New Phosphine-Functionalized NHC Ligands: Discovery of an Effective Catalyst for the Room-Temperature Amination of Aryl Chlorides with Primary and Secondary Amines
作者:Craig A. Wheaton、John-Paul J. Bow、Mark Stradiotto
DOI:10.1021/om400684n
日期:2013.11.11
dihydroimidazolium salts and demonstrate their utility as ligand precursors for Buchwald–Hartwig amination. Several examples of the general formula [1-Mes-3-2-(PR2)phenyl}imidazolidin-2-ylium][BF4] have been prepared, where phosphines of varying steric and electronic properties (R = Ph (9), Cy (10), 1-Ad (11)) are tethered by an o-phenylene group. The synthesis was not adaptable to N-aryl groups other than mesityl
我们报道了新型膦功能化的二氢咪唑鎓盐的便捷且高产率的合成,并证明了其作为布赫瓦尔德-哈特维格胺胺化的配体前体的效用。制备了一些通式[1-Mes-3- 2-(PR 2)苯基}咪唑烷基-2-基鎓] [BF 4 ]的实例,其中膦具有不同的空间和电子性质(R = Ph(9),Cy(10),1-Ad(11))由邻亚苯基连接。该合成不适用于除异丁基外的N-芳基,而是产生了意想不到的phospho盐物种。合成适用于式[1-Ar-3- 2-(PCy 2)苄基}咪唑啉-2-基] [BF 4 ],其使二氢咪唑N-芳基具有更大的空间变异性(Ar = Mes(21),Dipp(22))。对这些杂种NHC / P配体在Buchwald–Hartwig胺化催化(原位形成前催化剂)中的初步研究表明,11种是最活跃的。将分离出的游离NHC配体1-Mes-3- 2-(PAd 2)苯基}咪唑烷基-2-亚甲基(23)与[Pd(肉桂基)Cl]