Visible-light-driven cascade cyclization: a modular approach to functionalized 4-pyrrolin-2-ones

We report an efficient and modular strategy for the construction of densely functionalized 4-pyrrolin-2-ones <i>via</i> visible-light-driven Ru(II) photocatalysis. The radical cascade cyclization approach enables the diversity-oriented synthesis of benzylated and alkylated 4-pyrrolin-2-one scaffolds, utilizing readily accessible diaryliodonium salts (DAIRs) and <i>N</i>-(acyloxy)phthalimides (NHPI esters) as radical precursors. The methodology is further expanded to include other radical coupling partners, such as trifluoromethyl and arylsulfonyl radicals, affording a wide array of structurally diverse and synthetically valuable 4-pyrrolin-2-ones. The protocol is characterized by its robustness, broad substrate scope, high functional group tolerance, and scalability, collectively underscoring its synthetic utility.