Synthesis of New Schiff Base of 1,3-Oxazine and 1,3-Thiazine Derivatives Derived from 4-Phenyl Substituted Chalcones and Evaluation of their Antibacterial Activity

Abstract

Oxazine and thiazine heterocycles have distinctive interests due to their important class of natural and non-natural products and exhibit high biological activities in the pharmaceutical and biological fields. This work was planned to synthesize Schiff base of 1,3-oxazine and 1,3-thiazine derivative from 4-phenyl substituted chalcones. The structures of the newly synthesized targeted compounds were established from UV, IR, 1H NMR, 13C NMR and DFT calculations. The molecular properties HOMO-LUMO energy, energy gap, softness and harness were calculated using DFT/B3LYP/6-311G (d,p) basis set. in vitro Antibacterial activities of Schiff bases of 1,3-oxazines and 1,3-thiazines derivatives were investigated against Gram-positive (Staphylococcus aureus) and Gram-negative bacteria (Escherichia coli) and compared with each other. It was found that thiazine derivatives showed higher activity.