1. Organic Synthesis Research Laboratory, Sumitomo Chemical Co., Ltd., 1-98 Kasugade-naka, 3-chome, Konohana-ku, Osaka 554-8558, Japan, and Department of Chemistry, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima 739-8526, Japan %itagakim@sc.sumitomo-chem.co.jp