Copper supported on H+ modified manganese oxide octahedral molecular sieves (Cu/H OMS 2) as a heterogeneous biomimetic catalyst for the synthesis of imidazo[1,2 a] N heterocycles
Copper supported on acid modified manganese oxide octahedral molecular sieves (Cu/H OMS 2) was prepared and found to be a versatile catalyst for the oxidative synthesis of 3 aroylimidazopyridines with a broad substrate scope. Cu/H OMS 2 that was characterized by BET, XRD, XPS, FTIR, TEM, SEM, H2 TPR and O2 TPD techniques could also be used to synthesize 3 aroylimidazopyrimidines and applied in one pot, three component reactions of ketones, aldehydes and 2 aminopyridines. The catalytic system employs low loading Cu as the catalytic metal and support H OMS 2 as the electron transfer mediator (ETM) to sequentially lower the redox energy barrier, which generates a low energy pathway and enables the reaction to proceed in a biomimetic way. Moreover, Cu/H OMS 2 could be reutilized 4 times with a slight decrease in the catalytic activity.