Gold Single-Atom Catalysts Enable Selective Shuttle Hydrochlorination of Alkynes

Shuttle catalysis enables the transfer of reactive functional groups without relying on highly corrosive reagents. However, it remains largely confined to homogeneous systems, where catalyst recovery and reuse are often challenging. Here, we report a recyclable gold single-atom catalyst (SAC) supported on activated carbon (AC) for the selective shuttle hydrochlorination of terminal alkynes to vinyl chlorides, which are key intermediates in pharmaceutical synthesis. Spectroscopic and catalytic studies indicate that the combination of Au(I) single atoms with the AC carrier is essential for the unique chemo- and stereoselectivity observed. This heterogeneous system displays broad substrate compatibility, including sterically hindered alkynes, heterocycles, acid-labile groups, and drug-derived substrates. Upon reuse, gradual aggregation of gold single atoms into nanoparticles leads to activity losses, but the associated speciation changes are reversible by oxidative redispersion, while quantitative metal retention ensures recoverability. Overall, this study demonstrates how to extend heterogeneous SACs to shuttle catalysis, highlighting the complementary reactivity and distinct catalyst design requirements for developing recoverable, safer, and more sustainable heterogeneous transfer reactions.