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.
Highlights
The C-N cross-coupling has been recognized as one of the most important transformations in organic chemistry because it can be conveniently used to synthesize a wide range of organics including many natural products and pharmaceuticals
The localized surface plasmon resonance (LSPR) effect is a collective oscillation of conduction electrons in metallic nanoparticles, which resonate with the electromagnetic field ofincident light in visible light range[13,14,15]
Graphene supported copper nanoparticles were prepared by reducing Cu2O/graphene composites[22]
Summary
The C-N cross-coupling has been recognized as one of the most important transformations in organic chemistry because it can be conveniently used to synthesize a wide range of organics including many natural products and pharmaceuticals. Simple copper salts were found to promote the coupling of arylboronic acids with imidazoles in protonic solvents[10] These homogeneous processes using soluble Cu complexes as the catalysts exhibit high catalytic efficiency, the difficulty in separating the catalysts from the reaction mixtures is still a serious problem. The conduction electrons of the nanoparticles of gold (Au), silver (Ag) and copper (Cu) can gain visible light energy through the LSPR effect to produce energetic “hot” electrons, which facilitate the reaction process and improve the yield of chemical synthesis under mild conditions[16]. We report that Cu/graphene catalyst exhibits excellent photocatalytic activity for N-arylation of imidazoles and arylboronic acids at room temperature under visible light irradiation
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
