The work of the book is devoted to a study of a series of organic reactions from readily available and less costly starting materials such as coumarins, pyrazoles, and chromones. These heterocyclic compounds were readily converted to polyketomethylene compounds by treatment with active methylene compounds such as triacetic acid lactone, dimedone, 3-methyl-1-phenyl-5-pyrazolone and nitrogenous bases such as hydrazine hydrate, phenyl-hydrazine, hydroxylamine respectively under different reaction conditions and the structures of all new compounds were identified on the basis of IR, NMR, and mass spectroscopy. Some of these synthesized compounds have been investigated for anti-inflammatory, analgesic, antipyretic and antibacterial activities. Most of the compounds have been found to possess significant activities and their effect was compared with the standard drugs.