125 Diels-Alder reaction
The Diels-Alder reaction, named after the German chemists who developed it, is a method
for producing simple ring compounds.
Figure 217 A diene adds to a dienophile in a simple Diels-Alder Reaction
Mechanism of a reaction between a diene and a dienophileIn the Diels-Alder reaction, a conjugated diene reacts with a dienophile. The dienophile is
named for its affinity to react with the diene.
Because dienes and dienophiles are often gases, this reaction usually takes place in a sealed
container at elevated pressure and temperature. The temperature required by this reaction
can be reduced by the presence of electron-witdrawing groups attached to the dienophile.
In some cases, such as furan and maleic anhydride, or cyclopentadiene and acrolein, the
reaction will take place at room temperature in an ethoxyethane solution.
The reaction shown above is highly unlikely due to the lack of substituents on the diene and
dienophile. The dienophile will usually have a carbonyl, nitro, or other electron-withdrawing
group attached. Any substituents attached to the diene or dienophile will end up in the
final product.
Figure 218 A substituated dienophile reacts to form a product with the same
substituents.