Copper-Catalyzed Cyclization of Alkynes with Cyclic Iodine(III) Sulfoximines: Access to Benzo[d]isothiazole-1-oxides.

Heterocyclic iodine(III) reagents are typically employed as group transfer agents, with the scaffold itself discarded as waste. Here, we overturn this paradigm by introducing a sulfoximine-based cyclic iodine(III) platform that enables direct scaffold incorporation into the final product. Under copper catalysis, the triflate hypervalent iodine(III) reagents undergo annulation with terminal alkynes to deliver benzo[d]isothiazole-1-oxides with broad functional group tolerance. The synthetic utility of this scaffold-incorporating strategy is further underscored by the identification of compound 3v as a micromolar ferroptosis inhibitor in cellular assays, demonstrating that this method can readily generate biologically relevant molecules with potential for further biological evaluation.