Patent ID: 8211910

Claim:
A compound of formula (I): or a salt thereof, wherein R 1 and R 2 each represents hydrogen atom; R 3 represents an alkyl group containing 1 to 6 carbon atoms, which being optionally substituted with halogen atom; R 4 and R 5 together represent a 3-membered cyclic structure including the carbon atom shared by R 4 and R 5 to form a spirocyclic structure with the pyrrolidine ring; R 6 and R 7 , each represents hydrogen atom; R 8 represents a halogen-substituted cycloalkyl group containing 3 to 6 carbon atoms; R 9 represents hydrogen atom or an alkyl group containing 1 to 6 carbon atoms; X 1 represents hydrogen atom or a halogen atom; and A represents a moiety represented by formula (II): wherein X 2 represents an alkyl group containing 1 to 6 carbon atoms or an alkoxy group containing 1 to 6 carbon atoms.