A Discrete Self-Assembled Pd12 Triangular Orthobicupola Cage and its Use for Intramolecular Cycloaddition
A Discrete Self-Assembled Pd12 Triangular Orthobicupola Cage and its Use for Intramolecular Cycloaddition
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DOI：
10.1002/chem.201803039
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发表时间：
2018-09-18
影响因子：
4.3
通讯作者：
Mukherjee, Partha Sarathi
中科院分区：
文献类型：
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作者：
Bhat, Imtiyaz Ahmad;Devaraj, Anthonisamy;Mukherjee, Partha Sarathi
用90度双取代受体顺式-[Pd(NO3)(2)(Tmeda)][tmeda=N，N-四甲基乙烷-1，2-二胺]与对称四氢吡啶供体L进行配位驱动自组装，合成了水溶性Pd12L6配位笼TC-1。Pd12L6协调组件是具有三角形斜顶状几何形状的协调笼的一个不常见的例子。用多核核磁共振波谱、电喷雾质谱、单晶X-射线衍射法对其进行了表征。四配基供体与顺式封闭的90度双配基受体的自组装通常产生三/四/六角桶或封闭的立方笼。然而，在目前的情况下，施主和受主以一种不寻常的方式排列，以生成一个正斜面冲天炉几何形状，其中两个三角形冲天炉共享一个共同的不规则六角形面。该笼用于O-丙烯酰化的亚苄基巴比妥酸衍生物在硝基甲烷中的分子内环加成反应。通过笼状催化的[4+2]环加成反应，在温和的反应条件下合成了几个五/四环氧嘧啶衍生物，转化率由好到高，而在没有笼状TC-1的情况下，在有机溶剂中类似的反应导致环化产物的转化率较低。与在高温回流条件下高催化剂载量合成类似化合物的文献报道相比，该方法特别重要。
Water-soluble Pd12L6 coordination cage TC-1 was synthesized by coordination-driven self-assembly of symmetrical tetrapyridyl donor L with 90 degrees ditopic acceptor cis-[Pd(NO3)(2)(tmeda)] [tmeda=N,N,N,N-tetramethylethane-1,2-diamine]. The Pd12L6 coordination assembly is an uncommon example of a coordination cage having triangular orthobicupola-like geometry. It was characterized by multinuclear NMR spectroscopy, ESI-MS, and single-crystal X-ray diffraction. Self-assembly of a tetratopic donor with a cis-blocked 90 degrees ditopic acceptor generally yields tri-/tetra-/hexagonal barrels or closed cubic cages. However, in the present case the donor and acceptor are arranged in an unusual fashion to generate an orthobicupola geometry in which two triangular cupola share a common irregular hexagonal face. The cage was used to perform intramolecular cycloaddition reactions of O-propargylated benzylidinebarbituric acid derivatives in nitromethane. Several penta-/tetracyclouracil derivatives were synthesized through cage-catalyzed [4+2] cycloaddition reactions in a concerted manner with good to high conversion under mild reaction conditions, whereas in the absence of cage TC-1 similar reactions led to lower conversion to the cyclized products in organic solvent. This approach is of particular importance compared to the literature reports on the synthesis of similar compounds under high-temperature reflux conditions with high catalyst loading.