beta-Aroylacrylic acids are convenient polyelectrophilic reagents in the synthesis of heterocycles, also they represent an important class of compounds with interesting biological activities and pharmacologic indications including fungicidal, antitumor, antibacterial, anti-ulcer, cytoprotective properties and human cytomegalovirus protease inhibiting activity. Also they are used as starting materials for the preparation of a novel series of pyridazinones and thiazoles, where many studies have been focused on pyridazinones which are characterized to possess good analgesic and anti-inflammatory activities. This book describes the utility of beta-(4-acetamido-benzoyl) acrylic acid as a key starting material for the preparation of a novel series of pyridazinones, thiazoles, and other Heterocycles via interaction with nitrogen, sulfur and carbon nucleophiles under Michael addition conditions and studies the antimicrobial activities of some of these compounds.