Recyclable copper catalysts based on imidazolium-tagged C2-symmetric bis(oxazoline) and their application in D–A reactions in ionic liquids
作者:Zhi-Ming Zhou、Zhi-Huai Li、Xiao-Yan Hao、Xiao Dong、Xin Li、Li Dai、Ying-Qiang Liu、Jun Zhang、Hai-feng Huang、Xia Li、Jin-liang Wang
DOI:10.1039/c1gc15788d
日期:——
ionic liquids have been developed as a new class of versatile catalysts. C2-symmetric and unsymmetric imidazolium-tagged bis(oxazoline) ligands were prepared, and the anions of the ligands were altered by ion-exchange reactions. The catalysts based on the new ligands and Cu(OTf)2 were applied in asymmetric Diels–Alder reactions between N-acryloyl/N-crotonoyloxazolidinones 15 and 1,3-cyclohexandiene/cyclopentadiene
功能咪唑 离子液体 已被开发为一种新型的通用型 催化剂。C 2对称和不对称咪唑标记的双(恶唑啉)配体 准备好了,阴离子 配体被离子交换反应改变。这催化剂 基于新的 配体和Cu(OTf)2用于N-丙烯酰基/ N-巴豆酰恶唑烷酮15和1,3-环己二烯/环戊二烯16不同离子液体 和在 二氯甲烷 (DCM)。这催化剂获得了高水平的活性和对映选择性,以及良好的可回收性:在[Bmim] NTf 2中以98%的转化率和97%的ee获得了环加合物(S)-17ab 。而且,催化剂可以回收20次,而不会明显降低活性或对映选择性。相比之下,我们推导出新的C 2对称性配体对于获得高ee值至关重要。毒性研究配体 第一次进行。