D 2对称手性卟啉[Co(1)]的钴(II)配合物是在温和条件下对多种苯乙烯衍生物进行高度非对映选择性和对映选择性环丙烷化的有效催化剂。在基于钴卟啉的体系中,重氮化合物的二聚反应(在金属介导的卡宾转移过程中常见的副反应)被最小化,从而避免了使用过量底物和缓慢添加重氮化合物的需求。[Co(1)]的高催化活性和选择性显然是由于钴离子和手性卟啉1的适当组合,因为使用了具有相同配体[Fe(1)的铁(III)配合物)Cl]以低收率和差的对映选择性提供所需的环丙烷产物。
The highly enantioselective cyclopropanation of styrenes and diazoacetates proceeded in alcohol or aqueous alcohol in the presence of the β-ketoiminato cobalt(II) complex. Water and alcohols accelerated the reaction and improved the diastereo- and enantioselectivities. In these media, the α,α-disubstituted styrenes were smoothly cyclopropanated with high enantiomeric excess.
Catalyst structure and the enantioselective cyclopropanation of alkenes by copper complexes of biaryldiimines: the importance of ligand acceleration
作者:Christopher J Sanders、Kevin M Gillespie、Peter Scott
DOI:10.1016/s0957-4166(01)00157-4
日期:2001.5
The use of chiral non-racemic biaryl copper(I) complexes in the enantioselective cyclopropanation of a number of olefins with either ethyl or tert-butyl diazoacetate: is described. Lack of ligand acceleration and the presence of equilibrium amounts of catalytically active uncomplexed Cu(I) ions account for lowered enantioselectivity when using certain ligands. (C) 2001 Elsevier Science Ltd. All rights reserved.
Asymmetric Cyclopropanation of Styrenes Catalyzed by Metal Complexes of <i>D</i><sub>2</sub>-Symmetrical Chiral Porphyrin: Superiority of Cobalt over Iron
作者:Ying Chen、X. Peter Zhang
DOI:10.1021/jo070997p
日期:2007.7.1
The cobalt(II) complex of D2-symmetric chiral porphyrin [Co(1)] is an effective catalyst for highly diastereoselective and enantioselective cyclopropanation of a broad range of styrene derivatives under mild conditions. Dimerization of diazo compounds, a common side reaction in metal-mediated carbene transfer processes, is minimized in a cobalt porphyrin-based system, obviating the need to employ excess
D 2对称手性卟啉[Co(1)]的钴(II)配合物是在温和条件下对多种苯乙烯衍生物进行高度非对映选择性和对映选择性环丙烷化的有效催化剂。在基于钴卟啉的体系中,重氮化合物的二聚反应(在金属介导的卡宾转移过程中常见的副反应)被最小化,从而避免了使用过量底物和缓慢添加重氮化合物的需求。[Co(1)]的高催化活性和选择性显然是由于钴离子和手性卟啉1的适当组合,因为使用了具有相同配体[Fe(1)的铁(III)配合物)Cl]以低收率和差的对映选择性提供所需的环丙烷产物。