The aim of the present work is to design and synthesize fused bicyclic or polycyclic ring systems containing isoxazole which incorporate heterocyclic moieties of biological value. The objective of this work was directed to annulate 5-aminoisoxazole derivatives as an important synthons which have binucleophilc function towards certain reagent. Furthermore, studying the biological activity of the prepared isoxazole derivatives as antitumor agents was achieved. Thus, in the light of the aforementioned importance of the 5-amino-3-methylisoxazole, the present work is planned to investigate the behavior of 5-amino-3-methylisoxazole (1) and its derivatives towards various reagents.