Ni(<scp>ii</scp>) and Pd(<scp>ii</scp>) pyridinyloxazolidine-compounds: synthesis, X-ray characterisation and catalytic activities in the aza-Michael reaction
作者:G. Attilio Ardizzoia、Stefano Brenna、Bruno Therrien
DOI:10.1039/c1dt11191d
日期:——
The 3-phenyl-2-(pyridin-2-yl)oxazolidine ligand (ppo) was synthesised and its coordination behaviour regarding Ni(II) and Pd(II) centres was studied. The reaction with K2PdCl4 affords [Pd(N,N′-ppo)Cl2] (1), in which ppo binds to palladiumvia the pyridyl nitrogen and the oxazolyl nitrogen atoms. On the contrary, reaction with NiCl2·6H2O produces [Ni(N,O-ppo)2Cl2] (2), in which two ppo ligands are coordinated via the pyridyl nitrogen and the oxygen atom of the oxazolidine ring. The X-ray diffraction analysis of the complexes confirms a square planar geometry for Pd(II) in 1 and an octahedral configuration around Ni(II) in 2, which, to the best of our knowledge, represents the first reported example of a structurally characterised nickel-oxazolidine compound. In addition, both complexes prove to be active catalysts under mild conditions in the aza-Michael reaction of (E)-4-phenylbut-3-en-2-one (benzalacetone) with aliphatic amines.
3-苯基-2-(吡啶-2-基)氧杂环丁胺配体(ppo)被合成,并研究了其与Ni(II)和Pd(II)中心的配位行为。与K2PdCl4反应生成[Pd(N,N′-ppo)Cl2](1),其中ppo通过吡啶氮原子和氧杂环氮原子与钯结合。相对而言,与NiCl2·6H2O反应生成[Ni(N,O-ppo)2Cl2](2),在该结构中,两个ppo配体通过吡啶氮原子和氧杂环中的氧原子进行配位。复合物的X射线衍射分析确认了1中Pd(II)的平面正方形几何形状,而2中的Ni(II)则呈八面体构型。据我们所知,这代表了首个结构表征的镍-氧杂环丁胺化合物的例子。此外,这两种复合物在温和条件下在(E)-4-苯基丁-3-烯-2-酮(苄基丙酮)与脂肪胺的阿扎-迈克尔反应中都显示出活性的催化性能。