Triethanolamine was found to be an efficient catalyst for the synthesis of new 1H-pyrazolo[1,2-a] pyridazine-5,8-diones by a one-pot reaction of maleic hydrazide, with aromatic aldehydes and malononitrile in H 2 O under ultrasonic irradiation. The advantages of this method are the use of an inexpensive and readily available catalyst, easy workup, improved yields, and the use of H 2 O as a green solvent. To assess their antibacterial activity, all the synthesized compounds were dissolved in DMSO and subjected to biological evaluation using the disc diffusion method against 3 Gram positive and 3 Gram negative bacteria.
Triethanolamine as an Inexpensive and Efficient Catalyst for the Green Synthesis of Novel 1H-Pyrazolo[1,2-a]pyridazine-5,8-diones under Ultrasound Irradiation in Water and Their Antibacterial Activity. -The reaction works well in the case of 2-mono-, 3-mono-and di-substituted benzaldehydes (II) but fails with 4-substituted benzaldehydes (V) forming intermediate Knoevenagel adducta (VI) only instead. A conventional heating method gives lower yields in all cases. Compounds (IVb)-(IVh) are tested against 6 bacterial species (Bacillus cereus, Bacillus thuringiensis, Staphylococcus aureus, Escherichia coli, Serratia marcescens and Shigella boydii). All compounds display significant activities against B. cereus and B. thuringiensis. -(KHORAAMABADI-ZAD*, A.; AZADMANESH, M.; KARAMIAN, R.; ASADBEGY, M.; AKBARI, M.; RSC Adv. 4 (2014) 88, 47721-47725, http://dx.doi.org/10.1039/C4RA07096H ; Fac. Chem., Bu-Ali Sina Univ., Hamedan 65178, Iran; Eng.) -M. Tismer
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