7364-21-8Relevant articles and documents
Parameterization of phosphine ligands demonstrates enhancement of nickel catalysis via remote steric effects
Wu, Kevin,Doyle, Abigail G.
, p. 779 - 784 (2017)
The field of Ni-catalysed cross-coupling has seen rapid recent growth because of the low cost of Ni, its earth abundance, and its ability to promote unique cross-coupling reactions. Whereas advances in the related field of Pd-catalysed cross-coupling have been driven by ligand design, the development of ligands specifically for Ni has received minimal attention. Here, we disclose a class of phosphines that enable the Ni-catalysed Csp^3 Suzuki coupling of acetals with boronic acids to generate benzylic ethers, a reaction that failed with known ligands for Ni and designer phosphines for Pd. Using parameters to quantify phosphine steric and electronic properties together with regression statistical analysis, we identify a model for ligand success. The study suggests that effective phosphines feature remote steric hindrance, a concept that could guide future ligand design tailored to Ni. Our analysis also reveals that two classic descriptors for ligand steric environment - cone angle and % buried volume - are not equivalent, despite their treatment in the literature.
Visible Light-Catalyzed Benzylic C-H Bond Chlorination by a Combination of Organic Dye (Acr+-Mes) and N-Chlorosuccinimide
Xiang, Ming,Zhou, Chao,Yang, Xiu-Long,Chen, Bin,Tung, Chen-Ho,Wu, Li-Zhu
, p. 9080 - 9087 (2020/08/14)
By combining "N-chlorosuccinimide (NCS)"as the safe chlorine source with "Acr+-Mes"as the photocatalyst, we successfully achieved benzylic C-H bond chlorination under visible light irradiation. Furthermore, benzylic chlorides could be converted to benzylic ethers smoothly in a one-pot manner by adding sodium methoxide. This mild and scalable chlorination method worked effectively for diverse toluene derivatives, especially for electron-deficient substrates. Careful mechanistic studies supported that NCS provided a hydrogen abstractor "N-centered succinimidyl radical,"which was responsible for the cleavage of the benzylic C-H bond, relying on the reducing ability of Acr?-Mes.
Palladium-Catalyzed Reductive Cross-Coupling Reaction of Aryl Chromium(0) Fischer Carbene Complexes with Aryl Iodides
Wang, Kang,Lu, Yu,Hu, Fangdong,Yang, Jinghui,Zhang, Yan,Wang, Zhi-Xiang,Wang, Jianbo
, p. 1 - 10 (2018/01/17)
The first palladium-catalyzed reductive cross-couplings of aryl chromium(0) carbene complexes with aryl iodides have been realized. This coupling reaction shows excellent functional group tolerance and high efficiency. Mechanistically, aryl chromium(0) carbene complexes undergo transmetalation with arylpalladium species to generate palladium(II) carbene intermediates, which is followed by migratory insertion. The catalytic cycle is then completed by hydrogen transfer and reductive elimination. Consistent with the mechanistic hypothesis, density functional theory (DFT) calculations support the involvement of a palladium carbene intermediate, and carbene migratory insertion is a facile step with an energy barrier of 5.1 kcal/mol. The carbene transfer step and the hydrogen transfer step are confirmed as the rate-limiting steps in the catalytic cycle.
METHOD FOR THE PREPARATION OF alpha-SUBSTITUTED ACRYL ALDEHYDES
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Paragraph 0177; 0182, (2016/04/19)
The invention discloses simple and rapid method for the preparation of α-substituted acryl aldehydes. More particularly, the invention discloses a method for the preparation of α-substituted acryl aldehydes via a gold-catalysed [1,3] rearrangement of the allenyl ethers with a record turnover frequency of 4600 h?1 at 0.05 mol % of the catalyst concentration in homogeneous gold(I) catalysis. The α-substituted acryl aldehydes synthesized by the instant process are used as building blocks in organic synthesis.
