Cycloaddition reactions are an efficient strategy for constructing cyclic compounds that are important building blocks for other chemicals. In these processes, π-electrons from different unsaturated molecules, such as alkenes, alkynes, or dienes accommodate to form new cyclic structures in a single step. π-electrons are those responsible for the π-bonds in double and triple bonds. In a double bond, one of the C-C bonds is a π-bond, while in a triple bond, two of the C-C bonds are π-bonds.
