ENDOTHELIN RECEPTOR ANTAGONISTS

The present invention provides novel compounds represented by general formula (I) wherein R1 is a straight or branched lower alkyl, a cycloalkyl-lower alkyl, an aryl-lower alkyl, a cycloalkyl, an aryl, an aryl-cycloalkyl, lower alkoxy, an aryloxy, or a heteroaryl; R2 is hydrogen, a straight or branched lower alkyl, a cycloakyl, or a cycloalkyl-lower alkyl; R3 and R3' are each the same or different and each is hydrogen atom, a straight or branched lower alkyl, a cycloalkyl, an aryl-lower alkyl, an aryl, or a heteroaryl; or R3 and R3' together form a ring structure; R3'' is hydrogen, lower alkyl or an aryl; or R2 and R3'' together form a lower alkylene group -(CH2)n- wherein n is an integer of 1, 2 or 3; or R2 and R3'' together form a group represented by the formula: -(CH2)p-Ar- or -Ar-(CH2)p-, respectively, wherein p is zero or an integer of 1 or 2, and Ar is an arylene or heteroarylene; C(=X) is C(=O), C(=S), C(=NH), C(=N-lower alkyl); C=NH-OH, or CH2; Y is a direct bond, -NH-, a lower alkyl-N=, an oxygen atom, or methylene; or C(=X) is CHOH and Y is a direct bond or methylene; R4 is -(CH2)s-Ar' wherein s is zero or an integer of 1, 2 or 3; and Ar' is an aryl, or heteroaryl; and R5 is carboxy, substituted or unsubstituted carboxamide, PO(OH)2, tetrazole, CH2OH, CN, or hydrogen; and salts thereof.