Guanidine‐annelated Heterocycles, VII: Synthesis and Antihypertensive Activity of 2,10‐Dimethyl‐5H, 10H‐1,2,4‐triazolo[5,1‐b]quinazolin‐5‐one

Abstract In some recent publications 2‐4 ), we reported the synthesis and antihypertensive activity of a number of condensed quinazoline and quinazolinone derivatives. Since the quinazolinone derivatives exhibited more potent activity in anesthetized animals, it would seem worth‐while to synthesize more derivatives in this series. Now, we wish to describe the method of preparing a new representative compound, which was characterized by bearing an annelated guanidine structural unit. This structural unit was found to be essential for hypotensive response when it was incorporated into a condensed ring system 5‐8 ).