Oxygen Atom Transfer Mechanism for Vanadium-Oxo Porphyrin Complexes Mediated Aerobic Olefin Epoxidation

• 作者: Xiao-Hui Liu Jia-Ying Huang Lei-Ming Tao Hai-Yang Yu Xian-Tai Zhou Can Xue Qi Han Wen Zou Hong-Bing Ji
• 来源期刊: 中国化学（英文版）
• 年，卷（期）: 2022,（1）
• 所属期刊栏目: Comprehensive Reports
• 页码范围: 115-122
• 页数: 8页
• 语种: 英文
• DOI: 10.1002/cjoc.202100576

摘要

The development of catalytic aerobic epoxidation by numerous metal complexes in the presence of aldehyde as a sacrificial reduct-ant (Mukaiyama epoxidation) has been reported,however,comprehensive examination of oxygen atom transfer mechanism involv-ing free radical and highly reactive intermediates has yet to be presented.Herein,meso-tetrakis(pentafluorophenyl) porphyrina-tooxidovanadium(Ⅳ) (VOTPFPP) was prepared and proved to be efficient toward aerobic olefin epoxidation in the presence of iso-butyraldehyde.In situ electron paramagnetic resonance spectroscopy (in situ EPR) showed the generation,transfer pathways and ascription of free radicals in the epoxidation.According to the spectral and computational studies,the side-on vanadium-peroxo complexes are considered as the active intermediate species in the reaction process.In the cyclohexene epoxidation catalyzed by VOTPFPP,the kinetic isotope effect value of 1.0 was obtained,indicating that epoxidation occurred via oxygen atom transfer mecha-nism.The mechanism was further elucidated using isotopically labeled dioxygen experiments and density functional theory (DFT)calculations.