Copper-catalyzed three-component radical relay alkenylation of sulfenamides

Herein, we report a copper-catalyzed three-component radical relay alkenylation of sulfenamides with Togni reagent and alkynes. This strategy provides a general and efficient route for the synthesis of chiral β-trifluoromethyl alkenyl sulfilimines in good yields with good chemo-, regio- and stereoselectivity. The resulting alkenyl sulfilimine products can be readily oxidized to access the corresponding chiral alkenyl sulfoximines. Mechanistic studies and density functional theory (DFT) calculations support a radical pathway and identify a concerted hydrogen-atom transfer (HAT) and radical coupling (RC) process as the key stereodetermining step.