The
Diels–Alder reaction is an
organic chemical reaction (specifically, a [4+2]
cycloaddition) between a conjugated
diene and a substituted
alkene, commonly termed the dienophile, to form a substituted
cyclohexene system. It was first described by
Otto Paul Hermann Diels and
Kurt Alder in 1928, for which work they were awarded the
Nobel Prize in Chemistry in 1950. The Diels–Alder reaction is particularly useful in synthetic organic chemistry as a reliable method for forming 6-membered systems with good control over regio- and stereochemical properties. The underlying concept has also been applied to other p-systems, such as
carbonyls and
imines, to furnish the corresponding heterocycles, known as the
hetero-Diels–Alder reaction. Diels–Alder reactions can be reversible under certain conditions; the reverse reaction is known as the
retro-Diels–Alder reaction.