Copper-Catalyzed Oxyalkynylation of C–S Bonds in Thiiranes and Thiethanes with Hypervalent Iodine Reagents

We report the oxyalkynylation of thiiranes and thietanes using ethynylbenziodoxolone reagents (EBXs) to readily access functionalized building blocks bearing an alkynyl, a benzoate, and an iodide group. The reaction proceeds with high atom efficiency most likely through an alkynyl–episulfonium intermediate. The transformation is copper-catalyzed and compatible with a large array of thiiranes and thietanes.