Direct Synthesis of Sulfonamides via Synergetic Photoredox and Copper Catalysis

Despite the frequent occurrence of sulfonamides in contemporary pharmaceuticals and agrochemicals, the synthesis of these compounds is limited by the availability of preexisting sulfur functionality, amine nucleophilicity, and functional group compatibility. Herein, we report the use of synergetic photoredox and copper catalysis to synthesize sulfonamides from a variety of aryl radical precursors, readily available amines, and a sulfur dioxide source in air at room temperature. The reactions proceeded smoothly with various electron-rich and electron-deficient amines to generate sulfonamides in a single-step process. Oxygen in air was deemed to be essential for both catalytic cycles, acting as a catalyst. Experimental studies, including electron paramagnetic resonance spectroscopy, provided insights into the possible mechanism.