Electrochemistry and Reactivity of Chelation-stabilized Hypervalent Bromine(III) Compounds

Nayereh Mohebbati; Igors Sokolovs; Philipp Woite; Märt Lõkov; Elisabeth Parman; Mihkel Ugandi; Ivo Leito; Michael Roemelt; Edgars Suna; Robert Francke

doi:10.1002/chem.202200974

Electrochemistry and Reactivity of Chelation-stabilized Hypervalent Bromine(III) Compounds

Chemistry. 2022 Jul 26;28(42):e202200974. doi: 10.1002/chem.202200974. Epub 2022 Jun 10.

Authors

Nayereh Mohebbati^{1

2}, Igors Sokolovs³, Philipp Woite⁴, Märt Lõkov⁵, Elisabeth Parman⁵, Mihkel Ugandi⁴, Ivo Leito⁵, Michael Roemelt⁴, Edgars Suna^{3

6}, Robert Francke^{1

2}

Affiliations

¹ Leibniz Institute for Catalysis, Albert-Einstein-Str. 29a, 18059, Rostock, Germany.
² Institute of Chemistry, Rostock University, Albert-Einstein-Str. 3a, 18059, Rostock, Germany.
³ Latvian Institute of Organic Synthesis, Aizkraukles 21, 1006, Riga, Latvia.
⁴ Department of Chemistry, Humboldt-University of Berlin, Brook-Taylor-Str. 2, 12489, Berlin, Germany.
⁵ Institute of Chemistry, University of Tartu, Ravila 14a, 50411, Tartu, Estonia.
⁶ Faculty of Chemistry, University of Latvia, Jelgavas 1, 1004, Riga, Latvia.

Abstract

Hypervalent bromine(III) reagents possess a higher electrophilicity and a stronger oxidizing power compared to their iodine(III) counterparts. Despite the superior reactivity, bromine(III) reagents have a reputation of hard-to-control and difficult-to-synthesize compounds. This is partly due to their low stability, and partly because their synthesis typically relies on the use of the toxic and highly reactive BrF₃ as a precursor. Recently, we proposed chelation-stabilized hypervalent bromine(III) compounds as a possible solution to both problems. First, they can be conveniently prepared by electro-oxidation of the corresponding bromoarenes. Second, the chelation endows bromine(III) species with increased stability while retaining sufficient reactivity, comparable to that of iodine(III) counterparts. Finally, their intrinsic reactivity can be unlocked in the presence of acids. Herein, an in-depth mechanistic study of both the electrochemical generation and the reactivity of the bromine(III) compounds is disclosed, with implications for known applications and future developments in the field.

Keywords: bromane; cyclic voltammetry; hypervalent halogen; oxidative coupling; unified pH.

Abstract

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