Associative Photocatalysis: Activation of Inert Haloarenes by Interaction-Centric Design

The power of photoredox catalysis is constrained by the intrinsic properties of the individual catalyst molecules. This creates an energetic ceiling that prevents the activation of highly stable chemical bonds. This study introduces an “associative photocatalysis” strategy that circumvents this limitation by deriving photochemical function from transient intermolecular interactions. The selective excitation of a non-covalently bound electron donor–acceptor complex initiates a sequential two-photon process. This approach enables the functionalization of previously unreactive haloarenes, facilitating a range of efficient transformations. The gram-scale synthesis and late-stage diversification of loratadine are also performed. By shifting the design focus from static molecular scaffolds to dynamic interactions, associative photocatalysis provides a new blueprint for unlocking challenging chemical reactivities and advancing sustainable synthesis.