Mesoporous mixed metal oxide nanocrystals: Efficient and recyclable heterogeneous catalysts for the synthesis of 1,2-disubstituted benzimidazoles and 2-substituted benzothiazoles

Present communication elicits the use of mesoporous mixed metal oxide nanocrystals of Al2O3-Fe2O3. Al2O3-V2O5 and Al2O3-CuO as heterogeneous catalysts for the preparation of series of medicinally significant 1,2-disubstituted benzimidazoles and 2-substituted benzothiazoles. These nanocrystalline catalysts exhibited remarkable catalytic activity with a high substrate to catalyst weight ratio (20:1) to achieve the synthetic targets in the range of yield 81-96%. The solvent-free microwave assisted synthesis of these compounds was an advantageous way which resulted in excellent yields in much lesser time (0.75-1.5 min) in comparison to conventional heating. The use of catalyst in eco-friendly green protocol and its reusability up to four cycles with similar catalytic response are the unique features of the heterogeneous catalysis. This protocol provided greater selectivity, cost-efficiency, clean reaction profiles, simple work-up procedure and high yields. (C) 2011 Elsevier B.V. All rights reserved.