The explosive growth of heterocyclic chemistry is emphasized by the large number of research publications, monographs, and reviews. The heterocyclic organic compounds are extensively disseminated in natural and synthetic medicinal chemistry and are vital for human life. Looking at the previous studies on quinazolinones derivatives, only limited information'sare available on their mass spectral along with the preparation of novel quinazolin-4-(3H)-one derivatives. The synthesis of novel heterocyclic derivatives has attracted considerable attention. Objective: Objective of this study, was to synthesize novel cyclic compound 2-methyl 7-Chloro-1, 3-benzooxazine-4-one (1) which then produced 3-Amino-2-Methyl 7-Chloro quinazolin-4(3H)-ones (2) through the reaction with hydrazine hydrate and novel 2-Methyl-6, 7-dimethoxy-quinazolin-4-one via the reaction between 2-Methyl-6, 7- dimethoxy-benzo-1,3-oxazin-4-one and hydrazine hydrate and study their electron impact ( EI ) mass spectral fragmentation.