Copper Single‐Atom Catalyst for Efficient C─S Coupling in Thioether Synthesis

Carbon‐heteroatom cross‐coupling reactions have become indispensable tools in synthetic chemistry. However, the formation of carbon–sulfur (C─S) bonds, which are essential for producing thioethers used in pharmaceuticals, agrochemicals, and advanced materials, remains significantly underdeveloped. Industrial C─S coupling methods still rely on expensive, homogeneous catalysts that suffer from poor recyclability and are susceptible to sulfur‐induced deactivation. In this work, we report a copper single‐atom catalyst, where Cu sites are atomically dispersed on mesoporous graphitic carbon nitride, to enable efficient, selective, and recyclable C─S cross‐coupling reactions under mild conditions and on a gram scale. The catalyst exhibits excellent resistance to thiol poisoning and maintains high performance over multiple catalytic cycles. Advanced characterization techniques, including aberration‐corrected electron microscopy, X‐ray absorption spectroscopy, and single‐atom‐sensitive electron energy loss spectroscopy, confirm the atomic dispersion and stable coordination environment of Cu sites. Combined with density functional theory simulations and radical scavenging experiments, our mechanistic investigations support a concerted oxidative addition pathway, which excludes radical intermediates. These results provide key insights into heterogeneous C─S coupling and demonstrate the power of single‐atom catalysts in addressing long‐standing challenges in sulfur chemistry, paving the way toward greener and more scalable processes for fine chemical and pharmaceutical synthesis.