Urgaonkar Sameer, Xu Ju-Hua, Verkade John G
Department of Chemistry, Gilman Hall, Iowa State University, Ames, Iowa 50011-3111, USA.
J Org Chem. 2003 Oct 31;68(22):8416-23. doi: 10.1021/jo034994y.
The new bicyclic triaminophosphine ligand P(i-BuNCH2)3CMe (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)3N (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.
新型双环三氨基膦配体P(i-BuNCH2)3CMe (3)由市售原料经三步合成，并已证明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、电子中性和富电子的芳基溴化物、氯化物和碘化物都参与了该过程。反应包括芳香胺（伯胺或仲胺）和仲胺（环状或非环状）。还表明，弱碱碳酸铯可与配体3一起使用，使得各种官能化底物（例如含有酯基和硝基的底物）可用于我们的胺化反应方案中。该配体为芳基碘胺化反应提供了一种非常通用、高效且温和的钯催化剂。尽管3对空气和湿气稍有敏感，但可以采用简单的操作程序，无需使用手套箱。将3在这些反应中的有效性与前氮杂环磷烷P(i-BuNCH2CH2)3N (2)的有效性进行比较发现，除了2（而非3）中存在跨环化的机会外，这两种配体之间还存在其他显著的立体电子差异，这有助于解释Pd/2和Pd/3催化体系活性的差异。
