5-(2-Aminothiazol-4-yl)-8-hydroxyquinoline2has been synthesized by treating thiourea with 5-chloroacetyl-8-hydroxyquinoline1. The amine 2was treated with aromatic aldehydes to furnish schiff bases6a-c which on treatment with phenyl isothiocyanate gave the corresponding thiazolo-s-triazines7a-c. Reaction of 2with phenyl isothiocyanate gave the corresponding aminocarbothiamide derivative8which on reaction with malonic acid in acetyl chloride afforded thiobarbituric acid derivative9. Coupling of 9with diazonium salt gave the phenyl hydrazono derivative10. However, reaction of2with carbon disulphide and methyl iodide afforded dithiocarbamidate12which on treatment with ethylenediamine,o-aminophenol and/or phenylenediamine gave the aminoazolo derivatives13-15, respectively. Other substituted fused thiazolopyrimidines 16-20have been also prepared by the reaction of2with some selected dicarbonyl reagents. The characterisation of synthesized compounds has been done on the basis of elemental analysis, IR, 1H-NMR and mass spectral data. All the newly synthesized compounds have been screened for their antimicrobial activities.