Patent ID: 7820700

Claim:
A compound represented by the formula (I A ) or a salt thereof: wherein the symbols have the following meanings: R 1 : H or halogen, R 3 : H or lower alkyl, R 5 : —CN, R 6 : H or halogen, X: —O—, —N(R 8 )—, or —S—, R 8 : H or lower alkyl R 7 : linear or branched alkyl having 1 to 8 carbon atoms, linear or branched alkenyl having 3 to 8 carbon atoms, —Y-(cycloalkyl which may contain an oxygen atom), —Y-phenyl, or —Y-monocyclic heteroaryl, where the linear or branched alkyl having 1 to 8 carbon atoms and linear or branched alkenyl having 3 to 8 carbon atoms may be substituted with one to three groups selected from the group consisting of —CN, —O-lower alkyl, —S-lower alkyl, and halogen, which may be the same or different from each other; the cycloalkyl which may contain an oxygen atom, phenyl, and monocyclic heteroaryl may be substituted with one to four groups selected from the group consisting of —CN, halogen, and lower alkyl, which may be the same or different from each other, Y: bond, lower alkylene, lower alkenylene, or -(lower alkylene)-O—, where, when X is a group represented by —N(R 8 )—, R 8 and R 7 are combined together with the adjacent nitrogen atom to form a nitrogen-containing saturated heterocycle and the nitrogen-containing saturated heterocycle may be substituted with one or two groups selected from the group consisting of lower alkyl, —O-lower alkyl, —CON(lower alkyl) 2 , —CO 2 -lower alkyl, halogen, phenyl, (cycloalkyl which may be substituted with lower alkyl), and —O-lower alkylene-cycloalkyl, which may be the same or different from each other.