Imidazole Derivatives as Accelerators for Ruthenium‐Catalyzed Hydroesterification and Hydrocarbamoylation of Alkenes: Extensive Ligand Screening and Mechanistic Study

Abstract

Abstract Imidazole derivatives are effective ligands for promoting the [Ru 3 (CO) 12 ]‐catalyzed hydroesterification of alkenes using formates. Extensive ligand screening was performed to identify 2‐hydroxymethylated imidazole as the optimal ligand. Neither carbon monoxide gas nor a directing group was required, and the reaction also showed a wide substrate generality. The Ru–imidazole catalyst system also promoted intramolecular hydrocarbamoylation to afford lactams. A Ru–imidazole complex was unambiguously analyzed by X‐ray crystallography, and it had a trinuclear structure derived from one [Ru 3 (CO) 12 ] and two ligands. This complex was also successfully used for hydroesterification. The mechanism was examined in detail by using D ‐ and 13 C‐labeled formates, indicating that the hydroesterification reaction proceeds by a decarbonylation–recarbonylation pathway.