已经开发出了使用H 2 O 2原位形成的锰配合物,可以以优异的收率(高达94%)和对映选择性(> 99%ee)对各种顺式,反式,端基和三取代的烯烃进行不对称环氧化。已经观察到配体施加的催化剂的疏水性与催化活性之间的关系。检查了酸添加剂的量和特性的影响,并且通过使用催化量的羧酸添加剂实现了改进的对映选择性。
Asymmetric Epoxidation of Alkenes Catalyzed by a Porphyrin-Inspired Manganese Complex
摘要:
A novel strategy for catalytic asymmetric epoxidation of a wide variety of olefins by a porphyrin-inspired chiral manganese complex using H2O2 as a terminal oxidant in excellent yield with up to greater than 99% ee has been successfully developed.
Asymmetric Counteranion-Directed Transition-Metal Catalysis: Enantioselective Epoxidation of Alkenes with Manganese(III) Salen Phosphate Complexes
作者:Saihu Liao、Benjamin List
DOI:10.1002/anie.200905332
日期:2010.1.12
Paired up: A highly active and enantioselective ion‐pair epoxidationcatalyst, consisting of an achiral MnIII–salen complex and a chiral phosphate counteranion, mediates the epoxidization of a wide range of alkenes with high yields and enantioselectivities (see scheme). The unique role of the counteranion is to stabilize an enantiomorphic conformation of the cationic Mn catalyst.
配对:高活性和对映选择性离子对环氧化催化剂,由非手性Mn III -salen配合物和手性磷酸抗衡阴离子组成,可介导高产率和对映选择性的多种烯烃的环氧化。抗衡阴离子的独特作用是稳定阳离子Mn催化剂的对映体构象。