A synthetic route to 2-substituted 6- and -7-hydroxy-5,8-dioxoquinolines has been evaluated. Reaction of 5,7-dinitro-8-hydroxycarbostyril (4) with phosphorus oxychloride followed by reaction with piperidine ormorpholine gave the 2-substituted 5,7-dinitro-8-quinolinols 5d and 5e. Catalytic hydrogenation, oxidation, and acid hydrolysis gave the corresponding 7-hydroxy-5,8-dioxoquinolines 9a and 9b. A similar sequence was used to proceed from 5-hydroxy-6,8-dinitrocarbostyril (12)i)ia2-chloro-6,8-dinitro-5-quinolinoI (13a) and 2-piperidino-6,8-dinitro-5-quinolinol (13b) to 2-piperidino-6-hydroxy-5,8-dioxoquinoline (14a).
ASJC Scopus subject areas
- Organic Chemistry