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

Citation

Chipman, A and Farshadfar, K and Smith, JA and Yates, BF and Ariafard, A, DFT-based comparison between mechanistic aspects of amine and alcohol oxidation mediated by IBX, Journal of Organic Chemistry, 85, (2) pp. 515-525. ISSN 0022-3263 (2019) [Refereed Article]

Copyright Statement

2019 American Chemical Society

DOI: doi:10.1021/acs.joc.9b02583

Abstract

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 3c4e σ* orbital which is too high in energy to be reachable.

Item Details

Item Type:Refereed Article
Keywords:amine oxidation, alcohol oxidation, IBX, hypervalent iodine, Density Functional Theory, mechanistic investigation
Research Division:Chemical Sciences
Research Group:Organic Chemistry
Research Field:Physical Organic Chemistry
Objective Division:Expanding Knowledge
Objective Group:Expanding Knowledge
Objective Field:Expanding Knowledge in the Chemical Sciences
UTAS Author:Chipman, A (Mr Antony Chipman)
UTAS Author:Smith, JA (Associate Professor Jason Smith)
UTAS Author:Yates, BF (Professor Brian Yates)
UTAS Author:Ariafard, A (Associate Professor Alireza Ariafard)
ID Code:137653
Year Published:2019
Funding Support:Australian Research Council (DP180100904)
Deposited By:Chemistry
Deposited On:2020-02-25
Last Modified:2020-03-20
Downloads:0

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