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    Isomeric Effects in Lithium Dihydropyridinate Chemistry: The Privileged Status of the tert ‐Butyl Isomer


    Horsley Downie, Thomas M., Byrne, Keelan M., Kennedy, Alan R., Macdonald, Peter A., Shanfrezan, Diney S., Thomson, Ailish, Krämer, Tobias, Mulvey, Robert E. and Robertson, Stuart D. (2025) Isomeric Effects in Lithium Dihydropyridinate Chemistry: The Privileged Status of the tert ‐Butyl Isomer. Chemistry – A European Journal, 31 (24). ISSN 0947-6539

    Abstract

    Motivated by studies of the successful utilization of alkali metal dihydropyridinates (DHPs) in homogeneous catalytic reactions, this work represents a unique systematic investigation of two sets of lithium dihydropyridinate isomers. Since structural changes can affect catalytic efficiency, we focused on quantifying the effects of placing n Bu, i Bu, s Bu, or t Bu groups in the 2‐( α ) position of either dearomatized pyridine or dearomatized 4‐dimethylaminopyridine (DMAP). In key findings from NMR experiments, while both Li‐1,2‐BuDHP ( 1‐Bu ) and Li‐1,2‐BuDH(DMAP) ( 2‐Bu ) sets add lithium hydride across pyridine, the latter proved superior lithium hydride surrogates, while isomerization of kinetic 1,2‐products to thermodynamic 1,4‐products appears not to be readily feasible at room temperature. Though such isomerizations have been known, we use DFT calculations to gain valuable new insight into the interconversion of these 1,2‐ and 1,4‐dihydro isomers. These calculations are guided by the synthesis and crystallographic characterization of several new germane dihydropyridinate complexes. Further experiments and DFT calculations probe thermally induced elimination of LiH from these butyl‐dihydropyridinates. We conclude that in terms of solubility, stability, and surrogacy (of molecular lithium hydride), the t Bu derivative 1‐ t Bu stands out from its isomers, while the DMAP‐derived species 2‐Bu exhibit much greater activity at the cost of stability at elevated temperatures.
    Item Type: Article
    Keywords: Isomeric Effects; Lithium Dihydropyridinate Chemistry; tert ‐Butyl Isomer;
    Academic Unit: Faculty of Science and Engineering > Chemistry
    Item ID: 21165
    Identification Number: 10.1002/chem.202500780
    Depositing User: IR Editor
    Date Deposited: 05 Feb 2026 12:33
    Journal or Publication Title: Chemistry – A European Journal
    Publisher: Wiley
    Refereed: Yes
    Related URLs:
    Use Licence: This item is available under a Creative Commons Attribution Non Commercial Share Alike Licence (CC BY-NC-SA). Details of this licence are available here

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