Design, synthesis and structural studies of oxathiepine, benzo[b][1, 4]thiazine and quinolin-4-ol derivative based on 3-bromo-4-hydroxy-7-methoxyquinolin-2-one

4-Hydroxy-7-methoxyquinolin-2-one (1) and its derivative 3-bromo-4-hydroxy-7-methoxyquinolin-2-one (2) serve as valuable intermediates for the synthesis of advanced hetero-compounds. The reactivity of compound (2) has been verified through multiple substitution reactions. Their reactions with 2-mercaptoacetic acid, 3-mercaptopropanoic acid, or 2-aminobenzoic acid resulted in the corresponding hetero-compounds with high yields. The synthesized compounds underwent thorough examination via elemental and spectral analyses. Additionally, DFT calculations confirmed their structures in accordance with spectral investigations. Furthermore, the study delved into the global chemical reactivity parameters.