Coumarin Derivatives: Microwave Synthesis and Biological Properties—A Review

Many molecules called coumarins with very varied biological activities and widely used in the food, pharmaceutical, cosmetic, and medical industries. Their structure has a significant impact on their biological activity and their possible applications. Advanced synthesis frequently leads to an increase in the production of various chemical wastes. The amount of hazardous organic substances used and produced is reduced by the application of environmentally friendly synthesis techniques. Numerous techniques are employed in green chemistry, including the use of ionic liquids and deep eutectic solvents, solvent-free synthesis, mechanical synthesis, multicomponent reactions, ultrasound, and microwaves. These green synthesis techniques have been successfully applied to all common condensation reactions for the synthesis of coumarin, including the Perkin, Knoevenagel, Pechmann, Kostanecki-Robinson, and Reformansky reactions. These methods not only reduce the use and production of toxic chemicals, but also improve the yield, purity, and energy consumption of the product. This review summarizes the methods of microwave synthesis of coumarin derivatives, as well as their biological activities.