1. Research & Development Center, Nagase & Co., Ltd., 2-2-3 Murotani, Nishi-ku, Kobe, Hyogo, 651-2241 Japan, Bio/Fine Chemicals Division, Nagase ChemteX Corporation, 1-52 Osadano-cho, Fukuchiyama, Kyoto, 620-0853 Japan, Saitama Factory, Taiho Pharmaceutical Co., Ltd., 200-22 Toyohara Motohara, Kamikawa-cho, Kodama, Saitama 367-0241 Japan, and Technological R & D Laboratories, Taiho Pharmaceutical Co., Ltd., 200-22 Toyohara Motohara, Kamikawa-cho, Kodama, Saitama 367-0241 Japan