1. Department of Medicinal Chemistry School of Pharmacy Qingdao University 308 Ningxia Road Qingdao Shandong 266021 People's Republic of China
2. Shenzhen Grubbs Institute and Department of Chemistry Guangdong Provincial Key Laboratory of Catalysis College of Science Southern University of Science and Technology 1088 Xueyuan Blvd., Nanshan District Shenzhen Guangdong 518055 People's Republic of China