35943-75-0Relevant academic research and scientific papers
Nickel-Catalyzed C-H Silylation of Arenes with Vinylsilanes: Rapid and Reversible β-Si Elimination
Elsby, Matthew R.,Johnson, Samuel A.
, p. 9401 - 9407 (2017)
The reaction of C6F5H and H2C=CHSiMe3 with catalytic [iPr2Im]Ni(2-H2C=CHSiMe3)2 (1b) exclusively forms the C-H silylation product C6F5SiMe3 with ethylene as a byproduct ([iPr2Im] = 1,3-di(isopropyl)imidazole-2-ylidene). Catalytic C-H bond silylation is facile with partially fluorinated aromatic substrates containing two ortho fluorine substituents adjacent to the C-H bond and 1,2,3,4-tetrafluorobenzene. Less fluorinated substrates react slower. Under the same reaction conditions, catalytic [IPr]Ni(η2-H2C=CHSiMe3)2 (1a) ([IPr] = 1,3-bis[2,6-diisopropylphenyl]-1,3-dihydro-2H-imidazol-2-ylidene) provided only the alkene hydroarylation product C6F5CH2CH2SiMe3. Mechanistic studies reveal that the C-H activation and β-Si elimination steps are reversible under catalytic conditions with both catalysts 1a and 1b. With catalytic 1a, reversible ethylene loss after β-Si elimination was also observed despite its inability to catalyze C-H silylation; the reductive elimination step to form the silylation product is much slower than reductive elimination to form the alkene hydroarylation product. Reversible ethylene loss was not observed with 1b, which suggests that the rate-limiting step in the reaction is neither C-H activation nor β-Si elimination but either ethylene loss or reductive elimination of cis-disposed aryl and SiMe3 moieties.
The influence of NHCs on C-Si and C-C reductive elimination: A computational study of the selectivity of Ni-catalyzed C-H activation of arenes with vinylsilanes
Liu, Xiao-Jun,Tian, Ying-Ying,Cui, Hong-Qiang,Fan, Hui-Jun
, p. 7912 - 7915 (2018/07/25)
Density functional theory calculations were performed to investigate the mechanism and origins of the NHC-controlled selectivity of Ni-catalyzed C-H activation of arenes with vinylsilanes. The key to the selectivity is the different impacts of NHCs on the C-Si/C-C reductive elimination of the square-planar/T-shaped intermediate.
