We report a photochemical method for the functionalization of pyridines with radicals derived from allylic C–H bonds. Overall, two substrates undergo C–H functionalization to form a new C(sp2)–C(sp3) bond. The chemistry harnesses the unique reactivity of pyridinyl radicals, generated upon single-electron reduction of pyridinium ions, which undergo effective coupling with allylic radicals. This novel mechanism enables distinct positional selectivity for pyridine functionalization that diverges from classical Minisci chemistry. Crucial was the identification of a dithiophosphoric acid that masters three catalytic tasks, sequentially acting as a Brønsted acid for pyridine protonation, a single electron transfer (SET) reductant for pyridinium ion reduction, and a hydrogen atom abstractor for the activation of allylic C(sp3)–H bonds. The resulting pyridinyl and allylic radicals then couple with high regioselectivity

Photochemical Organocatalytic Functionalization of Pyridines via Pyridinyl Radicals / Emilien Le Saux, Eleni Georgiou, Igor A. Dmitriev, Will C. Hartley, Paolo Melchiorre. - In: JOURNAL OF THE AMERICAN CHEMICAL SOCIETY. - ISSN 0002-7863. - STAMPA. - 145:1(2023), pp. 47-52. [10.1021/jacs.2c12466]

Photochemical Organocatalytic Functionalization of Pyridines via Pyridinyl Radicals

Paolo Melchiorre
Ultimo
Supervision
2023

Abstract

We report a photochemical method for the functionalization of pyridines with radicals derived from allylic C–H bonds. Overall, two substrates undergo C–H functionalization to form a new C(sp2)–C(sp3) bond. The chemistry harnesses the unique reactivity of pyridinyl radicals, generated upon single-electron reduction of pyridinium ions, which undergo effective coupling with allylic radicals. This novel mechanism enables distinct positional selectivity for pyridine functionalization that diverges from classical Minisci chemistry. Crucial was the identification of a dithiophosphoric acid that masters three catalytic tasks, sequentially acting as a Brønsted acid for pyridine protonation, a single electron transfer (SET) reductant for pyridinium ion reduction, and a hydrogen atom abstractor for the activation of allylic C(sp3)–H bonds. The resulting pyridinyl and allylic radicals then couple with high regioselectivity
2023
Photochemical Organocatalytic Functionalization of Pyridines via Pyridinyl Radicals / Emilien Le Saux, Eleni Georgiou, Igor A. Dmitriev, Will C. Hartley, Paolo Melchiorre. - In: JOURNAL OF THE AMERICAN CHEMICAL SOCIETY. - ISSN 0002-7863. - STAMPA. - 145:1(2023), pp. 47-52. [10.1021/jacs.2c12466]
Emilien Le Saux, Eleni Georgiou, Igor A. Dmitriev, Will C. Hartley, Paolo Melchiorre
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11585/911765
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