Palladium-catalyzed aminations of aryl halides with phosphine-functionalized imidazolium ligands
作者:Ji-cheng Shi、Pengyu Yang、Qingsong Tong、Li Jia
DOI:10.1039/b714892e
日期:——
110 degrees C, and 94% of conversion was afforded with the less sterical demanding 1a for a longer time. However, for the substrates with ortho-substituents, higher conversions were achieved with 1a. The Pd(OAc)2/1d catalytic system was also active for deactivated aryl chloride, and 71% isolated yield for the desired product was realized for coupling of 4-chloroanisole with morpholine at 2 mol% of catalyst
一系列的1-(2-二苯基膦基二茂铁基)乙基-3-取代的碘化咪唑鎓碘化物[3-取代基=甲基(1a); 异丙基(1b);叔丁基(1c); 1-腺苷(1d); 环己基(1e); 2,6-二甲基苯基(1f); 2,4,6-三甲基苯基(1g); 已经制备了2,6-二异丙基苯基(1h)],并作为钯在芳基卤化物与各种胺的胺化反应中的配体进行了评估。偶联过程的范围是对各种芳基溴化物和氯化物进行的,催化剂是由Pd(OAc)2的混合物在碱的存在下原位生成的。尽管NaOH或Cs2CO3以中等转化率促进了4-溴甲苯与吗啉的偶联,但发现NaO t Bu是与二恶烷,甲苯或DME组合的碱的选择。发现杂二齿螯合体系中咪唑的3-取代基的空间位阻仅对没有邻取代基的底物有利。受空间位阻较大的1d或1h在110°C的NaO t Bu存在下以0.2 mol%的钯负载量以几乎定量的转化率促进了溴苯与吗啉的偶合,而对空间要求较低的1a