Gieshoff T, Kehl A, Schollmeyer D, Moeller KD, Waldvogel SR. Insights into the Mechanism of Anodic N-N Bond Formation by Dehydrogenative Coupling.
J Am Chem Soc 2017;
139:12317-12324. [PMID:
28792218 DOI:
10.1021/jacs.7b07488]
[Citation(s) in RCA: 138] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The electrochemical synthesis of pyrazolidine-3,5-diones and benzoxazoles by N-N bond formation and C,O linkage, respectively, represents an easy access to medicinally relevant structures. Electrochemistry as a key technology 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 electrochemical set-ups also enhanced the applicability of this method.
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