4-Hydroxy-2-quinolones. 3. Synthesis and physicochemical properties of 1-R-3-carbethoxy-4-hydroxy-2-quinolones

Substituted Quinolinones. Part 19. New and Unexpected Results from Oxidation of 3-Acetyl-1-Alkyl- 4-Hydroxyquinolin-2(1H)-Ones Using Selenium Dioxide

“…This may be explained by structural stereo-restriction and also absence of Finally, when the dimers 6a, b were subjected to boiling in aqueous sodium hydroxide solution (15%), 1-alkyl-4-hydroxy-2-oxo-1,2-dihydroquinoline-3-carboxylic acids 15a, b (R = Me, Et) were obtained. 26 Formation of the acids 15a, b can be attributed to alkaline hydrolysis (saponification) at the α-pyrone followed by another hydrolysis leading to the α-keto acid disodium salts 13a, b. Consequently, decarbonylation took place affording the corresponding acids 15a, b (Scheme 5). It was found that α-keto acids 5a, b tend to undergo decarbonylation especially when treated with acidic or alkaline media or thermally.…”

4-Hydroxy-2-quinolones. 97. Simple synthesis of the esters of 4-halo-substituted 2-oxo-1,2-dihydroquinoline-3-carboxylic acids

“…The solid ester 4 was filtered off, washed with water, and dried. Yield 2.14 g (92%); mp 203-204°C A mixed test sample with an authentic specimen of ester 4 [9] gave no depression of melting point, the 1 H NMR and chromato-mass spectra of these compounds were identical.…”

One‐Pot Synthesis of 2‐Amino‐6‐(1,2‐dihydro‐4‐hydroxy‐2‐oxoquinolin‐3‐yl)‐4‐arylpyridine‐3‐carbonitriles Catalysed by NbCl5 and Their In Vitro Antimicrobial Studies

“…Quinolones exerts their activity against aerobic Gram‐negatives, some Gram‐positives and anaerobic bacteria by preventing bacterial DNA from unwinding and duplicating . The promising activity by quinolones led the development of numerous newer quinolones of which many were synthesized by simple and flexible synthetic routes . Since then, rarely encountered and less studied 3‐ substituted quinolones have become a subject of great interest to researchers.…”