氨基甲酸芳基酯用于氨的镍催化单芳基化。应用的、定义明确的单组分镍 (II) 预催化剂包含 Josiphos 配体,在空气中稳定,并且无需任何辅助还原剂即可运行。该催化剂体系还促进了氨基甲酸芳基酯与硫酸铵以及伯烷基胺的盐酸盐的胺化。它们的容易制备、稳健性和导向基团能力使氨基甲酸芳基酯成为特别有吸引力的合成中间体。
A revisit of organoaluminumreagents for cross-coupling reactions has opened up several types of C–C bond formation protocols through cleavage of phenolic/alcoholic C–O and C–F and ammonium C–N bonds. Catalyzed by the commercially available NiCl2(PCy3)2 catalyst, these reactions proceed smoothly with a wide range of substrates and broad functional group compatibility, providing a versatile methodology
was established to be a crucial parameter for this transformation. When combined with DoM and traditional Pd-catalyzed Suzuki-Miyaura strategies, the methodology offers concise routes to uniquely substituted molecules, avoiding the need for protection/deprotection of the phenol and the use of strongly nucleophilic cross-coupling partners.
DFT Studies Provide Mechanistic Insight into Nickel-Catalyzed Cross-Coupling Involving Organoaluminum-Mediated C–O Bond Cleavage
作者:Chao Wang、Masanobu Uchiyama、Ze-Kun Yang
DOI:10.1055/s-0036-1590863
日期:2017.12
Density functional theory (DFT) calculations were performed to examine the reaction pathway of Ni-catalyzed cross-coupling with organoaluminum through C–O bond cleavage. The results indicate that the strong Lewis acidity of organoaluminums significantly facilitates the transmetalation step, but not the oxidative addition or reductive elimination step.
进行密度泛函理论 (DFT) 计算以检查 Ni 催化通过 C-O 键裂解与有机铝交叉偶联的反应途径。结果表明,有机铝的强路易斯酸性显着促进了金属转移步骤,但不利于氧化加成或还原消除步骤。
Nickel-Catalyzed Suzuki–Miyaura Couplings in Green Solvents
作者:Stephen D. Ramgren、Liana Hie、Yuxuan Ye、Neil K. Garg
DOI:10.1021/ol401727y
日期:2013.8.2
The nickel-catalyzed Suzuki-Miyaura coupling of aryl halides and phenol-derived substrates with aryl boronic acids using green solvents, such as 2-Me-THF and tert-amyl alcohol, is reported. This methodology employs the commercially available and air-stable precatalyst, NiCl2(PCy3)(2), and gives biaryl products in synthetically useful to excellent yields. Using this protocol, bis(heterocyclic) frameworks can be assembled efficiently.
Suzuki−Miyaura Cross-Coupling of Aryl Carbamates and Sulfamates: Experimental and Computational Studies
作者:Kyle W. Quasdorf、Aurora Antoft-Finch、Peng Liu、Amanda L. Silberstein、Anna Komaromi、Tom Blackburn、Stephen D. Ramgren、K. N. Houk、Victor Snieckus、Neil K. Garg
DOI:10.1021/ja200398c
日期:2011.4.27
The first Suzuki-Miyaura cross-coupling reactions of the synthetically versatile aryl O-carbamate and O-sulfamate groups are described. The transformations utilize the inexpensive, bench-stable catalyst NiCl2(PCy3)(2) to furnish biaryls in good to excellent yields. A broad scope for this methodology has been demonstrated. Substrates with electron-donating and electron-withdrawing groups are tolerated, in addition to those that possess ortho substituents. Furthermore, heteroaryl substrates may be employed as coupling partners. A computational study providing the full catalytic cycles for these cross-coupling reactions is described. The oxidative addition with carbamates or sulfamates occurs via a five-centered transition state, resulting in the exclusive cleavage of the aryl C-O bond. Water is found to stabilize the Ni-carbamate catalyst resting state, which thus provides rationalization of the relative decreased rate of coupling of carbamates. Several synthetic applications are presented to showcase the utility of the methodology in the synthesis of polysubstituted aromatic compounds of natural product and bioactive molecule interest.