Imidazole-aryl coupling reaction via C−H bond activation catalyzed by palladium supported on magnetic reduced graphene oxide in deep eutectic solvent

The palladium-catalyzed direct C-H arylation reactions of heteroarenes with aryl halides have become as the extremely powerful method for the synthesis of biaryl or aryl-heteroaryl products compared to the traditional cross coupling reactions.1 Major issue of Pd-catalyzed direct arylation in terms of green chemistry is related to the use of toxic and non-renewable solvents such as Dimethylformamide (DMF), Dimethylacetamide (DMA).2 Deep eutectic solvents (DESs), have become more attractive in recent years due to their interesting properties and benefits, such as low cost of components, easy to prepare, tunable physicochemical properties, negligible vapor pressure, non-toxicity, biorenewability and biodegradability.3Also, despite the promising progress in C-H arylation reactions, the vast majority of C-H bond arylation of heterocyclic systems was achieved with homogeneous catalytic systems as it produces metal and ligand contamination.4 herein, we report the first example of heterogeneous catalyst for C−H arylation reaction of imidazole with aryl bromide by using 2,6-diaminopyridine (DAP)-PdII complex immobilized on the magnetic reduced graphene oxide (MRGO@DAP-Pdll). We also explore the possibility to use of DES as green and sustainable reaction media (Figure 1).

کلیدواژه ها:

C-H arylation ، Imidazole ، Heterogeneous catalyst ، Magnetic reduced graphene oxide ، Palladium ، Deep eutectic solvent.