Transition Metal Catalyst, Solvent, Base Free Synthesis of Diaryl Diselenides under Mechanical Ball Milling

A convenient, efficient, and general procedure for the synthesis of diaryl diselenides has been developed by the reaction of aryl diazonium tetrafluoroborates and potassium selenocyanate on the surface of alumina under ball-milling in the absence of any solvent, transition metal catalyst, and base in room temperature. A wide range of functionalized diaryl diselenides are obtained in high purity and high yield by this procedure. Background: Synthesis of diaryl diselenides was restricted into only a few Cu-catalyzed C-Se cross-coupling protocols where the use of ligands, high reaction temp, long reaction time were required. Objectives: The objective of this study is to achieve a sustainable protocol for the synthesis of diaryl diselenides. Method: Reaction of aryl diazonium fluoroborate with KSeCN was successfully performed under ball milling in the absence of any transition metal catalyst, ligands, base, and external heating to get diaryl diselenides. Results: A library of diaryl diselenides were obtained in good yields with different functional groups. Conclusion: First transition metal free protocol for the synthesis of diaryl diselenides has been developed successfully.