Studies on catalysts for selective functionalization of Group 14 compounds

在回流条件下，在催化量为5mol %的Pd(PPh_3)_4存在的条件下，用三甲基硅氰氰化羰基碳酸盐，高收率地氰化了β， γ -不饱和羰基腈。几种顺式和反式脂环底物的氰化反应进行干净（立体选择性> 99%），总体保留。与本催化反应相关的钯配合物的表征和反应表明，eta^3-烯丙基钯配合物与三甲基硅基氰化物的金属化很容易，而产生的氰基（eta^3-烯丙基）钯配合物只有在过量的三甲基硅基氰化物存在时才能产生相应的烯丙基氰化物。产物的立体化学表明，CN从钯侧攻击eta^3-烯丙基基团。研究了顺式-双（硅基）双（膦）铂配合物顺式-[Pt(SiPh_2Me)_2(PMe_2Ph)_2]和顺式-[Pt(SiFMe_2)_2(PEt_3)_2]和顺式-双（锡基）双（膦）钯配合物顺式-[Pd(SnMe_3)_2(PMe_3)_2]和顺式-[Pd(SnMe_3)_2(PMePh_2)_2]具有顺式取向的扭曲方平面结构。双（硅基）铂配合物在核磁共振时间尺度上表现出流动行为。在流态过程中，P、Si和Pt之间保持了自旋-自旋耦合；也就是说，这些核自旋态是分子内保守的。配合物的流动性归因于单分子通过伪四面体过渡态的扭转旋转。通过对溶液和固态的^<31>P核磁共振，可以明显地看出双（锡基）钯配合物的相似的流动性。

Allylic carbonates are cyanated in high yields to beta, gamma-unsaturated carbonitriles using trimethylsilyl cyanide in the presence of catalytic amount (5 mol%) of Pd(PPh_3)_4 in THF under reflux. The cyanations of several cis- and trans-alicyclic substrates proceed cleanly (stereoselectivity> 99%) with overall retention. Characterization and reaction of palladium complexes relevant to the present catalysis indicate that transmetallation of eta^3-allyl palladium complex with trimethylsilyl cyanide is facile, while the resulting cyano(eta^3-allyl)palladium complexes afford the corresponding allylic cyanides only when excess trimethylsilyl cyanide is present. Stereochemistry of the product indicates that the CN attacks the eta^3-allyl moieties from the palladium side.The structures and fluxional behavior of two cis-bis(silyl)bis(phosphine)platinum complex, cis- [Pt(SiPh_2Me)_2(PMe_2Ph)_2] and cis-[Pt(SiFMe_2)_2(PEt_3)_2], and two cis-bis(stannyl)bis(phosphine)palladium complex, cis-[Pd(SnMe_3)_2(PMe_3)_2] and cis-[Pd(SnMe_3)_2(PMePh_2)_2], were examined, The complexes have twisted square-planar structures with cis-orientation of the ligands. The bis(silyl)platinum complexes show fluxional behavior on the NMR time-scale. In the fluxional process, the spin-spin coupling between P, Si, and Pt are retained ; namely these nuclear spin states are intramolecularly conserved. The fluxionality of the complexes is attributed to the unimolecular twist-rotation via pseudo tetrahedral transition state. Similar fluxionality of the bis(stannyl)palladium complex is evident by utilizing both solution and solid state ^<31>P NMR.