1206-46-8Relevant articles and documents
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)
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.
Multicomponent Coupling Reaction of Perfluoroarenes with 1,3-Butadiene and Aryl Grignard Reagents Promoted by an Anionic Ni(II) Complex
Iwasaki, Takanori,Fukuoka, Asuka,Min, Xin,Yokoyama, Wataru,Kuniyasu, Hitoshi,Kambe, Nobuaki
, p. 4868 - 4871 (2016)
An anionic Ni complex was isolated and its structure determined by X-ray crystallography. With such an anionic complex as a key intermediate, a regio- and stereoselective multicomponent coupling reaction of perfluoroarenes, aryl Grignard reagents, and 1,3-butadiene in a 1:1:2 ratio was achieved, resulting in the formation of 1,6-octadiene derivatives containing two aryl groups, one from the perfluoroarene and the other from the aryl Grignard reagent, at the 3- and 8-positions, respectively.
Preparation of heptafluoronaphthyllithiums and -magnesiums: An unexpected difference in the reactivity of isomers C10F7H and C10F7Br towards organolithium and organomagnesium compounds
Shmakov, Mikhail M.,Bardin, Vadim V.,Prikhod'ko, Sergey A.,Adonin, Nicolay Yu
, (2019)
Significant differences in the reactivity of isomeric heptafluoronaphthalenes and bromoheptafluoronaphthalenes towards organolithium and organomagnesium compounds were found. Metalation of polyfluorinated naphthalenes 2-C10F7X (X = H, Br) occurs easily under the action of bases (BuLi, t-BuLi, LDA) as well as EtMgBr (X = Br) in ether. This fact was proven by 19F NMR spectroscopy and by trapping of 2-C10F7M (M = Li, MgBr, Mg(2-C10F7)) with electrophile ClSiMe3. The interaction of 1-C10F7Br with BuLi or EtMgBr proceeds in a similar way. In contrast to 2-C10F7H, isomeric 1-C10F7H is the less acidic substrate and undergoes only the nucleophilic alkyldefluorination when combined with BuLi or t-BuLi.
Hydrocarbon-Soluble Bis(trimethylsilylmethyl)calcium and Calcium-Iodine Exchange Reactions at sp2-Hybrized Carbon Atoms
Koch, Alexander,Wirgenings, Marino,Krieck, Sven,G?rls, Helmar,Pohnert, Georg,Westerhausen, Matthias
, p. 3981 - 3986 (2017)
Hydrocarbon-soluble and highly reactive [(L)xCa(CH2SiMe3)2] (L = tetrahydropyran, x = 4 (2a); L = tmeda, x = 2 (2b)) is synthesized by the metathesis reaction of Me3SiCH2CaI (1-I) with KCH2SiMe3. The durability of 2a in tetrahydropyran solution at 0 °C is sufficiently high for subsequent chemical transformations. The reaction of ICH2SiMe3 with calcium in diethyl ether yields unique cage compound [(Et2O)2Ca(I)2·(Et2O)2Ca(I)(OEt)·(Et2O)Ca(I)(CH2SiMe3)] (3). We demonstrate that alkylcalcium complexes are valuable reagents for calcium-iodine exchange reactions at Csp2-I functionalities.
Influence of N-Heterocyclic Carbene Steric Bulk on Selectivity in Nickel Catalyzed C-H Bond Silylation, Germylation, and Stannylation
Elsby, Matthew R.,Liu, Junyang,Zhu, Sha,Hu, Lingfei,Huang, Genping,Johnson, Samuel A.
