Selective hydroboration of electron-rich isocyanates by an NHC-copper(i) alkoxide

English, Laura E. and Horsley Downie, Thomas M. and Lyall, Catherine L. and Mahon, Mary F. and McMullin, Claire L. and Neale, Samuel E. and Saunders, Carla M. and Liptrot, David J. (2023) Selective hydroboration of electron-rich isocyanates by an NHC-copper(i) alkoxide. Chemical Communications, 59 (8). pp. 1074-1077. ISSN 1359-7345 (https://doi.org/10.1039/D2CC04742J)

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Abstract

The (IPr)CuOtBu catalysed reduction of 11 aryl and alkyl isocyanates with pinacolborane gave only the boraformamides, pinBN(R)C(O)H, in most cases. Overreduction, which hampers almost all isocyanate hydroborations, was restricted to electron poor aryl isocyanates (4-NC-C6H4NCO, 4-F3C-C6H4NCO, 3-O2N-C6H4NCO). Computational analysis showed stability of [(IPr)CuH]2, which was proposed to be the catalyst resting state, drives selectivity, suggesting an approach to prevent overreduction in future work. In the case of iPrNCO, formation of this species renders overreduction kinetically inaccessible. For 4-NC-C6H4NCO, however, the barrier height for the first step of over-reduction is much lower, even relative to [(IPr)CuH]2, resulting in unselective reduction.

  • Item type:Article
    ID code:89516
    Dates:
    Date
    Event
    31 January 2023
    Published
    26 December 2022
    Published Online
    23 December 2022
    Accepted
    Subjects:
    Science > Chemistry
    Department:Faculty of Science > Pure and Applied Chemistry
    Depositing user: Pure Administrator
    Date deposited:07 Jun 2024 15:51
    Last modified:29 Jun 2024 03:06
    URI:https://strathprints.strath.ac.uk/id/eprint/89516
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