Synthesis and antihypertensive activity of 3-[(substituted-carbonyl)amino]-2H-1-benzopyrans

The synthesis and antihypertensive activity of a series of novel 3-[(substituted-carbonyl)amino]-2H-1-benzopyran-4-ols, administered orally to spontaneously hypertensive rats, are described. Optimum activity in this series was observed for compounds with branched alkyl or branched alkylamino groups flanking the carbonyl or thiocarbonyl group (21, 31-33), which were approximately equipotent to cromakalim. Replacement of the 4-hydroxyl group by hydrogen, methoxy, or amino in this series only led to a slight reduction in potency. These observations are in marked contrast to the structure-activity relationships previously found for the 4-amidobenzopyran-3-ols. The antihypertensive activity of representative compounds 15 and 33 was attempted by preatreatment with glibenclamide, and thus these compounds may belong to the series of drugs which have been classified as potassium channel activators.