1448015-56-2Relevant academic research and scientific papers
Asymmetric epoxidation of unfunctionalized olefins with C2-symmetrical diphenol-derived axially coordinated homogeneous chiral bi-Mn(III) salen complexes
Dong, Tianyi,Wu, Xiaoju,Cai, Jiali,Huang, Jing
, p. 57 - 61 (2019)
A novel type of C2-symmetrical diphenol-derived and axially coordinated homogeneous chiral bi-Mn(III) salen complexes are synthesized and their catalytic effects in asymmetric epoxidation of unfunctionalized olefins are investigated in details. The results show that excellent enantioselectivities and high activities are achieved (enantioselectivities up to >99% in 99.9%) in the absence of expensive NMO. Compared with Jacobsen's catalyst, the configuration of C2-symmetrical homogeneous chiral bi-Mn(III) salen complex contribute to the catalytic reactivity and stability. Furthermore, these new homogeneous catalysts could be easily recovered and reused for 5 cycles without significant loss of their properties.
Novel bis-Salen Mn(III) chiral complexes of rigid structure axially coordinated with bis-diphenolate and bis-diamine for epoxidation of unfunctionalized olefins
Huang, Xuemei,Fu, Xiangkai,Wu, Xiaoju,Jia, Ziyong
, p. 4041 - 4044 (2013/07/25)
A series of bis-Salen Mn(III) chiral complexes of rigid structure axially coordinated with bis-diphenolate and bis-diamine ligands were synthesized and their catalytic performances in asymmetric epoxidation of indene and α-methylstyrene were investigated in detail. Compared with Jacobsen's catalyst and the corresponding monomer salen Mn(III) catalyst, bis-Salen Mn complex showed higher activity and enantioselectivity under the same reaction conditions. A point worth emphasizing was that the bis-diphenolate axially coordinated bis-Salen Mn catalysts afforded remarkable increases of ee values in the absence of axial base NMO for the asymmetric epoxidation of olefins, especially for the epoxidation of indene (ee: from 55% to 100%), however, the axial base is indispensable for the bis-diamine axially coordinated bis-Salen Mn(III) catalysts, these performance might attribute to the rigid difference of the structure. Furthermore, the catalyst could be conveniently recovered and reused at least five times without significant losses of both activity and enantioselectivity. Specially, it could also be efficiently used in large-scale reactions with superior catalytic disposition being maintained at the same level, which possessed the potentiality for application in industry.
