Photocatalytic halogen atom transfer enables general dicarbofunctionalization of alkenes with organic halides and CO₂

The dicarbofunctionalization of alkenes using organic halides and CO₂ provides a valuable platform for synthesizing carboxylic acids through two C-C bond-forming steps, motifs widely found in pharmaceuticals, agrochemicals, and functional materials. Existing strategies predominantly rely on sequential single-electron transfer (SET) events for substrate activation and carbanion generation, restricting their scope to readily reducible halides. Consequently, many organic halides with highly negative reduction potentials and strong C-X bonds, including electron-rich aryl bromides, aryl chlorides, and alkyl chlorides, remain largely unreactive. Here, we report a visible-light-driven photocatalytic strategy that combines halogen-atom transfer (XAT) and SET processes, where XAT enables generation of carbon-centered radicals from challenging halides, and SET promotes efficient carbanion formation for CO₂ incorporation. This approach enables three-component dicarbofunctionalization of alkenes with a broad range of aryl and alkyl halides, affording carboxylated products in yields of up to 94% across more than fifty examples.