Abstract: The present invention provides compounds represented by general formula (I): or pharmaceutical acceptable salts thereof, wherein R1 is hydrogen or lower alkyl; R2 is lower alkyl, halo-lower alkyl, cycloalkyl, heterocycloalkyl, aryl, aralkyl, arylalkenyl, aryloxy-lower alkyl, heteroaryl, heteroaryl-lower alkyl, etc; R3, R4, R5 and R6 are each hydrogen, halogen, cyano, lower alkyl, halo-lower alkyl, lower alkoxy, hydroxy, aryl, etc; provided that at least one of R3, R4, R5 and R6 is other than hydrogen. Compound (I) of the present invention shows a potent adenosine A2A receptor antagonistic activity, and are useful for treating or preventing a disease mediated by adenosine A2A receptors such as motor function disorders, depression, anxiety disorders, cognitive function disorders, cerebral ischemia disorders, restless legs syndrome and the like.