Synthesis and chemiluminescence of 10-hydroxy- and 10- aminopyridazino[4,5-b]quinoline-1,4(2H, 3H)-diones

Substituted anilines reacted with methyl 1-methyl-4-methylthio-2,5- dioxo-3-pyrroline-3-carboxylate (1) in refluxing methanol to give the corresponding methyl 1-methyl-2,5-dioxo-4-phenylamino-3-pyrroline-3- carboxylates (3a-e) which were converted in good yields to 2- methylpyrrolo[3,4-b]quinoline derivatives (4a-e) by heating in diphenyl ether. Reaction of 4a-e with hydrazine hydrate gave 10-hydroxypyridazino[4,5- b]quinoline-1,4(2H,3H)-diones (5a-e) in good yields. The desired 10- aminopyridazino[4,5-b]quinoline-1,4(2H, 3H)-diones (8a-e) were obtained by the chlorination of 4a-e with phosphorus oxychloride followed by ammonolysis with 28% ammonium hydroxide in good yields. Compounds (5) and (8) were found to be efficiently chemiluminescent in a similarly to luminol in the presence of H₂O₂ and horseradish peroxidase in a solution of a phosphate buffer pH 8.0.