supporting information, p. 436 - 450 (2019/01/04)
A series of Ni(0) compounds supported by electronically similar N-heterocyclic carbene (NHC) ancillary ligands with a range of %Vbur were used as catalysts for aryl C-H bond silylation, germylation, and stannylation. The NHC steric bulk strongly influenced the selectivity of C-H functionalization to give new carbon-heteroatom bonds versus alkene hydroarylation, despite little structural change in the resting state of the catalysts. Studies were performed by reacting C6F5H and H2C=CHER3 (ER3 = SnBu3, GePh3, SiMe3) using catalytic amounts of Ni(COD)2 and NHC ligands IPr, IMes, IBn, and iPr2Im. Catalytic C-H stannylation to give C6F5SnBu3 was facile with all ligands. The catalytic C-H germylation reaction was more difficult than stannylation but was demonstrated using H2C=CHGePh3 to give C6F5GePh3 for all but the largest NHC. The bulkiest NHC, IPr, gave a 96:4 ratio of the hydroarylation product C6F5CH2CH2GePh3 versus C6F5GePh3. The C-H silylation reactions required the highest temperatures and gave selective silylation product C6F5SiMe3 only for the smallest IBn and iPr2Im NHC ligands. Using the larger IMes carbene resulted in a 66:34 mixture of silylation and hydroarylation products, and the largest NHC, IPr, gave exclusive conversion to the hydroarylation product, C6F5CH2CH2SiMe3. DFT calculations are provided that give insight into the mechanism and key reaction steps, such as the relative difficulty of the critical β-Sn, Ge, and Si elimination steps.
Supramolecular Aggregation of Perfluoroorganyl Iodane Reagents in the Solid State and in Solution
Liebing, Phil,Pietrasiak, Ewa,Otth, Elisabeth,Kalim, Jorna,Bornemann, Dustin,Togni, Antonio
, p. 3771 - 3781 (2018/07/31)
The crystal structures of different perfluoroorganyl iodanes are described, including those of four new benziodoxole derivatives with RF = n-C3F7, n-C4F9, n-C8F17, and C6F5. In all of the compounds, the iodine atom shows significant Lewis acidity, and the fourth coordination site is readily filled by secondary bonding interactions to produce square-planar coordination. Although this geometry is a good model for benziodoxoles, benziodoxolone derivatives tend to aggregate further through additional weak I···O or I···aryl contacts. The different interactions lead to the formation of various assemblies with different dimensions in the solid state. The protonation of the reagents results in the formation of entirely different supramolecular structures, which are supported by hydrogen bonding. The structural features of the reagents in the solid state reflect well their behavior in solution, and the I–C(RF) bond is influenced by the coordination of Lewis basic solvents to the iodine atom and by hydrogen bonding with protic solvents. These solvent effects are more pronounced for reagents containing the trifluoromethyl fragment than for derivatives with longer RF chains.
Nickel-Catalyzed C-H Silylation of Arenes with Vinylsilanes: Rapid and Reversible β-Si Elimination
Elsby, Matthew R.,Johnson, Samuel A.
supporting information, p. 9401 - 9407 (2017/07/22)
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.
Formation of perfluorinated polyphenylenes by multiple pentafluorophenylation using C6F5Si(CH3) 3
Nishida, Masakazu,Hayakawa, Yoshio,Ono, Taizo
experimental part, p. 1314 - 1321 (2011/02/22)
Pentafluorophenylation of perfluoroarenes with C6F 5Si(CH3)3 was investigated by using NMR and MALDI-TOF-MS techniques. Successive multiple pentafluorophenylation easily occurred not only on the para-position but also on the ortho-positions to provide perfluorinated p-phenylene and m-phenylene compounds. The perfluoroarenes having electron-withdrawing substituents provided oligo- to poly-(phenylene)s depending on the added amounts of C6F 5Si(CH3)3, while the perfluoroarenes having electron-donor substituents gave H(C6F4)nF polymers produced from C6F5H, which was the decomposed product of C6F5Si(CH3)3.
Reactions of polyfluoroaromatic compounds with electrophilic agents in the presence of tris(dialkylamino)phosphine: 6. * Reactions of halogenotetrafluorobenzenes RC6F4X (X = Cl, Br, or I) with chlorotrimethylsilane
Bardin
, p. 780 - 785 (2007/10/03)
The rate of replacement of the halogen atom in isomers of RC6F4X (X = Cl, Br, or I) by the SiMe3 group under the action of Me3SiCl and P(NEt2)3 depends on the nature and the mutual arrangement of the substituents X and R. In addition to silyldehalogenation, compounds C6HF4X (X = Br or I) undergo silyldeprotonation and reduction to tetrafluorobenzenes.
Peculiarities in the cleavage by methyllithium of unsymmetrical disilanes
Hevesi,Dehon
, p. 8031 - 8032 (2007/10/02)
The title reactions did not produce the more stable silyl anions from the disilanes studied, they either occurred by attack at the more electrophilic silicon atom, or led to unexpected products.
