Nucleophilic Chlorination of 3‐Formyl‐4‐hydroxy‐quinolin‐2(1H)‐ones

摘要: Chlorination of 1-substituted 3-formyl-4-hydroxy-2-quinolones (1a, b) with phosphorylchloride leads to 4-chloro-3-dichloromethylquinolones (2), which can be hydrolyzed 4-chloro-3-formyl-quinolones (4). From the anilinomethylene quinolinediones (3), at low temperatures formylquinolones 4 obtained directly, whereas high cleavage tautomeric azomethine moiety followed by subsequent ring closure naphthyridines (7) takes place. With 1-unsubstituted (1d) either 3-dichloromethylquinolone (2d) or 2,4-dichloro-3-dichloro-methylquinoline (10) is depending on reaction conditions. Similar results are compounds (3). Attempts obtain 3-formyl-2,4-dichloroquinoline (11) were unsuccessful because in all experiments 2-chloro-group was converted an oxygen function.