1. Key Laboratory of Chemical Biology and Traditional Chinese Medicine Research, Ministry of Education, Key Laboratory of Phytochemical R&D of Hunan Province, College of Chemistry and Chemical Engineering, Hunan Normal University, Changsha, Hunan 410081, China
2. College
of Chemistry, Nankai University, Tianjin, 300071, China
3. Department
of Chemistry, Iowa State University, Ames, Iowa 50011, United States