SYNTHETIC STUDIES ON CONDENSED-AZOLE DERIVATIVES .5. SYNTHESIS AND ANTIASTHMATIC ACTIVITIES OF SULFAMOYLALKYLOXY[1,2,4]TRIAZOLO[1,5-B]PYRIDAZINES

A series of novel triazolo[1,5-b]pyridazin-6-yl)oxyalkylsulfonamides w as synthesized and evaluated for the ability to inhibit platelet activ ating factor (PAF)-induced bronchoconstriction in guinea pigs. The com pounds bearing a gem-dialkyl or a cycloalkylidene group at the 2 posit ion of the sulfamoylpropyloxy group in the side chain and a methyl gro up at the 7 position were found to have potent activity. Among them, 2 ,2-diethyl-3-(methyl[1,2,4]triazolo [1,5-b]pyridazin-6-yl)oxypropanesu lfonamide (13) showed excellent anti-asthmatic activity Compounds 13 m ay be of significant value in the treatment of asthma and other respir atory diseases. The structure-activity relationships in this series of compounds are discussed.