Application of a new bicyclic triaminophosphine ligand in Pd-catalyzed Buchwald-Hartwig amination reactions of aryl chlorides, bromides, and iodides
Application of a new bicyclic triaminophosphine ligand in Pd-catalyzed Buchwald-Hartwig amination reactions of aryl chlorides, bromides, and iodides
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DOI：
10.1021/jo034994y
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发表时间：
2003-10-31
影响因子：
3.6
通讯作者：
Verkade, JG
中科院分区：
文献类型：
--
作者：
Urgaonkar, S;Xu, JH;Verkade, JG
以市售原料经三步合成了新的双环三氨基膦配体P（i-BuNCH 2）（3）CMe（3），并证明了其在钯催化的芳基卤化物与一系列胺的反应中的有效性。贫电子、中性和富电子的芳基溴化物、氯化物和碘化物参与了该过程。反应包括芳族胺（伯胺或仲胺）和仲胺（环状胺或非环状胺）。还已经表明，弱碱Cs2 CO 3可以与配体3一起使用，允许多种官能化的底物（例如，含有酯和硝基的那些）用于我们的胺化方案中。该配体为芳基碘胺化提供了一种非常通用、有效和温和的钯催化剂。虽然3对空气和湿气稍有敏感，但可以采用简单的程序，避免需要手套箱。3在这些反应中的效力与前氮杂磷杂三环P（i-BuNCH 2CH 2）（3）N（2）的效力的比较揭示，除了在2中（而不是在3中）的转环机会之外，在这两个配体之间存在其他显著的立体电子对比，这有助于解释Pd/2和Pd/3催化体系的活性差异。
The new bicyclic triaminophosphine ligand P(i-BuNCH2)(3)CMe (3) has been synthesized in three steps from commercially available materials and its efficacy in palladium-catalyzed reactions of aryl halides with an array of amines has been demonstrated. Electron-poor, electron-neutral, and electron-rich aryl bromides, chlorides, and iodides participated in the process. The reactions encompassed aromatic amines (primary or secondary) and secondary amines (cyclic or acyclic). It has also been shown that the weak base Cs2CO3 can be employed with ligand 3, allowing a variety of functionalized substrates (e.g., those containing esters and nitro groups) to be utilized in our amination protocols. This ligand provides a remarkably general, efficient, and mild palladium catalyst for aryl iodide amination. Although 3 is slightly air and moisture sensitive, easy procedures can be adopted that avoid the need of a glovebox. Comparisons of the efficacy of 3 in these reactions with that of the proazaphosphatrane P(i-BuNCH2CH2)(3)N (2) reveal that in addition to the opportunity for transannulation in 2 (but not in 3), other significant stereoelectronic contrasts exist between these two ligands which help account for differences in the activities of the Pd/2 and Pd/3 catalytic systems.