Visible-light-driven Photocatalytic N-arylation of Imidazole Derivatives and Arylboronic Acids on Cu/graphene catalyst

Abstract

N-aryl imidazoles play an important role as structural and functional units in many natural products and biologically active compounds. Herein, we report a photocatalytic route for the C-N cross-coupling reactions over a Cu/graphene catalyst, which can effectively catalyze N-arylation of imidazole and phenylboronic acid, and achieve a turnover frequency of 25.4 h−1 at 25 oC and the irradiation of visible light. The enhanced catalytic activity of the Cu/graphene under the light irradiation results from the localized surface plasmon resonance of copper nanoparticles. The Cu/graphene photocatalyst has a general applicability for photocatalytic C-N, C-O and C-S cross-coupling of arylboronic acids with imidazoles, phenols and thiophenols. This study provides a green photocatalytic route for the production of N-aryl imidazoles.

Recent Progress in Plasmonic Hybrid Photocatalysis for CO2 Photoreduction and C–C Coupling Reactions

“…The electron-rich sites can easily adsorb imidazole molecules and inject into the molecules, facilitating the cleavage of N-H bonds, while positively charged sites can assist to cleave C-B bonds in phenylboronic acid molecules, and, as a result, C-N bonds are formed (Figure 16a). Furthermore, graphene can also absorb light, generating a strong photocurrent, and the work function of graphene, which is lower than that of Cu, causes hot electrons to transfer to Cu from graphene easily, which can result in the collection of energetic electrons at the Cu sites to accelerate the reaction [147]. Bhalla et al used supramolecular ensembles as reactors and stabilizers of CuNPs, which is similar to supramolecular ensemble-based Ag@Cu 2 O core@shell NPs [148].…”

“…These reports are not about the named C-C cross-coupling reactions, but they are meaningful in that they make good use of the plasmonic properties of CuNPs as a photocatalyst. In order to stabilize CuNPs, Cui et al introduced graphene to Cu because of the possible change of the electronic structure of Cu by the carbon vacancies or dangling bond in graphene [146,147]. Due to the LSPR effect of CuNPs, the electron density in Cu is polarized, causing charge heterogeneity at the surface of CuNPs with both relatively electronrich sites and positively charged sites.…”

Localized surface plasmon resonance assisted photoredox catalysis using newly fabricated copper-nanorods: a decarboxylative approach towards carbon–hydrogen bond formation under visible light

“…24 In the latter case, excited energetic electrons at the surface of the Cu nanoparticles accelerate the breaking of the N–O bond of nitro compounds, 24 and the [3+2]-cycloaddition reaction towards triazoles. 25 Moreover, Cu nanoparticles dispersed over graphene have also been explored for the photocatalytic C–O, C–N, and C–S cross-coupling of arylboronic acids with imidazoles, phenols and thiophenols. 25,26 To date, ‘C–C’ bond cleavage has only been observed by using hot charge carriers of Au nanoparticles.…”

“…25 Moreover, Cu nanoparticles dispersed over graphene have also been explored for the photocatalytic C–O, C–N, and C–S cross-coupling of arylboronic acids with imidazoles, phenols and thiophenols. 25,26 To date, ‘C–C’ bond cleavage has only been observed by using hot charge carriers of Au nanoparticles. 27…”