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DFT-based comparison between mechanistic aspects of amine and alcohol oxidation mediated by IBX

journal contribution
posted on 2023-05-20, 11:19 authored by Chipman, A, Farshadfar, K, Jason SmithJason Smith, Brian YatesBrian Yates, Alireza AriafardAlireza Ariafard

Density functional theory was utilized to investigate plausible mechanisms for amine and alcohol oxidation by an iodine(V) hypervalent reagent (IBX). In this contribution, we found that amine and alcohol oxidation both proceed by similar mechanisms. The reactions initiate from ligand exchange to give four coordinate intermediates followed by a redox process giving an iodine(III) species and oxidized substrates. Interestingly, for both the ligand-exchange and the redox steps a hypervalent twist is required for the reaction to proceed via an energetically more accessible route. The ligand-exchange process was found to be mediated by a proton-shuttling agent such as water, a second IBX, or a second substrate. While the ligand-exchange step for both amine and alcohol occurs with almost identical activation energy (particularly when water is considered as the shuttling agent), the redox step for the amine takes place with much lower activation energy than that for the alcohol. Finally, we ascertained that five coordinate amide iodine(V) complexes are unreactive toward redox reactions due to the fact that in such cases two electrons from the coordinated amide are required to occupy a 3c–4e σ* orbital which is too high in energy to be reachable.

Funding

Australian Research Council

University of Wollongong

History

Publication title

Journal of Organic Chemistry

Volume

85

Pagination

515-525

ISSN

0022-3263

Department/School

School of Natural Sciences

Publisher

Amer Chemical Soc

Place of publication

1155 16Th St, Nw, Washington, USA, Dc, 20036

Rights statement

© 2019 American Chemical Society

Repository Status

  • Restricted

Socio-economic Objectives

Expanding knowledge in the chemical sciences