A series of imidazole-5-carboxylic acids bearing alkyl, alkenyl, and hydroxyalkyl substituents at the 4-position and their related compounds were prepared and evaluated for their antagonistic activities to the angiotensin II (AII) receptor. Among them, the 4-(1-hydroxyalkyl)-imidazole derivatives had strong binding affinity to the AII receptor and potently inhibited the AII-induced pressor response by intravenous administration. Various esters of these acids showed potent and long-lasting antagonistic activity by oral administration. The most promising compounds were (5-methyl-2-oxo-1,3-dioxol-4-yl)methyl (CS-866) and (pivaloyloxy)-methyl esters of 4-(1-hydroxy-1-methylethyl)-2-propyl-1-[(2'-1H-tetrazol-5- ylbiphenyl-4-yl)-methyl]imidazole-5-carboxylic acid (26c). A study involving stereochemical comparison of 26c with the acetylated C-terminal pentapeptide of AII was also undertaken.

alpha-[(3S)-3-[[(S)-1-(Ethoxycarbonyl)-3-phenylpropyl]amino]-2-oxo-6 or 7-phenylperhydroazepin-1-yl]acetic acids (monoester monoacids) and their dicarboxylic acids were synthesized, and their angiotensin-converting enzyme (ACE) inhibitory activities were evaluated. The dicarboxylic acids having phenyl substituents at the 6R, 6S, and 7S positions on the azepinone ring showed potent inhibition in vitro. The corresponding monoester monoacids, when administered orally, suppressed the pressor response to angiotensin I administered intravenously. The monoester monoacids having the phenyl substituent at the 6-position showed a longer duration of action than one having the substituent at the 7-position. The structure-activity relationship was studied on the basis of the conformational energy calculation.

Statine, (3S,4S)-4-amino-3-hydroxy-6-methylheptanoic acid, and its analogues were prepared from 5,6-anhydro-3-deoxy-1,2-O-isopropylidene-d-glucofuranose. The key step is the stereospecific reaction of the epoxy sugar with the Grignard reagent.

alpha-[6-[[(S)-1-(Ethoxycarbonyl)-3-phenylpropyl]amino]-5-oxoperhydro -1,4-thiazepin-4-yl]acetic acids (monoester monoacids) and their dicarboxylic acids having the hydrophobic substituents at the 2- or 3-position of the thiazepinone ring were prepared and assayed for angiotensin-converting enzyme (ACE) inhibitory activity. The dicarboxylic acids having the pseudoequatorial amino groups at the 6-position and the pseudoequatorial hydrophobic substituents at the 2- or 3-position of the chair conformation of the thiazepinone ring had potent in vitro inhibitory activity. The monoester monoacids having the hydrophobic substituents at the 2-position suppressed pressor response to angiotensin I for a longer duration than those having the substituents at the 3-position when administered orally. The structure-activity relationship was studied by conformational energy calculations of the thiazepinone ring.

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