Unsymmetrical Chiral PCN Pincer Palladium(II) and Nickel(II) Complexes of (Imidazolinyl)aryl Phosphinite Ligands: Synthesis via Ligand C−H Activation, Crystal Structures, and Catalytic Studies
摘要:
Six unsymmetrical chiral PCN pincer Pd(II) complexes 3a-f based on (imidazolinyl)aryl phosphinite ligands were easily synthesized from imidazolinyl-containing m-phenol derivatives 2a-e by one-pot phosphorylation/palladation reaction via C-H bond activation of the related ligands. An unsymmetrical chiral PCN pincer Ni(II) complex, 4a, was first obtained in a similar way. The palladium-chloride complex 3e could be readily converted to the corresponding iodide derivative 5e by the halide exchange reaction with KI. All eight complexes were characterized by X-ray crystal structure determination. Each complex adopts a typical distorted-square-planar geometry. The Pd complexes were shown to be active catalysts with rather moderate enantioselectivities (up to 32% ee) for asymmetric Suzuki-Miyaura reaction.
Unsymmetrical Chiral PCN Pincer Palladium(II) and Nickel(II) Complexes of (Imidazolinyl)aryl Phosphinite Ligands: Synthesis via Ligand C−H Activation, Crystal Structures, and Catalytic Studies
作者:Ben-Shang Zhang、Wei Wang、Dan-Dan Shao、Xin-Qi Hao、Jun-Fang Gong、Mao-Ping Song
DOI:10.1021/om100232n
日期:2010.6.14
Six unsymmetrical chiral PCN pincer Pd(II) complexes 3a-f based on (imidazolinyl)aryl phosphinite ligands were easily synthesized from imidazolinyl-containing m-phenol derivatives 2a-e by one-pot phosphorylation/palladation reaction via C-H bond activation of the related ligands. An unsymmetrical chiral PCN pincer Ni(II) complex, 4a, was first obtained in a similar way. The palladium-chloride complex 3e could be readily converted to the corresponding iodide derivative 5e by the halide exchange reaction with KI. All eight complexes were characterized by X-ray crystal structure determination. Each complex adopts a typical distorted-square-planar geometry. The Pd complexes were shown to be active catalysts with rather moderate enantioselectivities (up to 32% ee) for asymmetric Suzuki-Miyaura reaction.
Diphenylprolinol-Derived Symmetrical and Unsymmetrical Chiral Pincer Palladium(II) and Nickel(II) Complexes: Synthesis via One-Pot Phosphorylation/Metalation Reaction and C−H Activation
作者:Jun-Long Niu、Qing-Tao Chen、Xin-Qi Hao、Qing-Xiang Zhao、Jun-Fang Gong、Mao-Ping Song
DOI:10.1021/om100234q
日期:2010.5.10
The symmetrical P-stereogenic bis-phosphoramidite PCP pincer Pd(II) complexes 1 and 2 were easily prepared by a “four-component, one-pot phosphorylation/palladation” procedure via C−H bond activation of the related ligands. In this synthetic procedure, (S)-diphenyl(pyrrolidin-2-yl)methanol was first phosphonated with PCl3 to afford the expected phosphorochloridate adduct, which then reacted in situ
通过“四组分,一锅磷酸化/ palpalation”程序,通过相关配体的CH键活化,可以轻松制备对称的P-立体异构双亚磷酰胺PCP钳形Pd(II)复合物1和2。在该合成程序中,首先将(S)-二苯基(吡咯烷-2-基)甲醇用PCl 3进行膦酸酯化,得到预期的氯代磷酸酯加合物,然后使其与间苯二酚或二取代的间苯二酚原位反应,然后用PdCl 2处理。含不对称P-立体异构亚磷酰胺和咪唑啉的PCN夹Pd(II)配合物3和Ni(II)配合物4的第一个例子可以以类似的方式,通过使用手性含咪唑啉来获得米-苯酚衍生物代替间苯二酚作为骨架。配合物的31 P NMR证实了一个单一的非对映异构体与P-立体异构中心有关,并且其绝对构型是通过X射线晶体结构测定来确定的。对在不对称烯丙基化反应中使用这些配合物的初步研究表明,不对称的夹钳式Pd配合物3表现出比相关对称的更高的催化活性。另一方面,更大体积的Pd络合物2具有更好