PCN Pincer Palladium(II) Complex Catalyzed Enantioselective Hydrophosphination of Enones: Synthesis of Pyridine-Functionalized Chiral Phosphine Oxides as NC<sub>sp<sup>3</sup></sub>O Pincer Preligands
作者:Xin-Qi Hao、Juan-Juan Huang、Tao Wang、Jing Lv、Jun-Fang Gong、Mao-Ping Song
DOI:10.1021/jo5015307
日期:2014.10.17
A series of chiral PCN pincer Pd(II) complexes VI–XIII with aryl-based aminophosphine–imidazoline or phosphinite–imidazoline ligands were synthesized and characterized. They were examined as enantioselective catalysts for the hydrophosphination of enones. Among them, complex IX, which features a Ph2PO donor as well as an imidazoline donor with (4S)-phenyl and N-Tol-p groups, was found to be the optimal
合成并表征了一系列具有芳基氨基膦-咪唑啉或次膦酸酯-咪唑啉配体的手性PCN夹心Pd(II)配合物VI - XIII。他们被检查为烯酮氢磷酸化的对映选择性催化剂。其中,具有Ph 2 PO供体以及具有(4S)-苯基和N- Tol- p基团的咪唑啉供体的配合物IX被认为是最佳催化剂。因此,在2–5 mol%的络合物IX存在下各种各样的烯酮与二芳基膦平稳地反应,以高收率得到对映体选择性高达98%ee的相应手性膦衍生物。尤其是,对于Pd中心具有强配位能力的杂芳基物质,例如含2-噻吩基,2-呋喃基和2-吡啶基的烯酮,也是当前催化体系的合适底物。例如,用二苯基膦将2-烯酰基吡啶进行氢磷酸化,然后用H 2 O 2氧化以高收率得到具有良好或优异的对映选择性的相应的吡啶官能化的手性氧化膦(10个实施例,至多95%ee)。此外,已经证明,所获得的含吡啶的氧化膦在与PdCl 2的反应中作为三齿配体,通过C sp 3