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

• Published in: Polycyclic aromatic compounds Vol. 42; no. 8; pp. 5183 - 5195
• Main Authors: Manhas, Neha, Singh, Parvesh, Koorbanally, Neil A.
• Format: Journal Article
• Language: English
• Published: Philadelphia Taylor & Francis 14.09.2022; Taylor & Francis Ltd
• Subjects: Aldehydes; Antibacterial; Antiinfectives and antibacterials; Drug resistance; E coli; Fluorination; Hybridization; Imines; Klebsiella; Methicillin; NMR; Nuclear magnetic resonance; Pseudomonas aeruginosa; Quinoline; Staphylococcus aureus; Strains (organisms); Structural analysis
• ISSN: 1040-6638; 1563-5333
• DOI: 10.1080/10406638.2021.1926293

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 1 H and 13 C 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.