Endothelin antagonistic heteroaromatic ring-fused cyclopentene derivatives

A heteroaromatic ring-fused cyclopentene derivative of the formula:

• ##STR20## wherein each of Ar.sup.1 and Ar.sup.2 is independently a phenyl group or a thienyl group wherein an optional hydrogen atom(s) on the aromatic ring may be replaced with 1 to 4 groups selected from the group consisting of a hydroxyl group, a carboxyl group, a C.sub.1 -C.sub.6 alkoxy carbonyl group, a mono- or di- C.sub.1 -C.sub.6 alkylaminocarbonyl group, a carbamoyl group, a tetrazol-5-yl group a methylenedioxy group, a C.sub.1 -C.sub.6 alkoxy group, a C.sub.1 -C.sub.6 alkyl group and a C.sub.2 -C.sub.6 alkenyl group (provided that the C.sub.1 -C.sub.6 alkoxy group, the C.sub.1 -C.sub.6 alkyl group and the C.sub.2 -C.sub.6 alkenyl group may be substituted by a hydroxyl group, an amino group, a mono- or di- C.sub.1 -C.sub.6 alkylamino group, a C.sub.1 -C.sub.6 alkoxy carbonyl group, a mono- or di- C.sub.1 -C.sub.6 alkylaminocarbonyl group, a carbamoyl group, a carboxyl group, a tetrazol-5-yl group, a 2-oxo-3H-1,2,3,5-oxathiadiazol-4-yl group, a 2,2-dioxo-3H-1,2,3,5-oxathiadiazol-4-yl group, or a 5-oxo-4H-1,2,4-oxadiazol-3-yl group);
• each of R.sup.1, R.sup.2 and is independently a hydrogen atom, a hydroxyl group or a C.sub.1 -C.sub.6 alkyl group, or R.sup.1 and R.sup.2, or and R.sup.2 and R.sup.3 together form a single bond;
• Y is a group of --CO--R.sup.4 (wherein R.sup.4 is a hydroxyl group, an amino group, a C.sub.1 -C.sub.6 alkoxy group, a mono- or di- C.sub.1 -C.sub.6 alkylamino group, an arylsulfonylamino group wherein an optional hydrogen atom(s) on the aryl ring may be replaced with a C.sub.1 -C.sub.6 alkyl group, or a C.sub.1 -C.sub.6 alkylsulfonylamino group which may be substituted by an aryl group on the alkyl moiety), a sulfo group, a phosphono group, a tetrazol-5-yl group a 2-oxo-3H-1,2,3,5-oxathiadiazol-4-yl group, a 2.2-dioxo-3H-1,2,3,5-oxathiadiazol-4-yl group, or a 5-oxo-4H-1,2,4-oxadiazol-3-yl group;
• and A is a group which forms together with the adjacent carbon-carbon double bond a heteroaromatic ring selected from the group consisting of pyridine, pyrimidine, pyridazine, pyrazine and thiazole (provided that an optional hydrogen atom(s) on the heteroaromatic ring may be replaced with a hydroxyl group, an amino group, a C.sub.1 -C.sub.6 alkoxy group, a halogen atom, a cyano group, a nitro group, a mono- or di- C.sub.1 -C.sub.6 alkylamino group, a carboxyl group, a C.sub.1 -C.sub.6 alkoxycarbonyl group, a C.sub.1 -C.sub.6 acyl group, an aroyl group, or a C.sub.1 -C.sub.6 alkyl group, C.sub.2 -C.sub.6 alkenyl group or C.sub.2 -C.sub.6 alkynyl group which may be substituted by a C.sub.1 -C.sub.6 alkoxy group or a C.sub.1 -C.sub.6 alkylamino group, and a nitrogen atom of said heteroaromatic ring may be oxidized to form an N-oxide group);
• or a pharmaceutically acceptable salt thereof.