Novel bis-Salen Mn(III) chiral complexes of rigid structure axially coordinated with bis-diphenolate and bis-diamine for epoxidation of unfunctionalized olefins
作者:Xuemei Huang、Xiangkai Fu、Xiaoju Wu、Ziyong Jia
DOI:10.1016/j.tetlet.2013.05.087
日期:2013.7
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
合成了一系列刚性结构与双二酚盐和双二胺配体轴向配位的双结构Salen Mn(III)手性配合物,并详细研究了它们在茚和α-甲基苯乙烯不对称环氧化反应中的催化性能。与Jacobsen催化剂和相应的单体Salen Mn(III)催化剂相比,双Salen Mn配合物在相同反应条件下显示出更高的活性和对映选择性。值得强调的一点是,在不存在轴向碱NMO的情况下,双二酚酸酯轴向配位的双Salen Mn催化剂可显着提高ee值,因为烯烃不对称环氧化,尤其是茚的环氧化(ee:从55% 100%),但是轴向碱对于双二胺轴向配位的双Salen Mn(III)催化剂是必不可少的,这些性能可能归因于结构的刚性差异。此外,该催化剂可以方便地回收和再使用至少五次,而活性和对映选择性均没有显着损失。特别地,它还可以有效地用于大规模反应中,同时保持优异的催化处置水平,这具有工业应用潜力。