A mild and efficient iridium-catalysed method for aldimine hydrogenation

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McKeown, Aidan and Taylor, Jonathan A. and Paterson, Laura C. and Lindsay, David M. and Kerr, William J. (2025) A mild and efficient iridium-catalysed method for aldimine hydrogenation. Advanced Synthesis and Catalysis, 367 (24). e70168. ISSN 1615-4150 (https://doi.org/10.1002/adsc.70168)

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Abstract

A mild and applicable protocol for aldimine hydrogenation has been developed using a bidentate iridium-N-hetrocyclic carbene-phosphine catalyst. Through a series of optimization studies, twenty-nine aldimine substrates have been successfully reduced to their corresponding amines in high isolated yields up to 99%. The developed methodology employs a low catalyst loading of just 1 mol% and proceeds under mild conditions, including under an atmospheric pressure of hydrogen gas. The process benefits from a broad solvent applicability, including notable green solvents, and tolerates aldimine substrates of varying solubility. Alongside, N-aryl-based aldimine substrates, the general protocol also accomodates more challenging N-alkyl species without the requirement of any further additive. From a mechanistic perspective, density functional theory calculations have been utilized to examine the formation, and subsequent reaction, of a crucial iridacycle intermediate, while also revealing that the C-H activation step is key for successful imine reduction. This mechanistic insight is then used to significantly elevate the performance of two poorer performing substrates.

ORCID iDs

McKeown, Aidan, Taylor, Jonathan A. ORCID logoORCID: https://orcid.org/0000-0003-2305-0708, Paterson, Laura C. ORCID logoORCID: https://orcid.org/0009-0006-5976-7099, Lindsay, David M. ORCID logoORCID: https://orcid.org/0000-0003-4498-5094 and Kerr, William J. ORCID logoORCID: https://orcid.org/0000-0002-1332-785X;
  • Item type:Article
    ID code:94368
    Dates:
    Date
    Event
    22 December 2025
    Published
    15 October 2025
    Published Online
    6 October 2025
    Accepted
    Subjects:Science > Chemistry
    Department:Faculty of Science > Pure and Applied Chemistry
    Depositing user: Pure Administrator
    Date deposited:07 Oct 2025 13:05
    Last modified:04 Feb 2026 17:55
    URI:https://strathprints.strath.ac.uk/id/eprint/94368
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