Electrochemical synthesis of N,N′-disubstituted indazolin-3-ones via an intramolecular anodic dehydrogenative N-N coupling reaction

The use of electricity as a traceless oxidant enables a sustainable and novel approach to N,N '-disubstituted indazolin-3-ones by an intramolecular anodic dehydrogenative N-N coupling reaction. This method is characterized by mild reaction conditions, an easy experimental setup, excellent scalability, and a high atom economy. It was used to synthesize various indazolin-3-one derivatives in yields up to 78%, applying inexpensive and sustainable electrode materials and a low supporting electrolyte concentration. Mechanistic studies, based on cyclic voltammetry experiments, revealed a biradical pathway. Furthermore, the access to single 2-aryl substituted indazolin-3-ones by cleavage of the protecting group could be demonstrated.

Automated summary

The use of electricity as a traceless oxidant provides a sustainable and novel approach to synthesize N,N'-disubstituted indazolin-3-ones through an intramolecular anodic dehydrogenative N-N coupling reaction. This method offers mild reaction conditions, easy experimental setup, excellent scalability, and high atom economy. Various indazolin-3-one derivatives were synthesized with yields up to 78% using inexpensive and sustainable electrode materials and a low supporting electrolyte concentration. Mechanistic studies suggest a biradical pathway and the cleavage of protecting group can be used to access single 2-aryl substituted indazolin-3-ones.