Ir-photocatalyzed radical cascade cyclization for the synthesis of indoline derivatives with a C3 quaternary center via gem‑difluoroalkylation/C(sp2) − H functionalization

Enhancing Photocatalytic Redox Activity of Polymeric Carbon Nitride for Valuable Fluorinated Heterocycles through Fast-Track Electron Highways

“…Therefore, it is speculated that a more oriented configuration, delocalized π-conjugation, and the incorporation of potassium ions into the CN structure are beneficial for fast interfacial electron delivery. Our results regarding the profound role of K + in the structure of heptazine-based polymeric carbon nitride to mediate electron transfer from the electronically excited semiconductor to BrCF 2 COOEt correlates well with the results of screening of bases (Table S4) and the results observed in a similar reaction using Ir-polypyrine complex as a homogeneous outersphere SET photocatalyst . Therein, higher yields of indoline were obtained using inorganic bases, such as KOH and K 2 CO 3 , while organic bases, such as NEt 3 and (iPr) 2 NEt, showed significantly lower yields under otherwise identical conditions.…”

“…Our results regarding the profound role of K + in the structure of heptazine-based polymeric carbon nitride to mediate electron transfer from the electronically excited semiconductor to BrCF 2 COOEt correlates well with the results of screening of bases (Table S4) and the results observed in a similar reaction using Ir-polypyrine complex as a homogeneous outersphere SET photocatalyst. 38 Therein, higher yields of indoline were obtained using inorganic bases, such as KOH and K 2 CO 3 , while organic bases, such as NEt 3 and (iPr) 2 NEt, showed significantly lower yields under otherwise identical conditions. As such, our findings not only enrich the field of carbon nitride organic photocatalysis but also clarify the profound role of K + in the earlier publications.…”

“…Fluorinated compounds have garnered significant attention due to their high electronegativity, compact atomic radius, and strong C–F bonds. − Heterocycles, such as indoline motifs, are core structures present in a wide range of natural products, pharmaceuticals, and biologically active compounds. − Recently, the importance of fluorinated indolines has increased due to their potential use in drug discovery and development . However, the synthesis of fluorinated indolines remains challenging, requiring transition-metal catalysts and potent oxidants (Scheme a). − Moreover, homogeneous catalysts often are nonrecyclable, and their usage is linked to reduced selectivity due to dehalogenation reactions that occur in substrates containing halogen substituents . Artificial photocatalytic systems converting low-cost feedstock into value-added chemicals are considered promising ways to address rising environmental issues and energy crises.…”