Synthesis, Structural Elucidation and Anti-Bacterial Evaluation of Fluorinated and Non-Fluorinated Schiff Bases of Quinazoline-4(3H)-One.

A relatively shorter procedure for the synthesis of 3-amino-2-methyl-3H-quinazolin-4-one (4) was developed. The subsequent condensation reaction of 4 with a variety of aldehydes afforded several novel Schiff bases (5a-r) counting its molecular hybridization with the indole, thiophene, and quinoline pharmacophoric units. Full structural elucidation of all Schiff bases was conducted with the help of 1H and 13C NMR coupled with two-dimensional (HMBC, HSQC and COSY) techniques, and provides a reference point for the structural characterization of all the future synthesized scaffolds with a similar core structure. Furthermore, the antibacterial screening of all Schiff bases was undertaken using four Gram-negative strains, Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumonia and Salmonella typhimurium, and two Gram positive-strains, Staphylococcus aureus, and methicillin-resistant Staphylococcus aureus (MRSA). In general, several compounds showed activity against MRSA. [ABSTRACT FROM AUTHOR]