Asymmetric cyclopropanation of styrenes catalyzed by metal complexes of D2-Symmetrical chiral porphyrin:: Superiority of cobalt over iron
Asymmetric cyclopropanation of styrenes catalyzed by metal complexes of D2-Symmetrical chiral porphyrin:: Superiority of cobalt over iron
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DOI：
10.1021/jo070997p
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发表时间：
2007-07-20
影响因子：
3.6
通讯作者：
Zhang, X. Peter
中科院分区：
文献类型：
--
作者：
Chen, Ying;Zhang, X. Peter
D-2-对称手性卟啉[Co（1）]的钴（II）配合物是一种有效的催化剂，在温和的条件下可用于苯乙烯衍生物的高非对映选择性和对映选择性的环丙烷化反应。重氮化合物的二聚化是金属介导的卡宾转移过程中常见的副反应，在钴卟啉基系统中最小化，避免了使用过量底物和缓慢添加重氮化合物的需要。[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，因为使用相同配体[Fe（1）Cl]的铁（III）络合物以低收率和差的对映选择性提供所需的环丙烷产物。
The cobalt(II) complex of D-2-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 substrates and slow addition of diazo compounds. The high catalytic activity and selectivity of [Co(1)] evidently resulted from the appropriate combination of the cobalt ion and the chiral porphyrin 1 as the use of iron(III) complex of the same ligand [Fe(1)Cl] afforded the desired cyclopropane products in low yields and poor enantioselectivity.