1. Shanghai-Hong Kong Joint Laboratory in Chemical Synthesis; Shanghai Institute of Organic Chemistry; The Chinese Academy of Sciences; 345 Ling Ling Road Shanghai 200032 P. R. China
2. Department of Chemistry; Center of Novel Functional Molecules; Institute of Molecular Functional Materials and State Key Laboratory of Synthetic Chemistry; The Chinese University of Hong Kong; Shatin, New Territories Hong Kong SAR P. R. China