Issue 19, 2022

Heme compound II models in chemoselectivity and disproportionation reactions

Abstract

Heme compound II models bearing electron-deficient and -rich porphyrins, [FeIV(O)(TPFPP)(Cl)] (1a) and [FeIV(O)(TMP)(Cl)] (2a), respectively, are synthesized, spectroscopically characterized, and investigated in chemoselectivity and disproportionation reactions using cyclohexene as a mechanistic probe. Interestingly, cyclohexene oxidation by 1a occurs at the allylic C–H bonds with a high kinetic isotope effect (KIE) of 41, yielding 2-cyclohexen-1-ol product; this chemoselectivity is the same as that of nonheme iron(IV)-oxo intermediates. In contrast, as observed in heme compound I models, 2a yields cyclohexene oxide product with a KIE of 1, demonstrating a preference for C[double bond, length as m-dash]C epoxidation. The latter result is interpreted as 2a disproportionating to form [FeIV(O)(TMP+˙)]+ (2b) and FeIII(OH)(TMP), and 2b becoming the active oxidant to conduct the cyclohexene epoxidation. In contrast to 2a, 1a does not disproportionate under the present reaction conditions. DFT calculations confirm that compound II models prefer C–H bond hydroxylation and that disproportionation of compound II models is controlled thermodynamically by the porphyrin ligands. Other aspects, such as acid and base effects on the disproportionation of compound II models, have been discussed as well.

Graphical abstract: Heme compound II models in chemoselectivity and disproportionation reactions

Supplementary files

Article information

Article type
Edge Article
Submitted
01 Marts 2022
Accepted
11 Apr. 2022
First published
12 Apr. 2022
This article is Open Access

All publication charges for this article have been paid for by the Royal Society of Chemistry
Creative Commons BY-NC license

Chem. Sci., 2022,13, 5707-5717

Heme compound II models in chemoselectivity and disproportionation reactions

R. Gupta, X. Li, Y. Lee, M. S. Seo, Y. Lee, S. Yanagisawa, M. Kubo, R. Sarangi, K. Cho, S. Fukuzumi and W. Nam, Chem. Sci., 2022, 13, 5707 DOI: 10.1039/D2SC01232D

This article is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported Licence. You can use material from this article in other publications, without requesting further permission from the RSC, provided that the correct acknowledgement is given and it is not used for commercial purposes.

To request permission to reproduce material from this article in a commercial publication, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party commercial publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements