. . . "tituent, or a benzyl group which may have a substituent (examples of the substituent of the phenyl group and the benzyl group include a hydroxyl group; a halogen atom such as a fluorine atom, chlorine atom, bromine atom, or iodine atom; a C1-C6 alkyl group such as a methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, sec-butyl group, t-butyl group, n-pentyl group, isopentyl" .