61589-14-8Relevant articles and documents
The Origin of the Regioselectivity in the 2+2 Photochemical Cycloaddition Reactions of N-Benzoylindole with Alkenes: Trapping of 1,4-Biradical Intermediates with Hydrogen Selenide
Hastings, David J.,Weedon, Alan C.
, p. 4107 - 4110 (1991)
The 1,4-biradical species previously proposed as intermediates in the formation of cyclobutane adducts in the photochemical cycloaddition reaction between N-benzoylindole and alkenes have been trapped with hydrogen selenide.The structures of the trapped biradicals are consistent with the proposal that the first bond formed between the triplet excited state of the indole derivative and the alkenes is from the indole 2-position to that terminus of the alkene which is less able to stabilise a radical centre.This allows prediction of the reaction regiochemistry.Key Words: N-benzoylindole; photochemical cycloaddition; 1,4-biradicals; trapping.
Manganese Catalyzed Direct Amidation of Esters with Amines
Fu, Zhengqiang,Wang, Xinghua,Tao, Sheng,Bu, Qingqing,Wei, Donghui,Liu, Ning
, p. 2339 - 2358 (2021/02/03)
The transition metal catalyzed amide bond forming reaction of esters with amines has been developed as an advanced approach for overcoming the shortcomings of traditional methods. The broad scope of substrates in transition metal catalyzed amidations remains a challenge. Here, a manganese(I)-catalyzed method for the direct synthesis of amides from a various number of esters and amines is reported with unprecedented substrate scope using a low catalyst loading. A wide range of aromatic, aliphatic, and heterocyclic esters, even in fatty acid esters, reacted with a diverse range of primary aryl amines, primary alkyl amines, and secondary alkyl amines to form amides. It is noteworthy that this approach provides the first example of the transition metal catalyzed amide bond forming reaction from fatty acid esters and amines. The acid-base mechanism for the manganese(I)-catalyzed direct amidation of esters with amines was elucidated by DFT calculations.
Methyl Esters as Cross-Coupling Electrophiles: Direct Synthesis of Amide Bonds
Zheng, Yan-Long,Newman, Stephen G.
, p. 4426 - 4433 (2019/05/08)
Amide bond formation and transition metal-catalyzed cross-coupling are two of the most frequently used chemical reactions in organic synthesis. Recently, an overlap between these two reaction families was identified when Pd and Ni catalysts were demonstrated to cleave the strong C-O bond present in esters via oxidative addition. When simple methyl and ethyl esters are used, this transformation provides a powerful alternative to classical amide bond formations, which commonly feature stoichiometric activating agents. Thus far, few redox-active catalysts have been demonstrated to activate the C(acyl)-O bond of alkyl esters, which makes it difficult to perform informed screening when a challenging reaction needs optimization. We demonstrate that Ni catalysts bearing diverse NHC, phosphine, and nitrogen-containing ligands can all be used to activate methyl esters and enable their use in direct amide bond formation.
