The 3-(5-(5-substituted furan-2-yl)-3-thioxo-2,3,7,8-tetrahydro-[1,2,4] triazolo [4,3-a]pyrimidin-7-yl)-2H-chromen-2-one (2a-c), 5-(5- substituted furan-2-yl)-7-(2-oxo-2H-chromen-3-yl)-7,8-dihydro-[1,2,4] triazolo [4,3-a] pyrimidin-3(2H)-one (3a-c) and 3-(7-(5- substituted furan-2-yl)-4,5-dihydro tetrazole [1,5-a] pyrimidin-5-yl)-2H-chromen-2-one (4a-c) were synthesised by reaction of 3-(6-(5-substitutd furan-2-yl)-2-hydrazinyl-1,4-dihydropyrimidin-4-yl)-2H-chromen-2-one (1a-c) with CS2/Pyridine, ClCOOEt / Pyrimidine and NaNO2/HCl respectiverly. All these synthesised derivatives were characterized by elemental and spectral analysis. All the derivatives were also monitored for antimicrobial activity.