Oxidative PCET-Triggered Benzylic C─H Iminolactonization via 1,5-HAT/Cyclization Enabled by Cage-Confined Photocatalysis.

We present a visible-light-driven photocatalytic platform based on a photosensitive metal-organic cage (PMOC), which enables selective recognition and activation of amidyl N─H bonds while suppressing competing homocoupling pathways. This system promotes a controlled intramolecular 1,5-HAT/cyclization cascade via an oxidative proton-coupled electron transfer (PCET) process, using commercially available BPO as oxidant and the in situ generated benzoate anion as the base. Mechanistic studies reveal that the cage architecture serves a dual role-facilitating oxidative PCET and enforcing product selectivity through spatial confinement-which steers the reaction through a unimolecular pathway, effectively inhibiting N─N homodimerization typical of bulk-phase systems. This work establishes cage-confined photocatalysis as a powerful strategy for directing nitrogen-centered radical (NCR) reactivity toward the synthesis of value-added heterocyclic compounds.