Microwave assisted synthesis of chalcones under solvent-free conditions resulted in a "green-chemistry" procedure for the preparation of 2-pyrazolines and isoxazoline derivatives in very good yields. Acetone was reacted with appropriately substituted benzaldehydes in the presence of basic alumina to furnish substituted chalcones (1, 2 and 3). These chalcones undergo facile and clean cyclization with phenyl hydrazine, 2,4-dinitrophenylhydrazine, semicarbazide and thiosemicarbazide to afford

more »

... ituted 3,5-arylated-2-pyrazoline derivatives (1a-1d, 2a-2d and 3a-3d). Reaction of these chalcones with hydroxylamine hydrochloride yielded 3, 5-arylated isoxazoline derivatives (1e, 2e and 3e). The structures of synthesized compounds have been confirmed by suitable spectroscopic techniques such as IR and 1 H NMR and analytical data. All the compounds were screened for their antibacterial activity against Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa and for antifungal activity against Candida albicans and Aspergillus fumigatus. The compounds exhibited moderate to excellent antibacterial and antifungal activities. The results obtained indicate that unlike classical heating, microwave irradiation results in higher yields in shorter reaction times and cleaner reactions in eco-friendly manner.