Molecular docking studies and facile synthesis of most potent biologically active N-tert-butyl-4-(4-substituted phenyl)-2-((substituted-2-oxo-2H-chromen-4-yl)methylthio)-6-oxo-1,6-dihydropyrimidine-5-carboxamide hybrids: An approach for microwave-assisted syntheses and biological evaluation.