We have reported 8-substituted 2-morpholin-4-yl-chromenones that are potent inhibitors of DNA protein kinase and are promising agents for potentiating radiotherapy and chemotherapy. To explore structure-activity relationships we wished to compare the activity of 8-substituted 2-morpholin-4-yl-quinolin-4-ones with their chromenone congenors. We have found an improved route to substituted quinolin-4-ones starting from 5-(bis-methylsulfanyl-methylene)-2,2-dimethyl-[1,3]dioxane-4,6-dione 1, which gave intermediate 2 on heating with 2-bromoaniline in trifluoroethanol. Reaction of 2 with 2 mole equivalents of morpholine in refluxing trifluoroethanol gave 3, which afforded 8-bromo-2-morpholin-4-yl-quinolin-4-one 4 on thermolysis. Bromide 4 was converted into 8-substituted 2-morpholin-4-yl-quinolin-4-ones using the Suzuki reaction. Further experiments showed the actual precursor of 4 was 5.