Syntheses of 3-Acyl-4-hydroxy-2(1H)-quinolones

Article abstract of DOI:10.1002/prac.19943360707

3-Acyl-4-hydroxy-2(1H)-quinolones 5 are obtained by hydrolytic ring opening and subsequent decarboxylation from the corresponding pyrano<3,2-c>quinolin-2,5(6H)-diones 4, which in turn are easily obtained from 1:2 condensation of of anilines 1 with diethyl malonate 2a or 1:1 condensation of diethyl alkyl- or arylmalonates 2b-e with 4-hydroxy-2(1H)-quinolones 3.Nitropyranoquinolinediones 6 furnish after ringopening 3-nitroacetyl-4-hydroxy-2(1H)-quinolones 8.Pyranoquinolines 7 and 9 with acetyl- or aminosubstituents are hydrolyzed during basic ringopening to yield 5.