1355956-94-3Relevant articles and documents
Pincer Cobalt Hydride Catalyzed Distinct Selective Hydrosilylation of Aryl Alkene and Alkyl Alkene
Fenske, Dieter,Fuhr, Olaf,Li, Xiaoyan,Sun, Hongjian,Xie, Shangqing
, (2020)
The reactions of unsymmetrical N-heterocyclic carbene (NHC) [CNC]-pincer preligands with CoMe(PMe3)4 gave rise to NHC [CNC]-pincer cobalt(III) hydrides, [(CcarbeneNaminoCnaphthyl)Co(H)(PMe3)2] (3a) and (3b), via Csp2-H activation and the unexpected trans-bischelate [Ccarbene, Namino] cobalt(II) complexes 4a and 4b via a disproportionation reaction, respectively. It was found that both 3a and 3b are efficient catalysts for hydrosilylation of alkenes. With aryl alkenes as substrates, 3a has high Markovnikov selectivity in excellent yields, while 3a is an efficient anti-Markovnikov catalyst in good yields with alkyl alkenes as substrates. The catalytic process could be promoted with pyridine N-oxide as an initiator. The catalytic mechanisms for the two different selectivities were proposed. Complexes 3a, 3b, 4a, and 4b were characterized by spectroscopic methods, and the molecular structures of 3b, 4a, and 4b were determined by single crystal X-ray diffraction.
Selectivity Reverse of Hydrosilylation of Aryl Alkenes Realized by Pyridine N-Oxide with [PSiP] Pincer Cobalt(III) Hydride as Catalyst
Dong, Yanhong,Xie, Shangqing,Zhang, Peng,Fan, Qingqing,Du, Xinyu,Sun, Hongjian,Li, Xiaoyan,Fuhr, Olaf,Fenske, Dieter
, p. 4551 - 4562 (2021/04/06)
Six silyl cobalt(III) hydrides 1-6 with [PSiP] pincer ligands having different substituents at the P and Si atoms ([(2-Ph2PC6H4)2MeSiCo(H)(Cl)(PMe3)] (1), [(2-Ph2PC6H4)2HSiCo(H)(Cl)(PMe3)] (2), [(2-Ph2PC6H4)2PhSiCo(H)(Cl)(PMe3)] (3), [(2-iPr2PC6H4)2HSiCo(H)(Cl)(PMe3)] (4), [(2-iPr2PC6H4)2MeSiCo(H)(Cl)(PMe3)] (5), and [(2-iPr2PC6H4)2PhSiCo(H)(Cl)(PMe3)] (6)) were synthesized through the reactions of the ligands (L1-L6) with CoCl(PMe3)3 via Si-H bond cleavage. Compounds 1-6 have catalytic activity for alkene hydrosilylation, and among them, complex 3 is the best catalyst with excellent anti-Markovnikov regioselectivity. A silyl dihydrido cobalt(III) complex 7 from the reaction of 3 with Ph2SiH2 was isolated, and its catalytic activity is equivalent to that of complex 3. Complex 7 and its derivatives 10-12 could also be obtained through the reactions of complexes 3, 1, 4, and 5 with NaBHEt3. The molecular structure of 7 was indirectly verified by the structures of 10-12. To our delight, the addition of pyridine N-oxide reversed the selectivity of the reaction, from anti-Markovnikov to Markovnikov addition. At the same time, the reaction temperature was reduced from 70 to 30 °C on the premise of high yield and excellent selectivity. However, this catalytic system is only applicable to aromatic alkenes. On the basis of the experimental information, two reaction mechanisms are proposed. The molecular structures of cobalt(III) complexes 3-6 and 10-12 were determined by single crystal X-ray diffraction analysis.
Synthesis and properties of [PCP] pincer silylene cobalt(i) complexes
Fan, Qingqing,Fenske, Dieter,Fuhr, Olaf,Huang, Wei,Li, Xiaoyan,Li, Yonghui,Sun, Hongjian,Xie, Shangqing,Yang, Haiquan
, p. 19950 - 19956 (2021/11/12)
In this study, two [PCP] pincer silylene cobalt(i) complexes [((Ph2POCH2)2CH)Co(PMe3)(SiCl((NtBu)2CAr))] (Ar = Ph (2) and 4-MePh (3)) were synthesized through the substitution reaction of t
Iron complex containing ortho-carborane Schiff base ligand as well as preparation method and application thereof (by machine translation)
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Paragraph 0064-0068, (2020/01/03)
The invention relates to an iron complex containing ortho- carborane Schiff base ligand, and a preparation method and application 60 - 100 °C of the iron complex :1), 8 - 12h,2) FeCl. 2 Compared, with the prior art 3 - 6h, the synthesis method
Distinct Catalytic Performance of Cobalt(I)- N -Heterocyclic Carbene Complexes in Promoting the Reaction of Alkene with Diphenylsilane: Selective 2,1-Hydrosilylation, 1,2-Hydrosilylation, and Hydrogenation of Alkene
Gao, Yafei,Wang, Lijun,Deng, Liang
, p. 9637 - 9646 (2018/10/02)
Selectivity control on the reaction of alkene with hydrosilane is a challenging task in the development of non-precious-metal-based hydrosilylation catalysts. While the traditional way of selectivity control relies on the use of different ligand type and/or different metals, we report herein that cobalt(I) complexes bearing different N-heterocyclic carbene ligands (NHCs) exhibit distinct selectivity in catalyzing the reaction of alkene with Ph2SiH2. [(IAd)(PPh3)CoCl] (IAd = 1,3-diadamantylimidazol-2-ylidene) is an efficient catalyst for anti-Markovnikov hydrosilylation of monosubstituted alkenes. [(IMes)2CoCl] (IMes = 1,3-dimesitylimidazol-2-ylidene) shows Markovnikov-addition selectivity in promoting the hydrosilylation of aryl-substituted alkenes. [(IMe2Me2)4Co][BPh4] (IMe2Me2 = 1,3-dimethyl-4,5-dimethylimidazol-2-ylidene) can catalyze hydrogenation of alkenes with Ph2SiH2 as the terminal hydrogen source. Mechanistic studies in combination with the knowledge on the steric nature of cobalt-NHC species suggest that (NHC)cobalt(I) silyl species and bis(NHC)cobalt(I) hydride species are the probable key intermediates for these hydrosilylation and hydrogenation reactions, respectively. The different steric nature of IAd versus IMes and the potential of IMes incurring π···π interaction with aryl-substituted alkenes are thought to be the causes of the observed 1,2- and 2,1-addition selectivity.
General and practical one-pot synthesis of dihydrobenzosiloles from styrenes
Kuznetsov, Alexey,Gevorgyan, Vladimir
supporting information; experimental part, p. 914 - 917 (2012/05/05)
A one-pot synthesis of dihydrobenzosiloles from styrenes has been developed. The reaction involves the nickel-catalyzed hydrosilylation of styrene with diphenylsilane, followed by the iridium-catalyzed dehydrogenative cyclization. This method is efficient for both electron-rich and -deficient styrenes and exhibits good functional group tolerance, as well as excellent regioselectivity. The forming dihydrobenzosiloles can be efficiently converted into valuable benzosiloles or 2-hydroxyphenethyl alcohols.
