Multicomponent reactions (MCRs) are chemical processes that involve three or more reactants combining to form a single product in a single step. These reactions are valuable in organic synthesis because they can create complex molecules efficiently, reducing the number of steps and materials needed. MCRs often lead to diverse product libraries, making them useful in drug discovery and materials science. One well-known example of an MCR is the Biginelli reaction, which combines aldehydes, ureas, and β-keto esters to produce dihydropyrimidinones. MCRs can also be categorized based on their mechanisms, such as one-pot reactions or cascade reactions, further enhancing their versatility in synthetic chemistry.