. . . . "More concretely, when X=S, R1 is a hydrogen atom, a halogen atom, a cyano group, a nitro group, an unsubstituted or substituted ester group preferably having 1 to 9 carbon atoms, an unsubstituted or substituted acyl group preferably having 1 to 9 carbon atoms, an unsubstituted or substituted alkyl group preferably having 1 to 8 carbon atoms, an unsubstituted or substituted alkoxy group preferably" . .