Abstract
When 2-aryl-5, 8-dichloropyrimido [4, 5-d] pyridazine (1) was reacted with a variety of nucleophiles, such as amines, sodium methoxide, sodium azide, sodium sulfide etc., 5, 8-disubstituted compounds (5) were obtained. Treatment of 2-phenyl-5-chloro-8-morpholinopyrimido [4, 5-d] pyridazine (9, [chemical formula] : morpholino) or 2-phenyl-5-morpholino-8-chloropyrimido [4, 55-d] pyridazine (10, [chemical formula] : morpholino) with nucleophiles gave the corresponding products with a different kind of substituents at 5-and 8-position (12 and 13). The phenyl group at 2-position seems to accelerate the substitution at position 5 and 8. The reaction of 2-phenyl-5, 8-bis (substituted thio) pyrimido [4, 5-d] pyridazine (5) with chlorine afforded the dichloride (1, Ar : phenyl). Among the synthesized disbstituted compounds, 5v, 5h, 5i, 5j, 5k, 5m, 5C, 5E, 5F, 5K, 5M and 5O showed diuretic activity.
