Isotope labelling is of utmost importance when it comes to ADME studies in the pharmaceutical industry. We hence report a synthetic procedure granting access to molecularly complex moieties from simpler starting materials as a four-component coupling reaction triggered by photochemical conditions. Using carbon dioxide as a coupling partner allows for the insertion of isotopically enriched carbon into molecules. The protocol shown here proceeds through a sequence of radical couplings based on polarity match initiated from sodium sulfinates as sulfonyl, electron-poor, radical. Malonates are also accessible from a slight modification of the general procedure, giving a double formal addition of carbon dioxide.