Quinazolin-4-one-3-yl-propan-2-one (2) was prepared by N-alkylation of Quinazolin-4(3H)one 1. The treatment of compound 2 with hydrazine hydrate yielded hydrazine derivative (3), which on condensation with variously substituted aryl aldehydes gave the corresponding hydrazones (4). Compound 3 on reaction with phenyl isocyanate and phenyl isothiocyanate transformed into the corresponding carbamates and thiocarbamates (5) respectively. Compound 3 also gave a tricyclic compound (6) when refluxed in presence of ammonium acetate and acetic acid, while hydrazone derivative (7) when treated with dehydroacetic acid.