Bis(N-Heterocyclic Carbene) Manganese(I) Complexes: Efficient and Simple Hydrogenation Catalysts.
Angew Chem Int Ed Engl 2023;
62:e202307987. [PMID:
37395302 DOI:
10.1002/anie.202307987]
[Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2023] [Revised: 06/29/2023] [Accepted: 06/30/2023] [Indexed: 07/04/2023]
Abstract
The use of bis(NHC) manganese(I) complexes 3 as catalysts for the hydrogenation of esters was investigated. For that purpose, a series of complexes has been synthesized via an improved two step procedure utilizing bis(NHC)-BEt3 adducts. By applying complexes 3 with KHBEt3 as additive, various aromatic and aliphatic esters were hydrogenated successfully at mild temperatures and low catalyst loadings, highlighting the efficiency of the novel catalytic system. The versatility of the developed catalytic system was further demonstrated by the hydrogenation of other substrate classes like ketones, nitriles, N-heteroarenes and alkenes. Mechanistic experiments and DFT calculations indicate an inner sphere mechanism with the loss of one CO ligand and reveal the role of BEt3 as cocatalyst.
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