. . . . . . . "The substituent capable of being introduced into these groups includes, for example, a halogen atom such as a fluorine atom, a chlorine atom, a bromine atom, an iodine atom; an alkoxy group such as a methoxy group, an ethoxy group, a tert-butoxy group; an aryloxy group such as a phenoxy group, a p-tolyloxy group; an alkoxycarbonyl group such as a methoxycarbonyl group, a butoxycarbonyl group, a ph" . .