1. Department of Applied Chemistry, Kogakuin University, Nakano 2665-1, Hachioji, Tokyo 192-0015, Japan
2. Department of Synthetic Organic Chemistry, Meiji Pharmaceutical University, Noshio 2-522-1, Kiyose, Tokyo 204-8588, Japan
3. Department of Medicinal Chemistry, Faculty of Pharmaceutical Sciences, Hokkaido University of Science, Maeda 15-4-1, Teine, Sapporo, Hokkaido 006-8585, Japan