A macrocyclic chiral manganese(III) Schiff base complex as an efficient catalyst for the asymmetric epoxidation of olefins
作者:A MARTINEZ、C HEMMERT、B MEUNIER
DOI:10.1016/j.jcat.2005.06.021
日期:2005.9.10
A new chiral macrocyclic Mn(III)-salen complex has been prepared with two salicylidene moieties linked together to their 3 and 3′ positions by an aliphatic polyether bridge. This complex provides a highly enantioselective (up to 93%) catalyst for epoxidation of cis-disubstituted olefins with sodium hypochlorite as an oxygen atom donor and can be recycled up to three times without significant loss in
We describe a general synthetic strategy for the preparation of a series of macrocyclicchiral manganese(III) salen complexes. The developed reaction pathway allows the modulation of the different key groups, namely, the chiral diimine, the bulky substituents in positions 3 and 3‘, and the linker used in the macrocyclization of the Schiff base. The different complexes presented here illustrate these
我们描述了一系列的大环手性锰(III)萨伦配合物的制备的一般合成策略。发达的反应途径允许调节不同的关键基团,即手性二亚胺,3和3'位的大取代基以及席夫碱大环化中使用的连接基。这里介绍的不同复合物说明了这些容易获得的结构变化。通过NaOCl或H 2 O 2对2,2'-二甲基亚甲基不对称环氧化反应,提高了催化剂的催化性能(5 mol%)。作为氧原子供体。根据配合物的特征和稳定性,获得了大量的对映体过量(ee值从30%到96%)。就立体感应而言,最有效的催化剂(ee值= 96%)包含二亚氨基环己基部分,位置3和3'的乙基和短的聚醚连接臂。