Light-mediated aerobic oxidation of C(sp³)–H bonds by a Ce(iv) hexachloride complex

Abstract

A photochemical C(sp3)–H oxygenation of arene and alkane substrates (including methane) catalyzed by [NEt4]2[CeIVCl6] under mild conditions (1 atm, 25 °C) is described.

Chloride Oxidation by One- or Two-Photon Excitation of N-Phenylphenothiazine

“…Chlorine atoms have long been known as a powerful tool for C–H activation yet historically have seen little use in practical applications due to the harsh reaction conditions necessary to generate Cl • . Over the last decade, a number of groundbreaking studies have demonstrated facile chloride oxidation using photoredox catalysts, which have enabled new approaches to functionalize inert C–H bonds. − Additionally, environmentally motivated applications rely on chloride oxidation as an important fundamental process for HCl splitting to store solar energy − or for electric gradient generation for sea water desalination. − However, the vast majority of these examples rely on noble metal photocatalysts to generate chlorine atoms because the one-electron reduction potential, (Cl • /– ), requires an incredibly potent photooxidant. − Indeed, chloride ions are so redox inert that they are frequently used as counterions for common photocatalysts such as ruthenium polypyridyl compounds. , Synthesizing ruthenium or iridium coordination compounds that are strong photooxidants requires skillful ligand engineering ,− and such catalysts often suffer from stability issues. − Moreover, photocatalysts based on noble metals are impractical at scale given the low natural abundance of these rare elements. Herein, we report a rare example of light-induced chloride oxidation catalyzed by an inexpensive, commercially available organic photocatalyst through unconventional one- and two-photon pathways.…”

Controlled monodefluorination and alkylation of C(sp3)–F bonds by lanthanide photocatalysts: importance of metal–ligand cooperativity

“…Photoexcitation to a more reducing excited state 3,75 follows, which leads to C–F cleavage and the generation of an ArCF 2 radical, as supported by experiments with a radical trapping substrate, Scheme 4. The nature of the resulting putative Ln–F species depends on the identity of the rare earth element.…”

“…C-F / Ln III (Ln = La, Sm, Yb) interactions have previously been hypothesized in the functionalization of C-F bonds mediated by lanthanide complexes. [37][38][39] Photoexcitation to a more reducing excited state 3,75 follows, which leads to C-F cleavage and the generation of an ArCF 2 radical, as supported by experiments with a radical trapping substrate, Scheme 4. The nature of the resulting putative Ln-F species depends on the identity of the rare earth element.…”

Photoelectrocatalytic organic synthesis: a versatile method for the green production of building-block chemicals

“…C–H oxygenation is an attractive strategy for synthesizing value-added oxygenated products (alcohols, aldehydes, and ketones) from cheap alkanes. 74,75 To date, a few PECs adopting this strategy have been successfully established. 76–79…”

“…C-H oxygenation is an attractive strategy for synthesizing value-added oxygenated products (alcohols, aldehydes, and ketones) from cheap alkanes. 74,75 To date, a few PECs adopting this strategy have been successfully established. [76][77][78][79] In 2017, Berlinguette and Sammis et al carried out C-H oxygenation at the a-position of the alkene and arene in a PEC taking BiVO 4 as the photoanode.…”