钯碳催化Suzuki-Miyaura反应合成芳杂环取代三苯胺衍生物

Palladium-on-carbon-catalyzed Suzuki-Miyaura Reaction for the Synthesis of Heteroaryl-substituted Triphenylamine Derivatives

以芳杂环卤代物和4-硼酸三苯胺为原料,以Pd/C为催化剂,在乙醇水溶液中经Suzuki-Miyaura(SM)反应合成了芳杂环取代三苯胺衍生物。以2-溴吡啶与4-硼酸三苯胺的反应为模型反应,考察了溶剂、碱、温度及催化剂用量对反应的影响。得到的最优反应条件为:2-溴吡啶0.25mmol,4-硼酸三苯胺0.375mmol,Pd/C催化剂占2-溴吡啶的物质的量的1.5%,乙醇水溶液〔4 mL,V(乙醇)∶V(水)=3∶1〕,碳酸钾0.5 mmol,反应温度80℃,在该条件下合成了12个芳杂环取代三苯胺衍生物,产率为54%～99%,所有产物均通过核磁共振氢谱进行结构确认。该反应体系在空气及水相中进行且催化剂易于分离回收。

A heterogeneous catalytic system was developed for the synthesis of heteroaryl-substituted triphenylamine derivatives via a Pd/C-catalyzed aerobic and ligand-free Suzuki-Miyaura(SM)reaction of heteroaryl halides with 4-(diphenylamino)phenyl boronic acid(DPBA)in aqueous media.The reaction conditions(solvent,base,temperature and Pd/C loading)were optimized using a model cross-coupling reaction between 2-bromopyridine and DPBA.The optimal conditions were as follows:2-bromopyridine0.25 mmol,DPBA 0.375 mmol,the molar fraction of Pd/C in 2-bromopyridine being 1.5%,ethanol aqueous solution[4 mL,V(EtOH)∶V(H2O)=3∶1],K2CO3 dosage 0.5 mmol,and reaction temperature 80℃.Under these optimal conditions,twelve triphenylamine derivatives were prepared with yields ranging from 54%to99%.The structures of the products were confirmed by 1HNMR.The reaction was performed under aerobic and aqueous conditions,and the catalyst was easily separated and recovered.Therefore,this protocol is convenient and environmental benign for the preparation of important heteroaryl-substituted triphenylamine derivatives.