Catalyst-Free Synthesis of O-Heteroacenes by Ladderization of Fluorinated Oligophenylenes

Mikhail Feofanov; Vladimir Akhmetov; Ryo Takayama; Konstantin Amsharov

doi:10.1002/anie.202007427

Catalyst-Free Synthesis of O-Heteroacenes by Ladderization of Fluorinated Oligophenylenes

Angew Chem Int Ed Engl. 2021 Mar 1;60(10):5199-5203. doi: 10.1002/anie.202007427. Epub 2021 Feb 15.

Authors

Mikhail Feofanov^{1

2}, Vladimir Akhmetov^{1

2}, Ryo Takayama¹, Konstantin Amsharov^{1

2

3}

Affiliations

¹ Friedrich-Alexander University Erlangen-Nuernberg, Department of Chemistry and Pharmacy, Organic Chemistry II, Nikolaus-Fiebiger Str. 10, 91058, Erlangen, Germany.
² Institute of Chemistry, Organic Chemistry, Martin-Luther-University Halle-Wittenberg, Kurt-Mothes-Strasse 2, 06120, Halle, Germany.
³ South Ural State University, pr. Lenina 76, 454080, Chelyabinsk, Russia.

Abstract

A novel catalyst-free approach to benzoannulated oxygen-containing heterocycles from fluorinated oligophenylenes is reported. Unlike existing methods, the presented reaction does not require an oxygen-containing precursor and relies on an external oxygen source, potassium tert-butoxide, which serves as an O^2- synthon. The radical nature of the reaction facilitates nucleophilic substitution even in the presence of strong electron-donating groups and enables de-tert-butylation required for the complete annulation. Also demonstrated is the applicability of the method to introduce five-, six-, and seven-membered rings containing oxygen, whereas multiple annulations also open up a short synthetic path to ladder-type O-heteroacenes and oligodibenzofurans.

Keywords: annulations; heterocycles; oligomers; radicals; reaction mechanisms.

Abstract

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