1. Department of Chemistry Tsinghua University Beijing 100084 P. R. China
2. The State Key Laboratory of Chemical Oncogenomics Key Laboratory of Chemical Biology Tsinghua Shenzhen International Graduate School Shenzhen 518055 P. R. China
3. Shenzhen Grubbs Institute and Department of Chemistry Guangdong Provincial Key Laboratory of Catalysis Southern University of Science and Technology Shenzhen 518055 P. R. China
4. School of Pharmaceutical Sciences Tsinghua University Beijing 100084 P. R. China