epresents CH; [0166] compounds wherein R1 and R2 represent C1-4 alkoxy, R3 represents a group other than a hydrogen atom, R4, R5, and R6 represent a hydrogen atom, A represents group (iii) wherein n is 0 (zero), p is an integer of 1 to 3, and R16 and R17, which may be the same or different, represent C1-4 alkyl or may form a five- to seven-membered saturated heterocyclic ring optionally substitute