COF固载铜盐催化苯硼酸与咪唑的Chan-Lam偶联反应

Copper Salt Anchored on a Covalent Organic Framework as Heterogeneous Catalyst for Chan-Lam Coupling Reaction

制备了一种含有联吡啶位点的共价有机骨架(COF)材料TpBpy,并通过配体上的联吡啶位点固载铜盐实现了功能化,得到的Cu@TpBpy具有大量的不饱和铜配位位点和高表面积,可用作苯硼酸与咪唑的Chan-Lam偶联反应的多相催化剂.通过优化溶剂、铜源、碱及反应时间等反应条件,发现使用质子极性溶剂MeOH时的反应产率最高,而Cu(OAc)2@TpBpy是效果最佳的催化剂,可溶性有机碱三乙胺(TEA)的促进效果最好.Cu(OAc)2@TpBpy在碱TEA的促进下于70℃催化咪唑与苯硼酸反应4 h后,得到目标产物1-苯基咪唑的最大产率为66%.在最优反应条件下进行了底物拓展,结果表明,取代基的位阻效应对催化体系影响显著,其中对位取代基的4-氯苯硼酸的产率最高(62%).

A bipyridine containing covalent organic framework(COF),namely TpBpy,modified with copper ions was prepared.The obtained Cu@TpBpy was used as a heterogeneous catalyst for C—N cross-coupling reaction of arylboronic acid with imidazole.To optimize the reaction conditions,we have screened various parameters such as the catalyst,solvent,base and reaction time.The experimental result showed that using the polar solvent MeOH gives the best yield with the promotion of base TEA,while Cu(OAc)2@TpBpy is the optimal catalyst.The reaction achieves maximum yield of 66%after 4 h reaction catalyzed by Cu(OAc)2@TpBpy with TEA in MeOH at 70℃.In the optimal reaction conditions,arylboronic acid with different substituents were examined in the coupling reaction with imidazole,among them,4-chlorophenylboric acid showed the best yield of 62%.