Nine-Membered Osmacycles Derived from Metathesis Reactions between Alkynes and an Osmafuran
Nine-Membered Osmacycles Derived from Metathesis Reactions between Alkynes and an Osmafuran
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DOI：
10.1021/om8010867
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发表时间：
2009-02
期刊：
影响因子：
2.8
通讯作者：
Yu-Mei Lin;Lei Gong;Hui Xu;Xumin He;T. Wen;H. Xia
中科院分区：
文献类型：
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作者：
Yu-Mei Lin;Lei Gong;Hui Xu;Xumin He;T. Wen;H. Xia
研究了五元锇呋喃Os{CHCHC（PPh 3）CHC（O）OEt} Cl 2（PPh 3）2（1）的炔插入扩环反应，得到了多个九元锇杂环.化合物1与PhC·CH反应得到9元配合物Os{<$CPhCH <$CPh-η2-CH <$CHC（PPh 3）<$C（O）OEt} Cl 2（PPh 3），它是一对异构体2a和2b的混合物，两个氯配体在金属中心上的位置不同。该反应涉及PhC-2CH通过[2 + 2]环加成过程头-尾双插入到osmacrylate 1中，这与炔的复分解聚合反应有关。用PMe 3处理2a和2b的混合物，选择性地得到Os{<$CPhCH <$CPh-η2-CH <$CHC（PPh 3）<$C（O）OEt} Cl 2（PMe 3）（3），2a的PMe 3取代的对应物。这些配合物可能作为内烯烃配位稳定的炔聚合中间体。将2a和2b的混合物在二氯甲烷中加热回流得到配合物Os{η2-CHPh <$CHCPh <$CHCC（PPh 3）C（O.
Ring-expansion reactions of the five-membered osmafuran Os{═CHC(PPh3)═C(O) OEt}Cl2(PPh3)2 (1) via alkyne insertion have been investigated, which lead to the formation of several nine-membered osmacycles. Reaction of 1 with PhC≡CH gives the nine-membered complexes Os{═CPhCH═CPh-η2-CH═CHC(PPh3)═C(O)OEt}Cl2(PPh3) as a mixture of a couple of isomers 2a and 2b with different disposition of the two chloride ligands on the metal centers. The reaction involves a head-to-tail double insertion of PhC≡CH into osmacycle 1 via [2 + 2] cycloaddition process, which is relevant to the polymerization of alkynes by metathesis reaction. Treatment of the mixture of 2a and 2b with PMe3 gives selectively Os{═CPhCH═CPh-η2-CH═CHC(PPh3)═C(O)OEt}Cl2(PMe3) (3), the PMe3-substituted counterpart of 2a. These complexes might serve as the intermediates for alkyne polymerization which are stabilized by the coordination of internal olefin. Heating the mixture of 2a and 2b in CHCl3 under reflux gives complex Os{η2-CHPh═CHCPh═CHCC(PPh3)C(O...