This book reported the literature survey of the chemistry of benzoxazin compounds including the methods of synthesis and their reactivity. In this context, we reported herein the behavior of 4-(4-oxo-4H-3,1-benzoxazin-2-yl)phenyl-4-methyl benzene sulfonate towards some active reagents as a facile and convenient route to some heterocyclic derivatives containing a quinazolone and/or sulfonate moieties. The methods of synthesis and the synthetic mechanisms of the aforementioned reactions were well presented and the structures of these compounds were assessed by analytical and spectral data. This book evaluated the synthesized compounds as antimicrobial agents against Gram positive bacteria (Bacillus Thuringenesis) and Gram negative bacteria (Klebseilla Pneumonia) strains. The results revealed that most of obtainable compounds exhibited high activities compared with Septazole as reference drug.