Pyranoquinolines. Part I. Syntheses and ultraviolet absorption characteristics of 6-chloro-4H-pyrano[3,2-h]quinoline-4-ones

Abstract

6-Chloro-2-phenyl and 2-p-anisyl-4H-pyrano[3,2-h]quinoline-4-ones, their 2,3-dihydro and 3-hydroxy derivatives, and 6-chloro-3-benzoyl-2-phenyl-4H-pyrano[3,2-h]quinoline-4-one are synthesized by the application of appropriate flavonoid syntheses to 5-chloro-7-acetyl-8-hydroxyquinoline (5). 5 was formed on Friedel–Crafts acetylation of 5-chloro-8-methoxy and -8-hydroxyquinolines. Ultraviolet spectra of 5 are studied at three different pH's in aqueous ethanol and those of the pyranoquinolines are studied in ethanolic solutions and compared with those of their corresponding simple flavonoids.