Nonpeptide endothelin antagonists I

A method of treating pulmonary hypertension comprising administering to a host suffering therefrom a therapeutically effective amount of a compound of formula I wherein formula I is ##STR462## or a tautomeric open chain keto-acid form thereof or a pharmaceutically acceptable salt thereof wherein

• R.sub.1 is cycloalkyl substituted or unsubstituted of from 3 to 12 carbon atoms,
• phenyl substituted with from 1 to 5 substituents, naphthyl unsubstituted or substituted with from 1 to 5 substituents, or
• heteroaryl unsubstituted or substituted with from 1 to 5 substituents;
• R.sub.2 is alkyl substituted or unsubstituted straight or branched of from 1 to 12 carbon atoms,
• cycloalkyl substituted or unsubstituted of from 3 to 12 carbon atoms,
• aryl which is unsubstituted or substituted with from 1 to 5 substituents,
• heteroaryl which is unsubstituted of substituted with from 1 to 3 substituents;
• R.sub.3 is substituted or unsubstituted straight or branched of from 1 to 12 carbon atoms,
• cycloalkyl substituted or unsubstituted of from 3 to 12 carbon atoms,
• aryl which is unsubstituted or substituted with from 1 to 5 substituents,
• heteroaryl which is unsubstituted or substituted with from 1 to 3 substituents;
• R.sub.4 is hydroxy or OR.sub.5,
• SR.sub.5, wherein R.sub.5 is alkyl or substituted alkyl of from 1 to 7 carbon atoms, or
• (CH.sub.2).sub.n OR.sub.5 wherein n is an integer of from 1 to 3;
• X is O or S;
• with the proviso that when R.sub.1 is monosubstituted phenyl and the substituent is p-methoxy, R.sub.3 is not unsubstituted phenyl, monosubstituted phenyl, or mesityl and with the further proviso when R.sub.2 is alkyl substituted, the substituent is not oxygen at the .alpha.-position to the furanone ring;
• and with the proviso that any of R.sub.1 through R.sub.4 are heterocyclic containing in unit dosage form.