Nickel complexes incorporating an amido phosphine chelate with a pendant amine arm: Synthesis, structure, and catalytic Kumada coupling
作者:Lan-Chang Liang、Wei-Ying Lee、Yu-Ting Hung、Yi-Chen Hsiao、Liang-Chien Cheng、Wei-Chen Chen
DOI:10.1039/c1dt11338k
日期:——
A series of organonickel(II) complexes incorporating an amido phosphine ligand tethered with an amino pendant have been prepared and characterized. Deprotonation of N-(dimethylaminoethyl)-2-diphenylphosphinoaniline (H[PNN]) with one equivalent of n-BuLi in ethereal or hydrocarbon solutions at −35 °C generates cleanly dimeric Li[PNN]}2 as yellow crystals. The reaction of NiCl2(DME) with Li[PNN]}2 in THF at −35 °C affords green crystalline [PNN]NiCl. Treating [PNN]NiCl with NaX in acetone solutions gives [PNN]NiX (X = Br, I). Alkylation or arylation of [PNN]NiCl with appropriate Grignard reagents in THF at −35 °C produces red crystalline [PNN]NiR (R = Me, Et, i-Bu, n-hexyl, CH2Ph, Ph). The chloride complex [PNN]NiCl was found to be an active catalyst precursor for Kumada coupling reactions of PhX (X = I, Br, Cl) with aryl or alkyl Grignard reagents, including those containing β-hydrogen atoms. The X-ray structures of Li[PNN]}2 and [PNN]NiX (X = Cl, Br, Me, Et, n-hexyl) are reported.
一系列包含氨基配体的有机镍(II)配合物已经被制备和表征。N-(二甲氨基乙基)-2-二苯基膦基苯胺(H[PNN])在-35 °C的醚或烃溶液中与等摩尔的n-BuLi去质子化,干净地生成黄色晶体二聚体Li[PNN]}2。NiCl2(DME)与Li[PNN]}2在-35 °C的THF中反应,得到绿色晶体[PNN]NiCl。将[PNN]NiCl与NaX在丙酮溶液中处理,得到[PNN]NiX(X = Br, I)。在-35 °C的THF中,使用适当的格里尼亚试剂对[PNN]NiCl进行烷基化或芳基化反应,生成红色晶体[PNN]NiR(R = Me, Et, i-Bu, n-hexyl, CH2Ph, Ph)。氯化物配合物[PNN]NiCl被发现是Kumada偶联反应的活性催化剂前体,该反应涉及PhX(X = I, Br, Cl)与芳基或烷基格里尼亚试剂的反应,包括那些含有β-氢原子的试剂。报告了Li[PNN]}2和[PNN]NiX(X = Cl, Br, Me, Et, n-hexyl)的X射线结构。