Polyglycerol-Supported Chromium-Salen as a High-Loading Dendritic Catalyst for Stereoselective Diels–Alder Reactions
作者:Chakib Hajji、Sebastian Roller、Maryam Beigi、Andreas Liese、Rainer Haag
DOI:10.1002/adsc.200606168
日期:2006.8
hyperbranched polyglycerol (PG) 3 as a polymeric support for asymmetric catalysis. A new polyglycerol-supported unsymmetrical salen ligand 4 is described, which was successfully purified by gel permeation chromatography (GPC) or by ultrafiltration. After the insertion of the metal, e.g., chromium, the corresponding polymeric chromium complex was used as catalyst for asymmetric Diels–Alder reactions between
在本文中,我们演示了超支化聚甘油(PG)3作为不对称催化的聚合物载体的应用。描述了一种新的聚甘油负载的不对称Salen配体4,它已通过凝胶渗透色谱法(GPC)或超滤成功地纯化。插入金属(例如铬)后,相应的聚合铬络合物被用作Danishefsky的二烯与苯甲醛之间不对称Diels-Alder反应的催化剂。催化活性(高达98%的转化率)和对映选择性(高达78%ee))与Jacobsen报告的原始催化剂相当。催化反应后,通过透析回收可溶性聚甘油负载的催化剂,并循环两次以提供与第一次实验相同的反应性,对映选择性略有降低。此外,该聚合物载体催化剂在连续操作的膜反应器中显示出高的保留率(99.02%)。