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

Imidazole derivatives are effective ligands for promoting the [Ru3(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,...

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Bibliographic Details
Published in:ChemCatChem 2015-03, Vol.7 (5), p.836-845
Main Authors: Konishi, Hideyuki, Muto, Takashi, Ueda, Tsuyoshi, Yamada, Yayoi, Yamaguchi, Miyuki, Manabe, Kei
Format: Article
Language:English
Subjects:
alkenes
carbonylation
ligand design
Ligands
reaction mechanisms
ruthenium
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Summary:Imidazole derivatives are effective ligands for promoting the [Ru3(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 [Ru3(CO)12] and two ligands. This complex was also successfully used for hydroesterification. The mechanism was examined in detail by using D‐ and 13C‐labeled formates, indicating that the hydroesterification reaction proceeds by a decarbonylation–recarbonylation pathway. Effective imidazole assistant: [Ru3(CO)12]‐catalyzed hydroesterification of alkenes by using formates is drastically accelerated by imidazole derivatives and exhibits a broad substrate scope for both alkenes and formates. The Ru–imidazole complex also catalyzes the intramolecular hydrocarbamoylation of alkenes.
ISSN:1867-3880
1867-3899
DOI:10.1002/cctc.201402986