Nonpeptide angiotensin II receptor antagonists. 2. Design, synthesis, and structure-activity relationships of 2-alkyl-4-(1H-pyrrol-l-yl)-1H-imidazole derivatives: profile of 2-propyl-1-[[2'-(1H-tetrazol-5-yl)-[1,1'-biphenyl]-4-yl]-methyl]-4-[2-(trifluoroacetyl)-1H-pyrrol-1-yl]-1H-imidazole-5-carboxylic acid (CI-996)