On the contrary , stable dienes are rather unreactive .
Undergo Diels -- Alder reactions only at elevated temperatures : for example , naphthalene can function as a diene , leading to adducts only with highly reactive dienophiles , such as N - phenyl - maleimide .
On the contrary , stable dienes are rather unreactive and undergo Diels -- Alder reactions only at elevated temperatures : for example , naphthalene can function as a diene , leading to adducts only with highly reactive dienophiles , such as N - phenyl - maleimide .