Use pyrazolo[1,5-a]pyrimidine 4 as a precursor for synthesis of new heterocyclic compounds, where condensation with aromatic aldehydes gives arylidene derivatives 8a-c. Furthermore, when compound 4 is combined with aromatic diazonium chlorides 9a-c, it forms pyrazolo[3,4-d] pyridazines 11a-c. Additionally, reacting The unisolated potassium salt 13 with phenacyl bromide derivatives 14a,b or chloroacetonitrile at room temperature, thieno[3'',4'':5',6']pyrido[4',3':3,4]pyrazolo[1,5-a]pyrimidines 17a,b or 22 are obtained. Finally, compound 4 reacts with DMFDMA to produce enamine 23. The zone of inhibition measurement was used to gauge the synthetic compounds' in vitro antibacterial activity. The outcomes showed encouraging antibacterial efficacy against the harmful bacterial strains that were examined.