Mechanistic Aspects of Metal Valence Change in SalenCo(III)OAc-Catalyzed Hydrolytic Kinetic Resolution of Racemic Epoxides
发表时间：2019-03-09
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- 论文类型：
- 期刊论文
- 第一作者：
- Ren, Wei-Min
- 通讯作者：
- Lu, XB (reprint author), Dalian Univ Technol, Coll Chem, State Key Lab Fine Chem, 2 Linggong Rd, Dalian 116024, Peoples R China.
- 合写作者：
- Wang, Yi-Ming,Zhang, Rong,Jiang, Jing-Yang,Lu, Xiao-Bing
- 发表时间：
- 2013-05-17
- 发表刊物：
- JOURNAL OF ORGANIC CHEMISTRY
- 收录刊物：
- SCIE、EI、PubMed、Scopus
- 文献类型：
- J
- 卷号：
- 78
- 期号：
- 10
- 页面范围：
- 4801-4810
- ISSN号：
- 0022-3263
- 摘要：
- The chiral SalenCo(III)OAc-catalyzed hydrolytic kinetic resolution (HKR) of racemic terminal epoxides to afford both enantioenriched epoxides and diols presents one of the most important achievements in asymmetric synthesis chemistry. Previous studies mainly focused on the development of highly efficient catalysts, while rare reports concerned the mechanistic understanding of metal valence change, associated with the formation of inactive Co(II)-Salen complex. Herein, we report the mechanistic aspects of catalyst deactivation regarding the transformation of Co(III) to Co(II) derivative in the HKR of racemic epoxides catalyzed by SalenCo(III)OAc complexes with an appended 1,5,7-triazabicyclo[4.4.0]dec-5-ene on the ligand framework by means of electrospray ionization mass spectrometry (ESI-MS). Continuous determination of transient cationic species in ESI-MS positive mode in conjunction with UV-vis spectroscopic studies at various time points provides evidence that a certain amount of SalenCo(III)OAc molecules were reduced to the corresponding Co(II) derivatives in the HKR of racemic propylene oxide or styrene oxide. To be accompanied by the reduction of Co(III) to Co(II), the resultant diols were oxidized to alpha-hydroxy ketones. These analyses along with some control experiments gave a mechanistic understanding of catalyst deactivation of SalenCo(III)OAc-catalyzed HKR of racemic epoxides regarding an unveiled redox reaction between Co(III)-Salen and diol, the hydrolyzed product.
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- 否
