1. Tsukuba Research Laboratory, Tokuyama Corporation, 40 Wadai, Tsukuba 300-4247, Japan, Faculty of Pharmaceutical Sciences, Nagasaki University, 1-14 Bunkyo-machi, Nagasaki 852-8131, Japan, and Institute for Fundamental Research of Organic Chemistry, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan