Organophotoredox-Catalyzed Annulation of Enamines with Sulfoxonium Ylides to Access Pyrroles via Radical Chain Mechanistic Scenarios
Yujing Wang , Mengyu Xu , Rui Fu , Jiaxin Lin , Mengting Cao , Xiaoguang Bao
Chinese Journal of Chemistry ›› 2025, Vol. 43 ›› Issue (18) : 2331 -2340.
Organophotoredox-Catalyzed Annulation of Enamines with Sulfoxonium Ylides to Access Pyrroles via Radical Chain Mechanistic Scenarios
Herein, organophotoredox-catalyzed annulation of enamines with sulfoxonium ylides to construct pyrrole derivatives is developed under transition-metal-free and mild condition. A broad range of readily accessible substrates are suitable for this protocol, providing a convenient and efficient approach to preparing pyrrole derivatives with satisfying yields. Mechanistically, a photoredox-mediated radical chain mechanistic pathway is proposed for this reaction by a synergistic experimental and computational study. Two key radicals, α-imino and α-carbonyl C-radicals derived from enamines and sulfoxonium ylides, respectively, could be generated via two steps of single-electron transfer in a photoredox catalytic loop. Subsequently, the formed α-carbonyl C-radical may attack the alkenyl moiety of enamines. Next, the formed radical adduct could undergo H-atom transfer with sulfoxonium ylides to regenerate the key α-carbonyl C-radical and thus fulfill the chain propagation process. The afforded adduct intermediate could undergo an intramolecular cyclization followed by dehydration to furnish the desired pyrrole derivatives.
Photoredox catalysis / Enamine / Sulfoxonium ylide / Pyrrole / Radical chain mechanism
2025 SIOC, CAS, Shanghai, & WILEY-VCH GmbH
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