Pyrazolidine-3,5-dione angiotensin-II receptor antagonists

The crystal structures of three angiotensin-II receptor antagonists involvi ng different spacer groups (CO, CONH and NHCO) between the aryl rings are p resented, namely 2-{4-[(3-butyl-1,4-dioxo-2,3-diazaspiro[4.4]non-2-yl)methy l]-benzoyl}benzoic acid, C26H28N2O5, (I), 2-{4-[(3-butyl-1,4dioxo-2,3-diaza spiro[4.4]non-2-yl)methyl]benzamido}benzoic acid, C26H29N3O5, (II), and 2-{ 4-[(3-butyl-1,4-dioxo-2,3-diazaspiro[4.4]non-2-yl)methyl]anilinocarbonyl}be nzoic acid monohydrate, C26H29N3O5.H2O, (III). The aryl rings of (II) are a lmost coplanar, in contrast with compounds (I) and (III). The conformation of (II) is induced by an intramolecular N- H . . .O hydrogen bond between t he amide and carboxylic acid groups.