Triazolinones as Nonpeptide Angiotensin II Antagonists. 1. Synthesis and Evaluation of Potent 2,4,5-Trisubstituted Triazolinones

Article abstract of DOI:10.1021/jm00069a015

A series of 2,4-dihydro-2,4,5-trisubstituted-3H-1,2,4-triazol-3-ones was prepared via several synthetic routes and evaluated as AII receptor antagonists in vitro and in vivo.The preferred compounds contained a <2'-(5-tetrazolyl)biphenyl-4-yl>methyl side chain at N⁴ and an n-butyl group at C⁵.A number of these bearing an alkyl or aralkyl substituent at N² showed in vitro potency in the nanomolar range (rabbit aorta membrane receptor), and several of these, e.g., the 2,2-dimethyl-1-propyl analogue (54, IC50 = 2.1 nM), effectively blocked the AII pressor response in conscious rats with significant duration (2.5 h at 1 mg/kg orally for 54).Among analogues possessing aryl substituents at N², ortho substitution on the phenyl moiety resulted in several derivatives with in vitro potency in the low nanomolar range.One of these, featuring a 2-(trifluoromethyl)phenyl substituent at N² (25, IC50 = 1.2 nM), was effective at 1 mg/kg orally in the rat model, with a duration of >6 h.Implications for hydrophobic and hydrogen-bonding interactions with the AT₁ receptor are discussed.