Claisen-Schmidt condensation

Different phenacyl bromides were reacted with 2-amino pyridine to give 2-aryl imidazo[1,2-a] pyridines, which on subsequent reaction with Vilsmeier-Haack reagent gave 2-aryl imidazo[1,2-a] pyridine carbaldehydes (4a-4b). Claisen-Schmidt condensation of 4a and 4b with different substituted acetophenones afforded chalcones (5a-5f). The reaction of chalcones with phenyl hydrazine gave six new derivatives of pyrazolyl imidazo[1,2-a]pyridines (6a-6f ) in good yields. The synthesized compounds were characterised on the basis of physical and spectral data. The compounds were evaluated for anti-inflammatory and anti-bacterial activities. The compounds 6a, 6b, and 6c exhibited potent anti-inflammatory activity and results are comparable with standard drug, ibuprofen. None of the compounds showed any significant antimicrobial activity even at a concentration of 1000 µg/ml against Gram +ve and Gram –ve organisms.