Nonpeptide Arginine Vasopressin Antagonists for Both V1A and V2 Receptors : Synthesis and Pharmacological Properties of 4'-(1, 4, 5, 6-Tetrahydroimidazo[4, 5-d][1]benzoazepine-6-carbonyl)benzanilide Derivatives and 4'-(5, 6-Dihydro-4H-thiazolo[5, 4-d][1]benzoazepine-6-carbonyl)benzanilide Derivatives

Arginine vasopressin (AVP) has a dual action mainly in the periphery, i.e., vasoconstriction and water reabsorption via V1A and V2 receptors; it may play a role in a number of diseases, including congestive heart failure (CHF), hypertension, renal discase, edema, and hyponatremia. We have attempted to develop a new series of orally active AVP antagonists for both V1A and V2 receptors based on the hypothesis that the blockade of both V1A and V2 receptors might be beneficial to CHF patients. In this report, a series of compounds structurally related to 4'-(1, 4, 5, 6-tetrahydroimidazo[4, 5-d][1]benzoazepine-6-carbonyl)benzanilide and 4'-(5, 6-dihydro-4H-thiazolo[5, 4-d][1]benzoazepine-6-carbonyl)benzanilide were synthesized and examined for AVP antagonist activity for both V1A and V2 receptors. As a result, it was found that the 4'-(1, 4, 5, 6-tetrahydroimidazo[4, 5-d][1]benzoazepine-6-carbonyl)-2-phenylbenzanilide derivatives showed potent binding affinity for both V1A and V2 receptors. Especially, 4'-(2-methyl-1, 4, 5, 6-tetrahydroimidazo[4, 5-d][1]benzoazepine-6-carbonyl)-2-phenylbenzanilide monohydrochloride (18, YM087=conivaptan hydrochloride) exhibited potent binding affinity and AVP antagonist activity, after intravenous administration, for both V1A and V2 receptors. Furthermore, YM087 exhibited the most potent oral activity for the V2 receptor. Details of the synthesis and pharmacological properties of this series are presented.