2879-83-6Relevant articles and documents
Synthesis of NHC-Iridium(III) Complexes Based on N-Iminoimidazolium Ylides and Their Use for the Amine Alkylation by Borrowing Hydrogen Catalysis
Guérin, Vincent,Legault, Claude Y.
supporting information, p. 408 - 417 (2021/02/01)
Anionic NHC ligands recently developed in our group, derived from N-iminoimidazolium ylides, were used to synthesize NHC-iridium(III) complexes. Their catalytic activities were evaluated in the amine alkylation of anilines using borrowing hydrogen catalysis. The high-yielding synthesis of a small library of complexes allowed a rapid screening of the ideal steric bulk of the NHC unit and basicity of the anionic tether for the investigated model reaction. A bulky aromatic N group on the imidazolidene moiety is required to achieve high catalytic activity, and the latter is proportional to the basicity of the anionic group. A selected substrate scope of the reaction was performed, providing fair to excellent yields of the desired alkylated anilines.
Effect of the ancillary ligand in N-heterocyclic carbene iridium(III) catalyzed N-alkylation of amines with alcohols
Feng, Xinshu,Huang, Ming
, (2021/06/21)
A series of air-stable N-heterocyclic carbene (NHC) Ir(III) complexes (Ir1-6), bearing various combinations of chlorine, pyridine and NHC ligands, were assayed for the N-alkylation of amines with alcohols. It was found that Ir3, with two monodentate 1,3-bis-methyl-imidazolylidene (IMe) ligands, emerged as the most active complex. A large variety of amines and primary alcohols were efficiently converted into mono-N-alkylated amines in 53–96% yields. As a special highlight, for the challenging MeOH, selective N-monomethylation could be achieved using KOH as a base under an air atmosphere. Moreover, this catalytic system was successfully applied to the gram-scale synthesis of some valuable compounds.
Ruthenium(ii) complexes with N-heterocyclic carbene-phosphine ligands for theN-alkylation of amines with alcohols
Huang, Ming,Li, Yinwu,Lan, Xiao-Bing,Liu, Jiahao,Zhao, Cunyuan,Liu, Yan,Ke, Zhuofeng
supporting information, p. 3451 - 3461 (2021/05/03)
Metal hydride complexes are key intermediates forN-alkylation of amines with alcohols by the borrowing hydrogen/hydrogen autotransfer (BH/HA) strategy. Reactivity tuning of metal hydride complexes could adjust the dehydrogenation of alcohols and the hydrogenation of imines. Herein we report ruthenium(ii) complexes with hetero-bidentate N-heterocyclic carbene (NHC)-phosphine ligands, which realize smart pathway selection in theN-alkylated reactionviareactivity tuning of [Ru-H] species by hetero-bidentate ligands. In particular, complex6cbwith a phenyl wingtip group and BArF?counter anion, is shown to be one of the most efficient pre-catalysts for this transformation (temperature is as low as 70 °C, neat conditions and catalyst loading is as low as 0.25 mol%). A large variety of (hetero)aromatic amines and primary alcohols were efficiently converted into mono-N-alkylated amines in good to excellent isolated yields. Notably, aliphatic amines, challenging methanol and diamines could also be transformed into the desired products. Detailed control experiments and density functional theory (DFT) calculations provide insights to understand the mechanism and the smart pathway selectionvia[Ru-H] species in this process.
