A transition metal-free cascade reaction using heterogeneous tin(IV)oxide catalyzed and iodine promoted synthesis of 3-aroylimidazo[1,2-a]pyridines

• Published in: Tetrahedron letters 2020-08, Vol.61 (34), p.152250, Article 152250
• Main Authors: Jadhav, Nirajkumar H., Sakate, Sachin S., Shinde, Dnyaneshwar R., Chaskar, Manohar G., Pawar, Ramdas A.
• Format: Article
• Language: English
• Subjects: 3-Aroylimidazo[1,2-a]pyridines; Acidity; Cascade reaction; Heterogeneous catalyst; SnO2/I2
• ISSN: 0040-4039; 1873-3581
• DOI: 10.1016/j.tetlet.2020.152250

[Display omitted] •The SnO2/I2 system investigated in the synthesis of 3-aroylimidazo[1,2-a]pyridines.•The Py-FTIR of the SnO2 shows both the Lewis and Brønsted types of acidic sites.•One-pot three-component synthesis of 3-aroylimidazo[1,2-a]pyridines.•The SnO2 NPs recycled successfully and showed high chemical stability. The cascade synthesis of 3-aroylimidazo[1,2-a]pyridines using chalcones and 2-aminopyridine was achieved over the SnO2/I2 catalytic system in toluene at ambient air atmosphere. The catalyst shows high activity towards the broad substrate scope of the various aromatic and heterocyclic chalcones with 2-aminopyridine, 4-methyl 2-aminopyridine, and 5-methyl 2-aminopyridine in good yields during the synthesis of 3-aroylimidazo[1,2-a]pyridines. The methodology was further extended for the one-pot three-component synthesis of 3-aroylimidazo[1,2-a]pyridines using acetophenone, benzaldehyde, and 2-aminopyridine derivatives. The present protocol describes the easy purification methodology in the synthesis of 3-aroylimidazo[1,2-a]pyridines.