Holbach Michael, Weck Marcus
School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332-0400, USA.
J Org Chem. 2006 Mar 3;71(5):1825-36. doi: 10.1021/jo051919+.
We report a modular approach toward polymer-supported, metalated, salen catalysts. This strategy is based on the synthesis of monofunctionalized Mn- and Co-salen complexes attached to a norbornene monomer via a stable phenylene-acetylene linker. The resulting functionalized monomers can be polymerized in a controlled fashion using ring-opening metathesis polymerization. This polymerization method allows for the synthesis of copolymers, resulting in an unprecedented control over the catalyst density and catalytic-site isolation. The obtained polymeric manganese and cobalt complexes were successfully used as supported catalysts for the asymmetric epoxidation of olefins and the hydrolytic kinetic resolution of epoxides. All polymeric catalysts showed outstanding catalytic activities and selectivities comparable to the original catalysts reported by Jacobsen. Moreover, the copolymer-supported catalysts are more active and selective than their homopolymer analogues, providing further proof that catalyst density and site isolation are key toward highly active and selective supported salen catalysts.
我们报道了一种制备聚合物负载的金属化席夫碱催化剂的模块化方法。该策略基于通过稳定的亚苯基乙炔连接基合成与降冰片烯单体相连的单官能化锰和钴席夫碱配合物。所得的官能化单体可以通过开环易位聚合以可控方式进行聚合。这种聚合方法能够合成共聚物，从而实现对催化剂密度和催化位点隔离前所未有的控制。所制备的聚合物锰和钴配合物成功用作烯烃不对称环氧化和环氧化物水解动力学拆分的负载型催化剂。所有聚合物催化剂均表现出与雅各布森报道的原始催化剂相当的出色催化活性和选择性。此外，共聚物负载的催化剂比其均聚物类似物更具活性和选择性，这进一步证明了催化剂密度和位点隔离是高活性和高选择性负载型席夫碱催化剂的关键。
