Chiral CNN Pincer Palladium(II) Complexes with 2-Aryl-6-(oxazolinyl)pyridine Ligands: Synthesis, Characterization, and Application to Enantioselective Allylation of Isatins and Suzuki–Miyaura Coupling Reaction
作者:Tao Wang、Xin-Qi Hao、Juan-Juan Huang、Kai Wang、Jun-Fang Gong、Mao-Ping Song
DOI:10.1021/om400945d
日期:2014.1.13
1-naphthyl) ligands 2a–f were conveniently prepared from commercially available 6-bromo-2-picolinaldehyde in two steps. Reaction of 2a–f with PdCl2 in toluene in the presence of sodium bicarbonate afforded the corresponding CNN pincer Pd(II) complexes 3a–f via aryl C–H bond activation of the related ligands. All of the new compounds have been fully characterized by elemental analysis (MS for ligands), 1H
从市售的6-溴-2-吡啶啉醛中分两步方便地制备了一系列手性2-芳基-6-(恶唑啉基)吡啶(芳基=苯基或1-萘基)配体2a – f。在碳酸氢钠存在下,2a – f与PdCl 2在甲苯中的反应通过相关配体的芳基C–H键活化,提供了相应的CNN钳位Pd(II)配合物3a – f。所有新化合物均已通过元素分析(配体的质谱),1 H和13 C NMR和IR光谱进行了全面表征。此外,Pd(II)配合物3c – f的分子结构已经通过X射线单晶衍射确定。所获得的手性钳催化剂成功地用于靛红与烯丙基三丁基锡的不对称烯丙基化,以高收率得到相应的3-烯丙基-3-羟基羟吲哚,对映选择性高达86%ee。这些钳子还可以催化不对称的Suzuki-Miyaura偶联反应,以高收率和良好的立体选择性(高达ee的68%)提供轴向手性联芳基产品。