SYNTHESES OF 3-ACYL-4-HYDROXY-2(1H)QUINOLONES

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 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.