Anion–cation synergistic metal-free catalytic oxidative homocoupling of benzylamines by triazolium iodide salts

Byrne, Joseph P.; Albrecht, Martin (2020). Anion–cation synergistic metal-free catalytic oxidative homocoupling of benzylamines by triazolium iodide salts. Organic & biomolecular chemistry, 18(37), pp. 7379-7387. Royal Society of Chemistry 10.1039/D0OB01472A

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Triazolium iodide salts are excellent catalysts for the selective oxidative coupling of benzylamines to yield imines. This metal-free reaction proceeds in quantitative spectroscopic yields when run in refluxing 1,2-dichlorobenzene and open to the air. No catalytic activity was observed with related triazolium tetrafluoroborate salts. Variation of catalyst and reaction atmosphere provides mechanistic insights, and revealed dioxygen as the terminal oxidant and the iodine/iodide couple as key redox component in the catalytic dehydrogenation pathway. While molecular iodine is competent as a catalyst in its own right, the triazolium cation triples the reaction rate and reaches turnover frequencies up to 30 h−1, presumably through beneficial interactions of the electron-poor azolium π system and I2, which facilitate the electron transfer from the substrate to iodine and concomitant formation of I−. This acceleration is specific for triazolium cations and represents a hybrid anion/cation catalytic process as a simple and straightforward route towards imine products, with economic advantages over previously reported metal-based catalytic systems.

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Department of Chemistry, Biochemistry and Pharmaceutical Sciences (DCBP)

UniBE Contributor:

Byrne, Joseph Peter and Albrecht, Martin

Subjects:

500 Science > 540 Chemistry

ISSN:

1477-0520

Publisher:

Royal Society of Chemistry

Funders:

[164] Marie Skłodowska-Curie actions ; [18] European Research Council

Projects:

[1282] Exploiting carbohydrate/N-heterocyclic carbene hybrid complexes as innovative multifunctional oxidation catalysts with tailoring of weak interactions allowing for development of enzyme mimics
[1134] Exploiting Synergistic Properties of Mesoionic Carbene Complexes: Teaching Rusty Metals Challenging Catalysis

Language:

English

Submitter:

Eik Szee Goh Aschauer

Date Deposited:

03 Feb 2021 12:22

Last Modified:

03 Feb 2021 12:22

Publisher DOI:

10.1039/D0OB01472A

BORIS DOI:

10.48350/151062

URI:

https://boris.unibe.ch/id/eprint/151062

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