Microwaves in organic synthesis: Facile synthesis of biologically active pyridazinone and iminopyridazine derivatives

Condensation of Wittig reagents 1a,b with arylhydrazones 2a,b by conventional and by microwave heating techniques furnished the corresponding pyridazines 3a-e. The arylhydrazones 7a,b were allowed to react with la,b under the same conditions to produce the pyridazinones 10a,b and iminopyridazines 11a,b respectively. On the other hand, the arylhydrazones 12a-c reacted with la to afford the pyridazinones 13a-c. Treatment of 3b with dimethylformamide dimethyl acetal (DMFDMA) produced the adduct 15. The utility of microwave heating technique led to the reduction of the reaction times to few minutes and to the improvement of the yields of the products. The in vitro biological activity of some newly prepared compounds against four types of fungi was studied.