The goal of this endeavor is to create novel heterocyclic compounds with strong biological activity predictions. Target compounds are expected to exhibit diverse biological activities due to their assortment of heterocyclic rings, which include coumarin, pyrimidine, imidazole, and thiazole moieties. Through the reaction of a variety of coumarin chalcones 1a - g with benzoimidazo-2-yl guanidine 2a and / or benzothiazo-2-yl guanidine 2b in pyridine under reflux conditions, a novel series of pyrimidinyl chromenone derivatives 3 – 14 were produced in high yields.The products' NMR, IR, and elemental analytical data were used to determine their molecular structures. A few novel products' antimicrobial properties were assessed. Compounds 9, 12, and 13 demonstrated the strongest antimicrobial activity against Candida albicans, while compound 9 had the greatest effect against Escherichia coli. Compounds 10 and 14 also demonstrated strong activity against Stphylococcus aureus, and compounds 3, 6, and 9 were the most effective against Pseudomonas aeruginosa.