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A theoretical study on Ir(III)-catalyzed intermolecular branch-selective allylic C−H amidation
  • Liang-Cheng Xu,
  • Xiang-Biao Zhang,
  • Ying-Gang Zhang
Liang-Cheng Xu
Anhui University of Science and Technology

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Xiang-Biao Zhang
Anhui University of Science and Technology
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Ying-Gang Zhang
Anhui University of Science and Technology
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Abstract

Herein, we report the mechanism of Ir(III)-catalyzed intermolecular branch-selective allylic C−H amidation, including the influence of substituent effect on yield and regioselectivity. The sequence of amidation reaction is alkene coordination, allylic C−H activation, oxidative addition of methyl dioxazolone, reductive elimination of allyl-Ir-nitrenoid complex, amine protonation and proto-demetallation. The apparent activation energy of amidation between hexene and methyl dioxazolone is 17.8 kcal/mol, and the energy difference between two transition state for formation amide is only 2.8 kcal/mol. The introduction of more electron-deficient groups at the allyl terminal increases the apparent activation energy, conversely, the introduction of electron-donating groups significantly reduces the apparent activation energy. Among them, the apparent activation energy of the reaction between aniline group substituted allyl and methyl dioxazolone is only 13.8 kcal/mol, which further improves the reaction yield. In addition, the introduction of more electron-withdrawing groups on dioxazolone can significantly improve the regioselectivity. When 3,4,5,-trifluorophenyl substituted dioxazolone and hexene occur C−N bond coupling reaction, the energy difference of the two transition states is as high as 9.0 kcal/mol, indicating that the regioselectivity is greatly improved. The mechanism explanation of allylic C−H amidation will provide strong theoretical support for streamlined synthesis of allyl branched amides.
23 Sep 2021Submitted to International Journal of Quantum Chemistry
25 Sep 2021Submission Checks Completed
25 Sep 2021Assigned to Editor
21 Oct 2021Reviewer(s) Assigned