Huang Jun-Jian, Zhang Xiao-Qi, Yang Jing-Jing, Gong Jun-Fang, Song Mao-Ping
College of Chemistry, Green Catalysis Center, Zhengzhou University, Zhengzhou 450001, China.
Dalton Trans. 2022 May 31;51(21):8350-8367. doi: 10.1039/d2dt01078j.
A series of new chiral PCN pincer Pd(II) complexes 3a-l with aryl-based (phosphine)-(imidazoline) ligands were conveniently synthesized from readily available starting materials with the key step being phosphination/C-H palladation reaction. All of the new complexes were characterized by H NMR, C{H} NMR, P{H} NMR, and elemental analysis. In addition, the molecular structures of complexes 3c, 3e, 3i, and 3k have been determined by X-ray single crystal diffraction analysis. The potential of the obtained pincer Pd(II) complexes in catalytic enantioselective hydrophosphination reaction was examined. With a loading of 5 mol% and in the presence of a KOAc base, complex 3e acted as an active and stereoselective catalyst for hydrophosphination of various 2-alkenoylpyridines with diphenylphosphine, providing optically active pyridine-containing phosphine derivatives with structural diversity in excellent yields with moderate to good enantioselectivities (up to >99 yield and 87% ee).
一系列带有芳基（膦）-（咪唑啉）配体的新型手性PCN钳形钯（II）配合物3a-l可通过易得的起始原料方便地合成，关键步骤是膦化/C-H钯化反应。所有新配合物均通过1H NMR、13C{H} NMR、31P{H} NMR和元素分析进行了表征。此外，配合物3c、3e、3i和3k的分子结构已通过X射线单晶衍射分析确定。研究了所得钳形钯（II）配合物在催化对映选择性氢膦化反应中的潜力。在5 mol%的负载量和醋酸钾碱存在下，配合物3e作为一种活性和立体选择性催化剂，用于各种2-烯丙酰基吡啶与二苯基膦的氢膦化反应，以中等至良好的对映选择性（高达>99%产率和87% ee）提供具有结构多样性的光学活性含吡啶膦衍生物，产率优异。
