Synthesis and antibacterial activities of some novel hybrid compounds based on 2-mercapto-3-arylquinazolin-4(3H)-one scaffold bearing specific coumarin

Two series of novel hybrid compounds, in which a variety of 2-mercapto-3-arylquinazolin-4(3H)-ones (3a-d)/6-bromo-2-mercapto-3-phenylquinazolin-4(3H)-one (9) act as fundamental moieties are incorporated in particular 3-(2-bromoacetyl)-2H-chromen-2-one (4) or 2-chloro-N-(2-oxo-2H-chromen-3-yl)acetamide (5) via alkylation of the thiol group in quinazolin-4(3H)-one ring, were synthesized. The key intermediates (3a-d) and (9) were prepared by the reaction of anthranilic acid (1)/2-amino-5-bromobenzoic acid (8) with carbon disulfide and appropriate aromatic amines in an alkaline medium. These compounds' structures were confirmed by comparing their physical characteristics and spectral data to the earlier ones. Ten novel products (6a-d, 7a-d, 10, 11) were synthesized and the structures were determined by their IR, H-1-NMR, C-13-NMR and HR-MS spectral data. Subsequently, their antimicrobial activities were estimated in vitro test against four bacterial strains including P. aeruginosa NRRL B-14781 and E. coli NRRL B-409 (Gram-negative), B. cereus ATCC 10876 and L. monocytogenes ATCC 13932 (Gram-positive), by agar well diffusion assay. The outcome showed that all hybrid compounds have potential inhibition of tested Gram-negative bacteria. Compound (6d) revealed remarkable antibacterial effects on P. aeruginosa and E. coli growth. Besides, compounds (6a), (7a), (7d) and (10) have also inhibitory effects on B. cereus strain at tested concentrations. The compounds mentioned above contain the 3-chlorophenyl/phenyl substituent at position 3 in the quinazoline ring.