Disclosed is a compound represented by the formula (I): or a pharmacologically acceptable salt thereof, wherein Ar 1 represents an imidazolyl group which may be substituted by a C1-6 alkyl group, or the like, Ar 2 represents a phenyl group which may be substituted by a C1-6 alkoxy group, or the like, X 1 represents a double bond or the like, and Het represents an imidazolyl group which may be substituted by a C1-6 alkyl group, or the like. The compound or the salt is effective as a therapeutic or prophylactic agent for a disease associated with A².
