The efficient, facile and green synthesis of 4-bromo pyrazolone by using N-bromo saccharine as valuable green reagent encouraged us to prepare some new fused heterocycles as furopyrazole, pyranopyrazole, imidazopyrazole, pyrazolothiazole, pyrazol thiazolopyrimidine, pyrazolothiazine, oxathinopyrazole, pyrazolobenzooxazine, and pyrazoloquinoxaline. The synthesis was carried out by a basic condensation of bromo pyrazolone 2 and a suitable reagent in a one-pot reaction using chitosan as a green basic catalyst. The reactions were carried out by microwave irradiation technique as a green source of energy as well as the conventional heating. The antioxidant activity of the prepared compounds was studied using 1,1-phenyl-2-picrylhydrazyl (DPPH) assay and their antibacterial activity against Gram-positive, Gram-negative bacteria and antifungal activity was evaluated.