The reaction of aromatic amines with propylene carbonate catalyzed by anion-cation cooperativity in ionic liquids

Ionic liquid 1-butyl-3-methyl-imidazolium acetate ([bmim]OAc) effectively catalyzed the reaction of aromatic amines with propylene carbonate to 5-methyl-3-aryloxazolidin-2-one. The effects of reaction temperature, time, and catalyst amount were investigated in detail. Under the optimized conditions, the yield of 5-methyl-3-phenyl-oxazolidin-2-one was 99%. The effects of cations and anions in ionic liquids were also studied. The cations play important role for the reaction and the catalytic activity follows the order of 1-butyl-3-methyl-imidazolium ([bmim]) > 1, 2-dimethyl-3-butyl imidazolium ([bmmim]) > 1-butyl-pyridinium ([bpy]), which is consistent with the order of hydrogen bond donor ability. Simultaneously, the anions are also crucial to the reaction and the catalytic activity of imidazolium based ionic liquids follows the order OAc > Cl > Br > BPh ₄, which is consistent with the order of the hydrogen bond acceptor ability.