Dialkyl Ether Formation by Nickel-Catalyzed Cross-Coupling of Acetals and Aryl Iodides
Arendt, Kevin M.,Doyle, Abigail G.
supporting information, p. 9876 - 9880 (2015/08/19)
A new substrate class for nickel-catalyzed C(sp3) cross-coupling reactions is reported. α-Oxy radicals generated from benzylic acetals, TMSCl, and a mild reductant can participate in chemoselective cross-coupling with aryl iodides using a 2,6-bis(N-pyrazolyl)pyridine (bpp)/Ni catalyst. The mild, base-free conditions are tolerant of a variety of functional groups on both partners, thus representing an attractive C-C bond-forming approach to dialkyl ether synthesis. Characterization of a [(bpp)NiCl] complex relevant to the proposed catalytic cycle is also described.
Solvolytic reactivity of pyridinium ions
Juric, Sandra,Kronja, Olga
, p. 314 - 319 (2015/05/05)
The leaving group abilities of pyridine, 4-methylpyridine, and 4-chloropyridine in SN1 solvolytic reactions have been determined by analyzing the rate constants of X,Y-substituted benzhydrylpyridinium salts obtained in various solvents. By applying the linear free energy relationship equation, log k = sf (Ef + Nf), the nucleofuge specific parameters of 4-substituted pyridine have been extracted. Because of solvation in the reactant ground state, the reactivity (nucleofugality, Nf) of a given pyridine decreases as the polarity of the solvent increases. High slope parameters (sf > 1) may be due to the spread of the energy levels of the benzhydrylium ion/pyridine pair intermediates in comparison to benzhydrylium ion/chloride pairs (sf ≈ 1). Because of slow heterolysis step of pyridinium salts in various solvents, some are stable under normal conditions.
Gold(i)-catalysed [1,3] O→C rearrangement of allenyl ethers
Kona, Chandrababu Naidu,Ramana, Chepuri V.
, p. 2152 - 2154 (2014/02/14)
A simple and rapid access to the α-substituted acryl aldehydes has been provided by developing a gold-catalysed [1,3] rearrangement of the allenyl ethers importantly with a record turnover frequency of 4600 h-1 (at 0.05 mol% of the catalyst concentration) in homogeneous gold(i) catalysis. The Royal Society of Chemistry.
Organocatalytic approach for C(sp3)-H bond arylation, alkylation, and amidation of isochromans under facile conditions
Muramatsu, Wataru,Nakano, Kimihiro
supporting information, p. 2042 - 2045 (2014/05/06)
A new catalytic approach for the synthesis of isochroman derivatives via direct C(sp3)-H bond arylation is described. The oxidation reaction with [bis(trifluoroacetoxy)iodo]benzene facilitates the regeneration of 2,3-dichloro-5,6-dicyano-1,4-benzoquinone in the C(sp3)-H bond arylation of isochroman. The reaction conditions can also be used for alkyl Grignard reagents and amides to afford the corresponding isochroman derivatives.
Efficient assembly of α-aryl and α-vinyl nitriles via iron-catalyzed ether bond activation
Fan, Xiaohui,Guo, Kun,Guan, Yong-Hong,Fu, Lin-An,Cui, Xiao-Meng,Lv, Hao,Zhu, Hong-Bo
supporting information, p. 1068 - 1071 (2014/02/14)
A novel and practical method for the synthesis of diverse α-aryl and α-vinyl nitriles was developed via an iron-catalyzed sp3 C-O ether bond cleavage with C-C bond formation in the reaction of π-activated ethers with TMSCN.
Efficient assembly of α-aryl and α-vinyl nitriles via iron-catalyzed ether bond activation
Fan, Xiaohui,Guo, Kun,Guan, Yong-Hong,Fu, Lin-An,Cui, Xiao-Meng,Lv, Hao,Zhu, Hong-Bo
supporting information, p. 1068 - 1071 (2015/02/18)
A novel and practical method for the synthesis of diverse α-aryl and α-vinyl nitriles was developed via an iron-catalyzed sp3 C-O ether bond cleavage with C-C bond formation in the reaction of π-activated ethers with TMSCN.
