14924-70-0Relevant articles and documents
A substituent- And temperature-controllable NHC-derived zwitterionic catalyst enables CO2upgrading for high-efficiency construction of formamides and benzimidazoles
Li, Hu,Li, Zhengyi,Wu, Hongguo,Yang, Song,Yu, Zhaozhuo,Zhang, Lilong,Zhu, Kaixun
supporting information, p. 5759 - 5765 (2021/08/23)
Chemocatalytic upgrading of the greenhouse gas CO2 to valuable chemicals and biofuels has attracted broad attention in recent years. Among the reported approaches, N-formylation of CO2 with an amine is of great significance due to its versatility in the construction of N-containing linear and cyclic skeletons. Herein, a stable N-heterocyclic carbene-carboxyl adduct (NHC-CO2) was facilely prepared and could be used as a recyclable zwitterionic catalyst for efficient CO2 reductive upgrading via either N-formylation or further coupling with cyclization under mild conditions (25 °C, 1 atm CO2) using hydrosilane as a hydrogen source. More than 30 different alkyl and aromatic amines could be transformed into the corresponding formamides or benzimidazoles with remarkable yields (74%-98%). The electronic effect of the introduced substituent on NHC-CO2 was found to evidently affect the thermostability and nucleophilicity of the zwitterionic catalyst, which is directly correlated with its catalytic activity. Moreover, NHC-CO2 could supply CO2 by in situ decarboxylation at a specific temperature that is dependent on the introduced substituent type. Experimental and computational studies showed that the carboxyl species on NHC-CO2 was not only a nucleophilic center, but also a C1 source which rapidly captures or substitutes ambient CO2 during hydrosilylation. In addition, a simple and green conceptual process was designed for the product purification and catalyst recycling, with a good feasibility for small-scale production.
Copper-Catalyzed N-Formylation of Amines through Tandem Amination/Hydrolysis/Decarboxylation Reaction of Ethyl Bromodifluoroacetate
Li, Xiao-Fang,Zhang, Xing-Guo,Chen, Fan,Zhang, Xiao-Hong
, p. 12815 - 12821 (2018/10/20)
Ethyl bromodifluoroacetate (BrCF2COOEt) was first used as the N-formylating reagent in the copper-catalyzed N-formylation of amines. A range of primary, secondary, cyclic arylamines, and aliphatic amines underwent the N-formylation smoothly to furnish the N-formamides in moderate-to-excellent yields.
Pd-catalyzed intermolecular amidation of aryl halides: The discovery that xantphos can be trans-chelating in a palladium complex
Yin, Jingjun,Buchwald, Stephen L.
, p. 6043 - 6048 (2007/10/03)
A general method for the intermolecular coupling of aryl halides and amides using a Xantphos/ Pd catalyst is described. This system displays good functional group compatibility, and the desired C-N bond forming process proceeds in good to excellent yields with 1-4 mol % of the Pd catalyst. Additionally, the arylation of sulfonamides, oxazolidinones, and ureas is reported. The efficiency of these transformations was found to be highly dependent on reaction concentrations and catalyst loadings. A Pd complex resulting from oxidative addition of 4-bromobenzonitrile, (Xantphos)Pd(4-cyanophenyl)(Br) (II), was prepared in one step from Xantphos, Pd2(dba)3, and the aryl bromide. Complex II proved to be an active catalyst for the coupling between 4-bromobenzonitrile and benzamide. X-ray crystallographic analysis of II revealed a rare trans-chelating bisphosphine-Pd(II) structure with a large bite angle of 150.7°.
