2,3-Dihydro-9H-isoxazolo[3,2-b]quinazolin-9-ones and 3,4-dihydro-(1,2)-oxazino [3,2-b]quinazolin-10(2H)-ones.

Two series of compounds, 2,3-dihydro-9H-isoxazolo[3,2-b]quinazolin-9-ones and 3,4-dihydro-(1,2)-oxazino-[3,2-b]quinazolin-10(2H)-ones, were synthesized and evaluated for anti-inflammatory, antipyretic and analgesic activity. The isoxazolo compounds were generally more active than their oxazino homologs. Three compounds, i.e., 2,3-dihydro-9H-isoxazolo [3,2-b]quinazolin-9-one (W-2429) and its 2- and 3-methyl congeners, were the most active of all compounds tested in this study. On the basis of the biological results herein reported, W-2429 is considerably more effective than acetylsalicylic acid in inhibiting carrageenan-induced edema and in reducing brewer's yeast-induced fever in rats. Also, it was found to be more potent than propoxyphene hydrochloride in the Randall-Selitto test for analgesic activity.