Electrochemical direct site-selective selenation of carbazoles

Selenium-substituted carbazoles are crucial molecular scaffolds in organic optoelectronic materials, and direct site-selective selenation of carbazole C-H bonds is a highly efficient, atom-economical, and environmentally benign synthetic strategy. However, the current method for direct C-3 selenation of inert carbazoles relies on the use of stoichiometric oxidants and metal catalysts under harsh reaction conditions, severely limiting their applicability and hindering their overall efficiency. Herein, we report the first electrochemical direct and selective C-3 selenation of carbazoles using diaryl diselenide as the selenium source under oxidant-, metal-free and mild conditions. The present electrochemical strategy features broad substrate scope, excellent functional group tolerance, easy scalability, and operational simplicity.