Abstract
magnified image New tricyclic pyrimidinone derivatives were obtained from the corresponding thiazolopyrimidinone or hydrazino systems. The annelation of tricyclic hydrazino compound with 1,2,4‐triazole and tetrazole moieties gave novel tetracyclic condensed pyrimidinones. The investigation of the antimicrobial properties of tricyclic and tetracyclic pyrimidinones, by agar‐well diffusion assay, was carried out against six pathogenic bacteria (Bacillus cereus, Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, Klebsiella spp, and Salmonella typhyrium) and four pathogenic fungi (Aspergillus flavus, Aspergillus niger, Aspergillus fumigatus, and Trichderma horozianum). Most of the compounds tested exhibited some degree of antimicrobial activity against microorganisms. Among these compounds, 4‐benzylidenhydrazino‐8‐cyano‐7‐(furan‐2‐yl)thiazolo[3,2‐a:4,5‐d′]dipyrimidin‐9‐one (12) showed the most favorable antibacterial activity, while compound 17 showed the highest effect on fungi. Interestingly, tetrazole derivative 19 displayed a remarkable effect on fungi much more than the corresponding 3‐substituted triazole derivatives on the one hand, whereas the lowest effect on bacteria on the other. J. Heterocyclic Chem., (2010).