1. Laboratory of Medicinal Chemistry, Gifu Pharmaceutical University, Mitahora-higashi, Gifu 502-8585, Japan, Pharmaceuticals & Biotechnology Laboratory, Japan Energy Corporation, Niizo-minami, Toda 335-0026, Japan, and Research Division, Sumitomo Pharmaceuticals, Kasugade-naka, Konohana-ku, Osaka 554-0022, Japan