A Comparative Study of Synthetic Approaches to 1-Methyl-2,5,8(1H)-quinolinetrione and 4-Methyl-2,5,8(1H)-quinolinetrione

The best overall yield for 1-methyl-2,5,8(1H)-quinolinetrione was obtained by the dichromate oxidation of 1-methyl-8-hydroxy-2-quinolone. 4-Methyl-2,5,8(1H)-quinolinetrione was synthesized by acetoacetylation of 2,5-dimethoxyaniline with 2,2,6-trimethyl-4H-1,3-dioxin-4-one followed by oxidation with ceric ammonium nitrate