1. Department of Chemistry, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan, Laboratory for Organic Chemistry, Swiss Federal Institute of Technology (ETH) Zürich, HCI F 315, Wolfgang-Pauli-Str. 10, 8093 Zürich, Switzerland, and Nakamura Functional Carbon Project, ERATO, JST Hongo, Bunkyo-ku, Tokyo 113-0033, Japan