Parahydrogen-induced polarization in hydrogenation reactions mediated by a metal-free catalyst
Zakharov, Danila O.; Chernichenko, Konstantin; Sorochkina, Kristina; Yang, Shengjun; Telkki, Ville-Veikko; Repo, Timo; Zhivonitko, Vladimir V. (2022-02-08)
D. O. Zakharov, K. Chernichenko, K. Sorochkina, S. Yang, V.-V. Telkki, T. Repo, V. V. Zhivonitko, Chem. Eur. J. 2022, 28, e202103501, https://doi.org/10.1002/chem.202103501
© 2021 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
https://creativecommons.org/licenses/by/4.0/
https://urn.fi/URN:NBN:fi-fe2022042530194
Tiivistelmä
Abstract
We report nuclear spin hyperpolarization of various alkenes achieved in alkyne hydrogenations with parahydrogen over a metal-free hydroborane catalyst (HCAT). Being an intramolecular frustrated Lewis pair aminoborane, HCAT utilizes a non-pairwise mechanism of H₂ transfer to alkynes that normally prevents parahydrogen-induced polarization (PHIP) from being observed. Nevertheless, the specific spin dynamics in catalytic intermediates leads to the hyperpolarization of predominantly one hydrogen in alkene. PHIP enabled the detection of important HCAT-alkyne-H₂ intermediates through substantial ¹H, ¹¹B and ¹⁵N signal enhancement and allowed advanced characterization of the catalytic process.
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