Preferable compounds of formula (I) according to the present invention includes a compound in which R2 is a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, or an alkyl group having 1 to 6 carbon atoms substituted with 1 to 5 halogen atoms, more preferably a compound in which R2 is an alkyl group having 1 to 6 carbon atoms or a trifluoromethyl group and yet more preferably