18753-27-0Relevant academic research and scientific papers
Silyldefluorination of Fluoroarenes by Concerted Nucleophilic Aromatic Substitution
Mallick, Shubhadip,Xu, Pan,Würthwein, Ernst-Ulrich,Studer, Armido
supporting information, p. 283 - 287 (2018/12/13)
The reaction of readily generated silyl lithium reagents with various aryl fluorides to provide the corresponding aryl silanes is reported. DFT calculations reveal that the nucleophilic aromatic substitution of the fluoride anion by the silyl lithium reagent proceeds through concerted ipso substitution. In contrast to the classical nucleophilic aromatic substitution, this concerted ionic silyldefluorination also occurs on more electron-rich aryl fluorides.
A well-defined NHC-Ir(III) catalyst for the silylation of aromatic C-H bonds: Substrate survey and mechanistic insights
Rubio-Pérez, Laura,Iglesias, Manuel,Munárriz, Julen,Polo, Victor,Passarelli, Vincenzo,Pérez-Torrente, Jesús J.,Oro, Luis A.
, p. 4811 - 4822 (2017/07/11)
A well-defined NHC-Ir(iii) catalyst, [Ir(H)2(IPr)(py)3][BF4] (IPr = 1,3-bis-(2,6-diisopropylphenyl)imidazol-2-ylidene), that provides access to a wide range of aryl- and heteroaryl-silanes by intermolecular dehydrogenative C-H bond silylation has been prepared and fully characterized. The directed and non-directed functionalisation of C-H bonds has been accomplished successfully using an arene as the limiting reagent and a variety of hydrosilanes in excess, including Et3SiH, Ph2MeSiH, PhMe2SiH, Ph3SiH and (EtO)3SiH. Examples that show unexpected selectivity patterns that stem from the presence of aromatic substituents in hydrosilanes are also presented. The selective bisarylation of bis(hydrosilane)s by directed or non-directed silylation of C-H bonds is also reported herein. Theoretical calculations at the DFT level shed light on the intermediate species in the catalytic cycle and the role played by the ligand system on the Ir(iii)/Ir(i) mechanism.
The preparation and analysis of the phenyldimethylsilyllithium reagent and its reaction with silyl enol ethers
Fleming, Ian,Roberts, Richard S.,Smith, Stephen C.
, p. 1209 - 1214 (2007/10/03)
Phenyldimethylsilyllithium is formed from lithium and phenyldimethylsilyl chloride by slow cleavage of the Si-Si bond of 1,1,2,2-tetramethyl-1,2-diphenyldisilane after the rapid formation of the disilane. 1,1,2,2-Tetramethyl-1,2-diphenyldisiloxane, produced from the silyl chloride by reaction with oxides and hydroxides on the lithium metal surface, is cleaved by dimethyl(phenyl)silyllithium to give lithium dimethyl(phenyl)silanoxide. Dimethyl(phenyl)silyllithium reacts with 1,2-dibromoethane to give dimethyl(phenyl)silyl bromide, which is so rapidly consumed by excess silyllithium reagent that it does not interfere with the double titration used to measure its concentration. Dimethyl(phenyl)silane, produced by protonation of the silyllithium reagent, is also consumed by the silyllithium reagent to give 1,1,2,2-tetramethyl-1,2-diphenyldisilane, which regenerates the silyllithium reagent, as long as lithium is still present. By-products in the preparation of dimethyl(phenyl)silyllithium include 1,3-diphenyl-1,1,2,2,3,3-hexamethyltrisilane, dimethyldiphenylsilane and 1,4-bis[dimethyl(phenyl)-silyl]benzene. Dimethyl(phenyl)silyllithium displaces the silyl group from the tert-butyldimethylsilyl enol ether of cyclohexanone to give the lithium enolate under relatively mild conditions.
