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Twofold π-Extension of Polyarenes via Double and Triple Radical Alkyne peri-Annulations: Radical Cascades Converging on the Same Aromatic Core

preprint
submitted on 17.02.2020 and posted on 19.02.2020 by Edgar Gonzalez-Rodriguez, Miguel A. Abdo, Gabriel dos Passos Gomes, Suliman Ayad, Frankie D. White, Nikolay P. Tsvetkov, Kenneth Hanson, Igor Alabugin
A versatile synthetic route to distannyl-substituted polyarenes was developed via double radical periannulations. The cyclization precursors were equipped with propargylic OMe traceless directing groups (TDGs) for regioselective Sn-radical attack at the triple bonds. The two peri-annulations converge at a variety of polycyclic cores to yield expanded difunctionalized polycyclic aromatic hydrocarbons (PAHs). This approach can be extended to triple peri-annulations, where annulations are coupled with a radical cascade that connects two preexisting aromatic cores via a formal C-H activation step. The installed Bu3Sn groups serve as chemical handles for further functionalization via direct cross-coupling, iodination, or protodestannylation, and increase solubility of the products in organic olvents. Photophysical studies reveal that the Bu3Sn-substituted PAHs are moderately fluorescent, and their protodestannylation serves as a chemical switch for high fluorescence. DFT calculations identified the most likely possible mechanism of this complex chemical transformation involving two independent peri-cyclizations at the central core.

Funding

NSF CHE-1800329

History

Email Address of Submitting Author

eg15n@my.fsu.edu

Institution

Florida State University

Country

United States

ORCID For Submitting Author

0000-0003-3458-1942

Declaration of Conflict of Interest

no conflict of interest

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