Compounds represented by general formula (I) or salts thereof, a process for producing the same, and a remedy for hyperphagia, adiposis, or diabetes which comprises the same as the active ingredient: wherein A represents nitrogen or a group represented by C-R5; Ar1 represents aryl optionally having substituent(s) selected from the group consisting of halogeno, lower alkyl, and lower haloalkyl; Ar2 represents aryl or heteroaryl optionally having substituent(s) selected from the group consisting of halogeno, lower alkyl, lower alkenyl, lower haloalkyl, lower alkoxy, lower alkylthio, lower alkylamino, lower dialkylamino, and aryl; R1 represents hydrogen or lower alkyl or is bonded to R5 to represent a bond; R2 represents hydrogen or lower alkyl; R?3 and R4¿ are the same or different and each represents hydrogen or lower alkyl, or R?3 and R4¿ are bonded to each other to represent C¿2-4? alkylene optionally having lower alkyl; and R?5¿ represents hydrogen, hydroxy, lower alkyl, or lower alkoxy or is bonded to R1 to represent a bond.