Diels-Alder reaction

The reaction between a conjugated diene and a substituted alkene (commonly termed the dienophile) to form a substituted cyclohexene system is called the Diels-Alder Reaction. The reaction can proceed even if some of the atoms in the newly-formed ring are not carbon. Some of the Diels-Alder reactions are reversible; the decomposition reaction of the cyclic system is then called the Retro-Diels-Alder.

This reaction is part of a much larger group of reactions, namely the 2 + 4 cycloadditions. The numbers 2 and 4 refer to the number of nonhydrogen atoms in the alkene and the diene, which form the ring. The term cyloaddition means that a ring is formed.

Otto Paul Hermann Diels[?] and Kurt Alder[?] got the Nobel Prize 1950.