abstract |
Compounds having the formula <IMAGE> and basic salts thereof, wherein R1 is hydrogen, alkyl, aryl, arylalkyl or <IMAGE> wherein R5 is alkyl or aryl; R2 is hydrogen or alkyl; R3 is hydrogen, alkyl, aryl or arylalkyl; and R4 is hydrogen, alkyl, or arylalkyl; have useful hypotensive activity. |