N-杂环卡宾钯配合物高效催化杂环类铃木偶联反应的研究

The highly efficient Suzuki-Miyaura cross-coupling of heterocycles by Pd-NHCs

目的通过N-杂环卡宾钯配合物催化铃木宫浦交叉偶联反应,合成一系列杂环类产物。方法将合成的N-杂环卡宾钯配合物作为催化剂,以芳基硼酸和氯代芳烃为底物催化合成目标产物,且分别考察不同极性溶剂和不同强度碱的影响以优化反应条件。结果合成了N-杂环卡宾钯配合物,筛选出最佳偶联反应条件:无水乙醇为溶剂,K_2CO_3为碱,反应温度为80℃,反应时间4 h,直接在空气中反应。合成了18个杂环类偶联结构,产率均在90%以上,结构均通过~1H NMR和^(13)C NMR进行了表征。结论本文合成的N-杂环卡宾钯配合物催化活性高,催化偶联反应条件温和,适用氯代杂环底物,可用于催化多种杂环类铃木偶联反应。

Objective To synthesize heterocyclic products with Suzuki-Miyaura cross-coupling reactions catalyzed by N-heterocyclic carbene palladium complexes.Methods A N-heterocyclic carbene palladium complex was synthesized as an efficient catalyst for the coupling reaction of aryl boronic acids and aryl chlorides.The conditions were optimzed via the change of catalyst loading,solvent with different polarity and base with different intensity.Results A N-heterocyclic carbene palladium complexes was synthesized.The optimal cross-coupling conditions were as follows,EtOH as solvent,K2CO3as base,reaction for4h in the air at80℃.The cross-coupling products,up to18examples,with yields up to90%,were obtained and characterized by1H NMR and13C NMR.Conclusion The N-heterocyclic carbene palladium complexes exhibited high catalytic efficiency for the Suzuki-Miyaura reactions,which could be used to synthesize a variety of heterocyclics under mild conditions and suitable for chlorinated heterocyclic substrates.