Assembly of Selenadiazine Scaffolds via Rh(III)-Catalyzed Amidine-Directed Cascade C-H Selenylation/[5 + 1] Annulation with Elemental Selenium.

By employing elemental selenium as the selenium source, we have realized the amidine-directed Rh(III)-catalyzed cascade C-H selenylation/[5 + 1] annulation for the direct construction of structurally novel selenadiazine, benzoselenadiazine, and benzoselenazol-3-amine frameworks with specific site selectivity and good functional group tolerance. Besides, the obtained products can serve as fundamental platforms for subsequent chemical transformations, and thus, the feasible SeNEx reaction, SeNEx/Michael addition, and simple conversion of the selenadiazine product into diverse other organoselenium molecules were demonstrated accordingly. Taken together, the developed methodology efficiently expands the chemical space of organoselenium species.