A Photochemical Strategy for Carbon Isotope Exchange with CO2

A novel photocatalytic approach for carbon isotope exchange is reported. Utilizing [¹³C]CO₂ as primary C1 sources, this protocol allows the insertion of the desired carbon isotope into phenyl acetic acids without the need of structural modifications or pre-functionalization, in one single step. The exceptionally mild conditions required for this traceless transformation are in stark contrast with previous methods requiring the use of harsh thermal conditions.