxazolo [4,5-c]pyridinones 10. 7 Finally, it is worth mentioning that isoxazoles have proved as key intermediates in the synthesis of biologically active oxygen heterocyclic triones.…”

Synthesis of Tricarbonylmethane Derivatives of Pyridines, Pyrimidines, Pyridazines, and Pyrazoles by Anionic ortho-Fries Rearrangement

“…Aliphatic ketones of type 4 are easily converted to their oximes or oxime ethers [19]. In view of the potential herbicidal activity of such derivatives we have prepared the oximes 6a±c, but obtained a mixture of isomers (E/Z isomers and oxim-enol/hydroxyaminomethylene ketone tautomers [20] are possible).…”

“…In view of the potential herbicidal activity of such derivatives we have prepared the oximes 6a±c, but obtained a mixture of isomers (E/Z isomers and oxim-enol/hydroxyaminomethylene ketone tautomers [20] are possible). Therefore, we have converted these mixtures directly by thermal Beckmann rearrangement [19] to the oxazolo[4,5-c]pyridones 7a±c. The three component reaction of 1 with triethyl orthoformiate and aniline lead to the phenylaminomethylenepyridine-dione 5.…”