Document Type

Article

Publication Date

2024

Publication Title

Journal of Organic Chemistry

Abstract

The potassium metal reduction of aryl isocyanates(aryl = phenyl, p-tolyl, 3,5-dimethylphenyl, 4-biphenylyl, and 1-naphthyl) in THF with 18-crown-6 or in HMPA results in the formation of the corresponding triaryl isocyanurate anion radicals. Continued exposure to potassium results in loss of the isocyanurate anion radical and the eventual formation of the respective biaryl anion radical. The 1,1′-binaphthyl anion radical is found to undergo a cyclodehydrogenation reaction, which leads to formation of the perylene anion radical. When authentic triaryl isocyanurates are reduced with metal, the heterocyclic ring undergoes fragmentation with elimination of carbon monoxide to produce a triarylbiuret dianion. This ring opening reaction is initiated by the two-electron reduction of the neutral isocyanurate species. The biaryl anion radical is formed when the biuret dianion is reduced further with metal. A possible mechanism for biaryl formation involves a heterolytic cleavage of an aryl C−N bond and release of an aryl radical once the triarylbiuret dianion is further reduced. A subsequent intermolecular reaction between two aryl radicals forms the corresponding biaryl, which can then be reduced to the anion radical. Notably, when a mixture of two different triaryl isocyanurate compounds is reduced in solution, the corresponding mixed biaryl anion radical is generated.

Funding Source

Acknowledgement is made to the donors of the American Chemical Society Petroleum Research Fund for support of this research (ACS-PRF 51677-UR4) and Illinois State University for additional funding. This article was published Open Access thanks to a transformative agreement between Milner Library and ACS Publications.

DOI

10.1021/acs.joc.4c01844

Comments

First published in The Journal of Organic Chemistry: https://doi.org10.1021/acs.joc.4c01844

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