《Pendant Alkoxy Groups on N-Aryl Substitutions Drive the Efficiency of Imidazolylidene Catalysts for Homoenolate Annulation from Enal and Aldehyde》 was published in Angewandte Chemie, International Edition in 2020. These research results belong to Kyan, Ryuji; Sato, Kohei; Mase, Nobuyuki; Narumi, Tetsuo. Application In Synthesis of 1,3-Dimesityl-1H-imidazol-3-ium chloride The article mentions the following:
Hydrogen-transfer in the tetrahedral intermediate generated from an imidazolylidene catalyst and α,β-unsaturated aldehyde forms a conjugated Breslow intermediate. This is a critical step affecting the efficiency of the NHC-catalyzed γ-butyrolactone formation via homoenolate addition to aryl aldehydes. A novel type of imidazolylidene catalyst with pendant alkoxy groups on the ortho-N-aryl groups is described. Catalyst of this sort facilitates the formation of the conjugated Breslow intermediate. Studies of the rate constants for homoenolate annulation affording γ-butyrolactones, reveal that introduction of the oxygen atoms in the appropriate position of the N-aryl substituents can increase the efficiency of imidazolylidene catalysts. Structural and mechanistic studies revealed that pendant alkoxy groups can be located close to the proton of the tetrahedral intermediate, thereby facilitating the proton transfer. The results came from multiple reactions, including the reaction of 1,3-Dimesityl-1H-imidazol-3-ium chloride(cas: 141556-45-8Application In Synthesis of 1,3-Dimesityl-1H-imidazol-3-ium chloride)
1,3-Dimesityl-1H-imidazol-3-ium chloride(cas: 141556-45-8) is a ligand for arylation of aldehydes and for carbene catalyzed intermolecular arylation of C-H bonds. It is used as a phosphine-free ligand in various metal-catalyzed coupling reactions, often with advantageous results in difficult cases.Application In Synthesis of 1,3-Dimesityl-1H-imidazol-3-ium chloride
Referemce:
Imidazole – Wikipedia,
Imidazole | C3H4N2 – PubChem