Trineopentylphosphine: A Conformationally Flexible Ligand for the Coupling of Sterically Demanding Substrates in the Buchwald–Hartwig Amination and Suzuki–Miyaura Reaction
作者:Steven M. Raders、Jane N. Moore、Jacquelynn K. Parks、Ashley D. Miller、Thomas M. Leißing、Steven P. Kelley、Robin D. Rogers、Kevin H. Shaughnessy
DOI:10.1021/jo400435z
日期:2013.5.17
palladium provides a highly effective catalyst for the Buchwald–Hartwig coupling of sterically demanding aryl bromides and chlorides with sterically hindered aniline derivatives. Excellent yields are obtained even when both substrates include 2,6-diisopropyl substituents. Notably, the reaction rate is inversely related to the steric demand of the substrates. X-ray crystallographic structures of Pd(TNpP)2,
三叔戊基膦(TNpP)与钯的结合为空间受限的芳族溴化物和氯化物与空间受阻的苯胺衍生物的布赫瓦尔德-哈特维格偶联提供了一种高效的催化剂。即使两个底物都包含2,6-二异丙基取代基,也可获得优异的产率。值得注意的是,反应速率与底物的空间需求成反比。Pd(TNpP)2,[Pd(4- t -Bu-C 6 H 4)(TNpP)(μ-Br)] 2和[Pd(2-Me-C 6 H 4)的X射线晶体结构(TNpP)(μ-Br)] 2被报道。这些结构表明,TNpP配体的构象柔韧性在允许催化剂偶联受阻底物方面起着关键作用。Pd / TNpP系统对受阻芳基溴化物的Suzuki偶联也显示出良好的活性。