Oxidant-Controlled Stereoselectivity in the Pd-Catalyzed Allylic Oxidation of cis-Vinylsilanes
摘要:
The allylic oxidation of cis-vinylsilanes is reported. The reaction requires a low catalyst loading of Pd(OAc)(2) without the need for an external ligand. Interestingly, trans-vinylsilanes are unreactive, whereas allylic oxidations of cis-vinylsilanes proceed in good yields giving a single diastereo- and regioisomer of the branched allylic acetate trans-vinylsilane when benzoquinone is employed. The use of PhI(OAc)(2) as oxidant in place of benzoquinone provides the branched, cis-vinylsilane as the major product. Additionally, the first intramolecular allylic C-H etherifications of cis-vinylsilanes to give oxygen heterocycles are also described.
Stereodivergent Formation of Alkenylsilanes:syn oranti Hydrosilylation of Alkynes Catalyzed by a Cyclopentadienylcobalt(I) Chelate Bearing a Pendant Phosphane Tether
作者:Li Yong、Karin Kirleis、Holger Butenschön
DOI:10.1002/adsc.200606028
日期:2006.5
alkynes is catalyzed by the di-tert-butylphosphanylethylcyclopentadienylcobalt chelate 1. While the reaction of internal alkynes exclusively affords syn hydrosilylation products with triethylsilane, the reaction with triethoxysilane shows predominant anti stereoselectivity. Reactions of terminal alkynes are less selective with triethylsilane and result in cyclotrimerization when triethoxysilane is used
Synthesis and structure of thienyl Fischer carbene complexes of Pt<sup>II</sup> for application in alkyne hydrosilylation
作者:Zandria Lamprecht、Frederick P. Malan、Simon Lotz、Daniela I. Bezuidenhout
DOI:10.1039/d1nj00791b
日期:——
Transmetallation of group 6 thienylene Fischer carbenecomplexes to PtII precursors yielded new examples of neutral platinum(II) bisethoxycarbene complexes with either 2-thienyl (T) or 5-thieno[2,3-b]thienylene (TT) carbene substituents. The use of analogous aminocarbene group 6 precursors proceeded to give isomeric platinum(II) product mixtures where the resultant bisaminocarbene ligands displayed
将第6组亚噻吩菲舍尔卡宾配合物金属化成Pt II前体产生了具有2-噻吩基(T)或5-噻吩并[2,3- b ]亚噻吩基(TT)卡宾取代基的中性铂(II)双乙氧基卡宾配合物的新实例。使用类似的氨基卡宾第6组前驱体可制得同分异构的铂(II)产品混合物,由于空间需求的TT取代基导致围绕Pt-氨基卡宾键的旋转受到限制,所得的双氨基卡宾配体显示出不同的取向。定义明确的Pt II在使用苯乙炔和三乙基硅烷底物的基准氢化硅烷化反应中,将乙氧基卡宾配合物筛选为催化剂前体。观察到对β- E异构体(E)-三乙基(苯乙烯基)硅烷的明显选择性,并且证明(预)催化剂可循环利用,在无溶剂反应中具有活性,并显示出高炔烃官能团耐受性。
Supported Palladium–Gold Alloy Catalysts for Efficient and Selective Hydrosilylation under Mild Conditions with Isolated Single Palladium Atoms in Alloy Nanoparticles as the Main Active Site
Supported Pd–Au alloy catalysts were developed for the highly efficient and selective hydrosilylation of α,β-unsaturated ketones and alkynes. The Pd/Au atomic ratio of the Pd–Au alloy and the supporting material affected the catalytic activity, and supported Pd–Au alloy nanoparticles with a low Pd/Au atomic ratio functioned as highly active heterogeneouscatalystsundermildreactionconditions. Structural
[NiX
<sub>2</sub>
(NHC)
<sub>2</sub>
] Complexes in the Hydrosilylation of Internal Alkynes
作者:Joris Berding、John A. van Paridon、Vincent H. S. van Rixel、Elisabeth Bouwman
DOI:10.1002/ejic.201100015
日期:2011.5
A number of nickel(II) dihalide complexes with small monodentate N-heterocyclic carbene ligands was synthesized and tested for their catalytic activity in the hydrosilylation of internal alkynes. The nickel(0) active species was obtained from the starting nickel(II) complex by reduction with diethylzinc. In all cases the catalytic reaction yielded the syn product selectively. The fastest catalysts
Investigation of the factors controlling the regioselectivity of the hydrosilylation of alkynes catalysed by trans-di-μ-hydridobis(tricylcohexylphosphine)bis(silyl)diplatinum complexes
作者:Constantinos A. Tsipis
DOI:10.1016/s0022-328x(00)93435-1
日期:1980.3
The hydrosilylation of terminal and internalalkynes and also of some hydroxy-alkynes catalysed by trans-di-μ-hydridobis(tricyclohexylphosphine)bis(silyl)diplatinum complexes is described. These diplatinum complexes are very efficient catalysts for such hydrosilylations; high yields (80–98%) can be obtained under mild conditions with a catalysts/reactant ratio of 10−4–10−5/1. Addition of hydrosilanes