A facile and eco-friendly synthesis of imidazo[1,2-a]pyridines using nano-sized LaMnO3 perovskite-type oxide as an efficient catalyst under solvent-free conditions

LaMnO3 perovskite nanoparticles were prepared using a sal-gel method. The physical and chemical properties of the catalyst were determined using X-ray diffraction, transmission electron microscopy, scanning electron microscopy, Energy dispersive X-ray spectroscopy, BET method and Fourier transform infrared spectroscopy. The XRD results indicated that the LaMnO3 has a good crystalline phase at 600 degrees C. The BET surface area of the mesoporous perovskite materials (LaMnO3) was 475 m(2)/g and the average width of the pores was 8.7 nm. The experimental data revealed that the LaMnO3 particles were nano-sized. This perovskite-type oxide as a green and reusable catalyst showed excellent catalytic activity for the synthesis of imidazo[1,2-a]pyridines. LaMnO3 catalyst could be recovered and reused in five reaction cycles, giving a total TON = 2790 and TOF = 372. The products were prepared under solvent-free conditions without any additives. Principal features of this simple method include non-hazardous reaction conditions, low catalyst loading and excellent yields. (C) 2013 Elsevier B.V. All rights reserved.