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Updated: Jul 4, 2025

A Microwave-Assisted Direct Heteroarylation of Ketones Using Transition Metal Catalysis
Published on: February 16, 2020
Impact of the Methylene Bridge Substitution in Chelating NHC-Phosphine Mn(I) Catalyst for Ketone Hydrogenation
Ekaterina S Gulyaeva1,2, Ruqaya Buhaibeh1, Mohamed Boundor1
1LCC-CNRS, Université de Toulouse, CNRS, UPS, 205 route de Narbonne, 31077, Toulouse Cedex 4, France.
Abstract:
Systematic modification of the chelating NHC-phosphine ligand (NHC = N-heterocyclic carbene) in highly efficient ketone hydrogenation Mn(I) catalyst fac-[(Ph2PCH2NHC)Mn(CO)3Br] has been performed and the catalytic activity of the resulting complexes was evaluated using acetophenone as a benchmark substrate. While the variation of phosphine and NHC moieties led to inferior results than for a parent system, the incorporation of a phenyl substituent into the ligand methylene bridge improved catalytic performance by ca. 3 times providing maximal TON values in the range of 15000-20000. Mechanistic investigation combining experimental and computational studies allowed to rationalize this beneficial effect as an enhanced stabilization of reaction intermediates including anionic hydride species fac-[(Ph2PC(Ph)NHC)Mn(CO)3H]- playing a crucial role in the hydrogenation process. These results highlight the interest of such carbon bridge substitution strategy being rarely employed in the design of chemically non-innocent ligands.
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