Insights into the Mechanism of Anodic N-N Bond Formation by Dehydrogenative Coupling

The electrochem. synthesis of pyrazolidine-3,5-diones and benzoxazoles by N-N bond formation and C,O linkage, resp., represents an easy access to medicinally relevant structures.  Electrochem. as a key technol. ensures a safe and sustainable approach.  We gained insights in the mechanism of these reactions by combining cyclovoltammetric and synthetic studies.  The electron-transfer behavior of anilides and dianilides was studied and led to the following conclusion: The N-N bond formation involves a diradical as intermediate, whereas the benzoxazole formation is based on a cationic mechanism.  Besides these studies, we developed a synthetic route to mixed dianilides as starting materials for the N-N coupling.  The compatibility with valuable functionalities like triflates and mesylates for follow-up reactions as well as the comparison of different electrochem. set-ups also enhanced the applicability of this method.

Gieshoff, Tile; Kehl, Anton; Schollmeyer, Dieter; Moeller, Kevin D.; Waldvogel, Siegfried R.

J. Am. Chem. Soc., 2017, 139 (35), pp 12317–12324
Publication Date (Web): August 9, 2017

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