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

摘要:

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反应合成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，获得最优反应条件：2-溴吡啶（0.25 mmol），4-硼酸三苯胺（0.375 mmol），Pd/C（1.5 mol%），乙醇/水（4 mL，体积比3:1），碳酸钾（0.5 mmol），80℃。在最优反应条件下合成了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，为具有重要应用价值的芳杂环取代三苯胺衍生物提供了简便、环境有好的合成方法。

Abstract:

A heterogeneous catalytic system has been developed for synthesis of heteroaryl-substituted triphenylamine derivatives via a Pd/C-catalyzed aerobic and ligand-free Suzuki-Miyaura 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: 2-bromopyridine (0.25 mmol), DPBA (0.375 mmol), Pd/C (1.5 mol%), ethanol/water (4 mL, volume ratio of 3:1), K2CO3 (0.5 mmol) and 80 °C. Twelve triphenylamine derivatives were prepared with yields of 54-99% under the optimal conditions. The structures of the products were confirmed by 1H NMR. 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.