| abstract |
A compound represented by the formula (3): (where ring A represents a benzene ring or a 6-membered aromatic heterocycle; R1 represents a hydrogen atom; each of R2 and R3 represents a methoxy group; R4 represents an atom hydrogen, and R5 represents a hydrogen atom or an electron acceptor group selected from a halogen atom, a nitro group, a trifluoromethyl group, a trichloromethyl group, a cyano group, an acetyl group, an acid sulfonic group and an acid group alkyl sulfonic acid). |