1. Department of Chemistry Tokyo Institute of Technology 2-12-1 O-okayama, Meguro-ku Tokyo 152-8551 Japan
2. Present address: Showa Pharmaceutical University 3-3165 Higashi-Tamagawagakuen, Machida Tokyo 194-8543 Japan
3. Present address: Graduate School of Pharmaceutical Sciences Kyoto University Yoshida, Sakyo-ku Kyoto 606-8501 Japan