Electronically Tuned Chiral Ruthenium Porphyrins: Extremely Stable and Selective Catalysts for Asymmetric Epoxidation and Cyclopropanation
作者:Albrecht Berkessel、Patrick Kaiser、Johann Lex
DOI:10.1002/chem.200305045
日期:2003.10.6
cyclopropanation, and up to 14,200 for epoxidation, with ee values typically >90 % and approximately equal to 80 %, respectively. In one example, the axial CO ligand at the ruthenium was exchanged for PF(3), resulting in the first chiral ruthenium porphyrin with a PF(3) ligand reported to date. In cyclopropanations with ethyl diazoacetate, the latter catalyst performed exceedingly well, and gave a 95 % ee in the
我们报告了三种对映体纯和电子调谐钌羰基卟啉催化剂用于各种烯烃底物的不对称环丙烷化和环氧化。D(4)对称配体在每个9- [反-(1,2,3,4,5,6,7,8-八氢)的10位上带有甲氧基,甲基或三氟甲基-1,4:5,8-二甲氨基蒽)]-取代基在卟啉的介位上。在此偏远位置引入CF(3)取代基可大大提高催化剂的稳定性,对于环丙烷化而言,可实现高达7500的周转率,对于环氧化而言,可实现高达14,200的周转率,ee值通常> 90%且近似等于分别为80%。在一个示例中,钌上的轴向CO配体被交换为PF(3),导致迄今报道的首个具有PF(3)配体的手性钌卟啉。在用重氮乙酸乙酯进行环丙烷化反应中,后一种催化剂的性能非常好,在以1,1-二苯基乙烯为底物的情况下,ee的产率为95%。