Coupling reactions are chemical processes where two smaller molecules are joined together to form a larger, more complex molecule. These reactions often involve the formation of new carbon-carbon bonds and are essential in organic synthesis. Common examples include the Suzuki reaction and the Heck reaction, which utilize catalysts to facilitate the coupling of organic compounds. These reactions are widely used in the pharmaceutical and materials industries to create diverse compounds, including drugs and polymers. By enabling the efficient assembly of complex structures, coupling reactions play a crucial role in advancing chemical research and development.