147732-31-8Relevant articles and documents
Photocatalytic (Het)arylation of C(sp3)-H Bonds with Carbon Nitride
Das, Saikat,Murugesan, Kathiravan,Villegas Rodríguez, Gonzalo J.,Kaur, Jaspreet,Barham, Joshua P.,Savateev, Aleksandr,Antonietti, Markus,K?nig, Burkhard
, p. 1593 - 1603 (2021/02/09)
Graphitic carbon nitride materials have attracted significant interest in recent years and found applications in diverse light-to-energy conversions such as artificial photosynthesis, CO2 reduction, or degradation of organic pollutants. However, their utilization in synthetic photocatalysis, especially in the direct functionalization of C(sp3)-H bonds, remains underexplored. Herein, we report mesoporous graphitic carbon nitride (mpg-CN) as a heterogeneous organic semiconductor photocatalyst for direct arylation of C(sp3)-H bonds in combination with nickel catalysis. Our protocol has a broad synthetic scope (>70 examples including late-stage functionalization of drugs and agrochemicals), is operationally simple, and shows high chemo- and regioselectivities. Facile separation and recycling of the mpg-CN catalyst in combination with its low preparation cost, innate photochemical stability, and low toxicity are beneficial features overcoming typical shortcomings of homogeneous photocatalysis. Detailed mechanistic investigations and kinetic studies indicate that an unprecedented energy-transfer process (EnT) from the organic semiconductor to the nickel complex is operating.
Sp3 C-H Arylation and Alkylation Enabled by the Synergy of Triplet Excited Ketones and Nickel Catalysts
Shen, Yangyang,Gu, Yiting,Martin, Ruben
supporting information, p. 12200 - 12209 (2018/09/27)
Triplet ketone sensitizers are of central importance within the realm of photochemical transformations. Although the radical-type character of triplet excited states of diaryl ketones suggests the viability for triggering hydrogen-atom transfer (HAT) and single-electron transfer (SET) processes, among others, their use as multifaceted catalysts in C-C bond-formation via sp3 C-H functionalization of alkane feedstocks still remains rather unexplored. Herein, we unlock a modular photochemical platform for forging C(sp3)-C(sp2) and C(sp3)-C(sp3) linkages from abundant alkane sp3 C-H bonds as functional handles using the synergy between nickel catalysts and simple, cheap and modular diaryl ketones. This method is distinguished by its wide scope that is obtained from cheap catalysts and starting precursors, thus complementing existing inner-sphere C-H functionalization protocols or recent photoredox scenarios based on iridium polypyridyl complexes. Additionally, such a platform provides a new strategy for streamlining the synthesis of complex molecules with high levels of predictable site-selectivity and preparative utility. Mechanistic experiments suggest that sp3 C-H abstraction occurs via HAT from the ketone triplet excited state. We believe this study will contribute to a more systematic utilization of triplet excited ketones as catalysts in metallaphotoredox scenarios.