Microwave-promoted N-arylation of imidazole and amino acids in the presence of Cu2O and CuO in poly(ethylene glycol)

Resumo

Copper(I)-catalyzed N-arylation of imidazole with iodobenzene, its derivatives, and bromobenzene in poly(ethylene glycol) under microwave irradiation was studied. The influence of the following factors on the yield of arylation product was investigated: the nature of the source of copper and ligand, type of poly(ethylene glycol) (PEG) used, and substituents in iodoarene. An optimal catalytic system was selected: CuO/l-Hys/Cs₂CO₃/PEG-400, a possibility of recycling of copper-containing catalyst was demonstrated. N-Arylation of eight natural amino acids using catalysis with Cu₂O/Cs₂CO₃/PEG-400 and microwave irradiation was studied, the dependence of the reaction results on temperature, duration of the process, and the ratio of the starting reagents was found. The highest yields of the target products were reached in the case of leucine, valine, and phenylalanine.