Multicomponent couplings (MCCs), also called multicomponent reactions (MCRs), are special types of synthetic organic reactions in which three or more starting materials react to generate a single product. The product forms either sequentially in a tandem or domino fashion, or all at once. All or most of the atoms of those starting materials are incorporated into the newly formed product. MCCs are highly convergent, as a new molecule is formed from several starting molecules in one operation. One-component and two-component reactions are divergent, and complex molecules have to be synthesized by many sequential reaction steps, each involving one or two components.